A laboratory comparison of the interactions between three plastic mulch types and 38 active substances found in pesticides

Background: In semi-arid regions, the use of plastic mulch and pesticides in conventional agriculture is nearly ubiquitous. Although the sorption of pesticides on Low Density Polyethylene (LDPE) has been previously studied, no data are available for other plastics such as Pro-oxidant Additive Containing (PAC) plastics or “biodegradable” (Bio) plastics. The aim of this research was to measure the sorption pattern of active substances from pesticides on LDPE, PAC and Bio plastic mulches and to compare the decay of the active substances in the presence and absence of plastic debris. Methods: For this purpose, 38 active substances from 17 insecticides, 15 fungicides and six herbicides commonly applied with plastic mulching in South-east Spain were incubated with a 3 × 3 cm2 piece of plastic mulch (LDPE, PAC and Bio). The incubation was done in a solution of 10% acetonitrile and 90% distilled water at 35 _C for 15 days in the dark. The Quick Easy Cheap Effective Rugged Safe approach was adapted to extract the pesticides. Results: The sorption behavior depended on both the pesticide and the plastic mulch type. On average, the sorption percentage was ~23% on LDPE and PAC and ~50% on Bio. The decay of active substances in the presence of plastic was ~30% lesser than the decay of active substances in solution alone. This study is the first attempt at assessing the behavior of a diversity of plastic mulches and pesticides to further define research needs.This work was supported by the European Commission Horizon 2020 project Diverfarming (grant agreement 728003). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Sewage sludge application as a vehicle for microplastics in eastern Spanish agricultural soils

Microplastic pollution is becoming a major challenge with the growing use of plastic. In recent years, research about microplastic pollution in the environment has become a field of study with increased interest, with ever expanding findings on sources, sinks and pathways of microplastics. Wastewater treatment plants effectively remove microplastics from wastewater and concentrate them in sewage sludge which is often used to fertilise agricultural fields. Despite this, quantification of microplastic pollution in agricultural fields through the application of sewage sludge is largely unknown. In light of this issue, four wastewater treatment plants and 16 agricultural fields (0–8 sewage sludge applications of 20–22 tons ha−1 per application), located in the east of Spain, were sampled. Microplastics were extracted using a floatation and filtration method, making a distinction between light density microplastics (ρ −3) and heavy density microplastics (ρ > 1 g cm−3). Sewage sludge, on average, had a light density plastic load of 18,000 ± 15,940 microplastics kg−1 and a heavy density plastic load of 32,070 ± 19,080 microplastics kg−1. Soils without addition of sewage sludge had an average light density plastic load of 930 ± 740 microplastics kg−1 and a heavy density plastic load of 1100 ± 570 microplastics kg−1. Soils with addition of sewage sludge had an average light density plastic load of 2130 ± 950 microplastics kg−1 and a heavy density plastic load of 3060 ± 1680 microplastics kg−1. On average, soils’ plastic loads increased by 280 light density microplastics kg−1 and 430 heavy density microplastics kg−1 with each successive application of sewage sludge, indicating that sewage sludge application results in accumulation of microplastics in agricultural soils. Microplastics concentrations in soils are highly proportional to the number of sludge applications.</p

Interactions between agricultural mulching plastic debris and pesticides

In semi-arid regions, the use of plastic mulch and pesticides in conventional agriculture is nearly ubiquitous. The use of plastics and pesticides lead both to the release of residues in the soils. The degradation of plastic and pesticide residues in the soil have been previously studied, but not together despite the fact that pesticides may be sorbed to plastics and that the sorption may change the degradation rate. In fact, the sorption of pesticides on Low Density Polyethylene (LDPE) has been previously studied, but no data is available for other plastics such as Pro-oxidant Additive Containing (PAC) plastics or "biodegradable" (Bio) plastics. The aim of this research was to measure the sorption pattern of active substances from 38 pesticides on LDPE, PAC and Bio plastic mulches and to compare the decay of the active substances in the presence and absence of plastic debris. For this purpose, 38 active substances from 17 insecticides, 15 fungicides and 6 herbicides commonly applied with plastic mulching in South-east Spain were incubated at 35°C for 15 days with a 3×3 cm² square of plastic mulch (LDPE, PAC and Bio). The QuEChERS (Quick Easy Cheap Effective Rugged Safe) approach was adapted to extract the pesticides. The sorption behaviour depended on both, the pesticide and the plastic mulch type. On average, the sorption percentage was ~23% on LDPE and PAC, and ~50% on Bio. The decay of active substances in the presence of plastic was, on average, 30% lower than the decay of active substances in solution alone. Therefore, efficacy, transport, degradability and/or eco-toxicity of active substances from pesticides may be affected by sorption on plastics. Additionally the sorption of pesticides on plastic debris may affect the plastic degradability due to the toxicity of pesticides to some soil organisms

Fragmentation and depolymerization of microplastics in the earthworm gut: a potential for microplastic bioremediation?

The accumulation of microplastics poses potential risks to soil health. Here, we did a preliminary exploration on the potential of Lumbricus terrestris (Oligochaeta) to reduce low-density polyethylene (LDPE), polylactic acid (PLA), and polybutylene adipate terephthalate (PBAT) microplastic (20–648 µm) contamination in soils. The ingestion of microplastics-contaminated soil (1% of microplastics, dw/dw) in a mesocosm system and the ingestion of pure microplastics in the Petri Dish by earthworms were studied. Results show that earthworms survived in the microplastics-contaminated soil (0% mortality in 35 days) but barely when exposed solely to microplastics (30–80% mortality in 4 days). Size-dependent ingestion of microplastics was not observed. The fragmentation of LDPE microplastics in the gizzard facilitated by soil was confirmed by the significantly increased ratio of small-sized (20–113 µm) microplastics from the bulk soil to the gut (from 8.4% to 18.8%). PLA and PBAT microplastics were fragmented by gizzard without the facilitation of soil, the ratios of small-sized (20–113 µm) PLA and PBAT microplastics in the gut were 55.5% and 108.2% higher than in respective pristine distributions. Substantial depolymerization of PLA (weight-average molar mass reduced by 17.7% with shift in molecular weight distribution) and suspected depolymerization of PBAT were observed in the worm gut, while no change in the molar mass was observed for PLA and PBAT microplastics buried in the soil for 49 days. Our results suggest that ingested microplastics could undergo fragmentation and depolymerization (for certain polymers) in the earthworm gut. Further research is needed to reveal the mechanisms of polymer depolymerization in the earthworm gut and to evaluate the feasibility of microplastic bioremediation with earthworms

Exploring the potential of earthworm gut bacteria for plastic degradation

The use of plastic mulch films in agriculture leads to the inevitable accumulation of plastic debris in soils. Here, we explored the potential of earthworm gut-inhabiting bacterial strains (Mycobacterium vanbaalenii (MV), Rhodococcus jostii (RJ), Streptomyces fulvissimus (SF), Bacillus simplex (BS), and Sporosarcina globispora (SG) to degrade plastic films (⌀ = 15 mm) made from commonly used polymers: low-density polyethylene film (LDPE-f), polylactic acid (PLA-f), polybutylene adipate terephthalate film (PBAT-f), and a commercial biodegradable mulch film, Bionov-B® (composed of Mater-Bi, a feedstock with PBAT, PLA and other chemical compounds). A 180-day experiment was conducted at room temperature (x̄ =19.4 °C) for different strain–plastic combinations under a low carbon media (0.1× tryptic soy broth). Results showed that the tested strain–plastic combinations did not facilitate the degradation of LDPE-f (treated with RJ and SF), PBAT-f (treated with BS and SG), and Bionov-B (treated with BS, MV, and SG). However, incubating PLA-f with SF triggered a reduction in the molecular weights and an increase in crystallinity. Therefore, we used PLA-f as model plastic to study the influence of temperature (“room temperature” & “30 °C”), carbon source (“carbon-free” & “low carbon supply”), and strain interactions (“single strains” & “strain mixtures”) on PLA degradation. SF and SF + RJ treatments significantly fostered PLA degradation under 30 °C in a low-carbon media. PLA-f did not show any degradation in carbon-free media treatments. The competition between different strains in the same system likely hindered the performance of PLA-degrading strains. A positive correlation between the final pH of culture media and PLA-f weight loss was observed, which might reflect the pH-dependent hydrolysis mechanism of PLA. Our results situate SF and its co-culture with RJ strains as possible accelerators of PLA degradation in temperatures below PLA glass transition temperature (Tg). Further studies are needed to test the bioremediation feasibility in soils

Wind erosion processes and related glyphosate transport in the loess pampean region of Córdoba province, Argentina

The results of this experiment will provide: Insight on glyphosate and AMPA concentrations in wind-eroded sediment; Valuable information on the losses of glyphosate and AMPA to off-site environments due to wind erosion; A strong contribution to the Argentinean decision makers, stakeholders and the international community in the knowledge of glyphosate/AMPA transport by wind erosion, and its potential impact to the environment and human health.Fil: Bento, Célia P. M. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Geissen, Violette. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Riksen, Michel. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Mol, Hans. Wageningen University. Research Centre. RIKILT Institute of Food Safety; Países Bajos.Fil: Murialdo, Raquel. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales; Argentina.Fil: Ritsema, Coen. Wageningen University. Soil Physics and Land Management; Países Bajos.Fil: Reyna, Santiago. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales; Argentina.Otras Ingeniería del Medio Ambient

Soil contamination

Capítulo sobre "Contaminación del Suelo" que forma parte del libro colectivo "Amenazas del Suelo en Europa" editado por Jannes Stolte et al. y publicado por el Joint Research Centre de la Unión Europea. Es un trabajo de revisión que ha resultado del proyecto europeo RECARE (http://www.recare-project.eu/).This report presents the result of WP2 of the RECARE project. One of the objectives of WP2 is to provide an improved overview of existing information on soil threats and degradation at the European scale. In particular, this chapter 8 deals with soil contamination, providing comprehensive, thematic information on this soil threat in Europe with due attention given to the Driving force-Pressure-State-Impact-Response to soil threats.European Commission, Joint Research Centre. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement n° 603498 (RECARE).Peer reviewe

Influencia de tres tipos de vegetación riberena en el control de la erosión fluvial en Pantanos de Centla, México

Influence of three types of riparian vegetation on fluvial erosion control in Pantanos de Centla, Mexico. Wetlands constitute very important ecological areas. The aim of this study was to quantify the soil losses due to fluvial erosion from 2006 to 2008 in two riverbanks under three types of vegetal coverage dominated by Haematoxylum campechianum, Dalbergia brownei and Brachiaria mutica, in the Pantanos de Centla Biosphere Reserve, SE Mexico. The relationship between the texture, organic matter and pH of soils and soil losses was evaluated. We used erosion sticks to estimate soil losses in 18 plots (three plots per type, three vegetation types, two riverbanks). Soil loss decreased in this order: H. campechianum>B. mutica>D. brownei indicating that D. brownei scrubland has the most potential to retain soil. The higher erosive impact within H. campechianum sites can be related with the low density of these trees in the study areas, as well as the lack of association with other types of vegetation that could reinforce the rooting of the soil profile. Furthermore, soil losses in H. campechianum sites were dependent on soil texture. The soils under this type of vegetal coverage were mainly sandy, which are more vulnerable to the erosive action in comparison with fine textured soils or soils with higher clay content, like the ones found in D. brownei and B. mutica sites. Soil losses of 100 % in the second year ( B. mutica plots) can be attributed to the distribution of roots in the upper soil layer and also to livestock management along riverbanks. This study recognizes the importance of D. brownei scrublands in riverbank soil retention. Nevertheless it is necessary to consider the role of an entire vegetal community in future research. Rev. Biol. Trop. 57 (4): 1153-1163. Epub 2009 December 01

Em busca de um índice ecológico para a qualidade de solo tropical com base na macrofauna edáfica

The objective of this work was to construct a simple index based on the presence/absence of different groups of soil macrofauna to determine the ecological quality of soils. The index was tested with data from 20 sites in South and Central Tabasco, Mexico, and a positive relation between the model and the field observations was detected. The index showed that diverse agroforestry systems had the highest soil quality index (1.00), and monocrops without trees, such as pineapple, showed the lowest soil quality index (0.08). Further research is required to improve this model for natural systems that have very low earthworm biomass ( < 10 g m-2) and a high number of earthworm species (5–7), as it is in the tropical rain forest, whose soil quality index was medium (0.5). The application of this index will require an illustrated guide for its users. Further studies are required in order to test the use of this index by farmers.O objetivo deste trabalho foi construir um índice simples com base na presença/ausência de diferentes grupos da macrofauna edáfica para auxiliar na determinação da qualidade ecológica dos solos. O índice foi testado com dados de 20 locais do sul e centro do Estado de Tabasco, México, e foi observada uma correlação positiva entre o dados gerados pelo modelo e pelas observações de campo. O índice de qualidade de solo mostrou que diversos sistemas agroflorestais tiveram a mais alta qualidade de solo (1,0) e que os monocultivos sem árvores, como o de abacaxi, apresentaram a qualidade de solo mais baixa (0,08). Este modelo precisa ser melhor desenvolvido para ser aplicado eficientemente em sistemas que apresentam naturalmente baixas densidades de minhocas ( < 10 g m-2) e número elevado de espécies de minhocas (5–7), como ocorre em solos de floresta tropical, cujo índice de qualidade de solo apresentou valores médios (0,5). A aplicação desse índice precisará de um guia ilustrado para os seus usuários. Mais estudos são necessários para testar o seu emprego por fazendeiros

Pesticide residues in European agricultural soils – A hidden reality unfolded

Pesticide use is a major foundation of the agricultural intensification observed over the last few decades. As a result, soil contamination by pesticide residues has become an issue of increasing concern due to some pesticides' high soil persistence and toxicity to non-target species. In this study, the distribution of 76 pesticide residues was evaluated in 317 agricultural topsoil samples from across the European Union. The soils were collected in 2015 and originated from 11 EU Member States and 6 main cropping systems. Over 80% of the tested soils contained pesticide residues (25% of samples had 1 residue, 58% of samples had mixtures of two or more residues), in a total of 166 different pesticide combinations. Glyphosate and its metabolite AMPA, DDTs (DDT and its metabolites) and the broad-spectrum fungicides boscalid, epoxiconazole and tebuconazole were the compounds most frequently found in soil samples and the compounds found at the highest concentrations. These compounds occasionally exceeded their predicted environmental concentrations in soil but were below the respective toxic endpoints for standard in-soil organisms. Maximum individual pesticide content assessed in a soil sample was 2.05 mg kg−1 while maximum total pesticide content was 2.87 mg kg−1. This study reveals that the presence of mixtures of pesticide residues in soils are the rule rather than the exception, indicating that environmental risk assessment procedures should be adapted accordingly to minimize related risks to soil life and beyond. This information can be used to implement monitoring programs for pesticide residues in soil and to trigger toxicity assessments of mixtures of pesticide residues on a wider range of soil species in order to perform more comprehensive and accurate risk assessments.</p