Investigating foliar application of bulk and nanoparticles titanium dioxide on fennel productivity to mitigate the negative effects of saline irrigation water

BACKGROUND

Fennel essential oils are fragrance compounds used in food and pharmaceutical sectors. One of the major impediments to expansion of fennel farming in Egypt's reclamation areas is saline water. Titanium dioxide (TiO2) or TiO2 nano particles (TiO2NP) can be utilized to boost the yield of aromatic plants cultivated under saline irrigation water. Saline water, particularly which contains sodium chloride can harm fennel plant; consequently, it was predicted that fennel production would fail in Egypt's reclaimed area, where the primary source of irrigation is groundwater consisting sodium chloride. This study sought to help fennel respond to sodium chloride by applying Ti forms to their leaves in order to reduce the detrimental effects of sodium chloride on them for expanding their production in the newly reclamation areas as a natural source of essential oil. Ti forms were applied as foliar application at 0, 0.1, 0.2 TiO2, 0.1 TiO2NP, and 0.2 TiO2NP, mM under irrigation with fresh water (0.4 dS m-1), or saline water (51.3 mM or 4.7 dS m-1).

RESULTS

Plants exposed to 0.1 mM TiO2NP under fresh water resulted in the maximum values of morphological characters, estragole, oxygenated monoterpenes and photosynthetic pigments; while those subjected to 0.1 mM TiO2NP under saline water gave the greatest values of essential oil, proline, antioxidant enzymes and phenols. The greatest amounts of soluble sugars were recorded with 0.2 mM TiO2NP irrigated with saline water. Plants subjected to 0 mM TiO2 under saline water produced the greatest values of flavonoids, hydrogen peroxide and malondialdehyde.

CONCLUSION

To mitigate the negative effects of salty irrigation water on fennel plant production, TiO2NP application is suggested as a potential strategy.

Determination of metals in water samples within the irrigation area in Telo District, Kaffa Zone, South Western Ethiopia

Water contamination due to the accumulation of metal is not only an environmental problem, but it is also a global issue. The river flows alongside the town in its downward direction, where runoff from the uplands and municipal trash discharge during floods may contribute to the contamination of the river. Despite the fact that this river is the area's primary source of water, the water near the effluent release point is extremely corrosive. The nearby settlements depend on this untreated river water for drinking, irrigation, and other domestic uses since they have no access to a municipal water supply. The aim of the present study was to evaluate the degree of metal contamination in the Obasho river water samples collected from irrigation water sites in the Gurguba region. Three samples were collected from each of four irrigation water sites, which were 1.5 km away from each other. A total of 12 water samples were collected by following the standard water sample collection protocol. 100 mL of the irrigation water sample was digested in aquaragia, and AAS was used to determine the concentration of metals in the water samples. The concentration ranges of some metals were: Ca (1.84387-2.810824 mg/L), and its maximum limit in FAO is 20.0 mg/L; Mg (3.176942-4.543031 mg/L), and its maximum limit in FAO is 5.0 mg/L; Cr (0.039227-0.047872 mg/L), and its WHO/FAO permissible level is 0.1 mg/L; Co (0.036703-0.057218 mg/L), and its permissibility level is 0.05 mg/L WHO/FAO, Cd (0.006198-0.02856 mg/L), whose maximum limit in FAO is 0.01 mg/L, and Pb (0.065138-0.091131 mg/L) WHO/FAO permissible level is 5.0 mg/L. The mean concentrations of metals (Ca, Mg, Co, Cd, Pb, and Cr) in all study sites were below the regulatory limits except for Co and Cd; no water contamination was caused by these metals at the study sites. However, the mean concentration levels of Co in all study sites were above regulatory limits. The mean concentration of Co at Konit Kochito and Cd at Geremew Mamo, Konit Kochito, and Gereno Gebito is also greater than regulatory limits. A pair-wise comparison of some metals in study sites was carried out, thus the mean concentration of the irrigation water sites sample was significantly different from some metal concentration (p < 0.05) at the 95% confidence level. Generally, there was no cumulative effect of water contamination caused by Ca, Mg, Co, Cd, Pb, and Cr in Gurguba Kebele study sites, and it may not appear to pose very serious environmental problems at this moment. Thus, determining the metal content in irrigation water samples is crucial for ensuring the safety and sustainability of agricultural practices. It raises awareness regarding the contents of heavy metal contamination and sets limits for acceptable metal concentrations. It has also vital role in maintaining soil health.

Antibiotic susceptibility and genomic analysis of ciprofloxacin-resistant and ESBLs-producing Escherichia coli in vegetables and their irrigation water and growing soil

The rise of antibiotic resistance in Escherichia coli has become a major global public health concern. While there is extensive research on antibiotic-resistant E. coli from human and animal sources, studies on vegetables and their environments are limited. This study investigated the prevalence and characteristics of ciprofloxacin-resistant (CIPR) E. coli in 13 types of edible raw vegetables, along with their irrigation water and soil in Shaanxi, China. Of 349 samples collected (157 vegetables, 59 water, and 133 soil), a total of 48 positive samples were detected, with one CIPRE. coli strain isolated from each sample being selected for further analyses. A striking observation was its high prevalence in irrigation water at 44.1 %, markedly exceeding that in vegetables (12.0 %) and soil (4.5 %). The susceptibility of Forty-eight CIPRE. coli isolates was evaluated using the disc diffusion method for 18 different antibiotics, all these isolates were not only resistant to the tested fluoroquinolones antibiotics (levofloxacin, nalidixic acid), but also displayed a multi-drug resistance (MDR) pattern. Twenty-eight (58.3 %) of 48 CIPRE. coli isolates exhibited extended spectrum β-lactamases (ESBLs) (CIPR-ESBLs) producing phenotype. Subsequently, whole-genome sequencing was performed on these 28 isolates. We identified 12 serotypes and STs each, with O101: H9 (35.7 %, 10/28) and ST10 (21.4 %, 6/28) being the most common. Further classification placed these isolates into five phylogenetic groups: A (57.1 %, 16/28), B1 (32.1 %, 9/28), D (3.6 %, 1/28), B2 (3.6 %,1/28), and F (3.6 %,1/28). Notelly, Identical ST types, serotypes and phylogroups were found in certain CIPR-ESBLs-producing E. coli from both vegetables and adjacent irrigation water. Genomic analysis of the 28 CIPR-ESBLs-producing E. coli isolates unveiled 73 resistance genes, associated with 13 amino acid mutations in resistance-determining regions (QRDRs) and resistance to 12 types of antibiotics. Each isolate was confirmed to carry both ESBLs and fluoroquinolone resistance genes, with the Ser83Ala mutation in GyrA (96.4 %, 27/28) being the most prevalent. A detailed analysis of Mobile Genetic Elements (MGEs) revealed that IncFIB and IncFII plasmid subtypes were most prevalent in 60.7 % and 67.9 % of isolates, respectively, with 75 % containing over 10 insertion sequences (IS) each. Furthermore, we observed that certain ESBL and PMQR genes were located on plasmids or in proximity to insertion sequences. In conclusion, our research highlights the widespread presence of CIPRE. coli in irrigation water and thoroughly examines the genetic characteristics of CIPR-ESBLs-producing E. coli strains, underlining the need for ongoing monitoring and management to reduce multidrug-resistant bacteria in vegetables and their environment.

Health risk assessment of heavy metals in saffron (Crocus sativus L.) cultivated in domestic wastewater and lake water irrigated soils

Irrigation of crops with domestic wastewater (DW) is a common practice in developing countries like India. However, domestic wastewater irrigation poses a risk of migration of toxic heavy metals to edible parts of crops, which requires serious measures to prevent their uptake. In this study, the effect of DW irrigation in comparison with Sarbal Lake water (SLW) and borewell water (BW) on soil characteristics and cultivated saffron (Crocus sativus L.) was investigated. For this purpose, samples of water, soil, and saffron (corm, petal, and stigma) were collected from the suburban area of Pampore, Srinagar district, Jammu and Kashmir, India. The results showed that DW irrigation had the maximum significant (p < 0.05) influence on the physico-chemical and nutrient characteristics of the soil, followed by SLW and BW irrigation, respectively. The growth and yield parameters of saffron were also significantly (p < 0.05) increased in the case of DW irrigation as compared to SLW and BW. The quality ranking of the cultivated saffron was found to be in accordance with the ISO standard (III: BW and II: DW and SLW). On the other hand, DW irrigation showed a significant increase in heavy metal contents (mg/kg) of saffron plant parts such as As (0.21-0.40), Cd (0.04-0.09), Cr (0.16-0.41), Cu (7.31-14. 75), Fe (142.38-303.15), Pb (0.18-0.31), Mn (15.26-22.81), Hg (0.18-0.25), Ni (0.74-1.18), Se (0.13-0.22), and Zn (3.44-4.59), followed by SLW and BW. However, the levels of heavy metals did not exceed the FAO/WHO safe limits. Bioaccumulation factor (BAF), dietary intake modeling (DIM<0.006496), health risk assessment (HRI<0.028571), and target hazard quotient (THQ<1) analyses showed no potential health hazard associated with the consumption of saffron irrigated with DW and SLW. Therefore, the results of this study provide valuable insights into the optimization of irrigation sources for saffron cultivation.

Genomic characterization of a WHO critical priority isolate Enterobacter kobei ST2070 harboring OXA-10, KPC-2, and CTX-M-12 recovered from a water irrigation channel in Ecuador

The discharge of untreated or partially treated wastewater can have detrimental impacts on the quality of water bodies, posing a significant threat to public health and the environment. In Ecuador, previous research indicates a high prevalence of antimicrobial resistant (AMR) bacteria in surface waters affected by human activities, including irrigation channels. In this study, we analyzed sediment samples collected from an irrigation channel utilized for agricultural purposes in northern Ecuador, using microbiological techniques and whole-genome sequencing (WGS). Our investigation revealed the first documented occurrence of E. kobei in Ecuador and the initial report of environmental E. kobei ST2070. Furthermore, we identified the coexistence of OXA-10-type class D β-lactamase and KPC-2-type class A β-lactamase in the E. kobei isolate (UTA41), representing the first report of such a phenomenon in this species. Additionally, we detected various antibiotic resistance genes in the E. kobei UTA41 isolate, including blaCTX-M-12, fosA, aac(6')-lb, sul2, msr(E), and mph(A), as well as virulence genes such as bacterial efflux pump and siderophore biosynthesis genes. We also identified two intact prophage regions (Entero_186 and Klebsi_phiKO2) in the isolate. Our study presents the first evidence of E. kobei isolate containing two carbapenemase-encoding genes in environmental samples from Latin America. This finding indicates the potential spread of critical-priority bacteria in water samples originating from anthropogenic sources, such as urban wastewater discharges and livestock facilities.

Fine-scale spatiotemporal variations in bacterial community diversity in agricultural pond water

Microbial communities in surface waters are affected by environmental conditions and can influence changes in water quality. To explore the hypothesis that the microbiome in agricultural waters associates with spatiotemporal variations in overall water quality and, in turn, has implications for resource monitoring and management, we characterized the relationships between the microbiota and physicochemical properties in a model irrigation pond as a factor of sampling time (i.e., 9:00, 12:00, 15:00) and location within the pond (i.e., bank vs. interior sites and cross-sectional depths at 0, 1, and 2 m). The microbial communities, which were defined by 16S rRNA gene sequencing analysis, significantly varied based on all sampling factors (PERMANOVA P < 0.05 for each). While the relative abundances of dominant phyla (e.g., Proteobacteria and Bacteroidetes) were relatively stable throughout the pond, subtle yet significant increases in α-diversity were observed as the day progressed (ANOVA P < 0.001). Key water quality properties that also increased between the morning and afternoon (i.e., pH, dissolved oxygen, and temperature) positively associated with relative abundances of Cyanobacteria, though were inversely proportional to Verrucomicrobia. These properties, among additional parameters such as bioavailable nutrients (e.g., NH3, NO3, PO4), chlorophyll, phycocyanin, conductivity, and colored dissolved organic matter, exhibited significant relationships with relative abundances of various bacterial genera as well. Further investigation of the microbiota in underlying sediments revealed significant differences between the bank and interior sites of the pond (P < 0.05 for α- and β-diversity). Overall, our findings emphasize the importance of accounting for time of day and water sampling location and depth when surveying the microbiomes of irrigation ponds and other small freshwater sources.

Detection of human enteric viruses in fresh produce of markets, farms and surface water used for irrigation in the Tehran, Iran

Considering the major role of vegetables in the transmission of gastrointestinal diseases, investigation of the presence of gastrointestinal viruses is particularly important for public health. Additionally, monitoring and investigating potential points of contamination at various stages of cultivation, harvesting, and distribution can be important in identifying the sources of transmission. This study was conducted with the aim of identifying norovirus, adenovirus, hepatitis A virus, hepatitis E virus, rotaviruses, and astroviruses in vegetable samples from the fields and fruit and vegetable centers of Tehran City, and to investigate their presence in irrigation water by RT-qPCR. This study was carried out in two phases: initial and supplementary. During phase I, a total of 3 farms and 5 fruit and vegetable centers and a total of 35 samples from farms, 102 samples from fruit and vegetable centers and 8 agricultural water samples were collected. Zero, 16 and 1 samples were positive for at least one of the viruses from each of the sources, respectively. During phase II, 88 samples from 23 farms, 226 samples from 50 fruit and vegetable centers and 16 irrigation water samples were collected, with 23, 57 and 4 samples were positive for at least one virus, respectively. Rotavirus was the most frequently identified virus among the samples, followed by NoV GII, NoV GI, AstV, and AdV. HAV and HEV were not detected in any of the tested samples. The results of this study suggest that there may be a wide presence of viruses in vegetables, farms, and fruit and vegetable centers in Tehran City, which could have significant consequences considering the fact that many of these foods are consumed raw. Additionally, the detection of some of these viruses in irrigation water suggests that this may be a potential route for viral contamination of produce.

The fatal case of "Pigmentibacter" bacteremia following aspiration pneumonia in elderly patient

"Pigmentibacter ruber" was first reported in 2021, a novel bacterium of the family Silvanigrellaceae, isolated from human blood of the patient with aspiration pneumonia after the drowning accident in Republic of China. However, until now, there is only one report describing "P. ruber" infection, and no case of isolation from natural environment has been reported so far. Thus, the infectivity and pathogenicity of "Pigmentibacter" spp. has not been clearly understood. In this report, we described the fatal case of "Pigmentibacter" bacteremia subsequently occurred after aspiration pneumonia probably due to accidental ingestion of irrigation water in the elderly patient. Despite administration of broad-spectrum antibiotic, the patient dramatically deteriorated and eventually deceased. Whole-genome sequencing showed the strain isolated from the patient was identified as "Pigmentibacter" sp. (designated as strain Takaoka) and antimicrobial sensitivity testing showed it displayed high minimum inhibitory concentrations against various antibiotics including β-lactam. Further studies are needed to clarify the clinical characteristics of "Pigmentibacter" and its relative's infections and their antimicrobial sensitivity; however, the present case supported the clinical characteristics of "Pigmentibacter" infection, which can lead to bacteremia following aspiration pneumonia caused by mis-swallowing contaminated water, and poor outcome potentially due to multidrug resistances.

Virome analysis of irrigation water sources provides extensive insights into the diversity and distribution of plant viruses in agroecosystems

Plant viruses pose a significant threat to agriculture. Several are stable outside their hosts, can enter water bodies and remain infective for prolonged periods of time. Even though the quality of irrigation water is of increasing importance in the context of plant health, the presence of plant viruses in irrigation waters is understudied. In this study, we conducted a large-scale high-throughput sequencing (HTS)-based virome analysis of irrigation and surface water sources to obtain complete information about the abundance and diversity of plant viruses in such waters. We detected nucleic acids of plant viruses from 20 families, discovered several novel plant viruses from economically important taxa, like Tobamovirus and observed the influence of the water source on the present virome. By comparing viromes of water and surrounding plants, we observed presence of plant viruses in both compartments, especially in cases of large-scale outbreaks, such as that of tomato mosaic virus. Moreover, we demonstrated that water virome data can extensively inform us about the distribution and diversity of plant viruses for which only limited information is available from plants. Overall, the results of the study provided extensive insights into the virome of irrigation waters from the perspective of plant health. It also suggested that an HTS-based water virome surveillance system could be used to detect potential plant disease outbreaks and to survey the distribution and diversity of plant viruses in the ecosystem.

Evaluation of non-cancer risk owing to groundwater fluoride and iron in a semi-arid region near the Indo-Bangladesh international frontier

Groundwater quality in Hili, a semi-arid border region at Indo-Bangladesh border, was investigated in the post-monsoon season of 2021, succeeded by assessment of probabilistic health risk arising from fluoride (F-) and iron (Fe) intake, with the hypothesis that groundwater quality of the region was not satisfactory for human consumption and health, considering earlier reports on high groundwater F- and Fe in few of the neighboring districts. All water samples were found to be potable in terms of Ca2+, Mg2+, Cl-, SO42- and NO3-, , but F- and Fe exceeded prescribed safe limits for drinking water in about 48% and 7% samples. Almost all water samples were found to be good for irrigation in terms of sodium adsorption ratio (SAR), soluble sodium percentage (SSP), Kelly's index (KI), %Na and magnesium ratio (MR). The principal component analysis (PCA) identified three major factors influencing groundwater quality, explaining about 71.8% of total variance and indicated that groundwater quality was primarily influenced by geochemical factors. Carbonate and silicate weathering were mainly responsible for dissolution of minerals in groundwater. Non-carcinogenic risk due to cumulative impact of F-and Fe intake was in the order of THIChildren > THIInfant > THIAdult. As per Monte Carlo simulation run with 5000 trials to ascertain the order of probabilistic health risk, the most dominant governing factors behind non-carcinogenic risk caused by F-and Fe intake were their concentration (Ci) followed by ingestion rate (IR), and exposure duration (ED).

Comparative study of efficiencies of purification of cadmium contaminated irrigation water by different purification systems

Cadmium (Cd) contamination in rice threats food safety and human health. Control of Cd pollution has become an urgent need. Most existing studies on heavy metal pollution control have focused on industrial wastewater and few on irrigation water. Some researchers have found ecological ditches, plant ponds and constructed wetlands have the potential of treating heavy metal contaminated irrigation water, but they examined only one of the methods and the validity needs to be verified by field studies. Our study has filled the gap by combining the methods and using field experiments. We examined efficiencies of removal of Cadmium from irrigation water by 14 different combinations of ecological ditches, plant ponds, and constructed wetlands using field experiments. The effects of the purification on Cd concentration in paddy soil and rice grains were also examined. Results showed that there were significant differences among efficiencies of purification of Cd contaminated irrigation water using different systems and that pH, chemical form of Cd in irrigation water, vegetation coverage and biomass of aquatic plants significantly affect the efficiency. Of the 14 purification systems, seven resulted in the concentration of Cd in the effluent water meeting the National Standard for Irrigation Water Quality (GB5084-2021) for all days of the experiment period. The highest amount and rate of Cd removal were achieved by the combination of two-stage ecological ditch, two-stage plant pond, and one-stage constructed wetland, while the highest removal amount and rate per 100 m2 was achieved by the combination of one-stage plant pond and one-stage constructed wetland. Considering purification efficiency, area of coverage, and cost of construction and maintenance, we suggest that combination of plant pond and constructed wetland be a priority choice for purification of Cd pollution in irrigation water. Compared to the control data collected from rice grain and paddy soil irrigated by unpurified water, Cd concentration in rice grain and paddy soil irrigated by purified water declined by 5.08-19.42 % and 30.93-77.15 % respectively. All results showed that removal of Cd contamination from irrigation water effectively controlled cadmium pollution in rice grain and paddy soil. Our study not only contributes to pollution control practice, but also warrants further investigation of the mechanisms of how the treatment systems work. The most efficient method we identified could be applied locally, regionally and in areas of similar topography, climate, soil, vegetation, agriculture, and heavy metal pollution.

FeS and Fe3O4 Co-modified biochar to build a highly resistant advanced oxidation process system for quinclorac degradation in irrigation water

Advanced oxidation processes (AOPs), based on sulfate radical (SO4·-) produced by peroxymonosulfate (PMS), can effectively mineralize refractory organic pollutants. However, the coexistence of anions and natural organic matters in actual wastewater prevents the application of AOPs. A simple one-step method was used to prepare FeS/Fe3O4 co-modified biochar materials (FFB) that could activate PMS to degrade quinclorac (QNC) with a removal rate of 100%, even exhibiting optimum degradation of QNC reached 99.31% in irrigation water, demonstrating excellent anti-interference performance for co-existing anions and natural organic matter. Meanwhile, ecotoxicity analysis showed that the toxicity of degradation intermediates was lower than that of QNC. Characterization results demonstrated the even distribution of FeS and Fe3O4 onto biochar, supplying abundant Fe2+ to activate PMS producing reactive oxygen species (ROS), while the generated Fe3+ after reactive continue to be reduced with sulfur species to promote the cycle of Fe2+/Fe3+. The coexistence of ·OH, SO4·-, 1O2, and O2·- in the FFB/PMS-QNC system suggest the possession of two pathway with free radical and non-free radical pathways to degrade QNC. The density functional theory (DFT) was used to analyze the adsorption sites and adsorption energy of PMS, as well as the differential charge density, which further proved the generation of SO4·-, O2·- and 1O2. In addition, the electrochemical test results showed that electron transfer also played an important role in the degradation of QNC. This study provides a feasible approach for the removal of organic pollutants in actual water.

Effect of damming on hydrogeochemical characteristics and potential environmental risks in a large reservoir: Insights from different vertical layer sampling

The water environment of large reservoirs is fragility due to effects from hydrological regulation of damming and anthropogenic inputs. As a critical path to quantify the natural chemical weathering and assess environmental risks, solute chemistry of river has been widely focused on. However, the complexed hydrological conditions of large reservoir affect the chemical compositions, and the significance of solute vertical geochemistry as an indicator of chemical weathering and water quality health remains explore. Therefore, the Three Gorges Reservoir (TGR) was selected as a typical study area, which is the world's largest hydropower project and subject to frequent water quality problems. Then, the chemical compositions in stratified water were determined. Ca2+ (52.8 ± 4.3 mg/L) and HCO3- (180.9 ± 8.9 mg/L) were the most abundant ions among cations and anions, respectively. Incremental mean concentration of total major ions followed with the increase of riverine depth and flow direction. An improved inversion model was used to quantify the source contribution, which weathering of dolomite (34%) and calcite (38%) contributed the most to total cations, and the influences of agriculture and sewage discharge were limited. Additional contributions of evaporite and pyrite oxidation were found in analysis of deeper water samples, which also results in 2%-67% difference in estimated CO2 release flux using data from different depth, indicating additional information about sulfuric acid driven weathering was contained. Finally, the water quality of the reservoir was assessed for irrigation and non-carcinogenic risks. Results showed the stratified water of TGR can be used as a good water source of irrigation. However, NO3- (5.1 ± 1.1 mg/L) may have a potential non-carcinogenic risk to children, especially in surface water. To sum up, this study provided an indispensable supplement to the water chemistry archives in the TGR basin, serving as theoretical references for environmental management of large reservoirs.

Boron contamination and related health risk assessment in the soils collected from olive groves in İzmir province, Türkiye

Although boron (B) is an essential element for plants, high levels are also toxic. In this respect, pollution of soils by B may pose a serious problem for ecosystem and human health. On the other hand, studies evaluating the ecological and human health risks that may arise due to B contamination in agricultural soils are limited. In this study, it was aimed to determine the B pollution degree of the soils taken from the olive groves of İzmir province, which is approximately 180 km away from the B deposits in the Bigadiç district. In addition, the factors affecting boron adsorption and availability were discussed and the ecological and health risks of boron were evaluated. For this, soil samples were collected at depths of 0-30 cm from 118 olive groves and their B, Al, Fe, pH and organic matter contents were determined. The mean B content (47.08 mg/kg) of the study area was comparable to world-soil average B concentration (42 mg/kg). Also, B had a "low potential ecological risk" in the study area according to the ecological risk index results. On the other hand, based on the results of contamination factor (Cf) and enrichment factor (EF), "moderate contamination" and "significant enrichment" were found in the study area for B. These findings indicated that the B content in the study area is mainly related to the soil parent material, but irrigation water also contributes slightly to B content. Correlation analysis results suggested that Al and Fe contents of the soils in the study area may have an effect on B adsorption. The results of health risk assessment indicated non-carcinogenic effects are not expected for adults and children exposed to soil B content by ingestion, dermal contact and inhalation.

Boron contamination and its risk management in terrestrial and aquatic environmental settings

Boron (B) is released to terrestrial and aquatic environments through both natural and anthropogenic sources. This review describes the current knowledge on B contamination in soil and aquatic environments in relation to its geogenic and anthropogenic sources, biogeochemistry, environmental and human health impacts, remediation approaches, and regulatory practices. The common naturally occurring sources of B include borosilicate minerals, volcanic eruptions, geothermal and groundwater streams, and marine water. Boron is extensively used to manufacture fiberglass, thermal-resistant borosilicate glass and porcelain, cleaning detergents, vitreous enamels, weedicides, fertilizers, and B-based steel for nuclear shields. Anthropogenic sources of B released into the environment include wastewater for irrigation, B fertilizer application, and waste from mining and processing industries. Boron is an essential element for plant nutrition and is taken up mainly as boric acid molecules. Although B deficiency in agricultural soils has been observed, B toxicity can inhibit plant growth in soils under arid and semiarid regions. High B intake by humans can be detrimental to the stomach, liver, kidneys and brain, and eventually results in death. Amelioration of soils and water sources enriched with B can be achieved by immobilization, leaching, adsorption, phytoremediation, reverse osmosis, and nanofiltration. The development of cost-effective technologies for B removal from B-rich irrigation water including electrodialysis and electrocoagulation techniques is likely to help control the predominant anthropogenic input of B to the soil. Future research initiatives for the sustainable remediation of B contamination using advanced technologies in soil and water environments are also recommended.

Pathway analysis of food security by employing climate change, water, and agriculture nexus in Pakistan: partial least square structural equation modeling

Increasing population and augmented demand for food have put burden on water resources, crops, and livestock for future sustainability. Pakistan is facing difficulties of water shortage, low crops and livestock productivity, meagre livelihood, and intensive food insecurity. Hence, this study was conducted in Pakistan to explore the nexus of climate change, irrigation water, agriculture, rural livelihoods, and food security. The study is based on primary data of 1080 farmers gathered from 12 districts of the rice-wheat and cotton-wheat cropping systems. A partial least square structural equation modeling (PLS-SEM) was used to compute the nexus. Findings of path analysis indicated that climate change had a significant negative impact on irrigation water, crops, livestock, rural livelihood, and food security in both cropping systems. There was positive relationship between surface water and crops. In addition, groundwater and crops were also positively and significantly correlated. The impact of crop was positive and significant on rural livelihood and food security. Furthermore, rural livelihood and food security were positively and significantly influenced by livestock. Moreover, there was positive relationship between rural livelihood and food security. The cotton-wheat cropping system was more affected by climatic and natural hazards than rice-wheat cropping system. Interconnectivity among nexus components and their contribution to rural livelihood and food security indicate that government, policymakers, and other concerned stakeholders should effectively improve food security policies under climatic and natural hazards. Moreover, it helps in examining adverse impacts of hazards induced by climate change on nexus components, leading to the designing and adoption of sustainable climate change policies. The study's originality lies in its ability to provide a inclusive and integrated pathway of the interconnections and interdependencies among these variables, identifying key drivers of food insecurity in Pakistan. Moreover, outcome of the study has policy implications for developing sustainable policies and strategies to improve sustainable food security in the country.

Surface water quality for irrigation and industrial purposes: a comparison between the south and north sides of the Wei River Plain (northwest China)

Surface water is extensively used for irrigation and industrial purposes in the Wei River Plain. However, the surface water shows different characteristics in the southern and northern zones of the Wei River Plain. This study aims to investigate the differences in surface water quality between the southern and northern zones of the Wei River Plain and their influencing factors. To ascertain the hydrochemistry and its governing factors, graphical methods, ion plots, and multivariate statistical analyses were employed. The quality of the irrigation water was assessed using various irrigation water quality indices. In addition, water foaming, corrosion, scaling, and incrustation risks were determined to evaluate water quality for industrial uses. The spatial distribution of water quality was done using GIS models. This research revealed that the concentrations of EC, TH, TDS, HCO₃^-, Na⁺, Mg²⁺, SO₄^2- and Cl^- on the north side of the plain were twice as high as those on the south side. On both sides of the Wei River Plain, water‒rock interactions, ion exchange, and considerable evaporation were observed. Gypsum, halite, calcite, and dolomite all dissolve to produce significant anions and cations in the water, according to ion correlation analysis. However, additional sources of contaminants led to higher concentrations in the surface water on the north side than on the south side. Surface water in the south of the Wei River Plain has superior quality to that in the north, according to the overall findings of irrigation water and industrial water quality assessments. The findings of this study will boost better water resource management policies for the plain.

Nitrogen inputs by irrigation is a missing link in the agricultural nitrogen cycle and related policies in Europe

Irrigation, one of the 28 agri-environmental indicators defined in the European Common Agricultural Policy, is often neglected in agricultural nitrogen (N) budgets, while it can be a considerable source of N in irrigated agriculture. The annual N input from irrigation water sources (NIrrig) to cropping systems was quantified for Europe for 2000-2010 at a resolution of 10 × 10 km, accounting for crop-specific gross irrigation requirements (GIR) and surface- and groundwater nitrate concentration. GIR were computed for 20 crops, while spatially explicit nitrate concentration in groundwater was derived using a random forest model. We show that although GIR were relatively stable (46-60 km3 yr-1), the Nirrig in Europe increased over the 10-year period (184 to 259 Gg N yr-1), approximately 68 % of which occurred in the Mediterranean region. The main hotspots appeared in areas with both high irrigation requirements and high groundwater nitrate concentration, reaching up to averaged values of 150 kg N ha-1 yr1. These were mainly located in Mediterranean Europe (Greece, Portugal and Spain) and to a lesser extent in Northern Europe (The Netherlands, Sweden and Germany). By not including NIrrig, environmental and agricultural policies are underestimating the real extent of N pollution hotspots in European irrigated systems.

Spatial-temporal distribution, occurrence, water quality, and risk assessment of trace elements in ten rivers surrounding Chaohu Lake in China

As one of the five great lakes in China, the Chaohu Lake Basin is the main water source for regional economic and ecological development in Hefei city and is considered a source of drinking water. The spatial-temporal distributions and occurrence of soluble trace elements were studied in the surrounding ten rivers in the Chaohu Lake Basin as well as water quality and risk assessment during the normal and wet seasons. Principal component analysis (PCA) showed that the main source of river pollution during the two seasons was the mining industry. High values of most elements were found in the northwestern rivers in the two seasons. The temporal changes in the elements showed that the distributions of As, Mn, Cd, and Cu in the two seasons were very different, but the trends of Ni, Co, and V were basically the same. The sodium adsorption ratio (SAR) showed that almost all river samples needed to be treated before irrigation, and the water quality index (WQI) showed that most samples were of excellent water quality for drinking. The ecological risk assessment results showed that the risks in the two seasons were all slight. The results of the health risk evaluation suggested that no noncarcinogenic risks were found in the normal season and that the carcinogenic risks from Cr and As reached their highest levels in the normal and wet seasons, respectively. This research can provide vital data for rational water control and water quality conservation, offer a scientific basis for ecological environment safety, and offer a reference for carcinogenic and noncarcinogenic health risks to regional residents.

The effect of irrigation with treated and untreated wastewater on the yield and chemical composition of essential oil of Mentha spicata L. and Rosmarinus officinalis L

Today, the lack of quality water supply has led to the tendency to use unconventional water to irrigate agricultural products. Considering the importance and application of essential oils of mint plants in various pharmaceutical, food, and health industries and also considering the approach of using unconventional waters in the cultivation of medicinal plants, the present study aimed to investigate and compare the chemical composition of essential oils of two species of Mentha spicata L. and Rosmarinus officinalis L. which was designed and implemented for the first time under the influence of different treatments of municipal and industrial wastewater. For this purpose, first R. officinalis cuttings and roots of M. spicata were prepared and after preparing and leveling the ground, in the spring of 2020, it was transferred to the planting site and planted in the form of creek and ridges. The treatments studied in this study included well water (WW), treated municipal wastewater (TMW), untreated municipal wastewater (UMW), treated industrial wastewater (TIW), and untreated industrial wastewater (UIW) in a randomized complete block design with four repeat runs. After watering the plants continuously for 3 months, the plant branches were collected and transferred to the laboratory for drying. After extracting the essential oil by water distillation (Clevenger) method, the analysis and identification of the compounds were performed by a chromatograph coupled with a mass spectrometer (GC/MS). The results showed that the highest and lowest yields of M. spicata belonged to the samples treated with UMW and WW, respectively. Also, R. officinalis essential oil irrigated with UMW and UIW had the highest and lowest yields, respectively. The number of essential oil compounds in of M. spicata was between 5 and 19 and in R. officinalis between 14 and 23 under different treatments. The results of the analysis of essential oil compounds showed that D-carvone (57.77-57.44%) and D-limonene (8.70-26.65%) for M. spicata and α-pinene (26.12-34.85%), 1,8-cineole (18.95-23.70%), and camphene (9.93-12.80%) for R. officinalis were predominant compounds in all studied treatments. The results show that UMW is a suitable and efficient treatment to have the best quantity of M. spicata essential oil and the best quality and quantity of R. officinalis essential oil.

Assessment of the water quality of Bartın Kışla (Kozcağız) Dam by using geographical information system (GIS) and water quality indices (WQI)

This study was conducted to evaluate the water quality of the Kışla (Kozcagiz) Dam located in the province of Bartın in the Western Black Sea Region of Turkey. Water samples were collected monthly from 5 stations for a year and analyses were conducted using 27 water quality parameters. The quality of the dam and the water quality parameters were evaluated using different indices in comparison to the limits determined according to the standards set by the World Health Organization (WHO) and Turkey Surface Water Quality Regulation (SWQR). Water quality index (WQI), organic pollution index (OPI), sodium adsorption ratio (SAR), magnesium adsorption ratio (MAR), permeability index (PI), and metal pollution index (MPI) were calculated and spatial assessment of pollution was made seasonally by making use of the geographic information system (GIS). A piper diagram was used in determining the facies of the water. The types of Ca²⁺-Mg²⁺-HCO₃^- predominated in the dam water. Moreover, statistical analyses were used in order to determine if there was a significant difference between the parameters. WQI results generally indicate that the water quality was good in all seasons; however, only in the autumn, sampling points S1 (101.58), S2 (100.59), S4 (102.31), and S5 (102.12) showed poor water characteristics. According to the OPI results, while winter and spring yielded good water quality, summer samples were lightly polluted and autumn samples were moderately polluted. Given SAR results, it can be stated that the water of Kışla Dam could be used as irrigation water. Considering the standards specified by WHO and SWQR, the parameters generally exceeded the threshold values, but the water hardness value was much higher than 100 mg L^-1 specified in SWQR as very hard water. The principal component analysis (PCA) results showed that the pollution sources were anthropogenic. Thus, for the dam water to not be affected by the increasing pollutant factors, it should be continuously monitored, and attention should be paid to the irrigation methods used in agricultural activities.

Redistribution effect of irrigation on shallow groundwater recharge source contributions in an arid agricultural region

Recharge sources such as precipitation, mountain front recharge, mountain block recharge and confined water are the sources usually considered in quantitative studies of groundwater recharge. Changes in recharge processes caused by irrigation practices need to be fully considered for the accurate budgeting and management of water resources. Here, we put forward a conceptual framework for evaluating the shallow groundwater recharge process in arid irrigated agricultural areas using hydrochemical and stable isotope techniques, combined with an assessment of hydrogeological conditions and quantitative models. In general, the recharge effect of atmospheric precipitation on shallow groundwater in arid areas is relatively small. The contributions made by recharge sources in the studied river irrigated area, from greater to smaller, were confined groundwater (46.98 %), river water (45.48 %) and precipitation (7.55 %). The original range in groundwater recharge levels caused by river leakage also appeared to have expanded in response to the establishment of canal irrigation networks. Lateral groundwater flow and confined groundwater were the main recharge sources of shallow groundwater in areas fed by well irrigation and well-/spring-water irrigation (not taking into account any groundwater irrigation leakage). However, had the recharge of shallow groundwater by groundwater irrigation leakage, which reached 19.8-41.1 %, not been counted as contributing to actual groundwater recharge, the recharge contributions made by lateral groundwater flow and confined groundwater to shallow groundwater would have been significantly overestimated. This is because the groundwater recharge process has been modified by the various irrigation measures employed in arid agricultural areas, leading to a redistribution effect in groundwater recharge source contributions. This study provides a new perspective and intuitive data support for the development and utilization of water resources in arid regions.

Microbiological quality of irrigation water for cultivation of fruits and vegetables: An overview of available guidelines, water testing strategies and some factors that influence compliance

Contaminated irrigation water is among many potential vehicles of human pathogens to food plants, constituting significant public health risks especially for the fresh produce category. This review discusses some available guidelines or regulations for microbiological safety of irrigation water, and provides a summary of some common methods used for characterizing microbial contamination. The goal of such exploration is to understand some of the considerations that influence formulation of water testing guidelines, describe priority microbial parameters particularly with respect to food safety risks, and attempt to determine what methods are most suitable for their screening. Furthermore, the review discusses factors that influence the potential for microbiologically polluted irrigation water to pose substantial risks of pathogenic contamination to produce items. Some of these factors include type of water source exploited, irrigation methods, other agro ecosystem features/practices, as well as pathogen traits such as die-off rates. Additionally, the review examines factors such as food safety knowledge, other farmer attitudes or inclinations, level of social exposure and financial circumstances that influence adherence to water testing guidelines and other safe water application practices. A thorough understanding of relevant risk metrics for the application and management of irrigation water is necessary for the development of water testing criteria. To determine sampling and analytical approach for water testing, factors such as agricultural practices (which differ among farms and regionally), as well as environmental factors that modulate how water quality may affect the microbiological safety of produce should be considered. Research and technological advancements that can improve testing approach and the determination of target levels for hazard characterization or description for the many different pollution contexts as well as farmer adherence to testing requirements, are desirable.

Long-term effects on the agroecosystem of using reclaimed water on commercial crops

The use of reclaimed water for crop irrigation has been proposed as a suitable alternative for farmers in the coastal areas of Mediterranean countries, which suffer from greater water scarcity. In this work we study the impact on the water-soil-plant continuum of using reclaimed water for commercial crops irrigated over a long period, as well as the human risks associated with consuming the vegetables produced. Forty-four CECs were identified in the reclaimed water used for crop irrigation. Of these, twenty-four CECs were identified in the irrigated soil samples analysed. Tramadol, ofloxacin, tonalide, gemfibrozil, atenolol, caffeine, and cetirizine were the pharmaceuticals detected at the highest levels in the water samples (between 11 and 44 μg/L). The CECs with the highest average soil concentrations were tramadol (14.6 μg/kg), followed by cetirizine (13.2 μg/kg) and clarithromycin (12.7 μg/kg). In the irrigated vegetable samples analysed over the study period, carbamazepine, lidocaine, and caffeine were only detected at levels from 0.1 to 1.7 μg/kg. The CEC accumulation rate detected in the edible parts of the vegetables permanently irrigated with reclaimed water was very low (~1 %), whereas it was 33 % in the soils. The results revealed that consuming fruits harvested from plants irrigated for a long period with reclaimed water does not represent a risk to human health, opening the door to a circular economy of water. Nevertheless, for crop irrigation, future studies need to be conducted over longer periods and in other matrices to provide more scientific data on the safety of using reclaimed water.

Distinguishing and quantifying the fate of nitrate in irrigation water and nitrate produced by ammonium nitrification

When the sources of nitrogen include not only ammonium (NH₄⁺) fertilizer (ANF) but also nitrate (NO₃^-) from groundwater and rainfall (NRI), if the proportions of various types of NO₃^- are still based on the amount of ANF, the corresponding calculation method may be complicated. This paper established a water flow-nitrogen migration transformation model for the unsaturated zone in grain-planting and vegetable-planting areas, and studied the migration and transformation of NH₄⁺ and NO₃^- in the unsaturated zone when ANF and NRI coexist. This paper proposed for the first time the proportional coefficient method (PCM) and hypothetical assignment method (HAM) to distinguish and quantify the fate proportions of NO₃^- from NO₃^- produced by NH₄⁺ nitrification (NNR) and NRI. The results showed that the PCM was more practical than the HAM in quantifying the fate of NO₃^- from different sources. If only the root absorption ratio was used to evaluate the degree of nutrient supply to crops, the ratios of root absorption were as high as 40% (44.75-50.85%). NRI provided more nutrients in grain-growing areas than those in vegetable-growing areas. If the sum of the proportion of other fates was regarded as the degree of groundwater NO₃^- mitigation through irrigation in the unsaturated zone, except for the ratio of NO₃^- leaching to groundwater, the proportion of NO₃^- pollution mitigation was as high as 57.89% (57.89-92.99%), and the mitigation ability of groundwater NO₃^- pollution in grain-growing areas was higher than that in vegetable-growing areas.

Towards circular economy: Sustainable soil additives from natural waste fibres to improve water retention and soil fertility

Human activity is accompanied by the introduction of excessive amounts of artificial materials, including geosynthetics, into the environment, causing global environmental pollution. Moreover, climate change continues to negatively affect global water resources. With the intensification of environmental problems, material reusability and water consumption limitations have been proposed. This study replaced synthetic soil additives with biodegradable materials and analysed the potential and sustainable processing of natural fibrous materials, which form problematic waste. Waste fibres are the basis of innovative soil water storage technologies in the form of biodegradable and water-absorbing geocomposites (BioWAG). We analysed the influence of BioWAGs on plant vegetation and the environment through a three-year field experiment. Furthermore, biomass increases, drought effect reductions, and biodegradation mechanisms were analysed. Natural waste fibres had a positive influence, as they released easily accessible nutrients into the soil during biodegradation. BioWAGs had a positive influence on the biometric parameters of grass, increasing biomass growth by 430 %. Our results indicated that this is an effective method of waste fibre management that offers the possibility to manufacture innovative, environmentally friendly materials in compliance with the objectives of circular economy and the expectations of users.

Assessing levels of selected heavy metals with other pollutants in soil and water resources in Nandom District in the semi-arid northwestern Ghana

This study assessed heavy metal contaminations of soils in cultivated fields (or farms) and water samples from rivers, boreholes, and dug-out wells in Nandom District in semi-arid northwestern Ghana. Other parameters of water from the three sources were also measured and then compared to the permissible limits in the literature. The results showed that soils in farms across the study communities significantly (P ≤ 0.05) had higher levels of chromium (Cr = 0.456 ± 0.132 mgkg^-1), iron (Fe = 214.8 ± 1.52 mgkg^-1), lead (Pb = 0.854 ± 0.03 mgkg^-1), nickel (Ni = 2.813 ± 0.4 mgkg^-1), and arsenic (As = 1.753 ± 0.42 mgkg^-1) when compared to permissible limits set by World Health Organization (WHO) and Food and Agricultural Organization (FAO) for food crops. Water from the study sites significantly (P ≤ 0.0001) had lower levels of heavy metals than the permissible limits set by FAO for irrigation of growing crops. Thus, the water sources appear to be safe for irrigation in the study area. Nonetheless, these sources of water in Nandom District had significantly higher levels of total suspended solids, turbidity, and coliforms that were above the maximum limits indicated in the guidelines of WHO and the Government of Ghana for drinking water. Therefore, treatments of water for drinking are required to minimize any potential threats to public health.

Assessment of Ismailia Canal for irrigation purposes by water quality indices

Ismailia Canal is one of the significant streams of the Nile River in Egypt. The study aimed to determine the water quality of Ismailia Canal based on the regional and seasonal variability of physicochemical parameters, irrigation criteria, and the irrigation water quality index (IWQI). It was observed that the physicochemical parameters were within the acceptable FAO irrigation limits. All cations and anions values were within the acceptable FAO limits for irrigation, except the potassium (K⁺) concentrations were over the permissible irrigation limits. The one-way analysis of variance (ANOVA) suggested a significant seasonal variation in the canal's water quality concerning all parameters (p value ˂ 0.05). However, the regional variation among various sites was statistically insignificant (p value > 0.05). Statistical analysis was used to calculate the correlation coefficient between different parameters, and the study showed highly significant correlation coefficients between different pairs of water quality parameters. The correlation matrix showed that the pH significantly affected IWQI (r = 0.661). The irrigation criterion values for Ismailia Canal were good, and the WQI levels for irrigation utilization at all studied sites were satisfactory. Deterioration of water quality may occur due to industrial, municipal, and agricultural activities. Drainage water should be treated before being mixed with irrigation water to improve its suitability for irrigation.

Groundwater quality evaluation and human health risks assessment using the WQI, NPI and HQnitrate models: case of the Sfax intermediate aquifer, Sahel Tunisia

Groundwater is a vital natural resource required to satisfy the domestic and agricultural needs. In general, human health is linked to the quality of the consumed water. For instance, long-term exposure to high nitrate levels in groundwater may cause problems. Hence, the present study was conducted to assess the nitrate contamination of groundwater as well as its related health risks for the inhabitants of the Sfax region, Sahel Tunisia. Irrigation groundwater suitability has been evaluated with sodium content (%Na), electrical conductivity (EC), magnesium hazard (MH), sodium adsorption ratio (SAR), permeability index (PI), Kelly's ratio (KR) and soluble sodium percent (SSP). The results indicate that the selected groundwater is characterized by low to moderate quality for irrigation. Furthermore, the drinking water quality index (DWQI) was assessed using potential of hydrogen (pH), total dissolved solids (TDS), magnesium (Mg²⁺), calcium (Ca²⁺), sodium (Na⁺), chloride (Cl^-), sulfate (SO₄^2-), potassium (K⁺), bicarbonate (HCO₃^-) and nitrate (NO₃^-). The results indicate that 3.63% of samples have good quality of water, while 41.82% have poor to very poor water quality and the rest (54.55%) are unfit for drinking. The nitrate pollution index (NPI) model revealed that about 42% of the samples present significant to very significant type of pollution. Based on human health risk assessment, the children are at higher risks compared to the other affected groups. The obtained results could be used as a basic document for realistic management of groundwater quality and to provide an overview for decision-making authorities to take necessary actions.

Simultaneous detection of less frequent waterborne parasitic protozoa in reused wastewater using amplicon sequencing and qPCR techniques

Waterborne parasitic protozoa (WPP) infections have a worldwide distribution and are a source for epidemic and endemic human diseases. Although a variety of protozoa are commonly detected in wastewater and cited as causative agents of outbreaks, effluents from wastewater treatment plants (WWTPs) used for irrigation can contain other pathogenic protozoa that are not currently being controlled. The lack of control on a routine basis using rapid and sensitive methods to detect these parasites in water may keep them under-recognized. This study focused on using molecular tools, 18 S rRNA amplicon-based sequencing and qPCR, to characterize WPP distribution in wastewater samples from urban WWTPs used for irrigation. A total of eight wastewater samples (from secondary and tertiary disinfection treatment effluents) were collected. Potentially pathogenic protozoa identified by 18 S rRNA sequencing and/or qPCR in the analyzed samples included Acanthamoeba spp., Blastocystis sp., Entamoeba coli, Entamoeba dispar, Entamoeba hartmanni, Giardia intestinalis assemblage A and Toxoplasma gondii Positive results by qPCR were in non-quantifiable levels. Blastocystis sp. was the most represented protozoa among the sequences retrieved from the amplicon sequencing. Blastocystis ST1 and ST2 were the most abundant subtypes among the obtained OTUs. Moreover, Blastocystis sp. ST3, ST4, ST6 and ST8 were also detected, although in lower abundances. Results of this study showed that WWTP effluents used for irrigation can provide a source of WPP.

Effects of season and water type on the distribution and antimicrobial resistance of Enterococcus faecalis and E. faecium from surface and reclaimed water

AIMS

To evaluate the safety of irrigation water sources based on phenotypic antimicrobial resistance (AMR) in Enterococcus spp., a potential environmental reservoir for AMR determinants.

METHODS AND RESULTS

Eleven sites representing fresh and brackish water rivers, ponds and reclaimed water, were sampled over two years. Samples (n=333) yielded 198 unique isolates of E. faecalis and E. faecium which were tested for antimicrobial susceptibility by microbroth dilution. Species distribution was influenced by water type and season. E. faecalis was more likely found in freshwater rivers and in summer, and E. faecium in reclaimed water and in spring. Only 11% of isolates were pansusceptible, while 48.5% and 26.3% were single (SDR) and multidrug resistant (MDR), respectively. MDR was more likely detected in E. faecium than E. faecalis. Winter isolates were more likely than summer isolates to exhibit MDR than SDR.

CONCLUSIONS

E. faecalis and E. faecium in surface and reclaimed water exhibited diverse phenotypic AMR and a low-level resistance to clinically important antimicrobials such as ampicillin, vancomycin and linezolid.

SIGNIFICANCE AND IMPACT OF THE STUDY

Single and multidrug resistance in E. faecalis and E. faecium varied by season but not water type. AMR prevalence can assist decisions on the safety of irrigation water sources for fresh produce crops.

Low irrigation water minimizes the nitrate nitrogen losses without compromising the soil fertility, enzymatic activities and maize growth

Nitrate nitrogen (NO₃^-_N) leaching increased with nitrogen (N) fertilization under high water supply to the field negatively affected the maize growth and performance. This study aimed to understand the mechanisms of NO₃^-_N leaching on a biochemical basis and its relationship with plant performance with 5 different doses (0, 200, 250, 300, 350 kg N ha^- 1) of N fertilizers under low (60%; LW) and high (80%; HW) water holding capacity. Soil and plant enzymes were observed at different growth stages (V9, R1, R3, and R6) of the maize, whereas the leachates were collected at 10-days intervals from the sowing date. The LW had 10.15% lower NO₃^-_N leachate than HW, with correspondence increases in grain yield (25.57%), shoot (17.57%) and root (28.67%) dry matter. Irrespective of the irrigation water, RubisCo, glutamine synthase (GS), nitrate reductase (NR), nitrite reductase (NiR), and glutamate synthase (GOGAT) activities increased with increasing N fertilizer up to the V9 growth stage and decreased with approaching the maturity stage (R6) in maize. In HW irrigation, soil total N, GOGAT, soil nitrate (NO₃^-_N), leached nitrate (LNO₃^-_N), root N (RN), leaf N (LN) were positively correlated with N factors suggesting the higher losses of N through leaching (11.3%) compared to LW irrigation. However, the malondialdehyde (MDA), hydrogen peroxide (H₂O₂), superoxide (O₂^-), and proline were negatively correlated with the other enzymatic activities both under LW and HW irrigation. Thus, minimizing the NO₃^-_N leaching is possibly correlated with the LW and N300 combination without compromising the yield benefit and improving enzyme activities.

New standards at European Union level on water reuse for agricultural irrigation: Are the Spanish wastewater treatment plants ready to produce and distribute reclaimed water within the minimum quality requirements?

The new European regulation on minimum quality requirements (MQR) for water reuse (EU, 2020/741) was launched in May 2020 and describes the directives for the use of reclaimed water for agricultural irrigation. This Regulation will be directly applicable in all Member States from 26 June 2023. Since its publication in 2020, concerns have raised about potential non-compliance situations in water reuse systems. The present study represents a case study where three different water reuse systems have been monitored to establish their compliance with the MQR. Each water reuse system includes a wastewater treatment plant (WWTP), a distribution/storage system and an end-user point, where water is used for irrigation of leafy greens. The selected water reuse systems allowed us to compare the efficacy of water treatments implemented in two WWTPs as well as the impact of three different irrigation systems (drip, furrow and overhead irrigation). The presence and concentration of indicator microorganisms (Escherichia coli and C. perfringens spores) as well as pathogenic bacteria (Shiga toxin-producing, E. coli (STEC), E. coli O157:H7, and Salmonella spp.) were monitored in different sampling points (influent and effluent of the WWTPs, water reservoirs located at the distribution system and the end-user point at the irrigation system as well as in the leafy greens during their growing cycle. Average levels of E. coli (0.73 ± 1.20 log cfu E. coli/100 mL) obtained at the point where the WWTP operator delivers reclaimed water to the next actor in the chain, defined in the European regulation as the 'point of compliance', were within the established MQR (<1 log cfu/100 mL) (EU, 2020/741). On the other hand, average levels of E. coli at the end-user point (1.0 ± 1.2 log cfu/100 mL) were below the recommended threshold (2 log cfu E. coli/100 mL) for irrigation water based on the guidance document on microbiological risks in fresh fruits and vegetables at primary production (EC, 2017/C_163/01). However, several outlier points were observed among the samples taken at the irrigation point, which were linked to a specific cross-contamination event within the distribution/storage system. Regarding pathogenic bacteria, water samples from the influent of the WWTPs showed a 100% prevalence, while only 5% of the effluent samples were positive for any of the monitored pathogenic bacteria. Obtained results indicate that reclaimed water produced in the selected water reuse system is suitable to be used as irrigation water. However, efforts are necessary not only in the establishment of advance disinfection treatments but also in the maintenance of the distribution/storage systems.

Aeromonas spp. diversity in U.S. mid-Atlantic surface and reclaimed water, seasonal dynamics, virulence gene patterns and attachment to lettuce

Aeromonas, a ubiquitous taxon in water environments, is emerging as a foodborne pathogen of concern that remains understudied and under-reported. We evaluated the distribution of 331 Aeromonas spp. isolates collected from irrigation water over one year and characterised their virulence profile, attachment and ability to persist on lettuce. Water sources included non-tidal and tidal river, farm pond and reclaimed water. Twenty Aeromonas species were identified; A. veronii, A. hydrophila and A. jandaei predominated in all water types and seasons, comprising ~63% of isolates. Species distribution was most affected by water type. The highest and lowest diversity were detected in river and pond water, respectively. A. hydrophila and A. veronii ranked highest in frequency in fresh river and reclaimed water, while A. jandaei ranked first in pond water. Only two isolates carried all five virulence genes tested, while 46% of A. hydrophila (n = 50), 54% of A. veronii (n = 61) and 50% of A. jandaei (n = 32) isolates harboured multiple enterotoxin genes. Detection of alt and ast genes was more likely in summer collections, while ast detection was less likely in tidal brackish river and pond water isolates. Season was a factor in attachment to polystyrene, being strongest in spring isolates. The gene flaA was associated with strong attachment and was more likely to be detected in non-tidal fresh river isolates. A. hydrophila and A. jandaei isolates persisted on lettuce leaves for 24 h, but populations dwindled over 120 h, while loosely and strongly attached cells of A. veronii isolates persisted for 120 h. This study provides comprehensive data on Aeromonas species distribution and environmental traits. The associations revealed among diversity, water type, season, virulence factors and phyllosphere attachment capacity can inform agricultural water standards in novel ways. Moreover, understanding Aeromonas-plant interactions is an important step in advancing food safety of fruit and vegetables.

Radiocaesium in the environment of Fukushima

It has been 10 years since the accident at Fukushima Daiichi nuclear power plant in 2011. Large quantities of ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs were released into the environment, and 80% of ¹³⁷Cs still remains. In addition to the decrease by attenuation, the transfer of ¹³⁷Cs to plants, animals, and humans is decreasing due to movement and changing fractions with elapsed time. The activity concentration of ¹³⁷Cs in the atmosphere has decreased drastically, and the internal radiation dose due to inhalation is negligible. The activity concentration of ¹³⁷Cs in agricultural plants is decreasing due to decontamination of soil, application of potassium, and lower levels in irrigation water. The activity concentration of ¹³⁷Cs in wild animals is decreasing, and shows seasonal variation in wild boars. The activity concentration of ¹³⁷Cs in offshore seawater has decreased to 0.01 Bq l^-1. Therefore, the radiation dose is <1 mSv of the additional radiation dose.

Determination of safe limit for arsenic contaminated irrigation water using solubility free ion activity model (FIAM) and Tobit Regression Model

Irrigation water contaminated with arsenic acts as a potent source of contamination to humans through water-soil-crop-food transfer so quantification of safe limit for irrigation water is also critical. A pot experiment was conducted to determine the safe limit for As contaminated irrigation water with two soil types (alluvial and red) using ten levels of contaminated irrigation water (0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.50, 1.75, 2.0, 2.25 mg L^-1), applied 5 times in rice (Variety: Sushak Samrat),used as a test crop. The results reveal that the different fractions of arsenic in terms of its profusion followed the order F4 > F2 > F5 > F3 > F1 and F4 > F3 > F2 > F5 > F1 across all the doses of As for alluvial soil and red soil respectively. The safe limit of irrigation water in terms of risk assessment expressed as Hazard Quotient (HQ) was at 0.75 mg L^-1 and the solubility FIAM can effectively predict the As content in rice grain in both the soils. The Tobit Regression Model in alluvial soil quantified the safe limit for As in irrigation water from 1.20 to 0.10 mg L^-1 for available soil As 0.25-3.0 mg kg^-1 and in red soil, the range was from 0.10 to 0.40 mg L^-1 for soil As 1.0 to 0.25 mg kg^-1 provided that the As content in rice grain is < 0.4 mg kg^-1. This proved to be an effective protocol for estimation of safe limits after proper validation and calibration.

Assessment of microbial risk during Australian industrial practices for Escherichia coli O157:H7 in fresh cut-cos lettuce: A stochastic quantitative approach

Escherichia coli O157:H7 risk associated with the consumption of fresh cut-cos lettuce during Australian industrial practices was assessed. A probabilistic risk assessment model was developed and implemented in the @Risk software by using the Monte Carlo simulation technique with 1,000,000 iterations. Australian preharvest practices yielded predicted annual mean E. coli O157:H7 levels from 0.2 to -3.4 log CFU/g and prevalence values ranged from 2 to 6.4%. While exclusion of solar radiation from the baseline model yielded a significant increase in concentration of E. coli O157:H7 (-5.2 -log fold), drip irrigation usage, exclusion of manure amended soil and rainfall reduced E. coli O157:H7 levels by 7.4, 6.5, and 4.3-log fold, respectively. The microbial quality of irrigation water and irrigation type both had a significant effect on E. coli O157:H7 concentrations at harvest (p < 0.05). The probability of illness due to consumption of E. coli O157:H7 contaminated fresh cut-cos lettuce when water washing interventions were introduced into the processing module, was reduced by 1.4-2.7-log fold (p < 0.05). This study provides a robust basis for assessment of risk associated with E. coli O157:H7 contamination on fresh cut-cos lettuce for industrial practices and will assist the leafy green industry and food safety authorities in Australia to identify potential risk management strategies.

Global warming impact to River Basin of Blue Nile and the optimum operation of its multi-reservoir system for hydropower production and irrigation

The water resource of the Blue Nile River basin (BNRB) has been under pressure due to growing demands from many users, and the climate change impact. Potential impact of climate change for the maximum, median and minimum projected changes in the simulated streamflow of BNRB by a hydrologic model, VIC, driven by Representative Concentration Pathways climate scenarios, RCP4.5 and RCP8.5, of 4 GCMs (global climate models) downscaled dynamically by a regional climate model, WRF (Weather Research Forecasting) using a one-domain framework that covers the entire NRB for 2041-2070 and 2071-2100. These projected changes in streamflow were used to assess its future water allocations using a stochastic Dual Dynamic Programming (SDDP) algorithm and a hydro-economic model to optimize hydropower production and irrigated agriculture. Overall, it seems the Grand Ethiopian Renaissance Dam (GERD) reservoir will likely not operate at full storage level because the streamflow of BNRB is assumed to be regulated by three upstream reservoirs. The outflow from the reservoir of GERD or BNRB's annual flow at Khartoum is projected to increase under maximum, but is expected to decrease under minimum and median projected changes in streamflow for 2041-2070 and 2071-2100, respectively. Given the annual net benefit obtained from hydropower production and irrigated agriculture of the reservoir is projected to increase (decrease) under the maximum (median and minimum) projected changes in streamflow, the potential climate change impact should be considered in designing and developing the future water resources of BNRB.

Effects on polyphenol profile and antioxidant capacity

Metals in the environment have been an increasing research topic over the past decade, since they can be found in both natural and drinking water, including irrigation of crops and edible plants with contaminated water. The aim of this study was to investigate the uptake of Cr by arugula (Eruca sativa) in a greenhouse experiment, simulating the open field irrigation conditions. We also evaluate the toxic effects of Cr on oxidative stress by measuring the antioxidant capacity and polyphenol profile in the plant. The study examines the irrigation of arugula, during 15 and 21 days, with four Cr (VI) concentrations, ranging from 0 (control) to 250 μg. L⁻¹. Arugula plants were able to accumulate Cr when irrigated during 15 and 21 days in all the Cr concentrations evaluated. The estimated daily intake (EDI) shows that the amount of Cr accumulated by arugula plants does not represent a threat to human health.

Application of Cr levels induced some changes in content, profile and capacity of antioxidants depending on Cr concentration and time of exposure. Taking into account that E. sativa is consumed due to its polyphenol-related health benefits, the allowable Cr limits in irrigation water should be reviewed, in order to maximize health benefits associated with its consumption, and also to improve vegetable quality. Arugula is a valuable and nutritious food, that should not be excluded from a balanced diet. Chromium concentration in irrigation water as well as the speciation forms present in vegetables should be controlled.

Assessment of different nanofiltration and reverse osmosis membranes for simultaneous removal of arsenic and boron from spent geothermal water

One of the factors that determine agricultural crops' yield is the quality of water used during irrigation. In this study, we assessed the usability of spent geothermal water for agricultural irrigation after membrane treatment. Preliminary membrane tests were conducted on a laboratory-scale set up followed by mini-pilot scale tests in a geothermal heating center. In part I, three commercially available membranes (XLE BWRO, NF90, and Osmonics CK- NF) were tested using a cross-flow flat-sheet membrane testing unit (Sepa CF II, GE-Osmonics) under constant applied pressure of 20 bar. In part II, different spiral wound membranes (TR-NE90-NF, TR-BE-BW, and BW30) other than the ones used in laboratory tests were employed for the mini-pilot scale studies in a continuous mode. Water recovery and applied pressure were maintained constant at 60% and 12 bar, respectively. Performances of the membranes were assessed in terms of the permeate flux, boron and arsenic removals. In laboratory tests, the permeate fluxes were measured as 94.3, 87.9, and 64.3 L m^-2 h^-1 for XLE BWRO, CK-NF and NF90 membranes, respectively. The arsenic removals were found as 99.0%, 87.5% and 83.6% while the boron removals were 56.8%, 54.2%, and 26.1% for XLE BWRO, NF90 and CK-NF membranes, respectively. In field tests, permeate fluxes were 49.9, 26.8 and 24.0 L m^-2 h^-1 for TR-NE90-NF, BW30-RO and TR-BE-BW membranes, respectively. Boron removals were calculated as 49.9%, 44.1% and 40.7% for TR-BE-BW, TR-NE90-NF and BW30-RO membranes, respectively. Removal efficiencies of arsenic in mini-pilot scale membrane tests were all over 90%. Quality of the permeate water produced was suitable for irrigation in terms of the electrical conductivity (EC) and the total dissolved solids (TDS) for all tested membranes with respect to guidelines set by the Turkish Ministry of Environment and Urbanisation (TMEU). However, XLE BWRO, CK-NF and NF90 membranes failed to meet the required limits for irrigation in terms of boron and arsenic concentrations in the product water. The permeate streams of TR-BE-BW, TR-NE90-NF and BW30-RO membranes complied with the irrigation water standards in terms of EC, TDS and arsenic concentration while boron concentration remained above the allowable limit.

Effect of microcystins at different rice growth stages on its yield, quality, and safety

Microcystins (MCs) in water for irrigation may damage crop growth and enter food chains to threaten human health. To evaluate the potential risk of irrigation water contaminated with MCs, we exposed rice at each of the seedling, booting, and filling stages to irrigation water spiked with MCs at 1, 10, 100, and 1000 μg/L for 7 days. Afterwards, all rice underwent a recovery (without MCs) till the harvest. Low MCs (1 or10 μg/L) during different rice growth stages did not affect its yield and nutritional quality and had no risk to human health. High-concentration MCs (100 or 1000 μg/L) during the seedling or booting stage caused a larger decrease in the nutritional quality and yield of rice grains than that during the filling stage. In addition, MCs at 100 μg/L during the booting stage or at 1000 μg/L during the filling stage potentially threatened human health. The effect of MCs on rice yield, quality, and health risk was associated with the MC concentration and rice growth stage. Irrigation water contaminated with moderate-concentration MCs should be of concern at the early growth stage of rice.

Evaluation of chromium in vegetables and groundwater aptness for crops from an industrial (leather tanning) sector of South India

The main objective of the present study is evaluation of groundwater aptness for crops and chromium concentration in vegetables from an industrial (leather tanning) sector of South India using geospatial techniques. Seventy groundwater samples were collected from the open and tube wells during November 2017, February 2018, May 2018 and September 2018 to represent northeast (NE) monsoon (October-December), post-monsoon (winter) (January-February), pre-monsoon (summer) (March-May) and southwest (SW) monsoon (June-September) seasons, respectively. In addition, vegetables were also collected during the above-mentioned seasons from the market to assess the level of chromium content in them. All the groundwater samples were tested in the chemical laboratory using the American Public Health Association norms for various physicochemical parameters, viz. TDS, pH, sodium, potassium, calcium, magnesium, bicarbonate, chloride, sulfate, nitrate, fluoride and chromium. Northeast and southwest monsoon season samples mostly represented 'high to very high saline' and 'low alkaline' categories of irrigation water. However, post- and pre-monsoon samples represented 'high to very high saline' and 'low to medium alkaline' categories. 'High saline and low alkaline' water could be used for irrigation in all types of soil with less problem of exchangeable sodium. However, 'very high saline' water should not be applied for the crops having poor salt tolerance and soils having poor internal drainage. The concentration of chromium in groundwater and vegetables was within the permissible limits for human intake prescribed by the World Health Organization standards.

Detection of Cyclospora cayetanensis in produce irrigation and wash water using large-volume sampling techniques

The recent increase of reported cyclosporiasis outbreaks associated with fresh produce has highlighted the need for understanding environmental transmission of Cyclospora cayetanensis in agricultural settings and facilities. Conducting such environmental investigations necessitates robust sample collection and analytical methods to detect C. cayetanensis in water samples. This study evaluated three sample collection methods for recovery of C. cayetanensis oocysts from water samples during seeded recovery experiments. Two filtration-based methods, dead-end ultrafiltration (DEUF) and USEPA Method 1623.1, were evaluated for oocyst recovery from irrigation water. A non-filter-based method, continuous flow centrifugation (CFC), was evaluated separately for recovery from creek water and spent produce wash water. Median C. cayetanensis recovery efficiencies were 17% for DEUF and 16-22% for Method 1623.1. The DEUF method proved to be more robust than Method 1623.1, as the recovery efficiencies were less variable and the DEUF ultrafilters were capable of filtering larger volumes of high-turbidity water without clogging. Median C. cayetanensis recovery efficiencies for CFC were 28% for wash water and 63% for creek water, making it a viable option for processing water with high turbidity or organic matter. The data from this study demonstrate the capability of DEUF and CFC as filter-based and non-filter-based options, respectively, for the recovery of C. cayetanensis oocysts from environmental and agricultural waters.

Occurrence and human health risk assessment of antibiotics and their metabolites in vegetables grown in field-scale agricultural systems

The occurrence of antibiotics (ABs) in four types of commercially grown vegetables (lettuce leaves, tomato fruits, cauliflower inflorescences, and broad bean seeds) was analyzed to assess the human exposure and health risks associated with different agronomical practices. Out of 16 targeted AB residues, seven ABs belonging to three groups (i.e., benzyl pyrimidines, fluoroquinolones, and sulfonamides) were above the method detection limit in vegetable samples ranging from 0.09 ng g^-1 to 3.61 ng g^-1 fresh weight. Data analysis (quantile regression models, principal component and hierarchical cluster analysis) showed manure application, irrigation with river water (indirect wastewater reuse), and vegetable type to be the most significant factors for AB occurrence in the targeted crops. Metabolites were detected in 70 of the 80 vegetable samples analyzed, and their occurrence was both plant- and compound-specific. In 73 % of the total samples, the concentration of AB metabolites was higher than the concentration of their parent compound. Finally, the potential human health risk estimated using the hazard quotient approach, based on the acceptable daily intake and the estimated daily intake, showed a negligible risk for human health from vegetable consumption. However, canonical-correspondence analysis showed that detected ABs explained 54 % of the total variation in AB resistance genes abundance in the vegetable samples. Thus, further studies are needed to assess the risks of antibiotic resistance promotion in vegetables and the significance of the occurrence of their metabolites.

Quality assessment and potential health risk of heavy metals in leafy and non-leafy vegetables irrigated with groundwater and municipal-waste-dominated stream in the Western Region, Ghana

Vegetables cultivated in soil irrigated with untreated groundwater and municipal-waste-dominated (MWD) stream can elevate the concentration of heavy metals (Cd, Fe, Zn, Hg, Cr, and Ni) in edible parts of the crop, affecting food safety and public health worldwide. This study assessed the quality, sources, and distribution of heavy metals in surface soils, MWD stream and groundwater, and edible tissues of leafy and non-leafy vegetables from a major urban farm in the Sekondi-Takoradi metropolis, Ghana. Human health risk due to exposure to the metals in frequently consumed vegetables were investigated. Indigenous leafy vegetables (Corchorus olitorious and Amaranthus spinosus), exotic leafy vegetables (Lactuca sativa, Brassica oleracea, and Brassica rapa), and non-leafy vegetables (Capsicum annum, Raphanus sativus, Daucus carota, and Allium cepa) were collected from the urban farm. The mean concentration of Cd, Hg, and Fe ranged from 0.008 - 0.027, 0.001-0.013, and 4.517-36.178 mg/kg fw in edible parts of non-leafy vegetables, respectively and 0.011-0.035, 0.002-0.011, and 3.617-13.695 mg/kg fw in exotic or indigenous leafy vegetables. The vegetables were less impacted with the metals if compared to similar vegetables produced from other urban farms, locally and in some countries in Africa, Asia, and Europe. Water resource on the farm were not suitable for vegetable crop irrigation since mean concentration of E. coli (200 cfu/mL), Hg (0.009 mg/L), and Cd (0.019 mg/L) in the MWD stream and 80 % of the groundwater sources exceeded the safe limits recommended by the Food and Agriculture Organization. Geo-accumulation index for each metal in soil was ≤0, however, enrichment factor indicated a high anthropic enriched soil for Cr and Ni. Principal component analysis-multiple linear regression of the metals in soil identified mixed household waste/fertilizer, fertilizer, and crustal material as main sources for the heavy metal load in soil for which geogenic sources accounted for 74.3 %. Preferentially, Cd and Hg accumulated in Amaranthus spinosus, Daucus carota, and Corchorus olitorious. The estimated daily intake of each metal in the vegetables were below local and international daily dietary intake levels. At the 95th percentile concentration of each metal, target hazard quotient and the hazard index was <1 for adult male or female who consume the vegetables. Finally, appropriate agri-horticultural practices must be enforced to mitigate Cd, Ni, Cr, and Hg accumulation in the soil-vegetable system since the metals have profound adverse effect on human health.

Hydro-chemical and microbiological pollution assessment of irrigation water in Kızılırmak Delta (Turkey)

The Kızılırmak Delta is one of the most important agricultural production regions and it was included as part of the Ramsar Convention in 1998. The water used in agricultural irrigation is mostly supplied from drainage channels. In the present study, 120 water samples were collected from drainage channels and analyzed to characterize the groundwater chemistry and microbiological contamination. Sea water interface, discharge of sewage, wastewater from agricultural activities and livestock and uncontrolled solid waste landfills were identified as the most important pollutant sources in the delta. Serious microbiological pollution was detected in channel water samples. These results indicate that sewage waters mix with the channel waters in the delta. Also, the correlations of parameters such as EC, TDS, DO, Cl^- and SO₄^2- indicate that channel waters contain high dissolved minerals. It was concluded that especially agricultural pollution and waste water affects water resources negatively in the region.

Applying Quantitative Microbial Risk Assessment Model in Developing Appropriate Standards for Irrigation Water

This study aimed to apply a quantitative microbial risk assessment (QMRA) model to estimate the annual risk probability of Salmonella infection associated with the consumption of crops, which were irrigated with raw wastewater abstracted by farmers without official permission. Data generated from the model were used to propose realistic standards for Salmonella in irrigation water needed for safe crop production. Results demonstrated the presence of total coliforms, fecal coliforms, fecal streptococci, and Salmonella in wastewater samples. Salmonella was recorded on lettuce and spinach in 3 different harvesting events, although it was not found in data obtained for parsley plant. The QMRA scenario included surface irrigation, consumption of raw crops, and 1-day withholding period before harvest. The annual risk probability of Salmonella infection for consumers exceeded the target tolerable risk (7.7 × 10-4 ) for investigated crops. The Pearson's correlation coefficient between different annual risk probabilities showed significant correlation (p < 0.05). The levels of risk posed from spinach and lettuce were roughly similar, although they tended to be higher for lettuce. The optimum concentrations of Salmonella in irrigation water needed to satisfy the World Health Organization guidelines of disease burden (disability-adjusted life years 10-6 ) per person per year ranged from 34 to 119 via multiple-tube fermentation technique/100 mL, for spinach and lettuce plants, respectively. The study concluded that unofficial reuse of wastewater in irrigation is a principle route for crop contamination. Water quality monitoring programs should be integrated with QMRA investigations for better estimation of risk level. The fit parameters used could be tailored to cover a wide array of local situations in different countries. Models applied for viruses, helminths, and bacteria other than Salmonella are encouraged in future studies. Integr Environ Assess Manag 2020;16:353-361. © 2019 SETAC.

Microplastics in agricultural soils on the coastal plain of Hangzhou Bay, east China: Multiple sources other than plastic mulching film

Microplastic contamination in agroecosystems raises great concerns. Here, we investigated the impacts of mulching and irrigation on microplastic accumulation in cropped soils. Sixty soil samples covering mulching and no-mulching farmlands, and forty-five irrigation water samples were collected for analysis. Microplastics were obtained from the soils using continuous air flotation followed by density separation. Stereomicroscopy and micro-Fourier transform infrared spectroscopy (μ-FTIR) were used for identification. Mulching soils contained larger amounts of microplastics than non-mulching soils, with 571 pieces kg^-1 and 263 pieces kg^-1, respectively, on average. The abundances of films and fibers were significantly (p < 0.05) higher in the mulching soils. Microplastics in the soils and waters were dominated by fragments and fibers, respectively. The particle size of the microplastics in soils mostly ranged from 1 to 3 mm, and primarily from 90 μm to 1 mm in waters. Multiple polymers, e.g. polyethylene, polypropylene, polyester, rayon, acrylic and polyamide, and shapes found in the soil microplastics indicate contributions from irrigation and plastic waste residues other than plastic mulching. Future studies might include the long-term accumulation of microplastics in agroecosystems from multiple sources under intensively managed cropping systems.

Elimination of cyanobacteria and microcystins in irrigation water-effects of hydrogen peroxide treatment

Cyanobacterial blooms pose a risk to wild and domestic animals as well as humans due to the toxins they may produce. Humans may be subjected to cyanobacterial toxins through many routes, e.g., by consuming contaminated drinking water, fish, and crop plants or through recreational activities. In earlier studies, cyanobacterial cells have been shown to accumulate on leafy plants after spray irrigation with cyanobacteria-containing water, and microcystin (MC) has been detected in the plant root system after irrigation with MC-containing water. This paper reports a series of experiments where lysis of cyanobacteria in abstracted lake water was induced by the use of hydrogen peroxide and the fate of released MCs was followed. The hydrogen peroxide-treated water was then used for spray irrigation of cultivated spinach and possible toxin accumulation in the plants was monitored. The water abstracted from Lake Köyliönjärvi, SW Finland, contained fairly low concentrations of intracellular MC prior to the hydrogen peroxide treatment (0.04 μg L^-1 in July to 2.4 μg L^-1 in September 2014). Hydrogen peroxide at sufficient doses was able to lyse cyanobacteria efficiently but released MCs were still present even after the application of the highest hydrogen peroxide dose of 20 mg L^-1. No traces of MC were detected in the spinach leaves. The viability of moving phytoplankton and zooplankton was also monitored after the application of hydrogen peroxide. Hydrogen peroxide at 10 mg L^-1 or higher had a detrimental effect on the moving phytoplankton and zooplankton.

Nano-TiO2 enhances the adsorption of Cd(II) on biological soil crusts under mildly acidic conditions

Biological soil crusts (BSCs), which are ubiquitous in paddy fields, are known to remove pollutants from paddy fields systems. The Nano-TiO₂ enhanced the removal of Cd(II) by BSC under acidic irrigation water was found, and its mechanism was investigated. After the addition of nano-TiO₂, the Cd(II) removal efficiency of BSC_S increased by 26.70% than that of pure BSCs, and the Nano-TiO₂ induced faster removal velocity as well. Zeta potential and potentiometric titration results revealed that BSCs generated more negative charges and sites concentration after addition of Nano-TiO₂ at acidic environment. The carboxyl and amino/hydroxyl groups were the main functional groups on BSC and the BSC + TiO₂. The higher concentration of amino/hydroxyl groups in BSC + TiO₂ (0.33 ± 0.08 mmol/g) was present than that of pristine BSCs (0.62 ± 0.02 mmol/g), and they were with similar concentration of phosphate groups and carboxyl groups. This result was attributed to the Nano-TiO₂ stimulated the BSCs to produce more extracellular polysaccharides and proteins. Our findings would provide novel strategy for the removal of cadmium from acidic irrigation water.