School Of Environment And Earth Sciences

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    Mercury in multimedia system of Itacai�nas Basin, Brazilian Amazon: An integrated approach to understand its distribution, origin, and ecological risk
    (Academic Press Inc., 2023-01-23T00:00:00) Sahoo, Prafulla Kumar; Dall'Agnol, Roberto; Sim�es Rolo de Deus, Simonny do C.; Salom�o, Gabriel Negreiros; Felix Guimar�es, Jos� Tasso; Angelica, R�mulo Sim�es; Ramos, Silvio Junio; Furtado da Costa, Marlene; Oswaldo de Siqueira, Jose
    This study presents the first integrated study on total Hg (THg) level in surface soil (SS), bottom soil (BS), stream sediments (SD), lake sediments (LS), stream water (SW), and lake water (LW) of Itacai�nas River Watershed (IRW), Brazil to investigate the source and distribution of Hg in different environmental media considering contrasts of geological domains and sub-basins and its potential ecological and human risk. Hg content in most of the soils and sediments were above the upper crustal average values (56 ?g/kg), however, when compared to the legal limits set by the Resolution CONAMA (Conselho Nacional de Meio Ambiente: soil 500 ?g/kg; sediment 486 ?g/kg), only 1 soil sample from Parauapebas sub-basin and 4 sediment samples from Viol�o Lake exceeded the limit. None of the SW and LW samples (<0.2 ?g/L; CONAMA limit for Class II freshwater) are markedly contaminated by Hg. The SS and BS show similar contents and spatial distribution of Hg with higher contents being registered mostly in the Itacai�nas and Parauapebas sub-basins, which are closely correlated with SD. This suggests that Hg levels are largely of geogenic origin and anthropogenic effect is highly limited. Principal Component Analysis (PCA) results show that Hg is strongly associated with total organic carbon (TOC), loss on ignition (LOI), and SO3, indicating organic matter as the main factor controlling the distribution of Hg and this is the major cause of accentuated Hg enrichment in lake sediments. The ecological risk index revealed a low pollution risk for most of the solid samples, except 11% LS and <1.5% SS and SD samples, which registered moderate risk. Health risk assessment indicated no adverse non-carcinogenic health effect on either adults and children in terms of Hg contamination. This information will be useful for Hg risk assessment in the Caraj�s region and future environmental research in this direction in the Amazonia. � 2023 Elsevier Inc.
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    A Holocene record of floodplain development in the northernmost portion of the Araguaia Belt, southeastern Amazonia
    (Elsevier B.V., 2021-11-01T00:00:00) Tasso Felix Guimar�es, Jos�; Kumar Sahoo, Prafulla; Monteiro Pontes, Paulo R�genes; Negreiros Salom�o, Gabriel; Ribeiro da Costa, Francisco; Maria Queiroz de Melo, Adayana; Sousa da Silva, Marcio; Oliveira da Silva J�nior, Renato
    This work aimed to understand the drivers of landscape evolution and floodplain formation in a Precambrian Shield area of southeastern Amazonia. This area evolved during the Quaternary into a denudational system with strong structural control, which produced valley side slopes between the Araguaia Belt (AB) and the topmost Parna�ba basin and narrow floodplains in the lower Vermelho River. These floodplains developed at approximately 11215�11410 cal yr BP with the deposition of muds on the weathered basement rocks of the Couto Magalh�es Formation in the Ab (CMF) long before sea-level stabilization on the Amazon coast. The chondrite- and upper continental crust-normalized patterns, along with Al/Ti and La/Th ratios, clearly indicate that muds were derived from the CMF-AB. The strong positive correlation of most of the trace elements and rare earth elements (REEs) with Al and Ti indicates their control by aluminous clay phases and a similar transport process. Overbank flows of the Vermelho River resulted in the deposition and vertical accretion of sands from the fluvial channel over the floodplain, forming discontinuous marginal levees after 4520�4710 cal yr BP. The accreted sands with the predominance of Si, Zr, and Hf and the depletion of most of the major and trace elements are likely associated with quartz enrichment and a strong sorting of heavy minerals, which is also supported by Al2O3/SiO2 vs Fe2O3/SiO2. The tributaries of the lower Vermelho River were active until 3890�4095 cal yr BP, and subsequently, the channel was abandoned as a result of the filling process. At approximately 3440�3560 cal yr BP, the floodplain was influenced by prolonged and severe droughts that fully exposed the muddy deposits and caused the enrichment of Fe-Mnoxyoxide phases. The affinity of most of the potentially toxic elements with Al signifies that these floodplain deposits are a natural record for geochemical background studies. � 2021 Elsevier B.V.
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    Geochemistry Of Proglacial Lake Deposits Of Upper Alaknanda Basin
    (Central University of Punjab, 2018) Ali, Yousuf; Pattanaik K, Jitendra
    Many researchers have recorded climatic upheaval in the Himalaya during the Late Quaternary. The chemical weathering in the Upper Alaknanda basin has changed during the glacial and interglacial period. Different sediment archives such as pro-glacial deposits and terrace deposits act as repository to understand the paleo-weathering intensity of the sediment.In this study geochemistry of sediments of pro-glacial lake deposits found in the Badirinath valley of upper Alaknanda basin was carried out to understand the paleo-climate of the study area by identifying the clay minerals, intensity of chemical weathering and to estimate the distance travelled from the source. The lake deposits are thinly laminated and lack boulder and pebble layers. Sediment deposits at the right bank of Alaknanda River near Bamini village are more likely lake deposits as compare to left bank deposits which is terrace. By clay mineral identification, it is concluded that the paleo-climate of the pro-glacial lake deposits were cold and is deposited during glacial period. XRF analysis in terms of CIA calculation, A-CN-K plot and A-CNK-FM plot suggests that there is low degree of chemical weathering occurred in the study area. The percentage of clay silt fractionation calculation by gravity setting method conforms that the sediment were not travelled far from their source.