Environmental analysis of the eutrophication and spread of aquatic macrophytes in a tropical reservoir: a case study in Brazil.

Land use changes threaten the maintenance of water quality and challenge the management of tropical reservoirs. In particular, eutrophication alters several ecosystem functions and services, compromising multiple uses of water. For example, in the Lajeado Reservoir (Araraquara, São Paulo, Brazil), aquatic macrophytes rapidly spread and occupied more than 90% of the system's surface area (from 2016 to 2019). In such a scenario, this research aimed to evaluate the eutrophication causes and impacts to provide technical and scientific support to public agencies and propose remediation alternatives. First, a diagnosis of the study area was performed, using available data on land use, water quality, and climate (between 2010 and 2018). Second, water and sediment samples were collected for physical, chemical, and ecotoxicological analyses. The Ecological Risk Assessment consisted of a triad of Lines of Evidence, including physical-chemical, chemical, and ecotoxicological results. The expansion of agricultural activities (e.g., sugarcane cultivation) and diffuse pollution were highlighted among possible causes, and water quality was affected by increases in the concentration of nutrients (e.g., nitrogen and phosphorus), metals (e.g., iron), and emerging contaminants (e.g., pesticides and caffeine). As a result, the Lajeado Reservoir presented a high ecological risk, and alternatives for macrophyte removal are needed. This research involved several stakeholders (i.e., community, government agencies, and universities) who participated more effectively in environmental monitoring and recovery.

Assessing single effects of sugarcane pesticides fipronil and 2,4-D on plants and soil organisms.

The continuous growth in global population since the beginning of the 20th century result in the necessity of food and energy provision favoring the intensive use of agricultural products such as pesticides. Although pesticides are important to prevent losses in the conventional chemically based agriculture, they frequently present side effects, which goes against agricultural production. The use of pesticides cause direct and indirect effects to soil organisms unbalancing essential soil processes (e.g. primary production, organic matter decomposition, nutrient cycling). Under tropical conditions, very little is known regarding the effects of pesticides to terrestrial organisms. Hence, the aim of the present study was to assess the ecotoxicological effects of the herbicide DMA® 806 BR (active ingredient: 2,4-D) and the insecticide Regent® 800 WG (active ingredient: fipronil), on terrestrial plant species (the dicot Raphanus sativus var. acanthioformis and the monocot Allium cepa), and soil invertebrates (the collembolan Folsomia candida and the enchytraeid Enchytraeus crypticus), using natural (NS) and artificial soils (TAS). For both pesticides, negative effects on non-target species were observed at concentrations lower than the doses recommended to prevent pests in sugarcane fields. For both soils, the dicot species was the most affected by the herbicide (R. sativus > A. cepa > F. candida > E. crypticus) and the collembolan species was the most affected by the insecticide (F. candida > E. crypticus = R. sativus = A. cepa). Although the order of the organisms' sensitivity for both pesticides was the same in both soils, results showed that the extent of the effects was soil dependent. Considering the ecologically relevant concentrations tested, and their severe effects to non-target organisms, it may be concluded that the use of fipronil and 2,4-D under recommended conditions may pose a risk to the terrestrial environment.

Hazard assessment of the pesticides KRAFT 36 EC and SCORE in a tropical natural soil using an ecotoxicological test battery.

Pesticides are widely used in agricultural fields to control plant diseases, weeds, and pests; however, the unforeseeable consequences of releasing these compounds into the soil and their effects on terrestrial invertebrates are matters of grave concern. The aim of the present study was to determine the direct impact of 2 pesticides, KRAFT® 36 EC (an insecticide; a.i. abamectin) and SCORE® (a fungicide; a.i. difenoconazole), on nontarget terrestrial invertebrates. Ecotoxicological tests were performed to evaluate the chronic and acute toxicity of these compounds to a potworm (Enchytraeus crypticus), a collembolan (Folsomia candida), and a mite (Hypoaspis aculeifer). The results showed that, for both pesticides, the collembolan F. candida was the most sensitive species, followed by the enchytraeid E. crypticus and the mite H. aculeifer. Effect concentrations at 50% of organisms' reproduction calculated for F. candida, E. crypticus, and H. aculeifer were 0.06, 2.8, and >32 mg of abamectin/kg dry weight soil and 28.9, 125, and 145.5 mg of difenoconazole/kg dry weight soil, respectively. Environmentally relevant concentrations of both pesticides significantly affected the collembolan species. The existence of a potential risk from abamectin and difenoconazole for soil invertebrates even at recommended doses could be identified. Environ Toxicol Chem 2018;37:2919-2924. © 2017 SETAC.