Article

Ecotoxicity of copper input and accumulation for soil biodiversity in vineyards

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  • Novasol Experts
  • NovaSol Experts
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Abstract

Copper has been successfully used in the sulfate form as a fungicide to control grapevine diseases since 150 years, yet high Cu accumulation in vineyards may alter soil life. Although actual Cu additions are about tenfold lower than 50 years ago, the use of Cu in the context of the agroecological transition is still debated. Indeed, copper is one of the rare pesticides allowed for organic farming. Therefore, we performed a meta-analysis on Cu ecotoxicity by selecting 19 articles out of 300 articles relevant to copper and soil biological quality. Results show that microbial activity decreased by 30% when more than 400 kg of Cu was applied yearly per ha. Nematodes abundance remained unchanged for copper application up to 3200 kg/ha/year. Collembola and enchytraeid reproduction declined by 50% after application of 400 and 1895 kg Cu/ha/year, respectively. Earthworm biomass was reduced by 15% after application of 200 kgCu/ha/year. For soil Cu levels higher than 200 kg Cu/ha, microbial respiration decreased by 50% and no effect was observed on collembola. Overall, while toxicity is observed, the corresponding literature investigations involved Cu levels that are at least 50 times higher than the dose of 4 kg Cu/ha/year currently authorized by the European Commission for viticulture. As a consequence, applying copper at 4 kg/ha/year should not modify substantially soil biological quality and functions.

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... Le Concernant les protections phytosanitaires, les é tudes ciblé es restent rares en vignes. Les modalité s testé es sont variables d'une é tude à l'autre et les doses expé rimenté es sont rarement des doses ré alistes pour un usage agronomique raisonné (cas du cuivre par exemple, [54] [55]). ...
... Les é tudes considé ré es par ces instances pour pré coniser son interdiction (à l'aube de 2025) du fait de sa toxicité et de son accumulation dans les sols remontent à plus de 20 ans. Mais ces ré sultats ne sont plus en adé quation avec l'utilisation actuelle du produit [54] [55]. Le cuivre est aujourd'hui utilisé à des doses maximales de 4 kg/ha/an en viticulture biologique alors que dans les anné es 80/90, les doses é taient 10 fois supé rieures. ...
... L'inté rê t de ce genre d'approche pour la recherche est é galement d'ê tre cohé rente avec la ré alité des pratiques mises en place au terrain et ainsi de ré pondre de faç on la plus pertinente possible aux questionnements et aux attentes des professionnels de l'agriculture. C'est par exemple le problè me rencontré dans les é tudes scientifiques sur l'impact du cuivre sur la qualité biologique du sol, où les modalité s d'apport (dose, fré quence) n'ont aucune commune mesure avec les pratiques ré alisé es par les viticulteurs dans leurs vignes [54] [55]. Ê tre au plus proche des pratiques des viticulteurs pré sente é galement l'avantage de pouvoir identifier et é valuer des innovations techniques issues des viticulteurs eux-mê mes. ...
Article
La filière viticole est associée à des enjeux économiques et à des problématiques environnementales qui nécessitent qu’elle s’engage dans la transition agroécologique de façon urgente. Dans cette transition, les sols et leur biodiversité constituent un levier écologique fondamental en renfort des leviers agronomiques classiques. A cette fin, bien connaître la qualité biologique des sols viticoles et évaluer l’impact des différentes pratiques et modes de production est indispensable. Cet article présente les résultats d’une synthèse et méta-analyse de la littérature scientifique faisant le bilan des connaissances et des lacunes sur la qualité biologique des sols viticoles.
... Practices such as weed management, tillage and pesticide use are associated with a decline in soil quality, in particular soil erosion and compaction and/or loss of organic matter (Kazakou et al., 2016;Louchart et al., 2001;Salome et al., 2014;Salom e et al., 2016;Steenwerth and Belina, 2008). Moreovoer, soil management practices in vineyards such as tillage, use of herbicides, insecticides and fungicides (including copper) have direct and indirect impacts on the ecology and physiology of many soil organisms (Buckley and Schmidt, 2001;Eijsackers et al., 2005;Gaupp-Berghausen et al., 2015;Karimi et al., 2021;Ostandie et al., 2021;Pelosi et al., 2014). ...
... Permanent grass cover is also positively associated with a higher diversity and biomass of microorganisms: it increased organic matter content in vineyard soils and, consequently, increased fungal counts (Whitelaw-Weckert et al., 2007). Practices such as adding wood pruned from the vines, and more generally mulch, to the soil have a potential synergistic effect on soil biodiversity, soil health (limitation of soil erosion and potentially soil water retention) and climate change mitigation (carbon storage) (Karimi et al., 2021). Soil moisture is a key driver of soil biodiversity and drought is the climate-change factor with the most negative effect on soil biodiversity (Blankinship et al., 2011;Holmstrup et al., 2010). ...
Chapter
For decades, and at global scales, vineyard landscapes have experienced a profound intensification of management. These socio-ecosystems are now facing major environmental, agronomical and economic issues that challenge their future sustainability. In this context, implementing agroecological management of these landscapes is no longer an alternative, and multiple lines of evidence demonstrate the central role of biodiversity and associated ecosystem services for the future functioning of these landscapes. In this paper, we provide a comprehensive overview of this evidence, indicate major gaps in our current knowledge and highlight how biodiversity could become a major asset in the design of multifunctional vineyard landscapes in the context of global change.
... Practices such as weed management, tillage and pesticide use are associated with a decline in soil quality, in particular soil erosion and compaction and/or loss of organic matter (Kazakou et al., 2016;Louchart et al., 2001;Salome et al., 2014;Salom e et al., 2016;Steenwerth and Belina, 2008). Moreovoer, soil management practices in vineyards such as tillage, use of herbicides, insecticides and fungicides (including copper) have direct and indirect impacts on the ecology and physiology of many soil organisms (Buckley and Schmidt, 2001;Eijsackers et al., 2005;Gaupp-Berghausen et al., 2015;Karimi et al., 2021;Ostandie et al., 2021;Pelosi et al., 2014). ...
... Permanent grass cover is also positively associated with a higher diversity and biomass of microorganisms: it increased organic matter content in vineyard soils and, consequently, increased fungal counts (Whitelaw-Weckert et al., 2007). Practices such as adding wood pruned from the vines, and more generally mulch, to the soil have a potential synergistic effect on soil biodiversity, soil health (limitation of soil erosion and potentially soil water retention) and climate change mitigation (carbon storage) (Karimi et al., 2021). Soil moisture is a key driver of soil biodiversity and drought is the climate-change factor with the most negative effect on soil biodiversity (Blankinship et al., 2011;Holmstrup et al., 2010). ...
... Most of the copper used as a feed additive ends up in the manure, which is considered a substantial source of copper input in arable crops and fodder production, especially when pig slurry and manures from conventional farms are imported in organic farms [11], but it has no relevance in the control of soil-borne pathogens. Being an element having scarce mobility in soil, repeated foliar applications of copper-based plant-protection products lead to copper accumulation in the soils [12] and to potentially consequent negative impacts on soil fertility (negative effects reviewed by La Torre et al. [13], for example), even though studies put the negative effects in perspective (as reviewed by Karimi et al. [14], for example). ...
... A plausibility check using estimates of Katsoulas et al. [21] indicates that our estimates for olives presented here are rather conservative and that real copper use in olives might even be higher, with a significant impact on overall European copper use. While grapevine is widely known as a main copper-consuming crop [2,6,12,14,37,38], the importance of olives and nuts has not been well documented so far and was quite unexpected for many experts. This might result from the fact that these crops can only be cultivated in relatively few Mediterranean countries, and from the rapid growth of the organic production area in these countries (Supplementary Materials Table S4). ...
Article
Full-text available
The reduction of copper-based plant-protection products with the final aim of phasing out has a high priority in European policy, as well as in organic agriculture. Our survey aims at providing an overview of the current use of these products in European organic agriculture and the need for alternatives to allow policymakers to develop strategies for a complete phasing out. Due to a lack of centralized databases on pesticide use, our survey combines expert knowledge on permitted and real copper use per crop and country, with statistics on organic area. In the 12 surveyed countries (Belgium, Bulgaria, Denmark, Estonia, France, Germany, Hungary, Italy, Norway, Spain, Switzerland, and the UK), we calculated that approximately 3258 t copper metal per year is consumed by organic agriculture, equaling to 53% of the permitted annual dosage. This amount is split between olives (1263 t y−1, 39%), grapevine (990 t y−1, 30%), and almonds (317 t y−1, 10%), followed by other crops with much smaller annual uses (<80 t y−1). In 56% of the allowed cases (countries × crops), farmers use less than half of the allowed amount, and in 27%, they use less than a quarter. At the time being, completely abandoning copper fungicides would lead to high yield losses in many crops. To successfully reduce or avoid copper use, all preventive strategies have to be fully implemented, breeding programs need to be intensified, and several affordable alternative products need to be brought to the market.
... From an exhaustive meta-analysis on Cu ecotoxicology relative to 19 articles out of 300 papers relevant to copper and soil biological quality performed by Karimi et al. [32], it was assessed that Cu accumulated in the soil over the years started to be deleterious for earthworm's biomass at concentrations above 200 kg Cu/ha/year. Moreover, literature analysis shows a substantial gap in the relation to ecotoxicological effects at doses below 4 kg Cu/ha/year chronic contamination, in particular, in relation to the long-term effects on soil biodiversity [32]. ...
... From an exhaustive meta-analysis on Cu ecotoxicology relative to 19 articles out of 300 papers relevant to copper and soil biological quality performed by Karimi et al. [32], it was assessed that Cu accumulated in the soil over the years started to be deleterious for earthworm's biomass at concentrations above 200 kg Cu/ha/year. Moreover, literature analysis shows a substantial gap in the relation to ecotoxicological effects at doses below 4 kg Cu/ha/year chronic contamination, in particular, in relation to the long-term effects on soil biodiversity [32]. This data highlights the need for studies that address the environmental risk linked to the historical use of copper in European vineyard soils. ...
Article
The extensive employment of copper-based fungicides has increased copper concentration in vineyard soils. The present study’s objectives were to monitor copper concentration in two vineyard soils during two cropping seasons and study the ecotoxicological effects on the earthworm Eisenia fetida. Total, soluble, and bioavailable copper fractions were measured at the end of two cropping seasons and different depths in two vineyards of central Italy, characterised by three anticryptogamic control methods: copper compounds, chitosan, and combined treatments of them. A laboratory experiment to assess the effects on Eisenia fetida was conducted with soil samples collected in the vineyards with a mean copper concentration of 60 mg/kg and two higher concentrations of 90 and 150 mg/kg. Results showed low levels of total copper concentration in the first 20 cm of soils, regardless of antifungal treatment, highlighting prudent management of the vineyards under study, but the soluble fractions showed a significant increase in all samples during the two cropping seasons. At the dose of 150 mg/kg, earthworms suffer during the first two days, showing weight loss and DNA damage, but they are able to recover until day 28, showing no permanent harm at this copper concentration in soil.
... The recent European regulation on the fungicidal use of copper raises the question of the state of scientific knowledge on the environmental impacts of this pesticide, especially on soil biodiversity. In a report published in 2019, the European Commission highlighted the lack of data about non-targeted soil organisms; this motivated our review and meta-analysis of available data presented in Karimi et al. (2021), focusing on soil biological quality. ...
... However, when their available fractions exceed certain thresholds, they might induce toxicity symptoms to plants and soil organisms (Brunetto et al., 2016). For instance, Cu causes a decrease in the number and diversity of Collembola and earthworms, as well as a decline in microbial biomass and inhibition of cyanobacterial metabolic activities (Karimi et al., 2021;Pipe, 1992). Soil respiration activity is severely compromised and limited at high Cu concentrations (Fritze et al., 1996;Romero-Freire et al., 2016). ...
Article
Full-text available
Intensive agricultural management significantly affects soil chemical properties. Such impacts, depending on the intensity of agronomic practices, might persist for several decades. We tested how current soil properties, especially heavy metal concentrations, reflect the land-use history over a 24,000 ha area dominated by intensive apple orchards and viticulture (South Tyrol, ITA). We combined georeferenced soil analyses with land-use maps from 1850 to 2010 in a space-for-time approach to detect the accumulation rates of copper and zinc and understand how present-day soil heavy metal concentrations reflect land-use history. Soils under vineyards since the 1850s showed the highest available copper concentration (median of 314.0 mg kg⁻¹, accumulation rate between 19.4 and 41.3 mg kg⁻¹·10 y⁻¹). Zinc reached the highest concentration in the same land-use type (median of 32.5 mg kg⁻¹, accumulation rate between 1.8 and 4.4 mg kg⁻¹·10 y⁻¹). Using a random forest approach on 44,132 soil samples, we extrapolated land-use history on the permanent crop area of the region, reaching an accuracy of 0.72. This suggests that combining current soil analysis, historical management information, and machine learning models provides a valuable tool to predict land-use history and understand management legacies.
... Karimi and coauthors recently wrote an enlightening review on Cu ecotoxicity on soil biodiversity in vineyards using results from a literature review (Karimi et al. 2021). This is particularly welcome in a context where wine growers, and in particular organic farmers, are confronted with the absence of efficient alternative to Cu against downy mildew and the future possibility of a Cu ban (Andrivon et al. 2018). ...
... These treatments are currently still allowed in organic farming due to the lack of alternatives. While extremely high copper concentrations were found to negatively affect soil biodiversity, allowed amounts (< 4 kg per ha) are considered to not harm soil biodiversity (Karimi et al., 2021). However, other studies found that even low copper contamination can alter the spatial distribution of soil bacteria and fungi (Mackie et al., 2013) and cause severe damages on yeasts (Grangeteau et al., 2017). ...
Article
Full-text available
CONTEXT In the European Union (EU-27) and UK, animal farming generated annually more than 1.4 billion tonnes of manure during the period 2016–2019. Of this, more than 90% is directly re-applied to soils as organic fertiliser. Manure promotes plant growth, provides nutritious food to soil organisms, adds genetic and functional diversity to soils and improves the chemical and physical soil properties. However, it can also cause pollution by introducing toxic elements (i.e., heavy metals, antibiotics, pathogens) and contribute to nutrient losses. Soil organisms play an essential role in manure transformation into the soil and the degradation of any potential toxic constitutes; however, manure management practices often neglect soil biodiversity. OBJECTIVE In this review, we explored the impact of manure from farmed animals on soil biodiversity by considering factors that determine the effects of manure and vice versa. By evaluating manure's potential to enhance soil biodiversity, but also its environmental risks, we assessed current and future EU policy and legislations with the ultimate aim of providing recommendations that can enable a more sustainable management of farm manures. METHODS This review explored the relationship between manure and soil biodiversity by considering 407 published papers and relevant legislative provisions. In addition, we evaluated whether benefits and risks on soil biodiversity are considered in manure management. Thereafter, we analysed the current legislation in the European Union relevant to manure, an important driver for its treatment, application and storage. RESULTS AND CONCLUSIONS This review found that coupling manure management with soil biodiversity can mitigate present and future environmental risks. Our analyses showed that manure quality is more important to soil biodiversity than manure quantity and therefore, agricultural practices that protect and promote soil biodiversity with the application of appropriate, high-quality manure or biostimulant preparations based on manure, could accelerate the move towards more sustainable food production systems. Soil biodiversity needs to be appropriately factored in when assessing manure amendments to provide better guidelines on the use of manure and to reduce costs and environmental risks. However, radical changes in current philosophies and practices are needed so that soil biodiversity can be enhanced by manure management. SIGNIFICANCE Manure quality in the EU requires greater attention, calling for more targeted policies. Our proposed approach could be applied by European Union Member States to include soil protection measures in national legislation, and at the EU level, can enable the implementation of strategic goals.
... Fernández-Calviño et al. (2010) reported that microbial enzymatic activity (phosphatase) in Portuguese vineyard soils decreased drastically above 250 mg Cu kg −1 . A recent meta-analysis of Cu in vineyard soils showed that microbial respiration was reduced by half above a stock of 200 kg Cu ha −1 (Karimi et al. 2021). Excess copper may thus cause ecotoxicity in vineyard soils, although the ecotoxic thresholds vary widely depending on certain soil parameters like organic matter (OM) content or pH. ...
Article
Full-text available
Accumulation of copper (Cu) in soils due to the application of fungicides may be toxic for organisms and hence affect winegrowing sustainability. Soil parameters such as pH and dissolved organic matter (DOM) are known to affect the availability of Cu. In this study, we investigated the contribution of chromophoric and fluorescent DOM properties to the prediction of Cu availability in 18 organic vineyard soils in the Bordeaux winegrowing area (France). The DOM parameters, assessed through absorbance and fluorescence analyses, and proxies for Cu availability (total soluble Cu and free ionic Cu2+) were measured in 0.01 M KCl extracts. Total soluble Cu (CuKCl) varied 23-fold while free ionic Cu2+ varied by a factor of 4600 among the soils. DOC concentrations were similar among the soils, but the samples differed in the quality of DOM as assessed by optical spectroscopy. Multilinear regression models with and without DOM quality parameters were investigated to predict Cu availability. The best model for CuKCl successfully explained 83% of variance and included pH, CuT, and two DOM fluorescence quality indices, the FI fluorescence index, which distinguishes between microbial and higher plant origins, and the HIX humification index. For the prediction of Cu2+, pH alone explained 88% of variance and adding DOM parameters did not improve modelling. The two Cu availability proxies were related to pH. This study confirms the prominent role of pH in Cu availability and underlines the importance of DOM quality to better predict Cu solubility.
... Cuivre, sol, biodiversité des sols, toxicité, viticulture durable Comment citer cet article : Imfeld G., Duplay J. et Payraudeau S., 2021 -Prise en compte du stockage et de la disponibilité du cuivre dans les sols viticoles pour en évaluer son écotoxicité. Commentaires sur l'article de Karimi, et al. (2021) K arimi et ses co-auteurs ont récemment présenté une éclairante revue sur l'écotoxicité du cuivre sur la biodiversité du sol dans les vignobles en s'appuyant sur une méta-analyse de la littérature académique internationale (Karimi et al., 2021a(Karimi et al., , 2021b. Cette étude est particulièrement bienvenue dans un contexte où les viticulteurs, et en particulier les viticulteurs biologiques, sont confrontés à l'absence de traitements alternatifs au cuivre efficaces contre le mildiou, et à l'éventualité d'une interdiction d'utilisation du cuivre (Andrivon et al., 2018). ...
... For instance, excess Cu in vineyard topsoils alters microbial diversity (Lejon et al. 2008;Viti et al. 2008) and activity (Fernández-Calviño et al. 2010;Soler-Rovira et al. 2013), and reduces the abundance (Khalil et al. 1996) and activity (Eijsackers et al. 2005) of earthworms. A meta-analysis by Karimi et al. (2021) on the ecotoxicity of Cu suggests that Cu starts to be deleterious to soil organisms above 200 kg Cu ha −1 , which corresponds to a concentration of Cu of 67 mg kg −1 soil (assuming Cu remains in the top 20cm soil layer and assuming a soil density of 1.5) observed in numerous vineyard topsoils. In addition, excess Cu negatively affects the growth of plants sown in the inter-row or after the vine has been grubbed up (Michaud et al. 2007). ...
Article
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Copper (Cu) contamination of soils may alter the functioning and sustainability of vineyard ecosystems. Cultivating Cu-extracting plants in vineyard inter-rows, or phytoextraction, is one possible way currently under consideration in agroecology to reduce Cu contamination of vineyard topsoils. This option is rarely used, mainly because Cu phytoextraction yields are too low to significantly reduce contamination due to the relatively “low” phytoavailability of Cu in the soil (compared to other trace metals) and its preferential accumulation in the roots of most extracting plants. This article describes the main practices and associated constraints that could theoretically be used to maximize Cu phytoextraction at field scale, including the use of Cu-accumulating plants grown (i) with acidifying plants (e.g., leguminous plants), and/or (ii) in the presence of acidifying fertilizers (ammonium, elemental sulfur), or (iii) with soluble “biochelators” added to the soil such as natural humic substances or metabolites produced by rhizospheric bacteria such as siderophores, in the inter-rows. This discussion article also provides an overview of the possible ways to exploit Cu-enriched biomass, notably through ecocatalysis or biofortification of animal feed.
... Tous les produits, qu'ils soient conventionnels ou biologiques, ont aussi un impact négatif sur la biodiversité, et plus spécifiquement la faune araignée, les coccinelles, mais aussi les carabes, chrysopes et autres parasitoïdes (Nash et al., 2010). De plus, l'impact d'un produit sur la biodiversité s'avère tout aussi difficile à établir, comme en témoignent les vifs débats concernant la problématique de l'utilisation du cuivre (voir l'article de Imfeld et al., 2021, en réponse aux résultats présentés par Karimi et al., 2021), une des substances très utilisées en viticulture biologique. Enfin, la biodiversité du vignoble ne se limite pas aux parcelles de vigne. ...
Thesis
La Responsabilité Sociétale des Entreprises (RSE) est devenue un enjeu majeur du secteur agroalimentaire face aux défis de l’alimentation, de l’environnement, des conditions sociales du travail et des attentes sociétales fortement exprimées. Pour y répondre, les entreprises déploient de nombreux dispositifs de renforcement des contraintes de production, au-delà du strict respect des réglementations nationales et européennes, comme des démarches de certifications générales de l’entreprise (norme ISO 26 000), et diverses actions pouvant être communiquées auprès des consommateurs par le biais notamment d’allégations et certifications-produits. La question de la valorisation de la RSE repose donc sur l’éthique de l’entreprise, l’image qu’en a le consommateur, tout autant que la fonctionnalité des produits qu’elle propose sur le marché.A partir de l’exemple du marché du vin, l’objectif de cette thèse est de mieux comprendre les motivations des consommateurs pour valoriser ces démarches de RSE sur les marchés. Le travail méthodologique s’appuie sur les acquis de l’économie expérimentale, en proposant des extensions conceptuelles susceptibles de mesurer efficacement l’évolution des consentements à payer (CAP) des consommateurs pour des produits responsables. La crédibilité des marchés expérimentaux proposés et la pertinence des informations transmises aux consommateurs, sont assurées par des démarches pluridisciplinaires avec les sciences œnologiques et écologiques, mais aussi par une approche de recherche partenariale avec le milieu professionnel.La première partie de cette thèse permet de mesurer les réactions des consommateurs vis-à-vis des certifications, tout en évaluant les premiers arbitrages entre les différentes caractéristiques des produits. Si nous démontrons l’existence d’une pérennité de niches de marché des certifications, nous expliquons pourquoi cette interprétation doit être relativisée, notamment du fait des croyances des consommateurs concernant ces affichages responsables. En particulier, nous avons pu proposer une analyse du CAP influencé par un affichage purement environnemental concernant la biodiversité, grâce à la mise en place d’un indicateur opérationnel (‘Biodiv-Score’). Nous analysons alors les réactions des consommateurs sur le niveau de cet indicateur et mesurons précisément les croyances et les attentes associées au label BIO par rapport à la biodiversité.Ces attentes ne sont pas nécessairement durables dans le temps et dépendent de différents leviers que nous abordons dans la deuxième partie de cette thèse. Tout d’abord, à partir d’une méthodologie originale de mesure des CAP que nous proposons (G&A Method), nous provoquons une plus grande réflexion des consommateurs sur la place accordée au sensoriel, aux performances environnementales et sanitaires des produits, et au processus de production. Nous montrons alors que, si les entreprises viticoles ne pourront se passer de faire un produit qui plaise au consommateur sur le plan sensoriel, l’engagement dans une démarche responsable est indispensable pour maintenir leurs parts de marchés sur le long terme. Par ailleurs, nous abordons la question des interactions sociales qui influencent l’achat, en traitant l’implication des entreprises dans le bien-être au travail de leurs salariés. Il apparaît que si la volonté personnelle de correspondre à une norme sociale est un moteur indéniable de la transition vers une consommation responsable, la pression du regard de l’autre n’est significative que si cet autre appartient effectivement à l’environnement social du consommateur.Ces résultats nous conduisent à tirer les enseignements sur le plan des stratégies d’entreprises, non seulement par rapport aux développement d’une production vertueuse, mais aussi par rapport aux choix stratégiques des circuits de commercialisations (vente en grande distribution, en direct, via nternet…) qui conditionnent le contexte d’achat et de la valorisation RSE.
... Soil Cu contamination in vineyard and orchard soils, although moderate compared to that of Cu-polluted soils located near Cu mines (Zotti et al., 2014), Cu smelting factories (Wang et al., 2014) or at wood preservation sites (Kolbas et al., 2020), has consequences for the functioning and the sustainability of these ecosystems since it has chronic effects on the dynamics of soil populations. Karimi et al. (2021) performed a meta-analysis of Cu ecotoxicity and reported that Cu harms soil microorganisms at concentrations above 200 kg Cu ha − 1 (Cu of 67 mg kg − 1 soil), which is currently the level found in many vineyard and orchard topsoils. Excess Cu reduces microbial activity (Soler-Rovira et al., 2013) and biodiversity (Viti et al., 2008) in vineyard topsoils, and reduces microbial biomass and C mineralization rates in apple orchard topsoils (Wang et al., 2009). ...
Article
Siderophores are biogenic metallophores that can play significant roles in the dynamics of a range of metals, including Cu, in the soil. Understanding the impact of siderophores on the mobility and the availability of metals in soil is required to optimize the efficiency of soil remediation processes such as phytoextraction. This study compared the ability of siderophores desferrioxamine B (DFOB) and pyoverdine (Pvd) to mobilize metals in a series of Cu-contaminated soils, and investigated the extent their metal mobilization efficiency changed over time and with the level of Cu contamination of the soil. Siderophores were supplied (or not) to Cu-contaminated soils and metal mobility was assessed through their total concentration in 0.005 M CaCl2 extract. DFOB selectively mobilized Fe and Al while Pvd also mobilized Cu and Ni, Co, V and As but to a lesser degree. The 1:1 relationship between DFOB in the CaCl2 extract and Fe + Al mobilized from the solid phase suggests that DFOB mobilized metals by ligand-controlled dissolution. The accumulation of Cu in soil enhanced the adsorption of DFOB and Pvd at the surface of soil constituents and the mobilization of Fe to the detriment of Al by the two siderophores. The metal mobilization efficiency of DFOB and to a lesser extent of Pvd decreased over 22 days. According to ¹⁵N-Pvd analyses, Pvd degradation at least partly contributed to the progressive reduction in the metal mobilization efficiency of Pvd. The processes behind these results and the relevance of these results for manipulating the availability of Cu (and Fe) in soil are discussed.
... 93 High Cu is also associated with destroying a variety of soil biological activities. 94 For example, Karimi et al. 96 reported that high Cu decreases the activities and respirations of soil microorganisms, including collembola, nematodes, enchytraeid, and earthworms. It was suggested that the soil Cu application threshold remains at 4 kg/ha/year. ...
Article
The extensive use of high-concentration copper (Cu) in feed additives, fertilizers, pesticides, and nanoparticles (NPs) inevitably causes significant pollution in the ecological environment. This type of chain pollution begins with animal husbandry: first, Cu accumulation in animals poisons them; second, high Cu enters the soil and water sources with the feces and urine to cause toxicity, which may further lead to crop and plant pollution; third, this process ultimately endangers human health through consumption of livestock products, aquatic foods, plants, and even drinking water. High Cu potentially alters the antibiotic resistance of soil and water sources and further aggravates human disease risks. Thus, it is necessary to formulate reasonable Cu emission regulations because the benefits of Cu for livestock and plants cannot be ignored. The present review evaluates the potential hazards and benefits of high Cu in livestock, the environment, the plant industry, and human health. We also discuss aspects related to bacterial and fungal resistance and homeostasis and perspectives on the application of Cu-NPs and microbial high-Cu removal technology to reduce the spread of toxicity risks to humans.
Article
The extensive use of copper-based fungicides in orchards, especially in vineyards, leads to the accumulation of copper, which has caused growing concern. However, data on the acquisition of antibiotic resistance in opportunistic pathogens under copper-based fungicides are scarce. In this study, we investigated the potential development of antibiotic resistance in Escherichia coli K12 under selective copper hydroxide pressure. The results indicated that copper hydroxide at concentrations of 100 mg/L and 200 mg/L evolved resistance against chloramphenicol and tolerance against tetracycline to 4–8 and 2.00–2.67 times than the initial minimal inhibitory concentrations (MICs), respectively. Whole-genome sequencing analysis showed that the obtained resistant strains carried gene mutations including AcrAB-TolC multidrug efflux pump (acrB and marR), outer membrane porin (evZ), and another indirect pathways. Furthermore, the expression of multidrug efflux pump genes and oxidative stress-related genes were significantly upregulated, whereas outer membrane porin genes were downregulated. Thus, our results could well explain the emergence of antibiotic resistance and resistance mechanisms selected by copper-based fungicide, and provide a basis for the management of copper-based fungicide in agriculture to avoid the spread of antibiotic resistance.
Article
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La synthèse de la littérature académique internationale a montré que la dose limite de cuivre de 4 kg/ha/an fixée par la Communauté Européenne ne semble pas avoir d'impact délétère sur la biodiversité des sols. Ce résultat doit être pris avec précaution, au vu du faible nombre d'études (seulement 19), des nombreux biais qui les caractérisent (un seul apport d'une forte dose et mesures d'impact à court-terme) et de la faible diversité de sols étudiés. En effet, la plupart de ces études s'intéresse à des sols à faible teneur en cuivre, donc potentiellement moins vulnérables à un nouvel apport de cuivre. Ainsi, bien que la dose de 4 kg/ha/an ne semble pas délétère pour la qualité biologique des sols pour certains vignobles à court-terme, d'autres plus sensibles (fortes teneurs en cuivre, pH, matière organique) peuvent courir un risque imminent. Cela signifie qu'il est nécessaire pour évaluer les risques de prendre en compte les particularités locales et aussi d'intensifier les recherches à l'échelle globale pour des solutions alternatives au cuivre qui seraient aussi efficaces pour la lutte anti-Mildiou mais également durables pour les sols, la biodiversité et nos terroirs.
Chapter
This chapter presents the European Union's wine policy and regulatory framework and discusses the main issues to be addressed in the wine sector's path toward increased sustainability. Policy choices taken in 2008 assured that the European wine sector became competitive in both the internal and foreign markets. In the next 20 years, sustainability and addressing the concerns of EU citizens about environment, food, and health are the major challenges for the European wine sector. In this context, the EU wine sector will need to address mainly the issues related to pesticide use reduction, unlocking possibilities of exploring genetic potential of the genus Vitis, incorporate low alcohol wine-based drinks within the wine definition, and provide relevant nutritional and ingredient information to consumers.
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Reduction of copper-based fungicides with the final aim of phasing out has a high priority in European policy as well as in organic agriculture. Our survey aims at providing an overview of the current use of copper-based plant protection products in European organic agriculture and the need for alternatives to allow policy makers to develop strategies for a complete phasing out. Due to a lack of centralized databases on pesticide use, our survey combines expert knowledge on permitted and real copper use per crop and country with statistics on organic area. In the 12 surveyed countries, covering together 83% of the European organically managed horticultural area, we calculated approximately 3258 t copper metal per year are consumed by organic agriculture, equalling to 53% of the permitted annual dosage. This amount is split between olives (1263 t y ⁻¹ , 39%), grapevine (990t y ⁻¹ , 30%), and almonds (317 t y ⁻¹ , 10%), followed by other crops with much smaller annual uses (<80 t y ⁻¹ ). Potato, usually considered a highly demanding plant for copper inputs, only uses 39 t y ⁻¹ of copper per year. In 56% of the allowed cases (countries × crops), farmers use less than half of the allowed amount, and in 27% less than a quarter, with some variability between countries. Considering the large volumes of copper used annually, replacement of copper seems only feasible if all preventive strategies from the crop protection pyramid are fully implemented and several affordable alternative plant protection products are successfully brought to the market.
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Viticulture is a key sector of the agricultural economy of the main wine-producing countries, e.g. Italy, France, Spain and the USA, but is also one of the main users of phytosanitary products and mechanization. Over the last 15 years, numerous studies of the effect of viticultural practices on soil quality have evidenced strong impacts on soil physical, chemical and biological quality. However, to date a global analysis providing a comprehensive overview of the ecotoxicological impacts of viticultural practices on soil biological quality is missing. Here, we conducted a meta-analysis of the literature in order to rank viticultural production systems and practices according to their impact on soil biodiversity and functioning in the context of the agro-ecological transition. We screened about one hundred articles and gathered data on more than 50 viticultural factors and 230 soil biological parameters. The results show that soil microorganisms are threefold to fourfold higher under organic viticulture than under conventional viticulture in terms of biomass, respiration and activity; and that biodynamic viticulture shows a similar trend than organic viticulture. Tillage, the absence of soil cover and mineral fertilization are significantly deleterious to the whole soil biodiversity, whereas cover crops, organic fertilizers and addition of grapevine pruning wood are beneficial. Pesticides—especially herbicides—have an ecotoxicological impact on soil organisms, notably on nematodes with losses of up to two-thirds of individuals. The pivotal role of biodiversity in soil functions implies that this degradation will have substantial consequences on the ecological and agronomical services provided by the soil for vine production. On this basis, we propose a potentially more agro-ecological and sustainable vine production system based on the more virtuous practices.
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Soil organisms represent the most biologically diverse community on land and govern the turnover of the largest organic matter pool in the terrestrial biosphere. The highly complex nature of these communities at local scales has traditionally obscured efforts to identify unifying patterns in global soil biodiversity and biogeochemistry. As a result, environmental covariates have generally been used as a proxy to represent the variation in soil community activity in global biogeochemical models. Yet over the past decade, broad-scale studies have begun to see past this local heterogeneity to identify unifying patterns in the biomass, diversity, and composition of certain soil groups across the globe. These unifying patterns provide new insights into the fundamental distribution and dynamics of organic matter on land.
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The paper reports the results of a laboratory test on the bioaccumulation and toxicological effects of sub-lethal soil concentration of copper, a widely used fungicide in organic farming, on DNA damage, a critical marker increasingly used in ecotoxicology in the earthworm Eisenia andrei. In the same experimental setting we evaluated gene expression of classical biomarker of stress induced by xenobiotic. [Heat Shock Protein 70 (HSP70) and Metallothionein (MET)], as well as genes coding for enzymes involved in detoxification of reactive oxygen species [Superoxide dismutase (SOD) and catalase (CAT)]. Additionally, expression of genes involved in the immune response were investigated: a Toll-like receptor (TLR), a receptor with cytolytic activity named Cytolytic Factor (CCF) and two antimicrobial peptides, fetidin (FET) and lysenin (LYS). Results showed significant time-dependent bioaccumulation of Cu and DNA damage at concentrations remarkably lower than those found in most agricultural soils worldwide. MET was increased as was FET and TLR. The present work gives new insights into the mechanisms of sub-lethal toxicity of copper as an environmental pollutant and in the identification of novel sub-lethal biomarkers of cellular response to the stressor such as immune response genes.
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Over the last two decades, a considerable effort has been made to decipher the biogeography of soil microbial communities as a whole, from small to broad scales. In contrast, few studies have focused on the taxonomic groups constituting these communities; thus, our knowledge of their ecological attributes and the drivers determining their composition and distribution is limited. We applied a pyrosequencing approach targeting 16S ribosomal RNA (rRNA) genes in soil DNA to a set of 2173 soil samples from France to reach a comprehensive understanding of the spatial distribution of bacteria and archaea and to identify the ecological processes and environmental drivers involved. Taxonomic assignment of the soil 16S rRNA sequences indicated the presence of 32 bacterial phyla or subphyla and 3 archaeal phyla. Twenty of these 35 phyla were cosmopolitan and abundant, with heter ogeneous spatial distributions structured in patches ranging from a 43-to 260-km radius. The hierarchy of the main environmental drivers of phyla distribution was soil pH > land management > soil texture > soil nutrients > climate. At a lower taxonomic level, 47 dominant genera belonging to 12 phyla aggregated 62.1% of the sequences. We also showed that the phylum-level distribution can be determined largely by the distribution of the dominant genus or, alternatively, reflect the combined distribution of all of the phylum members. Together, our study demonstrated that soil bacteria and archaea present highly diverse biogeographical patterns on a nationwide scale and that studies based on intensive and systematic sampling on a wide spatial scale provide a promising contribution for elucidating soil biodiversity determinism.
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Copper (Cu) distribution in soil is influenced by climatic, geological and pedological factors. Apart from geological sources and industrial pollution, other anthropogenic sources, related to the agricultural activity, may increase copper levels in soils, especially in permanent crops such as olive groves and vineyards. This study uses 21,682 soil samples from the LUCAS topsoil survey to investigate copper distribution in the soils of 25 European Union (EU) Member States. Generalized Linear Models (GLM) were used to investigate the factors driving copper distribution in EU soils. Regression analysis shows the importance of topsoil properties, land cover and climate in estimating Cu concentration. Meanwhile, a copper regression model confirms our hypothesis that different agricultural management practices have a relevant influence on Cu concentration. Besides the traditional use of copper as a fungicide for treatments in several permanent crops, the combined effect of soil properties such as high pH, soil organic carbon and clay, with humid and wet climatic conditions favours copper accumulation in soils of vineyards and tree crops. Compared to the overall average Cu concentration of 16.85 mg kg−1, vineyards have the highest mean soil Cu concentration (49.26 mg kg−1) of all land use categories, followed by olive groves and orchards.
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In soil, the link between microbial diversity and carbon transformations is challenged by the concept of functional redundancy. Here, we hypothesized that functional redundancy may decrease with increasing carbon source recalcitrance, and that coupling of diversity with C-cycling may change accordingly. We manipulated microbial diversity to examine how diversity decrease affects the decomposition of easily degradable (i.e. allochthonous plant residues) vs. recalcitrant (i.e. autochthonous organic matter) C-sources. We found that a decrease in microbial diversity (i) affected the decomposition of both autochthonous and allochthonous carbon sources hence reducing global CO2 emission by up to 40%, and (ii) shaped the source of CO2 emission towards preferential decomposition of most degradable C-sources. Our results also revealed that the significance of the “diversity effect” increases with nutrient availability. Altogether, these findings show that C-cycling in soil may be more vulnerable to microbial diversity changes than expected from previous studies, particularly in ecosystems exposed to nutrient inputs. Thus concern about the preservation microbial diversity may be highly relevant in the current ‘global changes’ context assumed to impact soil biodiversity and the pulse inputs of plant residues and rhizodeposits into the soil.
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The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, France, and co-rapporteur Member State, Germany, for the pesticide active substance copper compounds are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012. The conclusions were reached on the basis of the evaluation of the representative uses of copper compounds as a fungicide on grapes, tomatoes and cucurbits. The reliable end points appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. © 2018 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.
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Copper (Cu)-based fungicides have been used in viticulture to prevent downy mildew since the end of the 19th century, and are still used today to reduce fungal diseases. Consequently, Cu has built up in many vineyard soils, and it is still unclear how this affects soil functioning. The present study aimed to assess the short and medium-term effects of Cu contamination on the soil fungal community. Two contrasting agricultural soils, an acidic sandy loam and an alkaline silt loam, were used for an eco-toxicological greenhouse pot experiment. The soils were spiked with a Cu-based fungicide in seven concentrations (0–5000 mg Cu kg⁻¹ soil) and alfalfa was grown in the pots for 3 months. Sampling was conducted at the beginning and at the end of the study period to test Cu toxicity effects on total microbial biomass, basal respiration and enzyme activities. Fungal abundance was analysed by ergosterol at both samplings, and for the second sampling, fungal community structure was evaluated via ITS amplicon sequences. Soil microbial biomass C as well as microbial respiration rate decreased with increasing Cu concentrations, with EC50 ranging from 76 to 187 mg EDTA-extractable Cu kg⁻¹ soil. Oxidative enzymes showed a trend of increasing activity at the first sampling, but a decline in peroxidase activity was observed for the second sampling. We found remarkable Cu-induced changes in fungal community abundance (EC50 ranging from 9.2 to 94 mg EDTA-extractable Cu kg⁻¹ soil) and composition, but not in diversity. A large number of diverse fungi were able to thrive under elevated Cu concentrations, though within the order of Hypocreales several species declined. A remarkable Cu-induced change in the community composition was found, which depended on the soil properties and, hence, on Cu availability.
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ABSTRACT The purpose of this study was to evaluate Cu and Zn migration and fractions in sandy soil of vineyards. In Urussanga (SC), Brazil, soil samples were collected from a 4-year-old and 15-yearold vineyard, and from a forested area. In the soils, the chemical characteristics of Cu and Zn were analyzed by the EDTA method, which determines the fraction available in soil; 3050B method of the USEPA for total concentrations, which represents the pseudo-soil contents in the soil; and chemical fractionation, which estimates soluble fraction, exchangeable fraction, fraction associated with clay minerals, fraction associated with organic matter and residual fraction. The results show that there is accumulation of Cu and Zn in sandy soils cultivated with grapevines and with frequent fungicide applications. These higher levels were found in soils with longer cultivation time (15 years old), but were restricted to the superficial layers of the soil. Most of the Cu was extracted by EDTA method, and it may be considered as available to plants. The EDTA also extracted a small part of Zn. Most of the Cu in the vineyard soils can be characterized by low geochemical mobility, but in the uppermost soil layers of the oldest vineyard, there was an increase in Cu content associated with soil organic matter. Most of the Zn in the vineyard soil was associated with minerals, which indicates low mobility and also low potential for toxicity to plants and microorganisms.
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Although numerous studies have demonstrated the key role of bacterial diversity in soil functions and ecosystem services, little is known about the variations and determinants of such diversity on a nationwide scale. The overall objectives of this study were i) to describe the bacterial taxonomic richness variations across France, ii) to identify the ecological processes (i.e. selection by the environment and dispersal limitation) influencing this distribution, and iii) to develop a statistical predictive model of soil bacterial richness. We used the French Soil Quality Monitoring Network (RMQS), which covers all of France with 2,173 sites. The soil bacterial richness (i.e. OTU number) was determined by pyrosequencing 16S rRNA genes and related to the soil characteristics, climatic conditions, geomorphology, land use and space. Mapping of bacterial richness revealed a heterogeneous spatial distribution, structured into patches of about 111km, where the main drivers were the soil physico-chemical properties (18% of explained variance), the spatial descriptors (5.25%, 1.89% and 1.02% for the fine, medium and coarse scales, respectively), and the land use (1.4%). Based on these drivers, a predictive model was developed, which allows a good prediction of the bacterial richness (R²adj of 0.56) and provides a reference value for a given pedoclimatic condition.
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Evaluating the quality of ecosystems in terms of biological patrimony and functioning is of critical importance in the actual context of intensified human activities. Microbial diversity is commonly used as a bioindicator of ecosystems functioning. However, there is a lack of sensitivity of microbial diversity indicators in the case of moderate and chronic environmental degradation, such as atmospheric deposition of pollutants, agricultural practices, diffuse pollution by wastewater and climate change. As a consequence, there is a need for alternative bioindicators of soils and water quality. Here, we discuss the interest of adopting a more integrative approach based on biotic interaction networks beyond the simple diversity indicators. We review how the various biotic interactions can be integrated in the various microbial networks such as trophic, mutualistic and co-occurrence networks. Then we discuss the efficiency of microbial networks and associated metrics to detect changes in microbial communities. We conclude that the connectance, the number of links and the average degree of co-occurrence networks could vary from 10 to 50% in response to minor perturbations when microbial diversity parameters remain stable. Finally, we analyze studies that aimed at linking microbial networks and activity to evaluate the potential of such networks for providing simple and operational indicators of ecosystem quality and functioning.
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Copper has been intensively used in industry and agriculture since mid-18th century and is currently accumulating in soils. We investigated the diversity of potential active bacteria by 16S rRNA gene transcript amplicon sequencing in a temperate grassland soil subjected to century-long exposure to normal (≈15 mg kg−1), high (≈450 mg kg−1) or extremely high (≈4500 mg kg−1) copper levels. Results showed that bioavailable copper had pronounced impacts on the structure of the transcriptionally active bacterial community, overruling other environmental factors (e.g. season and pH). As copper concentration increased, bacterial richness and evenness were negatively impacted, while distinct communities with an enhanced relative abundance of Nitrospira and Acidobacteria members and a lower representation of Verrucomicrobia, Proteobacteria and Actinobacteria were selected. Our analysis showed the presence of six functional response groups (FRGs), each consisting of bacterial taxa with similar tolerance response to copper. Furthermore, the use of FRGs revealed that specific taxa like the genus Nitrospira and several Acidobacteria groups could accurately predict the copper legacy burden in our system, suggesting a potential promising role as bioindicators of copper contamination in soils.
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Elevated levels of copper in agricultural soils result from the use of Cu-containing compounds to control plant diseases and from application of manure or sewage sludge. Increased concentration of Cu in soils under long-term production of grapevine, citrus and other fruit crops have been recorded in numerous studies. The Bordeaux mixture, an efficient agent for prevention of vine «Downy Mildew», Plasmopara viticola, has been routinely used in Europe since the end of the 19th century with its concentrations and the number of treatments depending on weather conditions, infection intensity and vineyard management. The century-old practice of using Cu-sulphates and other copper containing fungicides to protect grapevine, but also other agricultural crops, in temperate and tropic climatic regions, resulted in significant Cu accumulation in soils [8]. Most of the copper accumulated in leaves and soil by spraying will be retained in topsoil through the biological cycle and tillage [9-11]. Comparison of copper contents of 110 to 1500 mg kg⁻¹ with its usual content in agricultural soils (20 – 30 mg kg⁻¹) points to their connection with such practice [12]. Copper can be either a micro nutrient or a toxic element which depends on the copper concentration. Determination of the total content of metals in soils is an important step in estimating the hazards to the vital roles of soil in the ecosystem, and also in comparison with the quality standards in terms of the effects of pollution and sustainability of the system. Increased anthropogenic inputs of trace metals in soils have received considerable attention since they can enter the food chain by different ways. Soils receiving repeated applications of fungicides, pesticides or manure exhibit high concentrations of extractable metals, especially copper. From the commercial aspect, wine-growers are now showing increasing interest in the effects of soil composition, its fertility and texture upon wine quality. Special importance is laid on the influence of soil geochemical characteristics, including accumulation of certain toxic elements, on grape and wine quality. A variety of factors, both spatial and temporal, affect the grape quality, many of them being specific exactly to the given wine-growing site. Grape growing conditions and enological potential have been created, among other factors, also by landscape characteristics: soil, climate and topography. These factors are much less changeable than biological (cultivar, stock) or human (ampelotechnics, vinification) factors and for this reason the concept of viticultural terroir is based on the simple relationship between soil and wine. Since terroir is defined as an interactive ecosystem, it is very difficult to evaluate scientifically its contribution to plant capacity to accumulate bioactive phytochemicals good for human health.
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In this study, the effects of arsenic, cadmium, copper and chromium treatments were examined on a nematode community structure and proportion of functional groups in the microcosm for 30 days. The toxic effects on the nematode community did not correspond with metals mobility (EDTA extraction) in soil as it was expected. The most toxic element with a significant degradation of community structure was chromium (low mobile), which negatively affected almost all observed ecological parameters (abundance, diversity and ecological indices). On the other hand, cadmium and arsenic influence was negligible even in the plots treated with the highest concentrations and the communities resembled to the control samples. Copper showed a stimulative effect on the community under low concentration (40 mg.kg
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A pot experiment was carried out to determine the effect of soil (loamy sand and sandy loam) contamination with copper doses of 0, 150, 450 mg Cu·kg-1 d.m. soil on the activity of β-glucosidase (EC 3.2.1.21), acid phosphatase (EC 3.1.3.2), alkaline phosphatase (EC 3.1.3.1) and arylsulfatase (EC 3.1.6.1) in soil. The resistance of these enzymes to copper pollution was also estimated. Soil samples were contaminated with copper chloride. The experiment was carried out in five replications, in two series. The first series was performed on uncropped soil and the second one - on cropped soil. The experimental plants were oat, spring rape and yellow lupine. The activity of soil enzymes was determined in the analyzed samples on the 25th and the 50th day of the experiment. The results of the experiment showed that copper contamination in doses of 150 mg to 450 mg·kg-1 soil significantly inhibits soil's biochemical activity. The sensitivity of the tested enzymes to copper was determined in the following order: alkaline phosphatase > arylsulfatase > acid phosphatase > β-glucosidase. The resistance of the above enzymes to copper depended on the cultivated plant species, soil type and the type of soil use and management. In samples of sandy loam, copper induced the smallest change in the activity of acid phosphatase and alkaline phosphatase, and in loamy sand - in the activity of arylsulfatase and acid phosphatase. In uncropped soil, copper was the least effective in changing the activity of arylsulfatase and acid phosphatase. All of the tested enzymes were less resistant to copper contamination in cropped than in uncropped soil. In soil planted with oat, β-glucosidase was the most resistant and arylsulfatase was the least resistant enzyme to copper contamination. In samples sown with spring rape, the analogous enzymes were arylsulfatase and alkaline phosphatase. In yellow lupine treatments, alkaline phosphatase was the most and β-glucosidase was the least resistant enzyme.
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Understanding the ecology of pathogenic organisms is important in order to monitor their transmission in the environment and the related health hazards. We investigated the relationship between soil microbial diversity and the barrier effect against Listeria monocytogenes invasion. By using a dilution-to-extinction approach, we analysed the consequence of eroding microbial diversity on L. monocytogenes population dynamics under standardised conditions of abiotic parameters and microbial abundance in soil microcosms. We demonstrated that highly diverse soil microbial communities act as a biological barrier against L. monocytogenes invasion and that phylogenetic composition of the community also has to be considered. This suggests that erosion of diversity may have damaging effects regarding circulation of pathogenic microorganisms in the environment.
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The vertical distribution of soil nematodes down to a depth of 50cm was studied in an age sequence of 0-, 5-, 10-, and 22-year-old Caragana microphylla plantations (treatments) in the Horqin Sandy Land, Northeast China. The abundances and generic compositions of nematode fauna in five soil layers (0–10, 10–20, 20–30, 30–40, and 40–50cm) were analyzed. 42 genera were observed in the nematode suspensions, and Acrobeles was the dominant genus in all treatments. The results showed that the total number of nematodes and the generic diversity in an age sequence of C. microphylla plantations decreased with increasing soil depth. Significant differences in the numbers of total nematodes, bacterivores (BF), plant parasites (PP), and omnivores–predators (OP) were observed between treatments and depths. BF was the most abundant trophic group in our study, followed by OP. The numbers of OP showed an obviously increasing trend with increasing age of C. microphylla plantation. The vertical distribution of the soil nematode communities was related to gradual changes in soil chemical properties, and it indicated that C. microphylla plantations have played positive roles in improving soil environmental conditions and restoring desertified ecosystems in the Horqin Sandy Land. The ecological indices selected were influenced by plantation chronosequence but not by soil depth.
Article
Microbial responses to Cu pollution as a function of Cu sources (Cu salts and commercial Cu fungicides) were assessed in a soil using basal soil respiration, and bacterial and fungal community growth, as endpoints. The soil was amended with different concentrations (0-32 mmol Cu kg-1) of Cu nitrate, Cu sulfate, Bordeaux mixture and 3 types of Cu oxychloride. Cu salts decreased soil pH, while this was not found with the other Cu sources. This difference in soil pH effects caused differences in the respiration, bacterial growth and fungal growth response. Basal soil respiration was negatively affected by Cu addition when the soil was spiked with Cu salts, but almost unaffected by commercial Cu fungicides. Bacterial growth was significantly and negatively affected by Cu addition for all the Cu sources, but Cu toxicity was higher for Cu salts than for commercial Cu fungicides. Fungal growth response was also different for Cu salts and commercial Cu fungicides, but only in the long-term. High Cu amendments using Cu salts stimulated fungal growth, whereas for commercial Cu fungicides, these concentrations inhibited fungal growth. Thus, the use of products similar to those used in commercial fungicides is a recommended practice for Cu risk assessments in soil.
Article
Because the extensive use of Cu-based fungicides, the accumulation of Cu in agricultural soil has been widely reported. However, little information is known about the bioavailability of Cu deriving from different fungicides in soil. This paper investigated both the distribution behaviors of Cu from two commonly used fungicides (Bordeaux mixture and copper oxychloride) during the aging process and the toxicological effects of Cu on earthworms. Copper nitrate was selected as a comparison during the aging process. The distribution process of exogenous Cu into different soil fractions involved an initial rapid retention (the first 8 weeks) and a following slow continuous retention. Moreover, Cu mainly moved from exchangeable and carbonate fractions to Fe-Mn oxides-combined fraction during the aging process. The Elovich model fit well with the available Cu aging process, and the transformation rate was in the order of Cu(NO3)2 > Bordeaux mixture > copper oxychloride. On the other hand, the biological responses of earthworms showed that catalase activities and malondialdehyde contents of the copper oxychloride treated earthworms were significantly higher than those of Bordeaux mixture treated earthworms. Also, body Cu loads of earthworms from different Cu compounds spiked soils were in the following order: copper oxychloride > Bordeaux mixture. Thus, the bioavailability of Cu from copper oxychloride in soil was significantly higher than that of Bordeaux mixture, and different Cu compounds should be taken into consideration when studying the bioavailability of Cu-based fungicides in the soil.
Article
The use of pesticides in crop fields may have negative effects on soil Oligochaeta Annelida, i.e., earthworms and enchytraeids, and thus affect soil quality. The aim of this study was to assess the effects of two commercial fungicide formulations on the earthworm Aporrectodea caliginosa and the enchytraeid Enchytraeus albidus in a natural soil. The fungicides were Cuprafor micro® (copper oxychloride), commonly used in organic farming, and Swing Gold® (epoxiconazole and dimoxystrobin), a synthetic fungicide widely used in conventional farming to protect cereal crops. Laboratory experiments were used to assess the survival, biomass loss and avoidance behaviour. No lethal effect was observed following exposure to the copper fungicide for 14 days, even at 5000mgkg(-1) of copper, i.e. 650 times the recommended dose (RD). However, a significant decrease in biomass was observed from 50mgkg(-1) of copper (6.5 times the RD) for A. caliginosa and at 5000mgkg(-1) of copper (650 times the RD) for E. albidus. These sublethal effects suggest that a longer period of exposure would probably have led to lethal effects. The EC50 avoidance for the copper fungicide was estimated to be 51.2mgkg(-1) of copper (6.7 times the RD) for A. caliginosa, and 393mgkg(-1) of copper (51 times the RD) for E. albidus. For the Swing Gold® fungicide, the estimated LC50 was 7.0 10(-3)mLkg(-1) (6.3 times the RD) for A. caliginosa and 12.7 10(-3)mLkg(-1) (11.0 times the RD) for E. albidus. No effect on biomass or avoidance was observed at sublethal concentrations of this synthetic fungicide. It was concluded that enchytraeids were less sensitive than earthworms to the two commercial fungicides in terms of mortality, biomass loss and avoidance behaviour. Therefore we discuss the different strategies possibly used by the two Oligochaeta species to cope with the presence of the pesticides were discussed, along with the potential consequences on the soil functions.
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Heavy metal pollution is a global issue due to health risks associated with metal contamination. Although many metals are essential for life, they can be harmful to man, animal, plant and microorganisms at toxic levels. Occurrence of heavy metals in soil is mainly attributed to natural weathering of metal-rich parent material and anthropogenic activities such as industrial, mining, agricultural activities. Here we review the effect of soil microbes on the biosorption and bioavailability of heavy metals; the mechanisms of heavy metals sequestration by plant and microbes; and the effects of pollution on soil microbial diversity and activities. The major points are: anthropogenic activities constitute the major source of heavy metals in the environment. Soil chemistry is the major determinant of metal solubility, movement and availability in the soil. High levels of heavy metals in living tissues cause severe organ impairment, neurological disorders and eventual death. Elevated levels of heavy metals in soils decrease microbial population, diversity and activities. Nonetheless, certain soil microbes tolerate and use heavy metals in their systems; as such they are used for bioremediation of polluted soils. Soil microbes can be used for remediation of contaminated soils either directly or by making heavy metals bioavailable in the rhizosphere of plants. Such plants can accumulate 100 mg g−1 Cd and As; 1000 mg g−1 Co, Cu, Cr, Ni and 10,000 mg g−1 Pb, Mn and Ni; and translocate metals to harvestable parts. Microbial activity changes soil physical properties such as soil structure and biochemical properties such as pH, soil redox state, soil enzymes that influence the solubility and bioavailability of heavy metals. The concept of ecological dose (ED50) and lethal concentration (LC50) was developed in response to the need to easily quantify the influence of pollutants on microbial-mediated ecological processes in various ecosystems.
Article
In the present study, the effect of the heavy-metal salt copper chloride (CuCl2 center dot 2H(2)O) in soils freshly spiked (3 d) and aged (70 +/- 10 d; mean SD) was studied in the test species Enchytraeus albidus, E. luxuriosus, and Folsomia candida. Up to nine soils were used: Besides the Organisation for Economic Co-operation and Development (OECD) artificial soil and the Agricultural Testing and Research Agency (Landwirtschaftliche Untersuchungs- und Forschungsanstalt, Speyer, Germany) 2.2 natural standard soils, the others were selected based on the EURO Soil approach, taking into account the effect of different soil parameters (pH, organic matter, grain size distribution, and carbon to nitrogen ratio). Additionally, the effect of the chloride ions was studied separately. The results revealed the following: First, a soil effect was observed; for example, in F. candida, median effective concentrations (EC50s) varied between 262 mg/kg in a sample from the same site as the original EURO Soil 5 soil and greater than 1,000 mg/kg in OECD soil. Second, an aging effect was observed, mainly in F. candida. For example, toxicity of offspring survival was increased twofold in the OECD soil and approximately eightfold with aging in the EURO Soil 7 soil, whereas the enchytraeid species did not react differently after aging. Third, an effect of chloride ions on reproduction of the animals was found; however, this effect was independent of the aging period. Fourth, species variation was seen in terms of sensitivity (EC50), decreasing in the following order: E. luxuriosus > E. albidus >> F. candida. Differences in toxicity of offspring survival between enchytraeids and F. candida might be explained by the different routes of uptake.
Article
Pollutants can be introduced to soil through the application of organic and inorganic fertilizers and pesticides and through atmospheric depositions. The objective of this research was to evaluate the influence of long-term (9–17 years) tillage systems on the behavior of pollutants in soils. Bioavailability and enrichment of heavy metals, arsenic, and organics, i.e. polychlorinated biphenyls (PCB’s) and a chlorinated phenol (2,4-DCP) were measured in a Eutric Cambisol and a Luvisol under conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). Soil samples were collected from 0 to 3, 3 to 10, and 10 to 25cm depths.The upper layer of NT soils was enriched in pollutants, but concentrations decreased with increasing soil depth. Atmospheric deposition of pollutants and input via organic fertilizers was noticeable in soils under long-term NT. Total amount of zinc (59mgkg−1) was significantly enriched in the 0–3cm depth of the Luvisol under NT and this was attributed to higher sorption capacity for heavy metal input via liquid manure. In the Eutric Cambisol, NT resulted in significant increase of cadmium extracted by aqua regia in the arable layer of 0–25cm. As a result of higher soil organic C, long-term accumulation of PCB’s in NT soils was more pronounced than in plowed soils. In plowed soils the mixing effect resulted in homogeneous distribution of pollutants within a soil depth of 0–25cm.The enrichment of organic C in RT and NT soils emphasizes the role of soils as a sink for pollutants, buffering the contaminants against leaching and transfer into crops.
Article
Copper adsorption by vineyard soils of the Geneva canton was evaluated by batch equilibration experiments in a pH range from 4 to 6. The adsorption curves fit significantly to Freundlich function log q = n log C + log Kf, where q is adsorbed Cu concentration on the solid phase and C is solution Cu concentration at the end of the equilibration time. Moreover, we found that Freundlich parameters n and log Kf are moderately correlated to pH, yielding the following equations: log Kf = 0.23 pH + 0.51 (R 2 0.59) and n = −0.12 pH + 1.06 (R 2 0.59). Such equations may be useful to predict Cu mobility for risk assessment studies.
Article
This study seeks to determine the impact of copper-based fungicides on the respiration of vineyard soils. The ISO-17155 is an international standard recommended for monitoring soil quality by the evaluation of the effects of pollutants on soil microbial activity. Respiration curves and derived parameters [i.e., basal respiration (R(B)), substrate-induced respiration (R(S)), lag time (t(lag)), growth rate (μ), time to the peak maximum (t(peakmax)), respiratory-activation quotient (Q(R)), and the cumulative O(2) consumption (C(R))] were determined from 95 vineyard soils that covered a wide range of Cu contents. Statistical analyses showed that most of the variance of the ISO-17155 parameters was due to soil pH and organic C content, but not to the Cu pollution. When the parameters were expressed as a function of soil organic C content, the effect of soil Cu content was found to be significant on R(S) and t(peakmax) but not on R(B) and C(R). The results indicated that threshold values of total (Cu(T)) and exchangeable (Cu(EX)) contents indicative of soil Cu pollution cannot be established. However, adequate management practices resulting in soil organic C contents>2% and pH>5.5 are recommended for preserving vineyard soil quality.
Article
Copper (Cu) containing fungicides have been used for more than one century in Europe on agricultural soils, such as vineyard soils. Total Cu concentrations in such soils can exceed toxicological limits that are commonly derived using artificially spiked soils. This study surveyed Cu toxicity in vineyard soils with reference to soils spiked with CuCl(2). Soil was collected in six established European vineyards. At each site, samples representing a Cu concentration gradient were collected. A control (uncontaminated) soil sampled nearby the vineyard was spiked with CuCl(2). Toxicity was tested using standard ecotoxicity tests: two plant assays (Lycopersicon esculentum Miller (tomato) and Hordeum vulgare L. (barley) growth), one microbial assay (nitrification) and one invertebrate assay (Enchytraeus albidus reproduction). Maximal total Cu concentrations in the vineyard sites ranged 435-690mgCukg(-1), well above the local background (23-105mgCukg(-1)). Toxicity in spiked soils (50% inhibition) was observed at added soil Cu concentrations from 190 to 1039mgCukg(-1) (mean 540mgCukg(-1)) depending on the assay and the site. In contrast, significant adverse effects were only found for three bioassays in vineyard samples of one site and for two bioassays in another site. Biological responses in these cases were more importantly explained by other soil properties than soil Cu. Overall, no Cu toxicity to plants, microbial processes and invertebrates was observed in vineyard soil samples at Cu concentrations well above European Union limits protecting the soil ecosystem.
Article
The collembolan Folsomia fimetaria L. was exposed in the laboratory to a range of elevated soil copper concentrations under two different contamination histories. These results were compared with the in situ abundance of F. fimetaria in a copper-contaminated field site. In the laboratory studies, an EC10 of 337 mg Cu/kg was observed for soil spiked with copper 1 d before the experiment. Using soil from a field site contaminated with copper more than 70 years previously, no effect was observed at concentrations as great as 2911 mg Cu/kg. Reproduction was threefold more sensitive than mortality or growth. Differences in copper sensitivity between sexes and between juvenile clutches were also indicated. The abundance of F. fimetaria showed no change with soil copper concentrations during the first year (spring sampling) of in situ observations. During the second year (autumn sampling), a reduced number per area was observed with increasing soil copper concentrations. Both the presence and abundance of other euedaphic collembolans generally exhibited distribution patterns similar to those of F. fimetaria. Thus, the contamination history and the toxicological endpoint were very important for interpreting the outcome of the standard laboratory toxicity test. Laboratory studies to some extent reflected the in situ abundance, but this depended on the contamination history and the field sampling time. Laboratory experiments using new copper-spiked soil provided the lowest effect levels.
Article
Four copper (0, 250, 500, and 750 kg Cu · haa−1) and pH (4.0, 4.7, 5.4, and 6.1 in 1 M KCl) treatments were applied to an arable agroecosystem. Effects on the nematode community were assessed after 10 years of exposure under field conditions. Both copper and pH had major influences on nematodes. The effect of copper was generally enhanced with decreasing soil pH. The lowest copper application rate which had a significant negative effect on the total number of nematodes was 250 kg. ha−1 at pH 4.0, which is equivalent to a copper concentration of 0.32 mg.L−1 in 0.01 M calcium chloride (Cu-CaCl2). Species composition and the abundance of trophic groups were more sensitive than the total number of nematodes. Combinations of high copper and low pH significantly reduced the number of bacterial-feeding nematodes, whereas the number of hyphal-feeding nematodes increased. Omnivorous and predacious nematodes showed the most sensitive response, becoming extinct when Cu-CaCl2 was 0.8 to 1.4 mg.L−1. Plant-feeding nematodes showed the largest differences in abundance and appeared to reflect the effects of copper and pH on primary production. The results suggest that the nematode community was also affected indirectly by copper and pH via other components of the soil food web. It is concluded that nematodes offer excellent perspectives to assess effects of pollutants at the community level.
Article
Copper-based fungicides have been applied in vineyard soils for a long time, which has resulted in increasing soil Cu concentration. However, information relating to non-target effects of these fungicides on microorganisms of these soils is scarce. The aim of this study was to determine the potential enzyme activities of vineyard soils in relation to Cu content and evaluate the potential risks of long-term application of Cu-based fungicides. For this purpose, a wide range of soil samples, having different total, exchangeable and bioavailable Cu contents, were collected from six regions of quality wines located in the NW Iberian Peninsula, and the activity of dehydrogenase, β-glucosidase, urease and phosphatase were measured. Overall, the results obtained indicate adverse effects of Cu on dehydrogenase, β-glucosidase and phosphatase activities and an inconsistent effect on urease activity. Threshold Cu concentrations at which changes in the enzyme activities became evident were 150–200 mg total Cu kg−1 and 60–80 mg bioavailable Cu kg−1.
Article
Aim The spatial organization of soil microbial communities on large scales and the identification of environmental factors structuring their distribution have been little investigated. The overall objective of this study was to determine the spatial patterning of microbial biomass in soils over a wide extent and to rank the environmental filters most influencing this distribution. Location French territory using the French Soil Quality Monitoring Network. This network covers the entire French territory and soils were sampled at 2150 sites along a systematic grid. Methods The soil DNA extracted from all these soils was expressed in terms of soil molecular microbial biomass and related to other soil and land-use data over French territory. Results This study provides the first extensive map of microbial biomass and reveals the heterogeneous and spatially structured distribution of this biomass on the scale of France. The main factors driving biomass distribution are the physico-chemical properties of the soil (texture, pH and total organic carbon) as well as land use. Soils from land used for intensive agriculture, especially monoculture and vineyards, exhibited the smallest biomass pools. Interestingly, factors known to influence the large-scale distribution of macroorganisms, such as climatic factors, were not identified as important drivers for microbial communities. Main conclusions Microbial abundance is spatially structured and dependent on local filters such as soil characteristics and land use but is relatively independent of global filters such as climatic factors or the presence of natural barriers. Our study confirms that the biogeography of microorganisms differs fundamentally from the biogeography of ‘macroorganisms’ and that soil management can have significant large-scale effects.
Article
Sorption of heavy metals to organic matter and mineral soil constituents can hardly be separated experimentally. Here we studied the retention capacity of organic matter and minerals from soils in a long-term field experiment in which the organic carbon content had been altered, but the mineral phase had remained constant over time. The sorption of Cu, Cd and Zn showed a non-additive contribution of soil organic matter and minerals to the sorption capacity of soil. Sorption on organic matter exceeded mineral sorption from 6 to 13 times. This is the first time that sorption to soil organic matter is quantified in bulk soils.
Article
The impact of a large rhizosphere alkalisation on copper (Cu) bioavailability to durum wheat (Triticum turgidum durum L.) initially exposed to a broad range of bulk soil pH (4.8–7.5) was studied. Plants were exposed to a Cu-contaminated soil treated with eight levels of lime (Ca(OH)2) and supplied with NO3 − or NH4 +-NO3 −. Nitrate-fed plants strongly increased their rhizosphere pH to about 6.9–7.6, whatever the initial pH. NH4 +-NO3 −-fed plants slightly acidified their rhizosphere down to 3.9. Free Cu2+ concentration in the rhizosphere was 3 orders of magnitude larger for NH4 +-NO3 − than NO3 −fed plants. Consequently, Cu bioavailability was 2.4- to 4.2-fold larger for NH4 +−NO3 −-fed plants which demonstrates the importance of rhizosphere alkalisation to restrict metal bioavailability in acidic soils. Copper bioavailability of NO3 −-fed plants initially exposed to a broad range of bulk soil pH was insensitive to bulk soil pH, as rhizosphere pH was ultimately neutral in any case.
Article
An ecosystem approach to soil toxicity testing allows for integration of the effects of chemical contaminants on different components of the soil food web (system structure) and ecosystem-level processes (system function). We used this approach to study copper contamination in small laboratory soil microcosms. Microcosm soils were treated with CuSO4 at the following concentrations: 0, 50, 100, 200, 400, and 800 mg Cu kg⁻¹ soil. Five, 10, 20 and 40 days after soil treatment, we made the following organism-level measurements: microbial biomass N, substrate-induced respiration (SIR) and soil urease activity; total nematode numbers; earthworm mortality, growth and body accumulation of Cu. Our process-level measurements were net N mineralization and litter decomposition.
Article
We studied microbial and protozoan activity, diversity and abundance as affected by Cu2+ amendments ranging from 0 to 1000 μg g−1 over a 70-day period. At the end of the experiment the microbial population size, as indicated by substrate-induced respiration, had normalized for all Cu2+ concentrations, but 1000 μg g−1. Protozoan abundance was negatively affected by Cu2+, although, only in the first few weeks. A more detailed analysis of the individual components that make up the microbial and micro-faunal populations (phospholipid fatty acid (PLFA) profile and protozoan morphotypes), however, yielded a somewhat more complex picture. For the three highest Cu2+ amendments (160, 400 and 1000 μg g−1), there still was a significant reduction in number of differentiable protozoan morphotypes. The bacterial PLFA pattern suggested a shift from Gram-negative towards Gram-positive bacteria for the high amendments, a process where protozoan grazing most likely played a significant role. The ratio of the trans/cis isomers of the 16:1ω7 fatty acid indicated that Cu2+, even at low and medium concentrations, induced physiological changes in the microbial population. The relatively slight changes in total microbial and micro-faunal abundance and activity, also at the highest Cu2+ concentrations, probably reflected the ability of the community to compensate for loss of taxa by functional substitution.
Article
Copper-based fungicides have been applied in apple orchards for a long time, which has resulted in increasing soil Cu concentration. However, the microbial and enzyme properties of the orchard soils remain poorly understood. This study aimed to evaluate the effect of long-term application of Cu-based fungicides on soil microbial (microbial biomass carbon (Cmic), C mineralization, and specific respiration rate) and enzyme (urease, acid phosphatase, and invertase activities) properties in apple orchards. Soil samples studied were collected from apple orchards 5, 15, 20, 30, and 45 years old, and one adjacent forest soil as for reference. The mean Cu concentrations of orchard soils significantly increased with increasing orchard ages ranging from 21.8 to 141 mg kg−1, and the CaCl2-extractable soil Cu concentrations varied from 0.00 to 4.26 mg kg−1. The soil mean Cmic values varied from 43.6 to 116 mg kg−1 in the orchard soils, and were lower than the value of the reference soil (144 mg kg−1). The ratio of soil Cmic to total organic C (Corg) increased from 8.10 to 18.3 mg Cmic g−1 Corg with decreasing orchard ages, and was 26.1 mg Cmic g−1 Corg for the reference soil. A significant correlation was observed between total- or CaCl2-extractable soil Cu and soil Cmic or Cmic/Corg, suggesting that the soil Cu was responsible for the significant reductions in Cmic and Cmic/Corg. The three enzyme activity assays also showed the similar phenomena, and declined with the increasing orchard ages. The mean soil C mineralization rates were elevated from 110 to 150 mg CO2–C kg−1 soil d−1 compared with the reference soil (80 mg CO2–C kg−1 soil d−1), and the mean specific respiration rate of the reference soil (0.63 mg CO2–C mg−1 biomass C d−1) was significantly smaller than the orchard soils from 1.19 to 3.55 mg CO2–C mg−1 biomass C d−1. The soil C mineralization rate and the specific respiration rate can be well explained by the CaCl2-extractable soil Cu. Thus, the long-term application of copper-based fungicides has shown adverse effects on soil microbial and enzyme properties.
Article
The article describes a laboratory experiment to determine the effect of copper oxychloride on the earthworm Eisenia fetida. Copper oxychloride was used because it is the most commonly used fungicide in South African vineyards but not much is known about its toxicity to earthworms. In an experiment lasting 8 weeks, newly hatched earthworms of the species E. fetida were exposed to copper oxychloride mixed into a urine-free cattle manure substrate. Four groups of 10 worms were used per concentration level (control (4.02), 8.92, 15.92, 39.47, 108.72, 346.85 mg Cu kg substrate(-1)). The following life-history parameters were measured: earthworm growth in consecutive weeks, survival rate, maturation time, cocoon production, reproduction success, total number of hatchlings produced, and incubation time. Earthworm growth and cocoon production were significantly reduced at copper oxychloride exposure concentrations of 8.92 mg kg(-1) and higher. Reproduction success in the 8.92 mg Cu kg substrate(-1) was highest. From an exposure concentration of 15. 92 mg Cu kg substrate(-1) and higher, there was a considerable impact of copper oxychloride on reproduction. This could be seen from a reduced reproduction success, a reduced mean and maximum number of hatchlings per cocoon, and a longer incubation time, indicating a strong effect of low copper oxychloride concentrations on this earthworm species.
Article
The effects of Cu amendment on indigenous soil microorganisms were investigated in two soils, a calcareous silty clay (Ep) and a sandy soil (Au), by means of a 1-year field experiment and a two-month microcosm incubation. Cu was added as 'Bordeaux mixture' [CuSO(4), Ca(OH)(2)] at the standard rate used in viticulture (B1=16 kg Cu kg(-1) soil) and at a higher level of contamination (B3=48 kg Cu ha(-1) soil). More extractable Cu was observed in sandy soil (Au) than in silty soil (Ep). Furthermore, total Cu and Cu-EDTA declined with time in Au soil, whereas they remained stable in Ep soil. Quantitative modifications of the microflora were assessed by C-biomass measurements and qualitative modifications were assessed by the characterization of the genetic structure of bacterial and fungal communities from DNA directly extracted from the soil, using B- and F-ARISA (bacterial and fungal automated ribosomal intergenic spacer analysis). In the field study, no significant modifications were observed in C-biomass whereas microcosm incubation showed a decrease in B3 contamination only. ARISA fingerprinting showed slight but significant modifications of bacterial and fungal communities in field and microcosm incubation. These modifications were transient in all cases, suggesting a short-term effect of Cu stress. Microcosm experiments detected the microbial community modifications with greater precision in the short-term, while field experiments showed that the biological effects of Cu contamination may be overcome or hidden by pedo-climatic variations.
Article
In soil, genetic structure modifications of indigenous bacterial community consecutively to a severe stress (mercury contamination) were delayed when the community was pre-exposed to various minor perturbations (heat, copper and atrazine). Such minor perturbations induced transitory community structure modifications leading to an increase of community stability towards a severe mercury stress. These results illustrated well the short-term pre-adaptation process for bacterial community hypothesizing that community submitted to perturbations become more resistant to withstand another stress.