Effect of long-term application of treated sewage water on heavy metal accumulation in vegetables grown in northern India

Comprehensive environmental impact assessment and irrigation wastewater suitability of the Arab El-Madabegh wastewater treatment plant, ASSIUT CITY, EGYPT

The presence of a wastewater treatment plant in the Arab El-Madabegh region, which discharges excessive amounts of raw effluent toward the nearby farming fields, is the area's main issue. Examining the harmful implications of raw effluent releases on groundwater quality, determining if treated wastewater effluent complies with regulations for discharge into the aquatic environment, and assessing irrigation appropriateness by the effluent are the main goals of this work. In order to accomplish these targets, twelve treated effluent samples from the Arab El-Madabegh wastewater treatment plant were gathered every two weeks starting in January 2012 and finishing in June 2012. They were tested to determine pH, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Temperature (Temp), Conductivity (EC), Turbidity (Turb.), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Organic Carbon (TOC), NO3-, SO42-, Cl-, Ca2+, PO43-, HCO3-, Na+, Mg2+, and heavy metals such as (Fe, Mn, K+, Cr, Pb, Zn, Ni, Cu, and Cd). The outcomes revealed that all Egyptian and Food and Agricultural Organization (FAO) standards for unrestricted irrigation were met by the treated effluents, except for COD, which exceeded than the Egyptian allowed limit. The evaluation indices of the effluent's EC, SAR, PI, MR, and MH were in the low-risk category according to indicators of water quality for irrigation, nevertheless, The SSP and RSC both showed slightly higher values (67.9% and 2.76, respectively). As well, The average values of heavy metals in treated wastewater effluent were found to be below permitted limits, with the exception of lead and phosphate, which exceeded permissible limits in Egypt. The environmental sustainability (ecological friendliness) of reusing and recycling tertiary treated wastewater can be achieved in agriculture to reduce the adverse impacts on the aquatic environment.

Increased health risk assessment in different vegetables grown under untreated sewerage irrigation regime due to higher heavy metals accumulation

Heavy metals are environmental pollutants and carcinogenic for human health if ingested. In developing countries, including Pakistan, untreated sewerage water is one of the major sources of irrigation for vegetable production in the vicinities of urban areas which might be toxic to human health due to heavy metals contamination. The present study was conducted to investigate the uptake of heavy metals by sewage water application and its impact on human health. The experiment consisted of five vegetable crops (Raphanus sativus L, Daucus carota, Brassica rapa, Spinacia oleracea, and Trigonella foenum-graecum L.) and two irrigation sources (clean water irrigation and sewage water irrigation). Each treatment was three time replicated for all five vegetables, and standard agronomic practices were applied. The results demonstrated that shoot and root growth in radish, carrot, turnip, spinach, and fenugreek was enhanced significantly with sewerage water, probably due to enhanced organic matter. However, pithiness was observed in the root of radish under sewerage water treatment. Very high concentrations of Cd, up to 7.08 ppm in turnip roots while up to 5.10 ppm in fenugreek shoot, were observed, and other vegetables also contained higher concentrations of Cd. Zn concentrations in the edible parts of carrot (control (C) = 129.17 ppm, sewerage (S) = 164.10 ppm), radish (C = 173.73 ppm, S = 253.03), turnip (C = 109.77 ppm, S = 149.67 ppm), and fenugreek (C = 131.87 ppm, S = 186.36 ppm) were increased by sewerage water treatment but a decrease in Zn concentration in spinach (C = 262.17 ppm, S = 226.97 ppm) was observed. Fe concentration in edible parts of carrot (C = 888.00 ppm, S = 524.80 ppm), radish (C = 139.69 ppm, S = 123.60 ppm), turnip (C = 195.00 ppm, S = 121.37 ppm), and fenugreek (C = 1054.93 ppm, S = 461.77 ppm) were also decreased by sewerage water treatment while spinach leaves had accumulated higher Fe (C = 1560.33 ppm, S = 1682.67 ppm) in sewerage water treatment. The highest bioaccumulation factor value was 4.17 for Cd in carrots irrigated with sewerage water. The maximum value of bioconcentration factor was 3.11 for Cd in turnip under control, and the highest value of translocation factor was 4.82 in fenugreek irrigated with sewerage water. Daily intake of metals and health risk index (HRI) calculation indicated that HRI for Cd was more than 1, suggesting toxicity in these vegetables while HRI for Fe and Zn is still under safe limit. Correlation analysis among different traits of all vegetables under both treatments revealed valuable information for selecting traits in the next crop breeding programs. It is concluded that untreated sewerage-irrigated vegetables, highly contaminated with Cd, are potentially toxic for human consumption and should be banned in Pakistan. Furthermore, it is suggested that the sewerage water should be treated to eliminate toxic compounds, particularly Cd, before irrigation usage and non-edible/phytoremediation crops might be grown in contaminated soils.

Optimizing textile dyeing wastewater for tomato irrigation through physiochemical, plant nutrient uses and pollution load index of irrigated soil

Reuse of wastewater for vegetable cultivation is becoming popular in order to augment the inadequate irrigation supplies and meet the growing demands of ground water for agriculture and industries production in different regions of the world. This study was investigated to optimize different stages of textile dyeing wastewater (TDW) for irrigation focusing on their effect on growth, yield and physiochemical attributes of tomato, plant nutrient use, heavy metals enrichment and pollution load of the irrigated soil. Textile wastewater were collected from the seven stages of (second wash after scouring and bleaching T2; enzyme treated water T3; second wash after bath drain T4; neutralization treatment T5; second wash after soaping T6; fixing treatment water T7; mixed effluent T8) of a dyeing process for physiochemical characterization and evaluation their irrigation feasibility for tomato cultivation in compare with the ground water (T1). The pot experiment consists of eight irrigation treatments was laid out following a completely randomized block design with three replications. Results showed the presence of plant nutrients and heavy metals in all the studied samples where T8 (mixed effluent) exceeded the limit of agricultural standard for almost all physiological parameters such as TDS, TSS, EC, BOD, COD affording the highest value. T8 also delivered the highest Cl- and heavy metals like Cd, Ni, Cr followed by T4 < T7. As a consequence, these provided comparatively higher enrichment factor (EF), pollution load index (PLI) and sodium absorption ratio (SAR) to transform fresh soil into the category of severe and slightly to moderate saline. Therefore, the yield and physiochemical attributes of tomato were dramatically reduced with T8 and T4 treatment. On the other hand, T2, T3 and T6 treatment had significant positive impact on growth and yield of tomato due to having higher N, P, K, S and lower heavy metals (Cu, Zn, Fe, Pb, Cd, Ni, Cr) than the recommended guideline. These features were contributed to cause minimum EF and PLI in the soil irrigated with T2, T3 and T6 stages of TDW. Correlation matrix demonstrated that EF and PLI of heavy metals (except Cd, Ni) were negatively related to yield, while positively related to SAR and fruit abortion. Although T6 (2nd wash after soaping) performed better in respect to growth, yield, yield attributes and nutrient use efficiency, principal component analysis revealed that T2 (2nd wash after scouring and bleaching) and T3 (enzyme treated water) were also belong to the same group of T6 and T1 (ground water). Thus, it may be suggested that T2, T3 and T6 stages of textile dyeing wastewater could be used profitably without ETP for vegetable cultivation and would effectively supplement not only the nutrient requirement of the crop but may also act as the alternate source of irrigation water. Although, further research is needed to sort out the health risk assessment through the heavy metals’ accumulation in the plant parts after irrigation with different stages of textile dyeing wastewater.

Determination of the Physicochemical Quality of Groundwater and its Potential Health Risk for Drinking in Oromia, Ethiopia

This study aimed to determine the physicochemical quality of groundwater and its potential health risk for drinking in Oromia, Ethiopia. The groundwater samples were collected from 17 sampling stations in the dry and wet season in the Sebeta zone, Oromia, from March to August 2020. Metals and physicochemical parameters, and selected heavy metals, such as iron (Fe), copper (Cu), manganese (Mn), chromium (Cr), zinc (Zn), and lead (Pb) were monitored. The data were analyzed using multivariate statistical methods (Pearson's Correlation and T-test). The means seasonal variations were higher in the dry season than in the wet season except for pH and Turbidity. The variation was significant for most parameters except Pb, Zn, chlorine, Total Alkaline, Magnesium Hardness, Calcium Hardness ), and Turbidity. There was a strong and positive correlation between Total dissolved solids (TDS) and Conductivity), (pH and Cr), (T.H. and Magnesium (Mg)), (bicarbonate and Calcium (Ca), (Zn and Turbidity) in the dry season; and (T.H. with Potassium (K), (Pb and Fe); (bicarbonate and T.H.); (Ca and Mg); (Na and T.A.,) in the wet season. The hazard index (H.I.) values in the dry season (HI = 1.331) were higher than in the wet season (HI_adults = 0.075). Likewise, the H.I. (dry season) was higher (HI_children = 1.861) than in the wet season (HI_children = 0.105). Chronic groundwater exposure at drinking sources in the dry season is a potential health risk to humans in general and is relatively high for children. Urgent management and close monitoring are required for drinking groundwater sources and other nearby residents' safety areas.

Appraisal of probabilistic levels of toxic metals and health risk in cultivated and marketed vegetables in urban and peri-urban areas of Delhi, India

A total of six vegetables (S. tuberosum, D. carota, S. lycopersicum, A. esculentus, S. oleracea and B. juncea) were analysed for five heavy metals (As, Cd, Cr, Hg, and Pb) to evaluate the contamination load in vegetables collected from five cultivated and two market sites (n = 504) at Delhi, India. The irrigation water samples and soil samples (n = 180) were only collected from cultivated sites. The results showed that the concentration of heavy metals in soil and water samples were well below the permissible level except for Cd 0.001-0.013 µg g^-1. Similarly, the concentration of Cd (>0.20 µg g^-1) was detected higher in all investigated vegetables except for tomato. The evaluation index value was highest for spinach and lowest for tomato. The transfer factor values and metal pollution index was maximum in spinach and okra. Principal component analysis (PCA), Tukey's HSD (Honestly Significant Difference) test, and one-way and two-way ANOVA (Analysis of Variance) were also applied to statistically analyse the results.

Wastewater irrigation in India: Current status, impacts and response options

Wastewater generated from urban agglomerations in India is estimated to be 26.4 km³ annually and 28% of it is treated. This has a potential to irrigate about 2.1 million-ha agricultural land, contribute 4 million Mg of plant nutrients, generate 2.8 million person-days of employment and reduce green house gas (GHG) emission by 73.7 million Mg CO₂-e. Farmers in peri-urban areas depend largely on raw and partially treated wastewater for livelihood via raising high value crops such as vegetable, fodders and fruits. Both controlled and uncontrolled disposal of waste waters leads to progressive and irreversible contamination of soils, surface and ground waters with pathogens, heavy metals and organic micro-contaminants and consequently their bio-transfer through the chain: sewage-soil-vegetation-animal-humans. This has led to the development of a considerable assortment of regulatory measures and guidelines aimed at reducing or eliminating wastewater related health risks. Because conventional treatment technologies are cost prohibitive, alternate methods based on biological and land treatment systems are being advocated. Since soils are the most logical sinks for wastewater, efforts are to optimise rates and methods of water application, quantify the sink capacity of soils to immobilise contaminants and protect the quality of produce. Reuse of diluted or undiluted wastewaters improves crop productivity by 10-36% though production sustainability depends on soil type, climatic conditions, crop grown, irrigation techniques and socio-political factors. Disposal of wastewater in tree plantations and constructed wetlands with consequent removal of toxic metals/compounds using hyper-accumulators/accumulators plants provide for a possible alternative. Ignoring the associated risks, using pisciculture for sewage disposal is quite popular in high rainfall areas. With growing water scarcities, it is utmost important to recognise wastewaters as a valuable resource and formulate appropriate policy initiatives considering the health and livelihood issues of the per-urban farmers and consumers of food as well as risks to environment.

Trace metal accumulation in pepper (Capsicum annuum L.) grown using organic fertilizers and health risk assessment from consumption

Organic farming and healthy nutrition are among the most popular topics of recent times. However, organic fertilizers, which are one of the important elements of organic agriculture, have the potential to threaten human health with the toxic substances they may contain. The present study aimed to observe the effect of farmyard manure, poultry waste and press mud on metal accumulation in pepper (Capsicum annuum L.) to determine the pollution severity of soil and to examine the health risk due to the consumption of organic fertilizer applied pepper. The multipurpose pot experiment was conducted to study the agronomical growth performance and accretion of metals in C. annuum grown with different organic fertilizers in the soil at the area of the Department of Botany, University of Sargodha, Pakistan. The trace metal contents in soil and C. annuum samples were analysed by atomic absorption spectrophotometer (AA-6300 Shimadzu Japan). Trace metal concentrations in soil samples ranged from 0.152 to 0.850, 2.167 to 5.812, 0.345 to 1.235, 2.682 to 5.875, 0.095 to 0.558, 6.132 to 17.062, 0.172 to 2.235 and 6.670 to 22.585 mg/kg for Cd, Co, Cr, Cu, Pb, Fe, Mn and Zn, respectively. In pepper samples, trace metal concentrations ranged from 0.364 to 2.206, 0.305 to 4.042, 0.272 to 1.160, 1.132 to 1.305, 0.164 to 0.204, 4.736 to 17.000, 0.844 to 1.150 and 14.751 to 18.385 mg/kg for Cd, Co, Cr, Cu, Pb, Fe, Mn and Zn, respectively. The accumulation of Cd and Pb had higher values of HRI than 1 and these values suggested that these metals had probability to cause health problems.

Accumulation of potentially harmful elements (PHEs) in lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.) irrigated with wastewater: a systematic review and meta-analysis and probabilistic health risk assessment

Water shortage and stress around the world lead to increasing wastewater reuse for the agricultural sector. In addition to its benefits, it can be a way to transfer pollutants such as potentially harmful elements (PHEs) to the human food chain. Many studies have been conducted for this purpose on various vegetables; however, no comprehensive study has been performed on lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.). In this respect, the study was aimed to meta-analyze the PHEs concentration in the edible part of lettuce and coriander vegetables irrigated by wastewater. Carcinogenic risk (CR) and noncarcinogenic risk (non-CR) assessments were also done for consumers. After reviewing 32 included articles (41 studies), the rank order of the PHEs in lettuce was obtained as Fe (194.76 mg/kg) > Zn (133.47 mg/kg) > Cu (55.70 mg/kg) > Ni (26.96 mg/kg) > Pb (12.80 mg/kg) > Cr (9.68 mg/kg) Cd (8.24 mg/kg) > As (1.13 mg/kg) and for coriander Fe (1056 mg/kg) > Zn (79.80 mg/kg) > Cr (28.34 mg/kg) > Ni (24.71 mg/kg) > Cu (17.46 mg/kg) > Pb (13.23 mg/kg) > Cd (2.23 mg/kg). Total target hazard quotient (TTHQ) for adults in all countries except UAE, France, and Kenya and for children all countries except Kenya was more than 1 value. The carcinogenic risk for adult groups in Nigeria, France, China, and Iran countries was not acceptable (CR > 1E-4). As a consequence, it can be noted that wastewater reuse in the agriculture sector can endanger the health of consumers.

Occurrence of heavy metal in water, soil, and plants in fields irrigated with industrial wastewater in Sabata town, Ethiopia

Industrial wastes have been increasingly discharged into water and soil, and causing environmental pollution in Ethiopia. This study examined the occurrence of heavy metal in water, soil, and plants in fields irrigated with industrial wastewater in Sabata town, Ethiopia. The composite samples of soil, water, and vegetables were collected accordingly to determine the concentration of heavy metals (Cu, Pb, Zn, Mn, and Ni) in each system during dry and wet seasons. The concentration of heavy metal was assayed using atomic absorption spectrophotometry. The data were statistically analyzed using one-way ANOVA. The heavy metal concentration was decreased in the order of Pb > Mn > Ni > Cu > Zn, Mn > Ni > Pb > Cu > Zn, and Ni > Pb > Mn > Cu > Zn in the water, soil, and vegetables in the area respectively. The variation of levels of heavy metal in the water, soil, and vegetable might be because of the effect of heavy metal speciation and valence, industry types, vegetable types and tissues, and soil. The bioconcentration factor of heavy metals was higher than that one for copper, signifying the increased probability of health risk for those who are consuming vegetables grown in the area. Thus, the government should take this into account and devise mitigation strategies through the implementation of heavy metal removal systems from contaminated water and soil, waste management strategies of recycling, centralized or decentralized treatment plant, changing of industrial residual into biogas production, and awareness creation for the society.

Irrigation water of different sources affects fruit quality attributes and heavy metals contents of un-grafted and commercial mango cultivars

In peri-urban areas, waste water is used to irrigate orchards due to scarcity of fresh water which increases heavy metals contents in soils, leaves and fruits. Due to excessive waste water irrigations, heavy metals enter into the food chain, which eventually causes metabolic disorders in humans. The present study was envisaged to investigate the effects of canal, tubewell and sewage water on the quality of mango fruits and heavy metals accumulation in soils, leaves and fruits. Leaf and fruit samples from an un-grafted (Desi mango) and six commercial cultivars of mango (Anwar Rataul, Aman Dusehri, Sufaid Chaunsa, Samar Bahisht Chaunsa, Kala Chaunsa and Anwar Rataul Late) grafted on Desi mango were collected from different mango orchards located in peri-urban areas of Multan (Pakistan) and analyzed for some physico-chemical attributes and heavy metals contents. Soil samples were also taken from these orchards irrigated with different water sources to assess the soils' heavy metals status. A significant variation was observed among the mango cultivars for their physico-chemical attributes. Sewage water irrigation improved total soluble solids (TSS), titratable acidity, ascorbic acid content, total phenolics, total carotenoids, total flavonoids and antioxidant activity of mango fruits. However, it did not affect fruit weight and shelf life. Among the heavy metals, copper and nickel contents were found in greater amounts in soils, leaves and fruits of sewage water irrigated orchards than canal and tubewell water irrigated ones. However, zinc and cadmium were not detected in any soil, water, leaf or fruit sample. The interaction among the sources of irrigation and the mango cultivars was significant for copper accumulation in different soil layers, copper and nickel accumulation in leaves of different mango cultivars, and fruit weight, titratable acidity, ascorbic acid content, total flavonoids and shelf life of mango fruits.

Evaluation of bacterial contamination and mutagenic potential of treated wastewater from Al-Samra wastewater treatment plant in Jordan

Jordan is one of the lowest countries in the world in terms of water resources. The reuse of treated wastewater is an important alternative to supply agricultural demands for water. In Jordan, Kherbet Al-Samra wastewater treatment plant (KSWWTP) is the largest and its effluent is mainly used for irrigation purposes. In this study, bacterial contamination and mutagenic potential were evaluated in six sites, beginning with KSWWTP and ending with King Tallal Dam. The results showed high contamination with many pathogenic bacteria and coliforms. The isolated pathogenic bacteria were Salmonella sp., Shigella sp., Bacillus cereus and Staphylococcus aureus. The isolated opportunistic pathogenic bacteria were Acinetobacter lwoffii, Elizabethkingia meningosepticum, Pseudomonas fluorescens and Bacillus licheniformis. These bacteria were found in all sampling sites without a specific prevalence pattern. Differences in temperature between seasons affect total coliform and other bacterial count. All water samples showed positive mutagenic activity and high bacterial pollution. Improving the disinfection efficiency in the wastewater treatment plant is important to minimize potential toxicity and exposure of public health to pathogenic bacteria, reduce water resources' contamination and environmental pollution. Increasing effluent sampling frequency from KSWWTP is required to monitor bacterial contamination and toxicity/mutagenicity level for water safety and public health risk assessments.

Prediction models for monitoring heavy-metal accumulation by wheat (Triticum aestivum L.) plants grown in sewage sludge amended soil

Prediction of heavy-metal concentration in the edible parts of economic crops, based on their concentration in soil and other environmental factors, is urgently required for human risk assessment. The present investigation aimed to develop regression models for predicting heavy-metal concentration in wheat plants via their contents in sewage sludge amended soil, organic matter (OM) content and soil pH. The concentration of heavy metals in the plant tissues reflected its concentration in the soil with high Fe followed by Al, Mn, Cr, Zn, Ni, Co, Cu, and Pb. Soil OM content had a significant positive correlation with all investigated heavy-metal concentrations in the different tissues of wheat plants, while soil pH was negatively significant with most heavy metals except spike Pb and grain Cr. The bio-concentration factor of Al, Cu, and Zn from soil to wheat root was >1, while that of shoot, spikes, and grains was <1 for all heavy metals. Significantly valid regression models were developed with fluctuated coefficient of determination (R²), high model efficiency (ME) values and low mean normalized average error (MNAE). The significant positive correlations between the concentration of some heavy metals in the soil and the same in wheat tissues indicate the potential of this plant as a biomonitor for these metals in contaminated soils. The significant correlations between heavy-metal concentrations in soil and its properties (pH and OM) with metal concentrations in wheat plants support the prediction model as an appropriate option. This study recommends the use of models with R² greater than 50% and recommend other researchers to use our models according to their own specific conditions.

Cadmium accumulation, translocation factor, and health risk potential in a wastewater-irrigated soil-wheat (Triticum aestivum L.) system

The accumulation of trace elements in wastewater-irrigated soils may introduce them to the food chain and therefore can threaten human health. The present study investigated the accumulation, translocation factor, and health risk potential of cadmium (Cd) in a soil-wheat system irrigated with treated wastewater compared with a reference soil (irrigated with fresh water). All treated wastewater-irrigated soils showed significantly higher levels of electrical conductivity (EC) than that of reference soil by 75-143%. Irrigation with treated wastewater increased both available and total Cd content in soil by 2-4 times. In all irrigated sites, Cd content was about twice as great as the maximum acceptable rate. Bioconcentration factor (BCF) and translocation factor (TF) indicated that Cd was mainly accumulated in the roots (BCF = 2.2-3.1), while little mobilization from roots to stems and grains was noted (TF_shoot/root = 0.07-0.21; TF_grain/root = 0.18-0.24). The average hazard quotient (HQ) for different age groups of the population varied in the range of 0.1-1.0, implying low non-carcinogenic health risk of Cd to local wheat-consuming residents. The risk of Cd to cause carcinogenic health risk (CR) was in the range of 1 × 10^-5 to 1 × 10^-4, indicating low to moderate potential risk. CR for different age groups was in the order: individuals above 18 years old > individuals 7-18 years old > individuals 0-6 years old. For reducing potential health risks to local people, it is imperative to continuously monitor heavy metal levels in the wheat-soil system and urgently adopt more efficient managerial strategies to reduce Cd contamination.

Toxicological potential of cobalt in forage for ruminants grown in polluted soil: a health risk assessment from trace metal pollution for livestock

The trace metal pollution in the environment is a highly concerned issue in these days. One of the important causes of trace metal pollution is the exhaust gases released from the vehicles on the roads. These dangerous gases pose life-threatening effects on the forage plants grown along the roadside as these plants are at direct risk to these trace metals. The aims of the present study were to determine the cobalt (Co) concentrations in soil, forages, and blood plasma of the buffaloes and to evaluate the Co deficiencies and toxicities in these samples. All samples were collected from six sites (Faisalabad roadside, Bhalwal roadside, Shaheenabad roadside, Mateela roadside, 50 Chak roadside, and Dera Saudi-control) of Sargodha city. The Co concentrations in these samples were determined by atomic absorption spectrophotometer (AA-6300 Shimadzu Japan). In soil samples, Co level ranged from 1.958 to 3.457 mg/kg in the six sampling sites. The highest Co level was observed at site 6 and the lowest at site 2. In forage samples, Co level ranged from 0.770 to 2.309 mg/kg in the six sampling sites. The highest Co level was observed at site 3 and the lowest at site 2. In blood plasma samples, Co level ranged from 2.644 to 4.927 mg/kg in the six sampling sites. The highest Co level was observed at site 1 and the lowest at site 3. The results showed higher Co values in the samples collected from the site IV while the bioconcentration factor for forage-soil was found highest in the samples collected from Site III. On the other hand, a correlation was found positively significant when soil and forage were correlated, and it was found negatively significant when blood and forage were correlated.

Heavy metals in food crops: Health risks, fate, mechanisms, and management

Food security is a high-priority issue for sustainable global development both quantitatively and qualitatively. In recent decades, adverse effects of unexpected contaminants on crop quality have threatened both food security and human health. Heavy metals and metalloids (e.g., Hg, As, Pb, Cd, and Cr) can disturb human metabolomics, contributing to morbidity and even mortality. Therefore, this review focuses on and describes heavy metal contamination in soil-food crop subsystems with respect to human health risks. It also explores the possible geographical pathways of heavy metals in such subsystems. In-depth discussion is further offered on physiological/molecular translocation mechanisms involved in the uptake of metallic contaminants inside food crops. Finally, management strategies are proposed to regain sustainability in soil-food subsystems.

Evaluation of Health Risks due to Heavy Metals in a Rural Population Exposed to Atoyac River Pollution in Puebla, Mexico

The health risks of Emilio Portes Gil’s population, for the exposition to the Atoyac River pollution in the State of Puebla, was evaluated. The objective was to determine the concentration of nine heavy metals by ingesting water from wells and spri ngs. The chronic daily water intake (CDI), hazard quotient (HQ), hazard index (HI), and carcinogenic risk index (CRI) in adults, teenagers, and children were estimated. The results showed that the concentration of Fe, Al, Ni, and Pb in some of the samples exceeded the recommended standards for human consumption and was significantly higher in the dry season. The hazard index (HI), due to the collective intake of metals, was higher in children (> 50% compared to adults), due to the consumption of spring water in the dry season. Risk of noncancerous diseases was not detected in the long term, since the indices did not exceed the unit (reference value). The carcinogenic risk from oral exposure to Cr (CRIchildren = 3.2 × 10−4), was greater than the acceptable limit (1 × 10−6) in the water spring, and Cr and Pb were the main metals that contributed to the potential health risk of the inhabitants. The study showed the risks by the intake of polluted water from the sources of supply in the region, and that the risk is higher in the dry season (> 100% compared with rainy season).

High Content of Lead Is Associated with the Softness of Drinking Water and Raised Cardiovascular Morbidity: A Review

Daily ingestion of lead (Pb), even through piped drinking water, has long time been an important issue of concern, attracting for decades research in environmental science and toxicology, and again comes to prominence because of recent high-profile cases of exposure of populations in several countries to Pb-contaminated water. Numerous studies have reported an association between Pb in water and the risk of cardiovascular pathologies. Low levels of magnesium and calcium, i.e., low degree of hardness of the drinking water, may accentuate Pb leaching from water pipes and furthermore increase Pb absorption. This review evaluates the evidence for an association between Pb exposure from drinking water and cardiovascular end points in human populations.

Elemental distribution in the edible leaves of Celosia trigyna from the western and northern regions of Nigeria

Celosia trigyna, which belongs to the plant family Amaranthaceae, is a plant used in traditional medicine to treat several conditions such as sores, chest pains, diarrhoea and menstrual cramps in many countries in Africa. It is also consumed by the local people in Nigeria as soups, sauces and stews. In this study, the distribution and bioaccumulation of the elements in C. trigyna species and growth soil from the western and northern regions of Nigeria was investigated to determine the effects of geographical location on the uptake of elements by the plant. Elemental concentrations in the leaves from the western region were found to be in decreasing order of Ca > Mg > Fe > Mn > Zn > Cu > Pb > As > Ni. Concentrations of elements in the leaves from the northern region were found to be in decreasing order of Ca > Mg > Fe > Mn > Zn >  Cu > As > Pb > Ni > Co > Cd. Proximate analysis of leaves from both regions compared well with the recommended dietary allowance making the leaves safe for human consumption. Principal component analysis was used to group elements having the same sources irrespective of their geographical locations. Cd, Co and Cr were not detected in the leaves from the western region. Concentrations of As and Pb were above maximum permissible limits in both regions, while Ayegunle and Bida (in the northern region) had the highest concentrations of Cd. The high level of these toxic metals may be attributed to anthropogenic activities. It is therefore important that the Nigerian agricultural extension system emphasizes the dangers of heavy metal contamination in leafy vegetables to farmers. Activities of the manufacturing industries in the study area should be adequately monitored under standard environmental protection laws.

Potential Toxic Metal Accumulation in Soil, Forage and Blood Plasma of Buffaloes Sampled from Jhang, Pakistan

This study was conducted to determine the concentration of toxic metals in soil, forage and blood plasma of lactating and non-lactating buffaloes in the district Jhang, Punjab, Pakistan. Soil samples were collected from varying distances from the road side. Plasma separation was achieved by centrifugation. The concentration of arsenic (As), selenium (Se), cadmium (Cd), chromium (Cr), iron (Fe), zinc (Zn), copper (Cu) and cobalt (Co) were determined by using Atomic Absorption Spectrophotometer. The results of the study showed that the mean As, Se and Cd concentrations in soil samples were lower while Cr, Fe, Zn, Cu and Co were higher than the official guidelines. In plasma samples, mean concentration values of Co, Zn, Fe, Cd, Se and As were lower while Cu and Cr were higher than the recommended concentrations. According to the results of the study there was no potential exposure of toxicity in buffaloes of the study area.

Metal accumulation in Raphanus sativus and Brassica rapa: an assessment of potential health risk for inhabitants in Punjab, Pakistan

Pakistan is an agricultural country and due to the shortage of clean water, most of the irrigated area (32,500 ha) of Pakistan was supplied with wastewater (0.876 × 109 m³/year). Concentrations of heavy metals in radish (Raphanus sativus) and turnip (Brassica rapa) taken from vegetable fields in Sargodha, Pakistan, were measured. Untreated wastewater was used persistently for a long time to irrigate these vegetable fields. A control site was selected that had a history of fresh groundwater irrigation. Mean metal concentrations were found for irrigation water, soil, and vegetables. In irrigation water, concentrations of Mo and Pb at three sites and Se at sites II and III were higher than the recommended limits. In vegetables, concentrations of Mo and Pb were above the maximum permissible limits. High bioconcentration factor was observed for Zn (12.61 in R. sativus and 11.72 in B. rapa) at site I and high pollution load index was found for Pb (3.89 in R. sativus and 3.87 in B. rapa) at site II. The differences in metal concentrations found in samples depended upon different soil nature and assimilation capacities of vegetables at different sites which in turn depended upon different environmental cues. The entrance of metal and metalloids to human body may happen through different pathways; however, the food chain is the chief route through which metals are transferred from vegetables to individuals. Health risk index observed for metals, (Mo, As, Ni, Cu, and Pb) higher than 1 indicated high risk through consumption of these vegetables at three sites.

Comparative performance evaluation of multi-metal resistant fungal strains for simultaneous removal of multiple hazardous metals

In the present study, five fungal strains viz., Aspergillus terreus AML02, Paecilomyces fumosoroseus 4099, Beauveria bassiana 4580, Aspergillus terreus PD-17, Aspergillus fumigatus PD-18, were screened for simultaneous multimetal removal. Highest metal tolerance index for each individual metal viz., Cd, Cr, Cu, Ni, Pb and Zn (500mg/L) was recorded for A. fumigatus for the metals (Cd, 0.72; Cu, 0.72; Pb, 1.02; Zn, 0.94) followed by B. bassiana for the metals (Cd, 0.56; Cu, 0.14; Ni, 0.29; Zn, 0.85). Next, the strains were exposed to multiple metal mixture (Cd, Cr, Cu, Ni, Pb and Zn) of various concentrations (6, 12, 18, 30mg/L). Compared to other strains, B. bassiana and A. fumigatus had higher cube root growth (k) constants indicating their better adaptability to multi metal stress. After 72h, multimetal accumulation potential of B. bassiana (26.94±0.07mg/L) and A. fumigatus (27.59±0.09mg/L) were higher than the other strains at initial multimetal concentration of 30mg/L. However, considering the post treatment concentrations of individual metals in multimetal mixture (at all the tested concentrations), A. fumigatus demonstrated exceptional performance and could bring down the concentrations of Cd, Cu, Ni, Pb and Zn below the threshold level for irrigation prescribed by Food and Agriculture Organization (FAO).

Heavy Metal Pollution in a Soil-Rice System in the Yangtze River Region of China

Heavy metals are regarded as toxic trace elements in the environment. Heavy metal pollution in soil or rice grains is of increasing concern. In this study, 101 pairs of soil and rice samples were collected from the major rice-producing areas along the Yangtze River in China. The soil properties and heavy metal (i.e., Cd, Hg, Pb and Cr) concentrations in the soil and rice grains were analyzed to evaluate the heavy metal accumulation characteristics of the soil-rice systems. The results showed that the Cd, Hg, Pb and Cr concentrations in the soil ranged from 0.10 to 4.64, 0.01 to 1.46, 7.64 to 127.56, and 13.52 to 231.02 mg·kg⁻¹, respectively. Approximately 37%, 16%, 60% and 70% of the rice grain samples were polluted by Cd, Hg, Pb, and Cr, respectively. The degree of heavy metal contamination in the soil-rice systems exhibited a regional variation. The interactions among the heavy metal elements may also influence the migration and accumulation of heavy metals in soil or paddy rice. The accumulation of heavy metals in soil and rice grains is related to a certain extent to the pH and soil organic matter (SOM). This study provides useful information regarding heavy metal accumulation in soil to support the safe production of rice in China. The findings from this study also provide a robust scientific basis for risk assessments regarding ecological protection and food safety.

Heavy Metal Residues in Soil and Accumulation in Maize at Long-Term Wastewater Irrigation Area in Tongliao, China

Soil and plant samples were collected from Tongliao, China, during the maize growth cycle between May and October 2010. Heavy metals, such as Cr, Pb, Ni, and Zn, were analyzed. The concentrations of Cr, Pb, Ni, and Zn in the wastewater-irrigated area were higher than those in the topsoil from the groundwater-irrigated area. The concentrations of metals in the maize increased as follows: Pb < Ni < Zn < Cr. In addition, Cr, Pb, and Ni mainly accumulated in the maize roots, and Zn mainly accumulated in the maize fruit. The results of translocation factors (TF) and bioconcentration factors (BCF) of maize for heavy metals revealed that maize is an excluder plant and a potential accumulator plant and can serve as an ideal slope remediation plant. In addition, the increasing heavy metal contents in soils that have been polluted by wastewater irrigation must result in the accumulation of Cr, Pb, Ni, and Zn in maize. Thus, the pollution level can be decreased by harvesting and disposing of and recovering the plant material.

Assessment of Yamuna and associated drains used for irrigation in rural and peri-urban settings of Delhi NCR

The present study assessed the quality of Yamuna River and the Najafgarh drain water for irrigational purposes in the Delhi region in terms of spatial variations in the physicochemical characteristics as well as heavy metal concentrations. The monitoring was done for the period July 2012-August 2013 representing pre-monsoon, monsoon, and post-monsoon sessions and considering six physicochemical parameters. Heavy metals such as cadmium, chromium, copper, nickel, zinc, and lead have been found in the river due to rampant discharge of industrial effluents into the river. The mean metal concentrations in the 15 sampling sites were in the range of (mg L(-1)) 0.02-0.64 (Cu), 0-0.42 (Cr), 0.13-2.22(Zn), 0.03-0.27 (Pb), 0-0.07 (Cd), and 0.01-0.13 (Ni). Multivariate statistics (PCA and HCA) were used to identify the possible sources of metal contamination and to examine the spatial changes in the Yamuna River as well as in the Najafgarh drain. This study reveals the occurrence of mean Cd concentration above the safe limit at Palla, Christian Ashram and Jagatpur of the Yamuna river while Punjabi Bagh of the Najafgarh drain necessitate treatment in terms of heavy metals such as Cd, Cu, Cr, Ni, Pb, and Zn before it could be rendered useful for irrigation.

Metal pollution of groundwater in the vicinity of Valiathura Sewage Farm in Kerala, south India

A comprehensive study was conducted to evaluate metal pollution of groundwater in the vicinity of Valiathura Sewage Farm in Thiruvananthapuram district, Kerala using the Heavy Metal Pollution Index (HPI). Forty two groundwater samples were collected during the summer season (April 2010) and the concentration of metals Fe, Cu, Zn, Cd and Pb were analyzed. Results showed that groundwater was contaminated mainly with Fe, Cu and Pb. Correlation analysis revealed that the sources of metals in groundwater in the study area are the same, and it may be due to the leachates from the nearby Sewage Farm, Parvathy Puthanar canal and solid wastes dumped in the residential area. Of the groundwater samples studied, 47.62 % were medium and 2.68 % were classified in HPI high category. HPI was highest (41.79) in DW29, which was adjacent to the polluted Parvathy Puthanar canal and Sewage Farm. The present study points out that the metal pollution causes the degradation of groundwater quality around the Sewage Farm during the study period.

Plant uptake of elements in soil and pore water: field observations versus model assumptions

Contaminant concentrations in various edible plant parts transfer hazardous substances from polluted areas to animals and humans. Thus, the accurate prediction of plant uptake of elements is of significant importance. The processes involved contain many interacting factors and are, as such, complex. In contrast, the most common way to currently quantify element transfer from soils into plants is relatively simple, using an empirical soil-to-plant transfer factor (TF). This practice is based on theoretical assumptions that have been previously shown to not generally be valid. Using field data on concentrations of 61 basic elements in spring barley, soil and pore water at four agricultural sites in mid-eastern Sweden, we quantify element-specific TFs. Our aim is to investigate to which extent observed element-specific uptake is consistent with TF model assumptions and to which extent TF's can be used to predict observed differences in concentrations between different plant parts (root, stem and ear). Results show that for most elements, plant-ear concentrations are not linearly related to bulk soil concentrations, which is congruent with previous studies. This behaviour violates a basic TF model assumption of linearity. However, substantially better linear correlations are found when weighted average element concentrations in whole plants are used for TF estimation. The highest number of linearly-behaving elements was found when relating average plant concentrations to soil pore-water concentrations. In contrast to other elements, essential elements (micronutrients and macronutrients) exhibited relatively small differences in concentration between different plant parts. Generally, the TF model was shown to work reasonably well for micronutrients, whereas it did not for macronutrients. The results also suggest that plant uptake of elements from sources other than the soil compartment (e.g. from air) may be non-negligible.

Accumulation of heavy metals in Spinacia oleracea irrigated with paper mill effluent and sewage

The present study on heavy metal contamination in soil and their accumulation in edible part (leaves) and roots of Spinacia oleracea (Spinach) on irrigation with paper mill effluent (PME)/sewage revealed that there was significant increase in the nickel (Ni, +227.17 %) content of the soil irrigated with PME, whereas in the soil irrigated with sewage chromium (Cr, +274.84 %), iron (Fe, +149.56 %), and cadmium (Cd, +133.39 %), contents were increased appreciably. The value of enrichment factor (EF) for Ni (3.27) indicated moderate enrichment in PME-irrigated soil. The EF of Fe, zinc (Zn), Cd, and Cr were <2 in PME effluent-irrigated soil which showed deficiency of minimal enrichment. In sewage irrigated soil, EF value for Cr, Fe, and Cd indicated moderate enrichment, while the values for Zn and Ni indicated deficiency of minimal enrichment. Among various metallic concentrations, the maximum concentration of Fe was observed in leaves (400.12 ± 11.47 mg/kg) and root (301.41 ± 13.14 mg/kg) of S. oleracea after irrigation with PME, whereas the maximum concentrations of Fe was found in leaves (400.49 ± 5.97 mg/kg) and root (363.94 ± 11.37 mg/kg) of S. oleracea after irrigation with sewage for 60 days. The bioaccumulation factor value was found maximum for Cd (2.23) in the plants irrigated with PME while that of Fe (0.90) in the plants irrigated with sewage. The undiluted use of PME/sewage for irrigation increased the concentration of Cr, Cd, Zn, Ni, and Fe metals which were accumulated in S. oleracea, posing a potential threat to human health from this practice of irrigation.