Impact of citronellol on river and soil environments using non-target model organisms and natural populations.

Citronellol is an acyclic monoterpenoid with a wide range of pharmacological activities (antibacterial, antifungal, anti-lice, repellent, lipolytic, anti-allergic, anti-inflammatory, antispasmodic, antidiabetic, anti-cholesterol, among other) and potential to replace synthetic products. However, the impact of citronellol on the environment remains unknown. We analysed, for the first time, the environmental impact of citronellol on river and soil environments using non-target model organisms and natural populations. The acute toxicity of citronellol on the aquatic invertebrate Daphnia magna, the plant Allium cepa L and the earthworm Eisenia fetida was quantified. The effect of citronellol in a river ecosystem was analysed using river periphyton communities taxonomically characterised and a river microbial community characterised through 16 S rRNA gene sequencing. Finally, a microbial community from natural soil was used to monitor the effect of citronellol on the soil ecosystem. The results showed that E. fetida was most sensitive to citronellol (LC50 = 12.34 mg/L), followed by D. magna (LC50 = 14.11 mg/L). Citronellol affected the photosynthesis of the fluvial periphyton (LC50 = 94.10 mg/L) and was phytotoxic for A. cepa. Furthermore, citronellol modified the growth and metabolism of both fluvial (LC50 = 0.19% v/v) and edaphic (LC50 = 5.07% v/v) bacterial populations. The metabolism of the microorganisms in the soil and water exposed to citronellol decreased with respect to the control, especially their ability to metabolise carbohydrates. Our results show that citronellol has a negative impact on the environment. Although acute effects cannot be expected, it is necessary to quantify the environmental levels as well as the long-term and persistent effects of this monoterpene.

Impact of Artemisia absinthium hydrolate extracts with nematicidal activity on non-target soil organisms of different trophic levels.

Natural pesticides are considered a good alternative to synthetic pesticides to reduce environmental impacts. However, biopesticides may have unknown effects on the environment, and can affect non-target organisms. In this study, the ecotoxicological effects of an aqueous extract (hydrolate) from Spanish populations of Artemisia absinthium (var. Candial) showing a promising biopesticide activity, were evaluated on non-target soil organisms from different trophic levels (natural microbial communities characterized through 16S rRNA gene sequencing, the earthworm Eisenia fetida and the plant Allium cepa). The hydrolate usually was considered as a by-product of the distillation to obtain essential oils. However, recently has been found to have nematicide properties. The hydrolate caused acute toxicity at values of LC50 of 3.87% v/v for A. cepa and 0.07 mL/g for E. fetida. All the concentrations except for the most diluted (1% v/v) reduced the bacterial physiological activity compared to controls (LC50 = 25.72% v/v after 24 h of exposure). The hydrolate also slightly altered the ability of the microbial community to degrade carbon substrates. These results indicate that the hydrolate from A. absinthium may affect the survival and metabolic abilities of key soil organisms.

Ecotoxicological Study of Tannic Acid on Soil and Water Non-Target Indicators and Its Impact on Fluvial and Edaphic Communities.

Tannic acid (TA) is a key tannin extensively used in the leather industry, contributing to around 90% of global leather production. This practice leads to the generation of highly polluting effluents, causing environmental harm to aquatic ecosystems. Additionally, tannins like TA degrade slowly under natural conditions. Despite efforts to reduce pollutant effluents, limited attention has been devoted to the direct environmental impact of tannins. Moreover, TA has garnered increased attention mainly due to its applications as an antibacterial agent and anti-carcinogenic compound. However, our understanding of its ecotoxicological effects remains incomplete. This study addresses this knowledge gap by assessing the ecotoxicity of TA on non-target indicator organisms in both water (Vibrio fischeri, Daphnia magna) and soil environments (Eisenia foetida, Allium cepa), as well as natural fluvial and edaphic communities, including periphyton. Our findings offer valuable insights into TA's ecotoxicological impact across various trophic levels, underscoring the need for more comprehensive investigations in complex ecosystems. Our results demonstrate that TA exhibits ecotoxicity towards specific non-target aquatic organisms, particularly V. fischeri and D. magna, and phytotoxicity on A. cepa. The severity of these effects varies, with V. fischeri being the most sensitive, followed by D. magna and A. cepa. However, the soil-dwelling invertebrate E. foetida shows resistance to the tested TA concentrations. Furthermore, our research reveals that substantial TA concentrations are required to reduce the growth of river microbial communities. Metabolic changes, particularly in amino acid and amine metabolism, are observed at lower concentrations. Notably, the photosynthetic yield of river periphyton remains unaffected, even at higher concentrations. In contrast, soil microbial communities exhibit greater sensitivity, with significant alterations in population growth and metabolic profiles at a very low concentration of 0.2 mg/L for all metabolites. In summary, this study offers valuable insights into the ecotoxicological effects of TA on both aquatic and terrestrial environments. It underscores the importance of considering a variety of non-target organisms and complex communities when assessing the environmental implications of this compound.

Effects of the insecticide fipronil in freshwater model organisms and microbial and periphyton communities.

Fipronil is a broad-spectrum insecticide whose release in the environment damages many non-target organisms. This study evaluated the toxicity of fipronil at two biological levels using in vivo conditions and environmentally relevant concentrations: the first based on two model organisms (aquatic invertebrate Daphnia magna and the unicellular freshwater alga Chlamydomonas reinhardtii) and a second based on three natural communities (river periphyton and freshwater and soil microbial communities). The physicochemical properties of fipronil make it apparently unstable in the environment, so its behaviour was followed with high performance liquid chromatography (HPLC) under the different test conditions. The most sensitive organism to fipronil was D. magna, with median lethal dose (LC50) values from 0.07 to 0.38 mg/L (immobilisation test). Toxicity was not affected by the media used (MOPS or river water), but it increased with temperature. Fipronil produced effects on the photosynthetic activity of C. reinhardtii at 20 °C in MOPS (EC50 = 2.44 mg/L). The freshwater periphyton presented higher sensitivity to fipronil (photosynthetic yield EC50 of 0.74 mg/L) in MOPS and there was a time-dependent effect (toxicity increased with time). Toxicity was less evident when periphyton and C. reinhardtii tests were performed in river water, where the solubility of fipronil is poor. Finally, the assessment of the metabolic profiles using Biolog EcoPlates showed that bacteria communities were minimally affected by fipronil. The genetic identification of these communities based on 16S rRNA gene sequencing revealed that many of the taxa are specialists in degrading high molecular weight compounds, including pesticides. This work allows us to better understand the impact of fipronil on the environment at different levels of the food chain and in different environmental conditions, a necessary point given its presence in the environment and the complex behaviour of this compound.

Ecotoxicity of a novel biopesticide from Artemisia absinthium on non-target aquatic organisms.

Biopesticides are increasingly being used to replace synthetic pesticides for pest control. This change raises concern for its environmental impacts, especially on non-target organisms. In this study, the ecotoxicological effects of a potential nematicide from Spanish populations of Artemisia absinthium (var. Candial) were evaluated on freshwater and aquatic non-target organisms. The study focused on the aqueous extract (hydrolate), the principal component of which ((-) -(Z) -2,6-dimethylocta-5,7-diene-2,3-diol) is responsible for its nematicidal effect. Until now, the hydrolate has been considered a byproduct of the process used to obtain essential oils, and there are no studies on its ecotoxicity from any plant with biopesticide properties. Our results indicated that A. absinthium hydrolate caused acute toxicity for non-target organisms at dilutions as low as 0.2%. The sensitivity of the organisms, from the most to the least sensitive, was: Daphnia magna (LC50 = 0,236%) > Vibrio fisheri (LC50 = 1,85%) > Chlamydomonas reinhardtii (LC50 = 16,49). Moreover, the A. absinthium organic extract was highly toxic to D. magna (LC50 = 0,093 mg/L). A. absinthium hydrolate toxicity was also tested on a natural river microbial community. Bacterial growth was not affected; the physiology of the community was only slightly modified, namely through an increased ability to degrade different substrates, mainly carbohydrates. This study provides for the first time an exhaustive assessment of the environmental exposure of a plant-derived biopesticide and shows that these products may cause a broad range of toxicity on non-target aquatic organisms.

Ecotoxicity of a new biopesticide produced by Lavandula luisieri on non-target soil organisms from different trophic levels.

Plant-based biopesticides have become an eco-friendly alternative to synthetic pesticides by reducing the undesired environmental impacts and side-effects on human health. However, their effects on the environment and especially on non-target organisms have been little studied. This study analyses the ecotoxicological effects of the extract of Lavandula luisieri on soil non-target organisms from different trophic levels: the earthworm Eisenia fetida, the plant Allium cepa and a natural-soil microbial community whose taxonomy was analysed through 16S rRNA gene sequencing. The extract tested is the hydrolate -product from a semi industrial steam distillation process- of a Spanish pre-domesticated variety of L. luisieri. This hydrolate has been recently shown to have bionematicide activity against the root-knot nematode Meloidogyne javanica. A previous study showed that the main components of the hydrolate are camphor and 2,3,4,4-Tetramethyl-5-methylidenecyclopent-2-en-1-one. Hydrolate caused acute toxicity (LC50 2.2% v/v) on A. cepa, while only a slight toxicity on E. fetida (LC50 > 0.4 mL/g). All the concentrations tested (from 1 to 100% v/v) caused a significant decrease in bacterial growth (LC50 9.8% v/v after 120 h of exposure). The physiological diversity of the community was also significantly altered, except in the case of the lowest concentration of hydrolate (1% v/v). The ability of soil microbial communities to use a variety of carbon sources increased for all substrates at the highest concentrations. These results show that both the plants and bacterial communities of the soil can be affected by the application of biopesticides based on these hydrolates, which highlights the need for a more detailed risk assessment during the development of plant-based products.

Development of a new methodology for the creation of water temperature scenarios using frequency analysis tool.

Thermal quality in river ecosystems is a fundamental property for the development of biological processes and many of the human activities linked to the aquatic environment. In the future, this property is going to be threatened due to global change impacts, and basin managers will need useful tools to evaluate these impacts. Currently, future projections in temperature modelling are based on the historical data for air and water temperatures, and the relationship with past temperature scenarios; however, this represents a problem when evaluating future scenarios with new thermal impacts. Here, we analysed the thermal impacts produced by several human activities, and linked them with the decoupling degree of the thermal transfer mechanism from natural systems measured with frequency analysis tools (wavelet coherence). Once this relationship has been established we develop a new methodology for simulating different thermal impacts scenarios in order to project them into future. Finally, we validate this methodology using a site that changed its thermal quality during the studied period due to human impacts. Results showed a high correlation (r2=0.84) between the decoupling degree of the thermal transfer mechanisms and the quantified human impacts, obtaining 3 thermal impact scenarios. Furthermore, the graphic representation of these thermal scenarios with its wavelet coherence spectrums showed the impacts of an extreme drought period and the agricultural management. The inter-conversion between the scenarios gave high morphological similarities in the obtained wavelet coherence spectrums, and the validation process clearly showed high efficiency of the developed model against old methodologies when comparing with Nash-Stucliffe criterion. Although there is need for further investigation with different climatic and anthropic management conditions, the developed frequency models could be useful in decision-making processes by managers when faced with future global change impacts.

Effects of 18 pharmaceuticals on the physiological diversity of edaphic microorganisms.

Pharmaceutical residues can enter the terrestrial environment through the application of recycled water and contaminated biosolids to agricultural soils, were edaphic microfauna can would be threatened. This study thus assessed the effect of 18 widely consumed pharmaceuticals, belonging to four groups: antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), blood lipid-lowering agents (BLLA) and ß-blockers, on the physiology of soil microbial communities from a ecological crop field. Biolog EcoPlates, containing 31 of the most common carbon sources found in forest and crop soils, were used to calculate both the averaged well colour development (AWCD), as an indicator of the entire capacity of degrading carbon sources, and the diversity of carbon source utilization, as an indicator of the physiological diversity. The results show that pharmaceuticals impact microbial communities by changing the ability of microbes to metabolize different carbon sources, thus affecting the metabolic diversity of the soil community. The toxicity of the pharmaceuticals was inversely related to the log Kow; indeed, NSAIDs were the least toxic and antibiotics were the most toxic, while BLLA and ß-blockers presented intermediate toxicity. The antibiotic sulfamethoxazole imposed the greatest impact on microbial communities at concentrations from 100 mg/L, followed by the other two antibiotics (trimethoprim and tetracycline) and the ß-blocker nadolol. Other chemical parameters (i.e. melting point, molecular weight, pKa or solubility) had little influence on toxicity. Microbial communities exposed to pharmaceuticals having similar physicochemical characteristics presented similar physiological diversity patterns of carbon substrate utilization. These results suggest that the repeated amendment of agricultural soils with biosolids or sludges containing pharmaceutical residuals may result in soil concentrations of concern regarding key ecological functions (i.e. the carbon cycle).

Phytotoxicity of 15 common pharmaceuticals on the germination of Lactuca sativa and photosynthesis of Chlamydomonas reinhardtii.

Pharmaceuticals reach terrestrial environments through the application of treated wastewaters and biosolids to agricultural soils. We have investigated the toxicity of 15 common pharmaceuticals, classified as nonsteroidal anti-inflammatory drugs (NSAIDs), blood lipid-lowering agents, ß-blockers and antibiotics, in two photosynthetic organisms. Twelve pharmaceuticals caused inhibitory effects on the radicle and hypocotyl elongation of Lactuca sativa seeds. The EC50 values obtained were in the range of 170-5656 mg L-1 in the case of the radicle and 188-4558 mg L-1 for the hypocotyl. Propranolol was the most toxic drug for both root and hypocotyl elongation, followed by the NSAIDs, then gemfibrozil and tetracycline. Other effects, such as root necrosis, inhibition of root growth and curly hairs, were detected. However, even at the highest concentrations tested (3000 mg L-1), seed germination was not affected. NSAIDs decreased the photosynthetic yield of Chlamydomonas reinhardtii, but only salicylic acid showed EC50 values below 1000 mg L-1. The first effects detected at low concentrations, together with the concentrations found in environmental samples, indicate that the use of biosolids and wastewaters containing pharmaceuticals should be regulated and their compositions assessed in order to prevent medium- and long-term impacts on agricultural soils and crops.

Global change impacts on river ecosystems: A high-resolution watershed study of Ebro river metabolism.

Global change is transforming freshwater ecosystems, mainly through changes in basin flow dynamics. This study assessed how the combination of climate change and human management of river flow impacts metabolism of the Ebro River (the largest river basin in Spain, 86,100km(2)), assessed as gross primary production-GPP-and ecosystem respiration-ER. In order to investigate the influence of global change on freshwater ecosystems, an analysis of trends and frequencies from 25 sampling sites of the Ebro river basin was conducted. For this purpose, we examined the effect of anthropogenic flow control on river metabolism with a Granger causality study; simultaneously, took into account the effects of climate change, a period of extraordinary drought (largest in past 140years). We identified periods of sudden flow changes resulting from both human management and global climate effects. From 1998 to 2012, the Ebro River basin was trending toward a more autotrophic condition indicated by P/R ratio. Particularly, the results show that floods that occurred after long periods of low flows had a dramatic impact on the respiration (i.e., mineralization) capacity of the river. This approach allowed for a detailed characterization of the relationships between river metabolism and drought impacts at the watershed level. These findings may allow for a better understanding of the ecological impacts provoked by flow management, thus contributing to maintain the health of freshwater communities and ecosystem services that rely on their integrity.

Addressing the local aspects of global change impacts on stream metabolism using frequency analysis tools.

Global change, as a combination of climate change, human activities on watersheds and the river flow regulation, causes intense changes in hydrological cycles and, consequently, threatens the good ecological status of freshwater biological communities. This study addresses how and whether the combination of climatic drivers and local human impacts may alter the metabolism of freshwater communities. We identified a few factors modulating the natural water flow and quality in 25 point spread within the Ebro river Basin: waste water spills, industrial spills, reservoir discharges, water withdrawals, agricultural use, and the presence of riparian forests. We assessed their impacts on the freshwater metabolism as changes in the annual cycle of both gross primary production-GPP - and ecosystem respiration-ER -. For this purpose, daily data series were analyzed by continuous wavelet transformation, allowing for the assessment of the metabolic ecosystem Frequency Spectrum Patterns (FSPs). Changes in the behavior of ecosystem metabolism were strongly associated with local characteristics at each sampling point, however in 20 out of 25 studied points, changes in metabolic ecosystem FSP were related to climatic change events (the driest period of the last 140years). The changes in FSP indicate that severe impacts on how biological communities use carbon sources occur as a result of the human water management - too much focus on human needs - during intense climatic events. Results show that local factors, and specially the flow regulation, may modulate the impact of global change. As example those points exposed to a more intense anthropization showed a clear disruption - and even disappearance - of the annual FSP. This information may help managers to understand the action mechanisms of non-climatic factors at ecosystem level, leading to better management policies based on the promotion of ecosystem resilience. The method here presented may help on improving the calculation of ecological flows to maintain the river metabolic annual cycles as close as possible to the natural ones.

Influence of global change-related impacts on the mercury toxicity of freshwater algal communities.

The climatic-change related increase of temperatures, are expected to alter the distribution and survival of freshwater species, ecosystem functions, and also the effects of toxicants to aquatic biota. This study has thus assessed, as a first time, the modulating effect of climate-change drivers on the mercury (Hg) toxicity of freshwater algal photosynthesis. Natural benthic algal communities (periphyton) have been exposed to Hg under present and future temperature scenarios (rise of 5 °C). The modulating effect of other factors (also altered by global change), as the quality and amount of suspended and dissolved materials in the rivers, has been also assessed, exposing algae to Hg in natural river water or a synthetic medium. The EC50 values ranged from the 0.15-0.74 ppm for the most sensitive communities, to the 24-40 ppm for the most tolerant. The higher tolerance shown by communities exposed to higher Hg concentrations, as Jabarrella was in agreement with the Pollution Induced Community Tolerance concept. In other cases, the dominance of the invasive diatom Didymosphenia geminata explained the tolerance or sensitivity of the community to the Hg toxicity. Results shown that while increases in the suspended solids reduced Hg bioavailability, changes in the dissolved materials - such as organic carbon - may increase it and thus its toxic effects on biota. The impacts of the increase of temperatures on the toxicological behaviour of periphyton (combining both changes at species composition and physiological acclimation) would be certainly modulated by other effects at the land level (i.e., alterations in the amount and quality of dissolved and particulate substances arriving to the rivers).

Acute toxicological effects on the earthworm Eisenia fetida of 18 common pharmaceuticals in artificial soil.

Following soil applications of recycled water and biosolids, pharmaceutical residues can eventually enter the terrestrial environment. In vitro and in vivo assays have largely focused on the acute ecotoxicity of these compounds in aquatic systems. However, studies on the ecotoxicological effects of pharmaceuticals in soil biota are especially scarce. The aim of this study was to investigate the acute toxicity of 18 pharmaceuticals (4 NSAIDs, 5 blood lipid-lowering agents, 6 ß-blockers and 3 antibiotics) that are usually found in the environment by using an Eisenia fetida bioassay. In addition, the presence of these pharmaceuticals in artificial soil was verified at the end of the test. Our results indicate that seven of the studied drugs cause acute adverse effects in E. fetida, in particular, the NSAIDs and the blood lipid-lowering agents. Ibuprofen (LC50=64.80 mg/kg) caused the highest acute toxicity for all tested compounds, followed by diclofenac (LC50=90.49 mg/kg) and simvastatin (LC50=92.70 mg/kg). Other tested pharmaceuticals from NSAIDs and blood lipid-lowering families have toxicity effects, from a LC50=140.87 mg/kg for gemfibrozil to 795.07 mg/kg for lovastatin. Atorvastatin, bezafibrate, ß-blockers and antibiotics showed no detectable lethality in E. fetida. The four NSAIDs showed evidence of modification of their original chemical structure after 14 days so the detected toxicity may be due to the original product as well as their degradation products. The three blood lipid-lowering agents seem to be more stable in soil. From an environmental perspective, the lethal concentrations of the tested drugs are much greater than those reported in wastewater and biosolids, therefore acute toxic effects may be improbable. However, little is known about the accumulation of these substances in soils after regular applications, so accumulative and chronic effects cannot be excluded. Moreover, more studies are needed to determine the role of the degradation products of these pharmaceuticals on terrestrial toxicity.

Impacts of agricultural irrigation on nearby freshwater ecosystems: the seasonal influence of triazine herbicides in benthic algal communities.

A small hydrological basin (Lerma, NE Spain), transformed from its natural state (steppe) to rain-fed agriculture and recently to irrigation agriculture, has been monitored across four seasons of an agricultural year. The goal of this study was to assess how and whether agricultural activities impacted the nearby freshwater ecosystems via runoff. Specifically, we assessed the toxicity of three triazine herbicides, terbuthylazine, atrazine and simazine on the photosynthetic efficiency and structure of algal benthic biofilms (i.e., phototropic periphyton) in the small creek draining the basin. It was expected that the seasonal runoff of the herbicides in the creek affected the sensitivity of the periphyton in accord with the rationale of the Pollution Induced Community Tolerance (PICT): the exposure of the community to pollutants result in the replacement of sensitive species by more tolerant ones. In this way, PICT can serve to establish causal linkages between pollutants and the observed biological impacts. The periphyton presented significantly different sensitivities against terbuthylazine through the year in accord with the seasonal application of this herbicide in the crops nowadays. The sensitivity of already banned herbicides, atrazine and simazine does not display a clear seasonality. The different sensitivities to herbicides were in agreement with the expected exposures scenarios, according to the agricultural calendar, but not with the concentrations measured in water, which altogether indicates that the use of PICT approach may serve for long-term monitoring purposes. That will provide not only causal links between the occurrence of chemicals and their impacts on natural communities, but also information about the occurrence of chemicals that may escape from traditional sampling methods (water analysis). In addition, the EC50 and EC10 of periphyton for terbuthylazine or simazine are the first to be published and can be used for impact assessments.

Irrigation agriculture affects organic matter decomposition in semi-arid terrestrial and aquatic ecosystems.

Many dryland areas are being converted into intensively managed irrigation crops, what can disrupt the hydrological regime, degrade soil and water quality, enhance siltation, erosion and bank instability, and affect biological communities. Still, the impacts of irrigation schemes on the functioning of terrestrial and aquatic ecosystems are poorly understood. Here we assess the effects of irrigation agriculture on breakdown of coarse organic matter in soil and water. We measured breakdown rates of alder and holm oak leaves, and of poplar sticks in terrestrial and aquatic sites following a gradient of increasing irrigation agriculture in a semi-arid Mediterranean basin transformed into irrigation agriculture in 50% of its surface. Spatial patterns of stick breakdown paralleled those of leaf breakdown. In soil, stick breakdown rates were extremely low in non-irrigated sites (0.0001-0.0003 day(-1)), and increased with the intensity of agriculture (0.0018-0.0044 day(-1)). In water, stick breakdown rates ranged from 0.0005 to 0.001 day(-1), and increased with the area of the basin subject to irrigation agriculture. Results showed that irrigation agriculture affects functioning of both terrestrial and aquatic ecosystems, accelerating decomposition of organic matter, especially in soil. These changes can have important consequences for global carbon budgets.