Soil Fungicide Research Articles

Fungicide Sensitivity of Phytophthora Isolates from the Washington Red Raspberry Industry.

Phytophthora rubi is an important pathogen causing Phytophthora root rot of red raspberries worldwide. Management of this disease is partially achieved with fungicides, but efficacy has been low, and growers are concerned about fungicide resistance. To determine whether fungicide resistance is developing, Phytophthora species were isolated from 26 raspberry fields with root rot, identified, and evaluated for sensitivity to four fungicides: mefenoxam, phosphorous acid, oxathiapiprolin, and dimethomorph. The majority of the recovered 152 Phytophthora isolates were P. rubi (143 isolates, 25 fields), with P. megasperma (8 isolates, 2 fields) and P. gonapodyides (1isolate, 1field) being found much less frequently. These results confirm P. rubi as the dominant species affecting the Washington red raspberry industry. Almost all tested isolates were sensitive to all four fungicide chemistries, although three isolates were less sensitive to mefenoxam, with effective concentration for 50% growth inhibition (EC50) values ranging from 3.53 to 100 μg active ingredient/ml. No resistance was detected against current fungicide label rates. However, other reasons were identified for why fungicides have been ineffective. Label rates vary widely by brand, and most fungicides are applied in the fall when P. rubi is inactive. In addition, some phosphorous acid products are only labeled for foliar applications, which have been shown to be less effective than soil applications in other agricultural systems. Efficacy trials are needed to compare foliar and soil fungicide applications at different times of the year for their ability to control Phytophthora root rot in red raspberry production fields.

Efficient and practical in-jar silicone rubber based passive sampling for simultaneous monitoring of emerging fungicides in water and soils

The occurrence and ecological impacts of emerging fungicides in the environment has gained increasing attention. This study applied an in-jar passive sampling device based on silicone rubber (SR) film to measuring the freely dissolved concentration (Cfree) of 6 current-use fungicides as a critical index of bioavailability in water and soils. The kinetics parameters including SR-water, soil-water, and organic carbon-water partition coefficients and sampling rates of the target fungicides were first attained and characterized well with their physicochemical properties. The in situ and ex situ field deployment in Hefei City provided the assessment of contaminated levels for these fungicides in rivers and soils. The Cfree of triadimefon and azoxystrobin was estimated at 0.54 ± 0.07–17.4 ± 2.5 ng L−1 in Nanfei River and Chao Lake, while triadimefon was only found in Dongpu Reservoir water with Cfree below 0.66 ± 0.04 ng L−1. The results exhibited that the equilibrium duration of 7 d was suitable for water application but a longer interval of 14 d was recommended for soil sampling. This work demonstrated the advantages of the proposed strategy in terms of fast monitoring within 2 weeks and high sensitivity down to detection limits in 0.5–5 ng L−1. The in-jar passive sampling device can be extrapolated to the evaluation for a wide coverage of organic pollutants in water and soils.

Different effects of polyethylene microplastics on bioaccumulation of three fungicides in maize (Zea mays L.)

Despite the ubiquity of microplastics (MPs) and pesticides in agricultural soils, the effects of MPs on the behavior and bioavailability of pesticides in soil–plant systems remain largely unknown. This study comparatively investigated the adsorption and dissipation of three commonly used fungicides (metalaxyl, azoxystrobin and tebuconazole) in soil as well as their accumulation and distribution in maize Zea mays L. with and without the amendment of polyethylene MPs (PE-MPs). The results showed that the adsorption of the fungicides to both MPs and soil was strongly dependent on their octanol/water partition coefficients (logKow). The addition of 5% PE-MPs significantly increased the adsorption of the hydrophobic fungicides azoxystrobin and tebuconazole to soil due to their greater adsorption affinity to PE-MPs than to soil, while the effect was negligible in the case of the hydrophilic fungicide metalaxyl. The enhanced adsorption of azoxystrobin and tebuconazole to soil with the amendment of PE-MPs decreased their bioavailable fractions in soil, especially the concentration in in situ pore water, resulting in prolonged persistence in soil and reduced accumulation in maize plants. PE-MPs caused a greater reduction in the dissipation and bioaccumulation of tebuconazole than azoxystrobin, presumably because PE-MPs were more effective in promoting the adsorption of tebuconazole (with a higher logKow) in soil. Comparatively, PE-MPs had little effect on the dissipation and bioaccumulation of metalaxyl since its bioavailability was almost unaffected. Our work provides effective information for the risk assessment of co-contamination of MPs and pesticides.

Tissue distribution, migration pathways and dietary risk assessment of fungicides in pomelo orchards in South China

Fungicides are used to protect vegetables and fruits from fungal diseases. Their ubiquitous utilization has resulted in water source contamination and human health concerns. However, the occurrence of fungicides in fruits and the potential implications for human health remain unclear. In this study, ninety-five fungicides were measured in pomelo and corresponding soil and leaf samples from two pomelo orchards in South China. The mean concentration of target fungicides (∑fungicides) in pulp (honey pomelo: 0.23±0.24 ng/g; shatian pomelo: 0.23±0.11 ng/g) were much lower than those in surface soil (0.53±0.57 ng/g; 1.41±1.85 ng/g) and leaf (6.97±3.20 ng/g; 28.5±11.1 ng/g). Triazole fungicides emerged as the predominant fungicides. Varied fungicides exhibit distinct tissue distribution in fruits, demonstrating diverse migration behaviors. The distribution of all fungicides followed the order: exocarp > mesocarp > endocarp > seed > pulp. No significant associations between fungicides in both soil and pulp suggest that the primary origin of fungicides in pulp may involve external exposure. Although the dietary risks of the target fungicides in pomelo were far lower than 1, it was not negligible. Our study provides novel insights into the residues and behavior of fungicides, offering foundational data for the dietary risk assessment of pomelo consumption.

Impact of Soil-Applied Thyme Oil on Strawberry Yield and Disease Abundance

ABSTRACT Strawberry growers across the United States are looking for sustainable alternatives to conventional pesticides for management of soil-borne or crown-rot causing pathogens, such as plant-extracts like thyme oil. The objectives of this study were to determine the impact of soil-applied thyme oil fungicides on strawberry plant health, yield, sweetness, and foliar disease, and on the assemblage of soil microbial communities in strawberry plasticulture systems. In 2021 and 2022 the interaction of three soil-applied fungicides and three foliar fungicide programs were explored. Thyme oil was not found to improve strawberry plant growth or yield when compared to strawberries in the control. However, plants treated with mefenoxam exhibited an average winter crown weight of 2.11 g, significantly lower than control and thyme oil treatments at 3.14 g and 3.16 g, respectively. This translated into a significant yield loss where mefenoxam treated plants exhibited lowered yields at 416.04 g of fruit per plant compared to 523.57 g and 521.53 g per plant in the control and thyme oil treatments, respectively. A high incidence of foliar and fruit diseases was present; however, no interaction of soil and foliar fungicide treatments were observed for yield or fruit sweetness. Minimal root protection from pathogens was observed for all treatments and Fusarium, Pythium and Phytophthora fungi were regularly observed. Mefenoxam was observed to increase the recovery of oomycetes, which may cause Pythium and Phytophthora. No benefit from thyme oil was observed at our site and its addition as a soil fungicide would likely not benefit most growers.

Asymmetries among soil fungicide residues, nitrous oxide emissions and microbiomes regulated by nitrification inhibitor at different moistures

Asymmetries among soil fungicide residues, nitrous oxide emissions and microbiomes regulated by nitrification inhibitor at different moistures

Control of potato wart disease (Synchytrium endobioticum) by fungicide soil treatments

Synchytrium endobioticum is the causative agent of potato wart disease and can remain in the soil for several years via its sporangia. Effective protection against this disease includes quarantine and the use of disease-resistant potato varieties. However, so far it has not been eradicated. The aim of this study was to determine the effect of fungicides for soil treatment to protect against potato wart. Experiments were conducted with propamocarb hydrochloride 722 SC g/l, metalaxyl M + fludioxonil 10 + 25 g/l, gimexazole 360 g/l, tolklofos methyl + thiram 30 + 30%, dimethomorph + cuproxy chloride 6 + 40WP, famoxadone + cymoxanil 22.5 + 30%, Mandipropamide + Mancoceb 5 + 60%, Zoxamide + Mancoceb 8.3 + 66.7% in the growth chamber and field conditions — showed that Famoxadone + Cimoxanil 22.5 + 30% is able to protect against the disease by 100% in both experimental conditions.

Unveiling the Aftermath: Exploring Residue Profiles of Insecticides, Herbicides, and Fungicides in Rice Straw, Soils, and Air Post-Mixed Pesticide-Contaminated Biomass Burning.

This study delved into the impact of open biomass burning on the distribution of pesticide and polycyclic aromatic hydrocarbon (PAH) residues across soil, rice straw, total suspended particulates (TSP), particulate matter with aerodynamic diameter ≤ 10 µm (PM10), and aerosols. A combination of herbicides atrazine (ATZ) and diuron (DIU), fungicide carbendazim (CBD), and insecticide chlorpyriphos (CPF) was applied to biomass before burning. Post-burning, the primary soil pesticide shifted from propyzamide (67.6%) to chlorpyriphos (94.8%). Raw straw biomass retained residues from all pesticide groups, with chlorpyriphos notably dominating (79.7%). Ash residue analysis unveiled significant alterations, with elevated concentrations of chlorpyriphos and terbuthylazine, alongside the emergence of atrazine-desethyl and triadimenol. Pre-burning TSP analysis identified 15 pesticides, with linuron as the primary compound (51.8%). Post-burning, all 21 pesticides were detected, showing significant increases in metobromuron, atrazine-desethyl, and cyanazine concentrations. PM10 composition mirrored TSP but exhibited additional compounds and heightened concentrations, particularly for atrazine, linuron, and cyanazine. Aerosol analysis post-burning indicated a substantial 39.2-fold increase in atrazine concentration, accompanied by the presence of sebuthylazine, formothion, and propyzamide. Carcinogenic PAHs exhibited noteworthy post-burning increases, contributing around 90.1 and 86.9% of all detected PAHs in TSP and PM10, respectively. These insights advance understanding of pesticide dynamics in burning processes, crucial for implementing sustainable agricultural practices and safeguarding environmental and human health.

Development of Simultaneous Determination Method of Pesticide High Toxic Metabolite 3,4-Dichloroaniline and 3,5 Dichloroaniline in Chives Using HPLC-MS/MS.

3,4-dichloroaniline (3,4-DCA) and 3,5-dichloroaniline (3,5-DCA) are, respectively, the primary metabolites deriving from the breakdown of phenylurea herbicides and dicarboximide fungicides in both soils and plants, whose residues in vegetable products have a heightened concern considering their higher health risks to humans and greater toxicity than the parent compounds in the environment. In this study, a sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of 3,4-DCA and 3,5-DCA residues in chive products based on the optimization of HPLC-MS/MS chromatographic and mass-spectrometric conditions using the standard substances and the modified QuEChERS preparation technique. The preparation efficiency of 3,4-DCA and 3,5-DCA from chive samples showed that acetonitrile was the best extractant. The combination of the purification agent graphite carbon black + primary secondary amine and the eluting agent acetonitrile + toluene (4:1, v/v) had a satisfactory purification effect. The linear correlation coefficients (R2) were more than 0.996 with the six concentration range of 0.001-1.000 mg/L for 3,4-DCA and 3,5-DCA. The limit of detection and limit of quantitation of this method was 0.6 and 2.0 µg/kg for 3,4-DCA, as well as 1.0 and 3.0 µg/kg for 3,5-DCA, respectively. The matrix effect range of 3,4-DCA and 3,5-DCA in chive tissues was from -9.0% to -2.6% and from -4.4% to 2.3%, respectively. The fortified recovery of 3,4-DCA and 3,5-DCA in chive samples at four spiked levels of 0.001-1.000 mg/kg was 75.3-86.0% and 78.2-98.1%, with the relative standard deviation of 2.1-8.5% and 1.4-11.9%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.6, 2.0, and 1.0, 3.03 for 4-DCA and 3,5-DCA, respectively. This study highlights that the analytical method established here can efficiently and sensitively detect residues of 3,4-DCA and 3,5-DCA residues for monitoring chive products. The method was successfully applied to 60 batches of actual vegetable samples from different regions.

Alterations in bee-plant-soil multitrophic interactions after fungicide soil application

Soil microorganisms play a key role in plant growth and health, and honey bees depend on plant pollen and nectar for their nutrition. Despite this clear above- and belowground connection, our knowledge about bee-plant-soil interactions is yet limited. Also, how these multitrophic interactions are affected by agricultural practices like pesticide applications is not well understood. Here we investigated possible non-target effects of soil application of the fungicide Benomyl on bee-plant-soil interactions in a greenhouse experiment with vetch (Vicia sativa L.). When plants were flowering honey bees were confined to their respective experimental soil treatments (untreated control, Benomyl and soil disinfection) in tents made from anti-insect mesh and micro-hives for foraging. At harvest, results showed that Benomyl and soil disinfection strongly affected key root and soil microorganisms essential for plant nutrition, such as mycorrhiza and rhizobia, and Gram-positive and Gram-negative bacteria, which coincided with phenotypic alterations in plant development and subsequently significant effects on honey bee nutrition and health, and finally honey production. In conclusion, our results show that soil application of the fungicide Benomyl strongly impact on bee-plant-soil multitrophic interactions, calling for further investigation on non-target effect of pesticides including multitrophic studies when evaluating environmental impacts of pesticides.

Attenuation and soil biodegradation of fungicides by using vegetated buffer strips in vineyards during a simulated rainfall–runoff event

Rainfall–runoff events occurring in vineyard fields can result in pesticide ground losses and the subsequent pollution of surface water bodies, derivate from the crop protection spray applications. In this study, the capacity of vegetated buffer strips (BS) to prevent surface water pollution due to the application of five fungicide products typically used in vineyards (copper, dimethomorph, oxathiapiprolin, zoxamide, acibenzolar-s-methyl, and laminarin) following a simulated run-off event has been assessed, and compared to that from a bare ground soil (BG). Two strips (5 m in length, each), one with vegetation and the other without were built up, and two different experiments were performed, a runoff event and a soil fungicide degradation kinetic evaluation. The runoff results show that fungicide mass retention in the strips ranged from 73 to 98% and that the presence of vegetation in BS increased the fungicide mass retention in the strips by almost 10% (on average) in comparison to the unvegetated strip. Moreover, soil degradation studies highlighted that the presence of vegetation reduces significantly the half-time life of almost all the studied fungicides by 55%, on average. Eight fungicide transformation products (TPs) were identified following a runoff event in the soil strips, but the abundance of these TPs was up to 78% lower in vegetated strips. These results highlight the effectiveness of using vegetated buffer zones in vineyards to protect aquatic ecosystem pollution.

The widespread presence of triazole fungicides in greenhouse soils in Shandong Province, China: A systematic study on human health and ecological risk assessments

Triazole fungicides (TFs) are extensively used on greenhouse vegetables and are ubiquitously detected in the environment. However, the human health and ecological risks associated with the presence of TFs in the soil are unclear. In this study, ten widely used TFs were measured in 283 soil samples from vegetable greenhouses across Shandong Province, China, and their potential human health and ecological risks were assessed. Among all soil samples, difenoconazole, myclobutanil, triadimenol, and tebuconazole were the top detected TFs, with detection rates of 85.2–100%; these TFs had higher residues, with average concentrations of 5.47–23.8 μg/kg. Although most of the detectable TFs were present in low amounts, 99.3% of the samples were contaminated with 2–10 TFs. Human health risk assessment based on hazard quotient (HQ) and hazard index (HI) values indicated that TFs posed negligible non-cancer risks for both adults and children (HQ range, 5.33 × 10−10 to 2.38 × 10−5; HI range, 1.95 × 10−9 to 3.05 × 10−5, <1). Ecological risk assessment based on the toxicity exposure ratio (TER) and risk quotient (RQ) values indicated that difenoconazole was a potential risk factor for soil organisms (TERmax = 1 for Eisenia foetida, <5; RQmean = 1.19 and RQmax = 9.04, >1). Moreover, 84 of the 283 sites showed a high risk (RQsite range, 1.09–9.08, >1), and difenoconazole was the primary contributor to the overall risk. Considering their ubiquity and potential hazards, TFs should be continuously assessed and prioritized for pesticide risk management.

Recent Advances in Nanoparticle-Based Optical Sensors for Detection of Pesticide Residues in Soil.

The excessive and unreasonable use of pesticides has adversely affected the environment and human health. The soil, one of the most critical natural resources supporting human survival and development, accumulates large amounts of pesticide residues. Compared to traditional spectrophotometry analytical methods, nanoparticle-based sensors stand out for their simplicity of operation as well as their high sensitivity and low detection limits. In this review, we focus primarily on the functions that various nanoparticles have and how they can be used to detect various pesticide residues in soil. A detailed discussion was conducted on the properties of nanoparticles, including their color changeability, Raman enhancement, fluorescence enhancement and quenching, and catalysis. We have also systematically reviewed the methodology for detecting insecticides, herbicides, and fungicides in soil by using nanoparticles.

Phytoextraction of lead (Pb) contaminated soil by switchgrass (Panicum virgatum L): Impact of BAP and NTA applications

The accumulation of Pb deposits in soil is a growing global concern. Soil remediation options include phytoextraction that involves the use of plants and associated soil microorganism. Switchgrass (Panicum virgatum L.), a second-generation bioenergy crop was used in this study due to its ability to produce high biomass and grow in metal polluted soils. Plants were grown in Pb-contaminated soil (5,802.5 mg kg−1) in an environmentally controlled greenhouse. Plants were treated with exogenous application of the plant growth regulator (PGR) benzylaminopurine (BAP) or complete foliar nutrient solution (Triple-12®) twice a week until harvested. Plants also received the soil fungicide propiconazole (Infuse™) that was followed by the soil chelate nitrilotriacetic acid (NTA). Two concentrations of NTA were compared (5 mM and 10 mM) and combined application of NTA (10 mM) + APG (alkyl polyglucoside). Soil fungicide (propiconazole) was used to arrest arbuscular mycorrhizal fungi (AMF) activities in the roots of switchgrass in order to enhance Pb-phytoextraction. Lead (Pb) was measured in dry plant materials using an ICP-OES. Phytoextraction by switchgrass was significantly improved by dual soil applications of 10 mM NTA, APG and foliar applications of BAP which resulted in the greatestaverage Pb concentration of 5,942 mg kg−1. The average dry mass of plants and the average value for total phytoextracted Pb (mg) per pot were significantly greatestfor plants treated with 10 mM NTA, APG and BAP. Also, plants treated with NTA and BAP showed average bioconcentration factor of 1.02. The results suggested that chemically enhanced phytoextraction significantly improved biomass production of switchgrass and at the same time increased phytoextracted Pb which is important for phytoremediation and bioenergy industry.

Effects of the presence of triclocarban on the degradation and migration of co-occurring pesticides in soil

Triclocarban (TCC), a bactericide widely used in personal care products, is frequently detected in soil and surface water, which may affect the environmental behavior of other environmental pollutants by changing the community structure of environmental microorganisms. This work evaluated the effects of TCC on the degradation and migration of seven herbicides and five fungicides in soil under co-occurrence conditions. TCC significantly increased the persistence of the pesticides in soil, and this effect increased with TCC concentration. For example, the half-life of metolachlor, atrazine, metribuzin, and metamitron increased 44%, 38%, 153%, and 33%, respectively, with 10 mg/kg TCC and increased 60%–640% with 100 mg/kg TCC. After 90 days, the residue of the pesticides in soil treated with TCC was significantly elevated relative to the control. TCC treatment could also increase the potential leaching risk of the herbicides in the soil, as indicated by an increased Groundwater Ubiquity Score (GUS) index. The reduced abundance of soil bacteria by TCC might be an essential reason for the impacts on the environmental behavior of the pesticides. This study confirmed that TCC could slow down the degradation of pesticides in soil, increase their persistence and even affect the leaching behavior, thus influencing the risks of the pesticides to the environment.

Evaluation of Fungicide Soil Drench Treatments to Manage Black Root Rot Disease of Avocado.

Four common fungicidal products were evaluated for their effect on symptoms caused by two nectriaceous black root rot fungi, Calonectria ilicicola and Dactylonectria macrodidyma, when applied as pot drenches to avocado (Persea americana) seedlings in the greenhouse. Applications of fludioxonil, thiophanate-methyl + etridiazole, prochloraz, and prochloraz MnCl at 2 and 4 weeks after inoculation with C. ilicicola significantly reduced root necrosis and improved root and aboveground plant biomass compared with water-treated controls. Fludioxonil reduced necrosis by 60% and had a significantly lower frequency of reisolation of C. ilicicola than the other three fungicide treatments. D. macrodidyma inoculation caused less severe symptoms in seedlings than C. ilicicola despite the longer duration of the trial. Pot drenches with fludioxonil, thiophanate-methyl + etridiazole, and prochloraz MnCl, but not prochloraz alone, significantly reduced root necrosis caused by D. macrodidyma. Prochloraz MnCl was the only fungicide treatment to increase root and plant biomass compared with water-treated controls. Both fludioxonil and prochloraz MnCl reduced the frequency of reisolation of D. macrodidyma from necrotic roots by about 50% compared with the other fungicides or water controls. The results indicated that drenches with these fungicides may suppress existing low to moderate black root rot infection, allowing new root growth and improved establishment in the orchard. Fungicide drenching must not replace best-practice disease management strategies in nurseries but may be a useful tool in crisis situations.

Effects of supplementary nutrients (soil-nitrogen or foliar-iron) on switchgrass (Panicum virgatum L.) grown in Pb-contaminated soil

Lead (Pb) soil contamination is widespread and poses a threat to human health. Even long-term exposure to low levels of Pb contaminated soils is potentially harmful to organisms. Soil remediation options include phytoextraction that has gained particular attention due to low cost and minimal soil disruption. The North American native switchgrass (Panicum virgatum L.), a second-generation bioenergy crop was used in this study due to its ability to produce high biomass and grow on marginal lands. In this study, the effects of supplementary soil nitrogen (N) or foliar iron (Fe) application on the growth and metal uptake of switchgrass were examined. Plants were grown under controlled conditions using Pb (5802.5 mg kg−1) contaminated soil. The soil nitrogen (N) application involved three levels: control (no added N), medium (500 mg kg−1), and high (1000 mg kg−1). Plants receiving the high N had the significantly greatest dry mass (DM) of the foliage and the highest Pb concentration. The iron (Fe) foliar application involved two levels: (1) deionized water and (2) iron (20 mg kg−1) solution. Plants were additionally treated with the soil fungicide propiconazole (2 mg L−1) and the soil chelate nitrilotriacetic acid (NTA) in order to enhance phytoextraction. Plants receiving the Fe foliar application had significantly higher DM of the foliage and significantly lower Pb concentrations in the roots and the foliage. These results will potentially improve phytoextraction by switchgrass grown in Pb contaminated soils.

Effect of Fungicides on Bayberry Decline Disease by Modulating Rhizosphere Soil Properties, Microflora, and Metabolites

Decline disease causes serious damage to bayberry, but the reasons behind this disease are not completely understood, although fungal pathogenicity factors have been proposed. Our past studies have identified that the adversity of this disease is linked to the application of soil fungicide. The objective of this study is to explore the mechanism and alleviation effect of the use of the fungicide prochloraz in this disease by investigating the plant and soil parameters. The results of the current study reveal that the application of prochloraz could improve the tree vigor and fruit quality of decline-diseased bayberry. The beneficial effect of prochloraz on plant growth and fruit quality may be associated with its influence on the rhizosphere soil properties and soil microbiota. Indeed, the application of prochloraz was shown to significantly affect the relative abundance and diversity of the rhizosphere soil microbiota, with it having a greater effect on bacteria than on fungi. Furthermore, the community composition of rhizosphere soil bacteria and fungi at the genus level was found to be significantly affected by the pH, available phosphorus, alkali-hydrolyzable nitrogen, and exchangeable magnesium, which exhibited a greater effect on bacteria than on fungi. In addition, prochloraz significantly affected the metabolic pathways of pyrimidine, galactose, butanoate, arginine, and proline and changed the contents of 58 metabolites, with an 18.59–149.48% increase seen in 51 metabolites and a 31.52–95.21% reduction seen in 7 metabolites. Interestingly, these metabolites were found to be significantly correlated with the rhizosphere soil microbiota at the levels of phylum, order, and genus. Overall, the results of this study provide an alternative choice for protecting bayberry from the damage caused by decline disease.

Widespread Presence of Triazole Fungicides in Greenhouse Soils in Shandong Province, China: A Systematical Study on Human Health and Ecological Risk Assessment

Widespread Presence of Triazole Fungicides in Greenhouse Soils in Shandong Province, China: A Systematical Study on Human Health and Ecological Risk Assessment

Effects of biochar on the fate of conazole fungicides in soils and their bioavailability to earthworms and plants.

The study showed novel findings about changes in the fate and bioavailability of conazole fungicides (CFs) after biochar (BC) addition to soil. Two contrasting soils (low- and high-sorbing of CF; L soils, H soils) were amended by three BCs (low-, moderate-, and high-sorbing of CF; L-BC, M-BC, H-BC) at 0.2% and 2% doses. Epoxiconazole (EPC) and tebuconazole (TBC) were then added to the soil-BC mixtures, and their degradation, bioaccumulation in earthworms (Eisenia andrei), and bioconcentration in lettuce (Lactuca sativa) were studied for three months. Also, stir bar sorptive extraction (SBSE) was performed to determine CF (bio)accessibility. The EPC and TBC degradation in the soil-BC mixtures followed usually the first-order decay kinetics. The BC addition prevalently decreased the pesticides degradation in the L soil mixtures but often increased it in the H soil mixtures. In general, EPC degraded less than TBC. BC type and dose roles in the pesticides degradation were unclear. The BC addition significantly reduced pesticide uptake to the earthworms in the L soil mixtures (by 37-96%) and in the H soil mixtures (by 6-89%) with 2% BC. The BC addition reduced pesticide uptake to the lettuce roots and leaves significantly-up to two orders of magnitude, and this reduction was strong in H soil mixtures at 2% of BC. The BC addition reduced the CF (bio)accessibility measured by SBSE in all L soil mixtures and some H soil mixtures with 2% BC. Although not significant, it also seems that the pesticide bioaccumulation, bioconcentration, and (bio)accessibility were decreasing according to the BC type (L-BC > M-BC > H-BC). The pesticide concentrations in the earthworms and lettuce correlated significantly to the SBSE results, which indicates this technique as a possible predictor of biotic uptake. Our results showed that the interactions were hard to predict in the complex soil-BC-pesticide system.