Seasonal differences in trace metal concentrations in the major rivers of the hyper-arid southwestern Andes basins of Peru.

The southern rivers of Peru originate in the Andes Mountains and flow in a southwestern direction to the Pacific Ocean through one of the most hyper-arid regions of the world. During each sub-equatorial summer from December to February, rains and snow melt in the Andes increase the streamflow in these rivers, even as they pass through the 100 km arid zone to the ocean. This study quantified seasonal dynamics of 34 trace metal elements (TM) and other constituent concentrations in four southern river basins of Peru (Chili-Quilca, Tambo, Camana-Majes-Colca, and Ocoña) during 2019-2020. Consistent with previous studies, we observed that: (1) the river water in the southern basins had relatively high concentrations of B, As, Fe, Al, Mn, P, Pb and Ni, with As the most ubiquitous toxic TM in all the basins, often detected at concentrations surpassing Peruvian and USEPA regulated concentrations; and (2) basins with the most to least toxic TM contamination were the Tambo > Chili-Quilca > Camana-Majes-Colca > Ocoña. Seasonal streamflow strongly influenced the concentrations of twenty TM, with 15 TM (Al, Au, Ba, Cd, Co, Cu, Fe, Gd, Mn, Ni, P, Pb, Ti, Yb and Zr) consistently higher in the wet season, and with As, B, Ge, Li, and Pd higher in the dry season. Our results improve the understanding of seasonal variability and vulnerability in western Andes superficial water sources, which are highly influenced by both local geogenic and anthropogenic conditions. A Spanish translation of this paper is available in the online Supplementary Material.

Phytoavailability and human risk assessment of heavy metals in soils and food crops around Sutlej river, India.

We assessed the phytoavailability of heavy metals in wheat and rice grown on soils along flood plains of Sutlej river (India) and its effects on human health. Surface soil samples along with wheat (pre-monsoon season) and rice (post-monsoon season) grain samples were collected during the years 2017 and 2018. Soil samples were analysed for total and DTPA-extractable metals and, wheat and rice grains samples for total metals. There were no significant (p < 0.05) changes in total metal concentration during both the years, but the concentration of DTPA-extractable metals was higher during pre-monsoon than post-monsoon season. The concentration of Pb, Cd, and Co in wheat grains, whereas the concentration of Cr, Co, Pb and Cd in rice grains surpassed their safe limits. Both DTPA-extractable metals (water soluble plus exchangeable) and non-exchangeable fractions explained more than 80% of the variations in metal uptake by plants. The bioaccumulation factor for DTPA-extractable metals (BCF) was above one, but Pollution Load Index for these metals (PLI) was less than one. The carcinogenic risks due to ingestion of wheat and rice grains were higher for Cd. The BAF, PLI and health risks were higher along transboundary of the river. These results suggest that exchangeable and non-exchangeable fractions are contributing towards metals uptake by wheat and rice along flood plain soils of the Sutlej river and the present study may act as a model for carrying out similar studies to find out the risks of heavy metals and it effect on human health in future.

Comportamento e avaliação de metais potencialmente tóxicos (Cu (II), Cr (III), Pb(II) e Fe(III)) em águas superficiais dos Riachos Capivara e Bacuri Imperatriz-MA, Brasil / Behavior and evaluation of potentially toxic metals (Cu(II), Cr(III), Pb(II) and Fe(III)) in surface waters of streams Capivara and streams Bacuri Imperatriz-MA, Brazil

RESUMOEsta pesquisa avaliou a dinâmica e a distribuição dos metais Cu (II), Cr (III), Pb (II) e Fe (III), em amostras de água superficiais no Riacho Capivara e Riacho Bacuri na cidade de Imperatriz, Maranhão. As amostras de água foram coletadas em 2 pontos de amostragem à montante e jusante da cidade de Imperatriz para avaliar a influência da urbanização. Foram analisados os metais potencialmente tóxicos Cu (II), Cr (III), Pb (II) e Fe (III) e os seguintes parâmetros físicos e químicos: pH, sólidos totais dissolvidos, turbidez, e condutividade elétrica. As determinações dos metais foram feitas por meio de espectrometria de absorção atômica em chama (FAAS). As variações observadas para os parâmetros físico-químicos (pH, Condutividade Sólidos Totais Dissolvidos e Turbidez) indicam alterações na qualidade da água em virtude de ações antrópicas. Foi observada a presença sistemática de todos os metais investigados durante todo o período amostrado. Os resultados obtidos demostraram que Cu (II), Cr (III), Pb (II) e Fe (III) encontram-se preferencialmente associados a material particulado em suspensão (MPS). As variações observadas para os parâmetros físico-químicos e nas concentrações dos metais investigados indicam haver contribuição de caráter antropogênico associada à litologia da região, o que juntamente com a sazonalidade e fontes difusas e pontuais, contribuem, para a deterioração das águas superficiais desses corpos hídricos.

ABSTRACTThis research evaluated the dynamics and distribution of Cu (II), Cr (III), Pb (II) and Fe (III) in samples of surface water in the streams Capivara and streams Bacuri in Imperatriz city, Maranhão state, Brazil. There were two water sampling points upstream and downstream of the city of Imperatriz to evaluate the influence of urbanization. Were analyzed the potentially toxic metals (Cu (II), Cr (III), Pb(II) and Fe(III)) and the following physical and chemical parameters: pH, total dissolved solids, turbidity and electrical conductivity. Measurements of Cu(II), Pb(II) and Fe(III) were made by means of atomic absorption spectrometry in the flame (FAAS). The variations observed for the physical and chemical parameters (pH, Conductivity and Total Dissolved Solids Turbidity) indicate changes in water quality due to human actions. We observed the systematic presence of all metals investigated over the sampling points. The results showed that Cu (II), Cr (III), Pb (II) and Fe (III) are preferentially associated with suspended particulate matter (SPM). The variations observed for the physical and chemical parameters and concentrations of the metals investigated indicate a contribution of anthropogenic character associated with the lithology region, which along with the seasonality and diffuse and point source contribute to the deterioration of surface water body of water.