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1.
Sci Total Environ ; : 143794, 2020 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-33272603

RESUMO

Viticulture plays an important role in generating income for small farms globally. Historically, vineyards use large quantities of phytosanitary products, such as Bordeaux mixture [Ca(OH)2 + CuSO4], to control plant diseases. These products result in the accumulation of copper (Cu) in the soil and increases the risk of transfer to water bodies. Thus, it is important to evaluate whether the presence of Cu-bearing particles in water is toxic to aquatic fauna. This study conducted chemical, mineralogical, and particle size evaluations on water samples and sediments collected from a watershed predominantly cultivated with old vineyards. The proportion of Cu-rich nanoparticles (<10 nm) in the sediment was ~27%. We exposed zebrafish to different dilutions of water and sediment samples that collected directly from the study site (downstream river) under laboratory conditions. Then, we evaluated their exploratory behavior and the stress-related endocrine parameter, whole-body cortisol. We also carried out two experiments in which zebrafish were exposed to Cu. First, we determined the median lethal concentration (LC50-96 h) of Cu and then assessed whether Cu exposure results in effects similar to those associated with exposure to the water and sediment samples collected from the study site. The water and sediment samples directly impacted the exploratory behavior of zebrafish, showing clear anxiety-like behavioral phenotype and stress in terms of cortisol increase (during the second rain event). The Cu exposure did not mimic the same behavioral changes triggered by the water and sediment samples, although it had caused similar stress in the fish. Our results highlight that even at low concentrations, the water and sediment samples from vineyard watershed runoff were able to induce behavioral and endocrine changes that may harm the ecological balance of an aquatic environment.

2.
Environ Sci Pollut Res Int ; 27(28): 35591-35603, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32594449

RESUMO

Rice (Oryza sativa L.) intermittent irrigation is a potential strategy to mitigate methane (CH4) and nitrous oxide (N2O) emissions, but the effects of dry-wetting intervals on soil electrochemical changes and plant characteristics should be considered. This study was conducted in a greenhouse evaluating CH4 and N2O fluxes in rice under five different irrigation management practices (continuous irrigation (CI), intermittent irrigation with flooding resumption in saturated soil condition (SSI) and soil moisture at field capacity (FCI), saturated soil and irrigation resumption with soil moisture bellow field capacity (FCS), and soil at field capacity (FCD)) and its relation to plant development and global warming potential (GWP). Soil electrochemical conditions and CH4 and N2O emissions were expressively affected by irrigation management. The CI system presented the greatest CH4 flux (20.14 g m-2) and GWP (462.7 g m-2 eq. CO2), whereas intermittent irrigation expressively reduced CH4 emissions. Overall, the N2O flux was low (bellow 20 µg m-2 h-1) even with N application, with greater emissions occurring at the FCD treatment at the beginning of the rice season. Soil moisture at field capacity had no CH4 flux but presented greater GWP (271 g m-2 eq. CO2) than intermittent irrigation systems due to N2O flux while compromising rice plant development. The best soil moisture condition to initiate a flooding cycle during intermittent irrigation is at saturated soil conditions.


Assuntos
Óxido Nitroso/análise , Oryza , Agricultura , China , Aquecimento Global , Metano/análise , Solo
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