Pesticides In Agricultural Soils Research Articles

Tolerance of pesticides and antibiotics among beneficial soil microbes recovered from contaminated rhizosphere of edible crops.

A total of 45 beneficial soil bacterial isolates (15 each of Pseudomonas, Azotobacter and phosphate solubilizing bacteria: PSB) recovered from polluted rhizosphere soils were morphologically and biochemically characterized. Bacterial isolates produced indole-3-acetic acid (IAA), phenolate siderophores; SA (salicylic acid) and 2, 3-dihydroxy benzoic acid (2, 3-DHBA), 1-amino cyclopropane 1-carboxylate (ACC) deaminase, solubilised insoluble phosphate (Pi), secreted exopolysaccharides (EPS) and produced ammonia and cyanogenic compound (HCN). Isolates were tested for their tolerance ability against 12 different agrochemicals (chemical pesticides) and 14 antibiotics. Among Pseudomonas, isolate PS1 showed maximum (2183µgmL-1) tolerance to all tested agrochemicals. Likewise, among all Azotobacter isolates (n=15), AZ12 showed maximum (1766µgmL-1) while AZ7 had lowest (950µgmL-1) tolerance ability to all tested agrochemicals. Moreover, among phosphate solubilizing bacterial isolates, maximum (1970µgmL-1) and minimum (1308µgmL-1) tolerance to agrochemicals was represented by PSB8 and PSB13 isolates, respectively. The antibiotic sensitivity/resistance among isolates varied considerably. As an example, Pseudomonas spp. was susceptible to several antibiotics, and inhibition zone differed between 10mm (polymyxin B) to 34mm (nalidixic acid). Also, isolate PS2 showed resistance to erythromycin, ciprofloxacin, methicillin, novobiocin and penicillin. The resistance percentage to multiple antibiotics among Azotobacter isolates varied between 7 and 33%. Among PSB isolates, inhibition zone differed between 10 and 40mm and maximum and minimum resistance percentage to multiple antibiotics was recorded as 47% and 20%, respectively. The persistence of pesticides in agricultural soil may contribute to an increase in multidrug resistance among soil microorganisms. In conclusion, plant growth promoting (PGP) substances releasing soil microorganisms comprising of inherent/intrinsic properties of pesticides tolerance and antibiotics resistance may provide an attractive, agronomically feasible, and long-term prospective alternative for the augmentation of edible crops. However, in future, more research is needed to uncover the molecular processes behind the development of pesticide tolerance and antibiotic resistance among soil microorganisms.

Assessment of the potential risk of leaching pesticides in agricultural soils: study case Tibasosa, Boyacá, Colombia

Agricultural soils need monitoring systems to address pesticide risks for humans and the environment. The purpose of this paper was to obtain leaching risk maps of the pesticides imidacloprid, lambda-cyhalothrin, and chlorpyrifos in agricultural soil under an onion (Allium cepa L.) crop in Tibasosa, Boyacá, Colombia. This was obtained by studying the soil types in the area, analyzing the behavior of pollutants in the soil profile, using a delay factor and an attenuation factor to finally include GIS allowing visualization of the areas of greater potential risk in the study area.

Estimation of the Most Widespread Pesticides in Agricultural Soils Collected from Some Egyptian Governorates

Pesticides are usually used in agriculture practice for field and post-harvest protection, whereas their prolonged persistence in the environment may lead to high toxicity to humans and animals. Therefore, the aim of this study was to investigate the detection of different pesticide residues in agricultural soil samples collected from four Egyptian governorates. A total of forty agricultural soil samples were collected during the period from April to June 2020. Samples were extracted using a QuEChERS method and analyzed using gas chromatography-mass spectrometry. Data revealed that agricultural soil samples from Damietta governorate were highly contaminated (80.00%) by different pesticide residues, followed by Fayoum (40.00%), Menia (36.36%), and Alexandria (10.00%) governorates. The pesticide residues detected in soil samples belonged to the following chemical groups; triazole (21.43%), organophosphate, neonicotinoid, and pyrethroid (10.71%), and others. Among the insecticides detected in soil samples from Damietta governorate were malathion, acetamiprid, and methomyl at concentrations of 10.315, 0.725, and 0.395 mg/kg respectively. The fungicide carbendazim was also detected in soil samples from Damietta governorate at a concentration of 18.303 mg/kg. Meanwhile, in Alexandria governorate, no fungicides were detected in soil samples. The herbicide, oxyfluorfen was detected in soil samples from Menia governorate, whereas pendimethalin and thiobencarb were detected in soil samples from Damietta governorate. Data also revealed that herbicides were not detected in soil samples from both Alexandria and Fayoum governorates. This study shed light on the presence of different pesticide residues in agricultural soil samples in Egypt, and which may affect agricultural products grown on contaminated agricultural soil.

A new, simple, efficient and robust multi-residue method based on pressurised-liquid extraction of agricultural soils to analyze pesticides by liquid chromatography coupled with a high resolution quadrupole time-of-flight mass spectrometer

ABSTRACT A new method for the analysis of pesticides in agricultural soils by using liquid chromatography coupled with a high-resolution quadrupole time-of-flight mass spectrometer (LC-QTOF-MS) has been developed. Twenty-four pesticides including herbicides, insecticides or fungicides have been studied. The linearity of the external calibration of the pesticides obtained from levels of concentration ranging from 0.010 to 400 µg/Lgives satisfactory results with the correlation coefficients higher than 0.99. The quantification limits of the equipment range from 0.010 to 1.250 µg/L and correspond to the lowest standard in the calibration range for which the residual deviation is less than 60%. An experimental design has been used to optimise the parameters of pressurised-liquid extraction (PLE) of pesticides in soils. The optimised conditions have been found by using methanol as extraction solvent at a temperature of 80°C, a pressure of 150 Bars and 2 extraction cycles of 5 minutes. The mean recoveries of pesticides (Mean) are higher than 72% with a relative standard deviation(RSD) less than 21%. These results demonstrate the good efficiency of PLE for the extraction of pesticides in agricultural soils of different nature. The LC-QTOF-MS is a sensitive, linear and robust instrument for the quantification of pesticides in unpurified soil extracts by external calibration. This analytical tool is not subjected to matrix effects of soil extracts.

REVITALIZATION OF PESTICIDE-POLLUTED AGRICULTURAL SOIL FUNCTIONS BY MICROBIOME TRANSPLANTATION

The continuous application and often the overuse of pesticides in agricultural soils influence in time soil microbiota abundance and metabolic activities, with final potential negative effects on soil functioning. Recently, bioaugmentation has emerged as an advantageous method for revitalizing agricultural soils affected by chemicals use. In this study, the hypothesis that transplantation of soil cores with optimal microbiota community structure could serve in affected soil microbiota restoration and pesticides degradation enhancement was evaluated. To assess soil core transplantation efficiency, in this study were investigated implication of soil microbiota structure and abundance in pyrethroids degradation in soil, as well pyrethroids impact on soil microbiota metabolic activity. The presence of pyrethroid pesticides as cypermethrin, deltamethrin and fenvalerate in agricultural soils from Turda was evidenced within range of 119 845 g.kg-1. They negatively impacted both soil bacterial and fungal community abundance, decreasing them with approximately 50%. The impact of transplanted soil cores on both soil microbiota abundance as well on cypermethrin, deltamethrin and fenvalerate concentration was also evidenced. A revitalization of microbiota abundance in contaminated soil was observed after transplant (increase with 1.5-fold generally). These data positively sustain that affected soil microbiota due to use of pyrethroid pesticide could be revitalized through transplant of soil cores with no contamination.

Plants affect the dissipation and leaching of anilide pesticides in soil mesocosms: Insights from compound-specific isotope analysis (CSIA)

The soil-plant system can act as a prevailing zone of pesticide dissipation in agroecosystems, which may influence pesticide leaching following rainfall events. Here we examined the contribution of leaching, dissipation and degradation of widely used anilide pesticides in planted and unplanted mesocosms with contrasting vineyard and forest soils. The mesocosms were spiked at 25 mg/kg with acetochlor, alachlor, S-metolachlor, butachlor and metalaxyl, and followed-up for 75 days. Successive rainfalls were applied on days 45, 60 and 75 to collect pesticide leachates. Bulk soil and rhizosphere samples were collected to evaluate pesticide dissipation. Up to 14% of initially spiked pesticides was exported by leaching. The first rainfall accounted for 69–99% of the total pesticide leaching. Pesticide dissipation in soil mesocosms on day 75 ranged from 58 to 99% and was larger in planted than in unplanted mesocosms. Compound-specific stable isotope analysis (CSIA) of the pesticides showed that biodegradation in both the vineyard and forest soil mesocosms occurred mainly in the soil solution that was leached following rainfall events rather than in the bulk soil. Changes in carbon isotope values (Δδ13C up to 13.9 ± 0.5‰) of acetochlor, alachlor, S-metolachlor and butachlor in leachates were more pronounced in planted than in unplanted mesocosms, indicating predominant pesticide degradation in the planted mesocosms. Pesticide biodegradation was favoured in the soil solution of soil-plant systems, independently of the soil type. Leaching of the soil solution, pesticide ageing and biodegradation in the bulk soil and the rhizosphere were the main processes of pesticide dissipation. Overall, this study emphasizes the variability of leaching and degradation of anilide pesticides in agricultural soils, and proposes a framework using CSIA to examine the contribution of dissipation processes in soil-plant systems.

GEODISPONIBILIDAD DE ELEMENTOS POTENCIALMENTE TÓXICOS EN SUELOS AGRÍCOLAS QUE REPRESENTAN RIESGO PARA EL AMBIENTE Y LA SALUD DE LA POBLACIÓN DEL NEVADO DE TOLUCA, MÉXICO

In the Nevado de Toluca, Mexico the indiscriminate use of pesticides for food production (principally potato) has generated negative impacts on the physical and chemical properties of soil, which represents an imminent risk to environmental and human health. The objective of this study was to evaluate the total concentration and geoavailability fraction of the main potentially toxic elements (As, Pb and Cd) from the most used pesticides in agricultural soils of the Nevado de Toluca. The determination of heavy metals (Pb and Cd) was carried out by atomic emission spectroscopy with inductive coupling and in the case of the As, by atomic absorption spectroscopy with hydride generation. The results revealed a considerable total concentration of potentially toxic elements in the area whose geoavailabilityis evident. Therefore, there is evidence of global in the short term by the abuse of pesticides in this important region of the Nevado of Toluca, Mexico.

Combined effects of mulch film-derived microplastics and atrazine on oxidative stress and gene expression in earthworm (Eisenia fetida)

With the wide use of mulch film and pesticides, mulch film-derived microplastics are very likely to produce combined effects with pesticides in agricultural soil. However, little is known about their combined toxicity on terrestrial organisms. This study aimed to investigate the combined toxicity of unused or farmland residual transparent low-density polyethylene mulch film-derived microplastics (MPs and MPs-aged, respectively) (550–1000 μm) and atrazine (ATZ; 0.02 and 2.0 mg/kg) on the earthworm (Eisenia fetida). After single and combined exposure to ATZ and microplastics for 28 d, the results showed an accumulation of reactive oxygen species, a decrease in superoxide dismutase, catalase, and glutathione-S-transferase activities, an increase in the malondialdehyde and 8-hydroxydeoxyguanosine levels, and abnormal expression of annetocin, heat shock protein 70, translationally controlled tumor protein and calreticulin genes. Integrated biological response (IBR) values calculated at the biochemical level indicated that the combined exposure to ATZ and microplastics, particularly to high concentrations of ATZ, induced greater oxidative stress in E. fetida compared with that of exposure to ATZ or microplastics alone. In addition, the IBR values calculated at the gene level did not show regular changes after combined exposure to ATZ and microplastics compared with those of a single exposure. The oxidative stress and abnormal expression of genes in E. fetida induced by MPs-aged were higher than those induced by MPs; a similar trend was observed for oxidative stress induced by MPs/MPs-aged + ATZ2.0, whereas an opposite trend was observed for the abnormal expression of genes in E. fetida induced by MPs/MPs-aged + ATZ0.02/ATZ2.0. Our results suggest that mulch film-derived microplastics have the potential to enhance the toxicity of ATZ within the soil environment.

Influence of plant beneficial Stenotrophomonas rhizophila strain CASB3 on the degradation of diuron-contaminated saline soil and improvement of Lactuca sativa growth.

Diuron is one of the major hazardous pollutants which posses severe risk to the environment and human healthiness. On the other hand, salinity is the most severe environmental stressor that limits crop productivity. Therefore, it is required to address this co-existing abiotic stresses in agricultural soil. Plant growth-promoting rhizobacteria have gained an engaging role in the degradation of pesticides in agricultural soil. However, their role against the restoration of diuron-contaminated saline soil is still not known. Thus, in this study, diuron-degrading, salinity-tolerant Stenotrophomonas rhizophila strain CASB3 was isolated and characterized. Strain CASB3 showed important PGP traits under normal and diuron or salt stresses. Complete degradation of 10-50mgL-1 diuron in the aqueous medium under normal and salinity stress conditions was achieved within 48-120h and 48-192h, respectively. A unique pathway for diuron biodegradation was proposed based on GC-MS analysis. In a greenhouse study, CASB3 inoculated into diuron-contaminated saline soil efficiently degraded diuron (50mgkg-1) by 94% in 42days and simultaneously resulted in an enhancement of root-shoot length (47.22-63.41%), fresh-dry biomass (136.36-156.66%), and photosynthetic pigments (36.93-92.28%) in Lactuca sativa plants. These results suggest the strain CASB3 could be used as a bioresource for the reclamation of diuron-contaminated saline soils.

Does in vitro selection of biocontrol agents guarantee success in planta? A study case of wheat protection against Fusarium seedling blight by soil bacteria.

Biological control is a great hope for reducing the overutilization of pesticides in agricultural soils. It often involves microorganisms or molecules produced by microorganisms that will be able to interact with either a plant or pathogens of this plant to reduce the growth of the pathogen and limit its negative impact on the host plant. When new biocontrol products are developed, strains were mostly selected based on their ability to inhibit a pathogen of interest under in vitro conditions via antagonistic effects. Strains with no in vitro effect are often discarded and not tested in planta. But is the in vitro selection of bacterial agents according to their antagonism activities towards a plant pathogen the best way to get effective biocontrol products? To answer this question, we used wheat and the fungal pathogen Fusarium graminearum as a study pathosystem model. A library of 205 soil bacteria was screened in 2 types of in vitro growth inhibition tests against F. graminearum, and in an in planta experiment. We find strains which do not have inhibition phenotypes in vitro but good efficacy in planta. Interestingly, some strains belong to species (Microbacterium, Arthrobacter, Variovorax) that are not known in the literature for their ability to protect plants against fungal pathogens. Thus, developing a biocontrol product against F. graminearum must be preferentially based on the direct screening of strains for their protective activity on wheat plants against fungal diseases, rather than on their in vitro antagonistic effects on fungal growth.

Distribution and health risk assessment of organochlorine pesticides in agricultural soils of the Aghili plain, Southwest Iran

Organochlorine pesticides (OCPs) are a well-known group of persistent man-made chemicals. In the present study, 55 agricultural soil samples were collected from the Aghili plain and analyzed for 20 OCPs with the aim of determining contamination profiles, spatial distribution, influencing factors and carcinogenic risks. Among different OCPs, only aldrin, dieldrin, 4,4-dichlorodiphenyldichloroethylene, and 4,4-dichlorodiphenyldichloroethane were detected. The other OCPs dosages were lower than the detection limit in all samples. The results of cancer risk assessment demonstrated no carcinogenic risks to an exposed population.

Dampak Residu Pestisida Terhadap Kepadatan Dan Keanekaragaman Jamur Tanah Pada Lahan Sayuran

The use of pesticides in agricultural soils in addition to a positive impact because it has a phytoponic effect for plants, also cause negative impacts on the environment. Pesticide residues in agricultural soils may cause disruption to the growth and diversity of useful microorganisms in the soil such as soil fungi. Fungi play an important role in nutrient cycling, disease control, binding of soil particles and as a remodel in the soil web chain. This research was conducted in farmer's land of Noelbaki village, Kupang Tengah sub-district, Kupang regency. The purpose of this research is to know the residue content of pesticide, population density and soil fungi diversity on vegetable land applied by pesticide and without pesticide. The research method is survey and sampling of soil on vegetable land application of pesticide and without pesticide soil type Vertisol and Inceptisol. The pesticide used as reference for test of active ingredient profenofos 500 g / l, lamda-cilhalotrin 106 g / l, permethrin 20.04 g / l, carbosulfan 200,11 g / l, dimetoate 400 g / l, mankozeb 80% and propineb 70% from classes of pyrethroids, carbamates and organophosphates. Analysis of pesticide residues on soil samples of soil pesticides Vertisol and Inceptisol detected residues of Lamda-cihalotrin and Dimethoat with concentrations of 0.060 ppm and 0.042 ppm respectively. Pesticide residue in the soil is below the BMR of 0.10 ppm. Population density analysis of Vertisol and Inceptisol soil type soil samples respectively (NV-1) 71.6 cfu g-1 and (NI-1) 21.6 cfu g-1 and without pesticides respectively (NV-2) 16.6 cfu g-1 and (NI-2) 29.2 cfu g-1. The analysis of soil pesticide soil diversity of Vertisol and Inceptisol soils respectively (NV-1) 1,608 (NI-1) 1,579 and without pesticide respectively (NV-2) 1.584 and (NI-2) 1,595. Result of analysis of medium soil fungi diversity where H> 1. The types of fungi that are identified are Penicillium, Aspergillus niger, Aspergillus candidus, Aspergilus flavus, Aspergilus nidulans, Fusarium, Trichoderma, and Mucor.

Geochemical determination and pollution assessment of heavy metals in agricultural soils of south western of Iran.

Soil contamination with heavy metals due to the application of fertilizers and biocides in agricultural activities is a potential threat for human health through the food chain. The present work was designed to study the spatial distribution of heavy metals, pollution level and possible reasons for their contamination in agricultural soils of Aghili plain, Khuzestan, Iran. The median concentrations of As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V, Zn, and Hg were 2.90, 0.29, 8.10, 39.0, 17.75, 354.0, 0.97, 58.35, 5.90, 34.0, 42.0, and 0.01mg/kg, respectively. The results revealed that average concentrations of all studied heavy metals with an exception of Co, Cu, and Ni, were lower than background values. Analysis of source identification showed that Zn, Pb, and Cu (P < 0.01, r > 0.9) and Co, Cr, Mn, Ni, and V (P < 0.01, r > 0.7) were mainly from anthropogenic. In addition, Cd probably was originated from agricultural activities (application of manure and phosphorous fertilizers). Enrichment factor values of all metals (except Ni), were in the range of non to moderate enrichment (EF < 5). According to the degree of contamination (Cd) and ecological risk factor (ERF), all stations were categorized as low to moderate contaminated sites (4.5 < Cd < 17), and biological communities in some locations may be at risk (ERF >65). Results indicate that application of fertilizers, herbicides and pesticides in agricultural soils has led to soil contamination and special management and educational plans are needed for public and farmers to prevent further adverse effects.

Does sea-dyke construction affect the spatial distribution of pesticides in agricultural soils? – A case study from the Red River Delta, Vietnam

The Red River Delta is a major agricultural production area of Vietnam with year-round use of pesticides for paddy rice cultivation and other production systems. The delta is protected from flooding, storm surges and saline water intrusion by a sophisticated river and sea-dyke system. Little is known about the effects of such a dyke system on pesticide pollution in the enclosed landscape. Our aim was to address this gap by i) determining pesticide prevalence in soils and sediments within a dyked agricultural area, and by ii) assessing whether and to which degree this dyke system might affect the spatial distribution of pesticides. After sampling paddy rice fields (topsoil) and irrigation ditches (sediment) perpendicular to the dyke in Giao Thuy district, we analysed 12 of the most commonly used pesticides in this area. In soils, we detected most frequently isoprothiolane (100% detection frequency), chlorpyrifos (85%) and propiconazole (41%) while in sediments isoprothiolane (71%) and propiconazole (71%) were most frequently found. Maximum concentrations reached 42.6 μg isoprotiolane kg−1 in soil, and 35.1 μg azoxystrobin kg−1 in sediment. Our results supported the assumption that the dyke system influenced residue distribution of selected pesticides. More polar substances increasingly accumulated in fields closer to the sea-dyke (R2 = 0.92 for chlorpyrifos and 0.51 for isoprothiolane). We can thus support initiatives from local authorities to use the distance to dykes as a mean for deliniating zones of different environmental pollution; yet, the degree at which dykes influence pesticide accumulation appear to be compound specific.

Adsorbing vs. Nonadsorbing Tracers for Assessing Pesticide Transport in Arable Soils

Core Ideas Atrazine preferential flow shortly after application was governed by soil type. Injection of atrazine at depth enhanced preferential flow. Uranine realistically illustrated the rapid and significant atrazine breakthrough. In reserve, bromide mimicked early atrazine breakthrough only with moraine soil. Using dye tracers as pesticide surrogates might assist in making sustainable decisions. The suitability of two different tracers to mimic the behavior of pesticides in agricultural soils and to evidence the potential for preferential flow was evaluated in outdoor lysimeter experiments. The herbicide atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] was used as a model compound. Two tracers were used: a nonadsorbing tracer (bromide) and a weakly adsorbing dye tracer (uranine). Two soils that are expected to show a different extent of macropore preferential flow were used: a well‐drained sandy‐loamy Cambisol (gravel soil) and a poorly drained loamy Cambisol (moraine soil). Conditions for preferential flow were promoted by applying heavy simulated rainfall shortly after pesticide application. In some of the experiments, preferential flow was also artificially simulated by injecting the solutes through a narrow tube below the root zone. With depth injection, preferential leaching of atrazine occurred shortly after application in both soil types, whereas with surface application, it occurred only in the moraine soil. Thereafter, atrazine transport was mainly through the porous soil matrix, although contributions of preferential flow were also observed. For all the application approaches and soil types, after 900 d, &lt;3% of the applied amount of atrazine was recovered in the drainage water. Only uranine realistically illustrated the early atrazine breakthrough by transport through preferential flow. Uranine broke through during the first intense irrigation at the same time as atrazine. Bromide, however, appeared earlier than atrazine in some cases. The use of dye tracers as pesticide surrogates might assist in making sustainable decisions with respect to pesticide application timing relative to rainfall or soil potential for preferential flow.

Residue patterns of currently, historically and never-used organochlorine pesticides in agricultural soils across China and associated health risks

Organochlorine pesticides (OCPs) with different usage states, such as currently, historically or never used, may show different behaviors and potential risks in the environment. It is essential to identify their distribution patterns and fates and to assess their associated health risks to humans. In this study, based on a nationwide sampling campaign across China, we determined the concentrations of currently (endosulfan), historically (chlordane and heptachlor) and never-used (aldrin, dieldrin and endrin) OCPs in agricultural soils. The total residue inventories of ∑Endosulfans, ∑Chlordanes, heptachlor and ∑Drins in soils were 260, 64.3, 54.2 and 88.6 t, respectively. The residues of endosulfan were influenced by current usage, showing a latitude transect trend. Drins were mainly from long-range transport, but the illegal usage in China still affected their residues. This finding indicates that endosulfan and drins in Chinese agricultural soils mainly follow the primary and secondary distribution pattern, respectively. Both primary and secondary distribution have a great impact on the distribution pattern of chlordane, which had been banned for only 4 years at the time we sampled. The health risks of these OCPs were estimated based on their concentrations. There were 0.813% and 1.63% of samples that exceeded the target values for chlordane and endrin according to the Netherlands guideline for unpolluted soil. Their residues in most of the samples posed no or few non-carcinogenic and carcinogenic risks to human beings. The results from this study will provide powerful support for pollution control and management.

Effect of controlled release formulations of diuron and alachlor herbicides on the biochemical activity of agricultural soils

The use of pesticides in agriculture is essential because it reduces the economic losses caused by pests, improving crop yields. In spite of the growing number of studies concerning the development and application of controlled release formulations (CRFs) of pesticides in agricultural soils, there are no studies about the effects of such formulations on the biochemical properties. In this paper the dissipation of diuron and alachlor in three agricultural soils for 127days, applied either as commercial or CRFs, was determined as well as their concomitant effects on soil biochemical properties. Dehydrogenase, urease, β-glucosidase and phosphatase activities were measured thought the experimental period. The application of alachlor as CRF increases its half-life time in soils, whereas no differences were noticed between diuron formulations due to its slower degradation, which takes longer than its release from the CRF. At the end of the incubation period, the enzymatic activities were the same after the use of diuron either as commercial or CRF, recovering the soil previous status. For alachlor formulations, no differences in enzymatic activities were again observed between both formulations, but their levels in soils were enhanced. Therefore, the use of these CRFs does not adversely affect the soil biochemical properties.

Phthalate esters and organochlorine pesticides in agricultural soils and vegetables from fast-growing regions: a case study from eastern China.

The present study investigated phthalate esters (PAEs) and organochlorine pesticides (OCPs) in agricultural soils and vegetables from eastern China. The concentrations of PAEs ranged from 109 to 5560ng/g in soils and 60.1 to 2390ng/g in cabbages, with average concentrations of 946 and 601ng/g, respectively. The concentrations of OCPs ranged from <0.1 to 662ng/g in soils and <0.1 to 42.8ng/g in cabbages, with average concentrations of 134 and 11.6ng/g, respectively. OCPs were mainly in the 0-30cm surface soil layers, while PAEs could infiltrate in deep soil profiles to 70-80cm layer. Potential source analysis traced the occurrence of OCPs to both historical application and current usage, whereas building materials and agricultural plastic film were possible input sources of PAEs in the ambient environment. OCPs showed no apparent effect on soil microbial communities, whereas significant negative relationship was observed between PAEs and fungi in soils (R=-0.54, p<0.01). Human health risk assessment data revealed marginal noncarcinogenic risks and low carcinogenic risks in these soils. Notably, PAEs posed a comparable or higher risk level compared with that of OCPs. This study suggests the need for better regulation on pollution control and management of PAE-elevated sites to protect soil quality and food safety.

Sorption-desorption mechanisms of imazapic and imazapyr herbicides on biochars produced from agricultural wastes

Interest in biochar application as soil amendment for mitigation of environmental contaminants is increasing considerably. However, there is still limited knowledge on how biochar influences immobilization of polar pesticides in agricultural soils. In this study, sorption and desorption of two polar persistent herbicides, imazapic and imazapyr, were evaluated in a rice field soil amended with oil palm empty fruit bunches (EFB) and rice husk (RH) biochars produced in different temperatures. The obtained results indicate that addition of biochars to the soils (1% (w/w)) could enhance both herbicides sorption. The extent of the effects, however, was found to be different in various biochars and herbicides. The biochars derived from EFB showed higher capabilities in sorption of both herbicides rather than RH biochars. The importance of pyrolysis temperature was determined based on the resultant biochar functionality. The outcomes of biochars elemental analyses, cation exchange capacity (CEC) values and fourier transform infrared spectroscopy (FTIR) spectra indicate that lower conversion temperature (300°C) increases materials surface functional groups. Therefore, low temperature biochars were found to be more efficient in sorption of polar molecules. The EFB biochars produced in 300°C was the most effective biochar which enhanced the sorption of imazapic and imazapyr up to 59.90% and 69.94%, respectively. It can be concluded that the biochars sorption properties were directly controlled by production variables (feedstock kind and pyrolysis temperature) and the sorption mechanisms were determined based on the physicochemical characteristics (polarity, hydrophilicity and ionizability) of the sorbate molecules.

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.