Effects of two different organic amendments addition to soil on sorption-desorption, leaching, bioavailability of penconazole and the growth of wheat (Triticum aestivum L.)

Uptake kinetics and distribution of flupyrimin by rice (Oryza sativa L.): Effects of subcellular fractionation and soil factors

Flupyrimin is an emerging neonicotinoid insecticide primarily used to control rice planthoppers. However, knowledge gaps exist regarding its uptake and transport in rice planting systems. Elucidating the absorption and distribution properties of flupyrimin in rice will help assess the potential risks of human exposure to flupyrimin via the food chain. Here, we studied the uptake kinetics and transport mechanisms of flupyrimin in rice plants grown under hydroponic and soil conditions. The hydroponic experiment indicated that flupyrimin was easily taken up by rice roots via a symplastic passive diffusion process and was mainly distributed in the cell soluble fractions (50.6 %－88.0 %). Compared with transportation from the roots to the stems, flupyrimin was ultimately transported from the stems to the leaves with a greater translocation factor (TF) (TFLeave/Stem = 27.8 > TFStem/Root = 3.1). In rice-soil systems, the accumulation of flupyrimin by rice plants is influenced primarily by the soil organic matter content, which leads to increased adsorption of flupyrimin onto soils (R2 > 0.897, P < 0.014). Interestingly, the concentration of flupyrimin in rice was significantly positively correlated with its amount in the soil pore water (CIPW) (R2 > 0.967, P < 0.003), indicating that the uptake and accumulation of flupyrimin in rice planting systems can be estimated by CIPW. These findings enhance our knowledge of flupyrimin absorption and distribution in rice plants from treated soils and are important for guiding its field application and conducting environmental risk assessments.

Uptake, translocation, and metabolism of thiamethoxam in soil by leek plants

Thiamethoxam (TMX) is commonly applied on leek plants by root irrigation. It might be taken up by leek plants and thus has lasting dietary risk. In this study, the uptake, translocation, and metabolism of TMX in leek plants were investigated. The results obtained from both the hydroponic and soil experiments indicated that TMX could be easily translocated upward and accumulated in leek shoots after being absorbed by roots. The total absorbed TMX amount (M_total) in leek plants from the tested soils varied greatly with its adsorption governed by soil characteristics. Interestingly, M_total was closely correlated with the concentration of TMX in in situ pore water, indicating that TMX in in situ pore water could be a useful approach to predict uptake of this chemical by leek plants from various soils. Profoundly, clothianidin (CLO) was detected with concentration of 0.07-1.54 mg/kg in roots and 0.27-4.12 mg/kg in shoots at 14 d, respectively, suggesting that TMX is easily converted into CLO in leek plants. The results showed that TMX used in soil is easily absorbed by leek and accumulated in edible parts accompanying with formation of CLO.

Uptake and translocation of triadimefon by wheat (Triticum aestivum L.) grown in hydroponics and soil conditions

Residual pesticides in soil may be taken in by plants and thus have a risk for plant growth and food safety. In this study, uptake of triadimefon and its subsequent translocation and accumulation were investigated with wheat as model plants. The results from hydroponics indicated that triadimefon was absorbed by wheat roots mainly through apoplastic pathway and predominantly distributed into the water soluble fractions (66.7-76.0%). After being uptaken by roots, triadimefon was easily translocated upward to wheat shoots and leaves. Interestingly, triadimefon in leaves was mainly distributed in the soluble fraction by 52.5% at the beginning, and gradually transferred into the cell wall by 47.2% at equilibrium. The uptake of triadimefon from soils by wheat plants was similar to that in hydroponics. Its accumulation were mainly governed by adsorption of the fungicide onto soils, and positively correlated with its concentration in in situ pore water (C_IPW). Thus, C_IPW can be suitable for predicting the uptake of triadimefon by wheat from soils. Accordingly, uptake of triadimefon by wheat was predicted well by using the partition-limited model. Our study provides valuable information for guiding the practical application and safety evaluation of triadimefon.

Reducing environmental risks of chlorpyrifos application in typical soils by adding appropriate exogenous organic matter: Evidence from a simulated paddy field experiment

Chlorpyrifos (CPF), as an organophosphate insecticide extensively used in the modern agricultural system, has been gradually banned in many countries due to its reported health risks to organisms, including humans. This study used simulated paddy field experiments and carbon-14 tracing to explore the possibility of reducing environmental risks of chlorpyrifos application through appropriate agronomic practice. Results showed ¹⁴C-CPF concentration in rice plants planted in the red soil (RS) was significantly higher than that in black soil (BS) and fluvo-aquic soil (FS). The application of biochar and chicken manure in RS reduced ¹⁴C-CPF accumulation in rice plants, and the content of ¹⁴C-CPF in rice grains decreased by 25% and 50%, respectively. Adding biochar to all three soils reduced the migration of ¹⁴C-CPF, especially in FS with the highest risk of ¹⁴C-CPF migration. The addition of chicken manure in FS reduced the migration of ¹⁴C-CPF and the total residual amount of ¹⁴C-CPF in the soil. In addition, chicken manure treatment increased the formation of ¹⁴C-bound residues (BRs) in soils and changed the distribution ¹⁴C-BRs in humus. The results indicated that the degree of environmental risks associated with the CPF application varies with soil types and could be reduced by introducing suitable exogenous organic matter into different soils, which is of great significance for guiding the scientific application of chlorpyrifos in agronomic practices.

Direct Prediction of Bioaccumulation of Organic Contaminants in Plant Roots from Soils with Machine Learning Models Based on Molecular Structures

Root concentration factor (RCF) is an important characterization parameter to describe accumulation of organic contaminants in plants from soils in life cycle impact assessment (LCIA) and phytoremediation potential assessment. However, building robust predictive models remains challenging due to the complex interactions among chemical-soil-plant root systems. Here we developed end-to-end machine learning models to devolve the complex molecular structure relationship with RCF by training on a unified RCF data set with 341 data points covering 72 chemicals. We demonstrate the efficacy of the proposed gradient boosting regression tree (GBRT) model based on the extended connectivity fingerprints (ECFP) by predicting RCF values and achieved prediction performance with R-squared of 0.77 and mean absolute error (MAE) of 0.22 using 5-fold cross validation. In addition, our results reveal nonlinear relationships among properties of chemical, soil, and plant. Further in-depth analyses identify the key chemical topological substructures (e.g., -O, -Cl, aromatic rings and large conjugated π systems) related to RCF. Stemming from its simplicity and universality, the GBRT-ECFP model provides a valuable tool for LCIA and other environmental assessments to better characterize chemical risks to human health and ecosystems.

Effects of accumulated straw residues on sorption of pesticides and antibiotics in soils with maize straw return

Outspread straw return practice leads to accumulation of structurally diverse organic materials in soils, including raw straw and straw residues. This practice provides a supplementary source of organic sorbents for compounds released into soils. However, effects of accumulated straw materials on sorption of compounds in soils remain poorly understood. Here we report that straw materials accumulated in soils display changing chemical structure and properties during decomposition, the majority of which distribute in exponential growth or decay manners with decomposition extents of materials. Sorption of straw materials toward 40 commonly used pesticides and antibiotics takes a compromise of decreasing crystalline index and increasing water absorption capacity of the sorbent materials during decomposition. This tradeoff in sorption leads to case-specific sorption trends of organic compounds in soils with straw return practice, following a composite linear sorption model of mixed soils and straw materials. The predictive model shows that relatively hydrophobic, hydrogen bond acceptor-rich chemicals (about 22.5% of the 40 compounds) display decreasing sorption capacity in organic matter-rich and/or relatively acidic soils with straw return. This finding may contradict the notion that crop straw return usually increases sorption and decreases leaching of compounds in soils.

Effect of Organic Residues on Pesticide Behavior in Soils: A Review of Laboratory Research

The management of large volumes of organic residues generated in different livestock, urban, agricultural and industrial activities is a topic of environmental and social interest. The high organic matter content of these residues means that their application as soil organic amendments in agriculture is considered one of the more sustainable options, as it could solve the problem of the accumulation of uncontrolled wastes while improving soil quality and avoiding its irreversible degradation. However, the behavior of pesticides applied to increase crop yields could be modified in the presence of these amendments in the soil. This review article addresses how the adsorption–desorption, dissipation and leaching of pesticides in soils is affected by different organic residues usually applied as organic amendments. Based on the results reported from laboratory studies, the influence on these processes has been evaluated of multiple factors related to organic residues (e.g., origin, nature, composition, rates, and incubation time of the amended soils), pesticides (e.g., with different use, structure, characteristics, and application method), and soils with different physicochemical properties. Future perspectives on this topic are also included for highlighting the need to extend these laboratory studies to field and modelling scale to better assess and predict pesticide fate in amended soil scenarios.

Chemical factors affecting uptake and translocation of six pesticides in soil by maize (Zea mays L.)

Uptake of residual pesticides in a soil by a certain crop plant may be governed by their physicochemical properties. Uptake and translocation of pesticides (imidacloprid, acetamiprid, tricyclazole, azoxystrobin, tebuconazole and difenoconazole) with the octanol/water partition coefficient (log K_ow) ranging from 0.57 to 4.36 were investigated in soil with maize as a model plant. The results show that all tested pesticides in soil were uptaken by maize with accumulation amount of 27.73, 17.75, 18.96, 12.56, 10.66 and 2.13 μg for imidacloprid, acetamiprid, tricyclazole, azoxystrobin, tebuconazole and difenoconazole at 14 d, respectively. The accumulation amount was negatively correlated with adsorption coefficients and positively correlated with pesticide concentration in in situ pore water (C_IPW). Root bioconcentration factor varied widely from 0.61 for imidacloprid to 974.64 for difenoconazole was positively correlated with log K_ow and molecular weight but negatively with water solubility. Conversely, translocation factor varied from 0 for difenoconazole to 1.64 for imidacloprid was negatively correlated with log K_ow but positively with water solubility. It determined that uptake, accumulation and translocation of the pesticides in soil by maize are governed by their physicochemical properties, especially log K_ow. C_IPW is an appropriate candidate to evaluate the accumulation of pesticides in maize from soil.

Influence of Glyphosate Formulations on the Behavior of Sulfentrazone in Soil in Mixed Applications

The selection of weed biotypes that are resistant to glyphosate has increased the demand for its use mixed with other herbicides, such as sulfentrazone. However, when chemical molecules are mixed, interactions may occur, modifying the behavior of these molecules in the environment, such as the sorption and desorption in soil. In this study, we hypothesized that the presence of glyphosate-formulated products might increase the sorption or decrease the desorption of sulfentrazone, thereby increasing the risk of the contamination of water resources. Therefore, our work aimed to evaluate the sorption, desorption, and leaching of sulfentrazone in the soil in an isolated and mixed application with different glyphosate formulations. The sorption coefficients (Kfs) for the sulfentrazone, sulfentrazone + Roundup Ready, sulfentrazone + Roundup Ultra, and sulfentrazone + Zapp Qi foram were 1.3, 2.1, 2.3, and 1.9, respectively. The desorption coefficients (Kfd) for the sulfentrazone, sulfentrazone + Roundup Ready, sulfentrazone + Roundup Ultra, and sulfentrazone + Zapp Qi foram were 65.7, 125.2, 733.3 and 239.8, respectively. The experiments demonstrated that the sorption and desorption of sulfentrazone in combination with the other formulated glyphosate products are altered, supporting the hypothesis suggested by this work, i.e., that the presence of other molecules is a factor that affects the behavior of herbicides in the soil. This phenomenon altered the vertical mobility of sulfentrazone. Situations involving mixtures of pesticides should be evaluated in order to improve our understanding of the dynamics of these molecules and thus avoid environmental contamination.

An analysis of the versatility and effectiveness of composts for sequestering heavy metal ions, dyes and xenobiotics from soils and aqueous milieus

The persistence and bioaccumulation of environmental pollutants in water bodies, soils and living tissues remain alarmingly related to environmental protection and ecosystem restoration. Adsorption-based techniques appear highly competent in sequestering several environmental pollutants. In this review, the recent research findings reported on the assessments of composts and compost-amended soils as adsorbents of heavy metal ions, dye molecules and xenobiotics have been appraised. This review demonstrates clearly the high adsorption capacities of composts for umpteen environmental pollutants at the lab-scale. The main inferences from this review are that utilization of composts for the removal of heavy metal ions, dye molecules and xenobiotics from aqueous environments and soils is particularly worthwhile and efficient at the laboratory scale, and the adsorption behaviors and effectiveness of compost-type adsorbents for agrochemicals (e.g. herbicides and insecticides) vary considerably because of variabilities in structure, topology, bond connectivity, distribution of functional groups and interactions of xenobiotics with the active humic substances in composts. Compost-based field-scale remediation of environmental pollutants is still sparse and arguably much challenging to implement if, furthermore, real-world soil and water contamination issues are to be addressed effectively. Hence, significant research and process development efforts should be promptly geared and intensified in this direction by extrapolating the lab-scale findings in a cost-effective manner.

Transport of 14C-prosulfocarb through soil columns under different amendment, herbicide incubation and irrigation regimes

This study sets out to evaluate the effect on the leaching of prosulfocarb through packed soil columns of applying green compost (GC) as an organic amendment (20% w/w), herbicide ageing over 28 days in the soil (incubation vs. no incubation), and two different irrigation regimes (saturated or saturated-unsaturated flows). Peak concentrations decreased after herbicide incubation in the columns for both unamended (S) and amended (S + GC) soils under both flow regimes. The leached amounts decreased when the herbicide was incubated for 28 days in S (2.1 and 1.9 times) and S + GC (2.9 and 1.6 times), under saturated or saturated-unsaturated flow, respectively. In the S columns, the total amounts retained (43.3%-60.8%) were lower than the ones obtained for the S + GC columns under saturated flow (77.4%-85.2%), suggesting a stronger interaction between the herbicide and the GC-amended soil. This behaviour was not observed under saturated-unsaturated flow, as the total amounts retained were similar in both the S and S + GC columns. Prosulfocarb was primarily retained in the first segment of the S (>28%) and S + GC (>43%) columns under all conditions. Incubation time did not greatly affect the herbicide retention, but it significantly increased the mineralized amount under saturated flow. The total balances of ¹⁴C-prosulfocarb were >73% and >80% in the S and S + GC columns, respectively, indicating that amendment decreased prosulfocarb loss by volatilization. Several factors, such as amendment, herbicide ageing and water flow, proved to be important for controlling the leaching of this herbicide through the soil profile.

Adsorption-desorption behavior of carbendazim by sewage sludge-derived biochar and its possible mechanism

Biochar application in agricultural soil for environmental remediation has received increasing attention, however, few studies are focused on sewage sludge based biochar. The present study evaluated the effect of raw sewage sludge and sewage sludge based biochars produced at different pyrolysis temperatures (100-700 °C) on the adsorption-desorption of carbendazim in soil. Sewage sludge derived biochar significantly enhanced the sorption affinity and limited the desorption capacity of the soil for carbendazim. A maximum removal efficiency of 98.9% and a greatest value of 144.05 ± 0.32 μg g-1 sorption capacity occurred in soil amended with biochar pyrolyzed at 700 °C (BC700). As the pyrolysis temperature and the amendment rate of biochars increased, the sorption of carbendazim was promoted and desorption was further inhibited. The adsorption-desorption hysteresis index of carbendazim was consistently higher in soils amended with biochars (>0.85) than in the unamended soil (0.42-0.68), implying that carbendazim could be immobilized in soil amended with sewage sludge derived biochars. The partition effect was dominant in the sorption process for carbendazim in the biochar-soil mixtures. This study will be helpful for the disposal of sewage sludge and its utilization, and it is the first report for the study the sorption-desorption process of carbendazim in soil amended with sewage sludge derived biochar. Furthermore, these findings may be also useful for understanding the distribution and transport of carbendazim in the environment and will be of great significance in remediation strategies for contaminated soil.

Accumulation and toxicological effects of nonylphenol in tomato (Solanum lycopersicum L) plants

Nonylphenol (NP) is one of the most worrisome and ubiquitous environmental endocrine disruptors. The tomato is one of the most important agricultural plants in the world. However, little is known about the toxicological effects of NP on tomato crops or the accommodative responses of tomato plants to NP stress. Thus, in this study, relevant tests were performed using pot experiments, and they indicated that when the NP concentration in the soil was elevated from 25 mg kg-1 to 400 mg kg-1, NP was progressively accumulated by the tomato plants. The NP induced growth inhibition and a declined in the total chlorophyll content, and it aggravated membrane lipid peroxidation in tomato plants. When confronted with NP stress, the tomato plants correspondingly induced their antioxidant enzymes via both molecular and protein pathways to relieve the NP-induced oxidative stress. All the above results would be illuminating for developing strategies to address NP-induced damage to agricultural output, food quality and public health.

Improved prediction of the bioconcentration factors of organic contaminants from soils into plant/crop roots by related physicochemical parameters

There has been an on-going pursuit for relations between the levels of chemicals in plants/crops and the source levels in soil or water in order to address impacts of toxic substances on human health and ecological quality. In this research, we applied the quasi-equilibrium partition model to analyze the relations for nonionic organic contaminants between plant/crop roots and external soil/water media. The model relates the in-situ root concentration factors of chemicals from external water into plant/crop roots (RCF(water)) with the system physicochemical parameters and the chemical quasi-equilibrium states with plant/crop roots (αpt, ≤1). With known RCF(water) values, root lipid contents (flip), and octanol-water Kow's, the chemical-plant αpt values and their ranges of variation at given flipKow could be calculated. Because of the inherent relation between αpt and flipKow, a highly distinct correlation emerges between log RCF(water) and log flipKow (R2 = 0.825; n = 368), with the supporting data drawn from 19 disparate soil-plant studies covering some 6 orders of magnitude in flipKow and 4 orders of magnitude in RCF(water). This correlation performs far better than any relationship previously developed for predicting the contamination levels of pesticides and toxic organic chemicals in plant/crop roots for assessing risks on food safety.

Recycling organic residues in soils as amendments: Effect on the mobility of two herbicides under different management practices

The addition of organic residues to soil to increase its organic matter content is considered as a viable option for sustainable food production in soils sensitive to degradation and erosion. However, the recycling of these organic residues in agricultural soils needs to be previously appraised because they can modify the behaviour of pesticides when they are simultaneously applied in agricultural practices. This study evaluated the changes in the mobility and persistence of two herbicides, triasulfuron and prosulfocarb, after two repeated applications in field experimental plots in an unamended soil and one amended with green compost (GC) for seven months. Different factors were studied: i) soil without amendment (S), ii) soil amended with two doses of GC (∼12 t C ha^-1, S + GC1 and 40 t C ha^-1, S + GC2), and iii) soils unamended and amended with different irrigation conditions: non-irrigated and with additional irrigation (2.8 mm per week). After the first application of herbicides, the results initially indicated no significant effects of soil treatments or irrigation conditions for triasulfuron mobility in agreement with the residual concentrations in the soil profile. The effect of irrigation was noted after one month of herbicide application and the effect of the soil treatment was significant after two months because the persistence of triasulfuron in S + GC2 was maintained until 50% of the applied amount. For prosulfocarb, the influence of soil amendment was significant for the initial persistence of the herbicide in S + GC2, higher than in S or S + GC1, in agreement with its adsorption constants for this soil. However, dissipation or leaching of the herbicide over time was not inhibited in this soil. After the repeated application of herbicides, the influence of the treatment of soils and/or irrigation was significant for the leaching and dissipation of both herbicides. The initial dissipation/degradation or leaching of herbicides was higher than after the first application, although persistence was maintained after five months of application in amended soils for triasulfuron and in unamended and amended soils for prosulfocarb. The results confirm that high doses of GC increased the persistence of both herbicides. This practice may offer the possibility of applying a tailored dose of GC to soil for striking a balance between residual concentrations and the soil agronomic effect.

Effects of earthworm casts on sorption-desorption, degradation, and bioavailability of nonylphenol in soil

Up to hundreds of milligrams per kilogram (dry weight) of nonylphenol (NP) reportedly entered the soil and sediment through the agricultural reuse of biosolids, pesticide application, etc. Organic pollutants in soil could not only further trigger groundwater contamination via leaching (that highly depends upon sorption-desorption and degradation phenomena) but also harm food safety by crop uptake (that mainly rests with the bioavailability of pollutants in soil). Thus, we first investigated the effects of earthworm casts (EWCs) on the sorption-desorption, degradation, and bioavailability of NP in soil under laboratory microcosm conditions, and then, analyzed the FT-IR spectra of EWC and soil samples (with and without EWC). The application of EWC could notably increase the sorption capacity of soils for NP and in turn significantly inhibited the desorption of NP from soil; responsively lengthened the half-time of NP in the soil; and reduced the uptake and translocation of NP in tomato seedlings and promoted their growth during the first 3 weeks. Finally, FT-IR spectra of EWC and soil samples indicated that the application of EWC increased the content of N, P, and organic matter in soil.

Impact of Spent Mushroom Substrates on the Fate of Pesticides in Soil, and Their Use for Preventing and/or Controlling Soil and Water Contamination: A Review

Intensive crop production involves a high consumption of pesticides. This is a cause of major environmental concern because the presence of pesticides in water is becoming increasingly common. Physicochemical methods based on soil modification with organic residues have been developed to enhance the immobilization and/or degradation of pesticides in agricultural soils, which may control both the diffuse and the point pollution of soils and waters. This review summarizes the influence of spent mushroom substrate (SMS) on the environmental fate of pesticides when both are simultaneously applied in agriculture. The processes of adsorption, leaching and dissipation of these compounds in SMS-amended soils were evaluated at laboratory and field scale. Relationships were established between the experimental parameters obtained and the properties of the soils, the SMS, and the pesticides in order to determine the effect that the application of SMS in agricultural soils has on the environmental impact of pesticides. Accordingly, this review highlights the use of SMS as a strategy for the prevention and/or control of soil and water contamination by pesticides to strike a balance between agricultural development and the use of these compounds.