Geochemical speciation and risk assessment of metals in sediments of the Lobo-Broa Reservoir, Brazil

Abstract

Purpose Brazilian sediment quality criteria were established based on pseudo-total metal contents, which is not suitable to determine their bioavailability and the ecological risk for aquatic biota. Therefore, the geochemical speciation of five metals (Cu, Fe, Ni, Pb and Zn) was determined to assess the distribution and ecological risk of sediments in a tropical shallow reservoir from Brazil. The paper aims to discuss these issues. Design/methodology/approach A survey of metals in ten representative stations of surface sediments (0-20 cm) from Carlos Botelho (Lobo-Broa) Reservoir was conducted during the dry season in April 2014. Sediment parameters were measured in situ. The geochemical speciation of metals was carried out using the modified three-stage BCR-701 procedure (Davutluoglu et al., 2011) and compared with pseudo-total metal contents. Findings Contamination at S-1 and S-8 was more severe than other sampling sites, especially for Cu, Ni, Pb and Zn. Metals such as Cu, Ni and Zn occasionally may be associated with adverse biological effects based on the comparison with sediment quality guidelines. The risk assessment code suggests no risk for Fe and low risk for Cu and Ni. Originality/value Geochemical speciation of metals could be useful in developing effective management strategies to control metal pollution in the Lobo-Broa Reservoir. Substantial amounts of Pb (classified as medium risk) were bound to humic substances and/or insoluble metal sulfides, and could pose serious risk to the benthic community through the food chain. Zinc at S-1, S-3 and S-8 showed high risk, indicating that an appreciable portion of Zn could be available to aquatic biota.

Ecological risk assessment for eutrophication and heavy metal pollution of Suyahu Reservoir sediments

“…The study found that the vertical distribution of these heavy metals in the bottom sediments is related to the level of contamination and rate of water exchange in the reservoir [8]. The geochemical speciation of metals in the sediments in the Lobo-Broa Reservoir has been analyzed and could be useful in developing effective management strategies to control metal pollution in this reservoir [9]. The surface sediments in bays and tributaries of the Danjiangkou Reservoir, which is an important strategic water source in China, has been studied, and the results show that its pollutants cause a state of high ecological risk [10].…”

Metal Toxicity During Short‐Term Sediment Resuspension and Redeposition in a Tropical Reservoir

“…Differences in climate and geochemistry between temperate and tropical aquatic ecosystems may also be of great importance when the fate of metals is compared (Silvério et al 2005;Cervi et al 2017;Wang et al 2019). Metals can be in solution, sorbed, or coprecipitated with mineral surfaces and organic matter, but in anoxic sediments, iron sulfides may be the primary solid phases controlling metal availability (Charriau et al 2011;Richards et al 2018).…”

Is it possible to evaluate the ecological status of a reservoir using the phytoplankton community?

“…Although the Broa reservoir is intended for recreation and research purposes, it is inserted in the Tietê-Jacaré hydrographic basin that has potentially polluting activities, such as agriculture, sand mining, livestock, and other point and diffuse sources (Periotto & Tundisi, 2013). The activities includes the disposal of untreated residential effluent, deforestation, sand mining, tourism, intensive sport fishing (Cervi et al, 2016) and agricultural activities, also with areas under legal protection (Tundisi & Tundisi, 2016). There are also reforestation initiatives in the region, besides the natural maintenance from the vegetation cover, highlighting the mosaic vegetation acting as a buffer zone (Tundisi & Tundisi, 2016).…”