Environmental Risk Assessment Based on High-Resolution Spatial Maps of Potentially Toxic Elements Sampled on Stream Sediments of Santiago, Cape Verde

Abstract

Geochemical mapping is the base knowledge to identify the regions of the planet with critical contents of potentially toxic elements from either natural or anthropogenic sources. Sediments, soils and waters are the vehicles which link the inorganic environment to life through the supply of essential macro and micro nutrients. The chemical composition of surface geological materials may cause metabolic changes which may favor the occurrence of endemic diseases in humans. In order to better understand the relationships between environmental geochemistry and public health, we present environmental risk maps of some harmful elements (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn) in the stream sediments of Santiago, Cape Verde, identifying the potentially harmful areas in this island. The Estimated Background Values (EBV) of Cd, Co, Cr, Ni and V were found to be above the Canadian guidelines for any type of use of stream sediments and also above the target OPEN ACCESSGeosciences 2014, 4 298 values of the Dutch and United States guidelines. The Probably Effect Concentrations (PEC), above which harmful effects are likely in sediment dwelling organisms, were found for Cr and Ni. Some associations between the geological formations of the island and the composition of stream sediments were identified and confirmed by descriptive statistics and by Principal Component Analysis (PCA). The EBV spatial distribution of the metals and the results of PCA allowed us to establish relationships between the EBV maps and the geological formations. The first two PCA modes indicate that heavy metals in Santiago stream sediments are mainly originated from weathering of underlying bedrocks. The first metal association (Co, V, Cr, and Mn; first PCA mode) consists of elements enriched in basic rocks and compatible elements. The second association of variables (Zn and Cd as opposed to Ni; second PCA mode) appears to be strongly controlled by the composition of alkaline volcanic rocks and pyroclastic rocks. So, the second PCA mode is also considered as a natural lithogenic mode. The third association (Cu and Pb; third PCA mode) consists of elements of anthropogenic origin.

Sediment Dynamics of the Neretva Channel (Croatia Coast) Inferred by Chemical and Physical Proxies

“…Under suitable assumptions on the spatial continuity of the variable to interpolate, kriging gives the best linear unbiased prediction of the interpolated values [33]. Spatial continuity parameters (range, nugget and sill) were evaluated using theoretical models fitting the experimental variograms calculated for each variable [34,35]. Universal kriging assumes that a continuous property called "regionalized variable" consists of two parts: a drift, or expected value, and a residual, or deviation from the drift.…”

“…Some authors indicate the ratio Cr/Ni as a possible tracer of geo-genic versus anthropogenic influences [56][57][58] and suggest it as suitable to determining geochemical baselines in the case of high natural concentrations [34,35,59]. In particular, Cr concentrations in south Dalmatia show a mean value of 126 µg/g; that is the highest value found in karstic regions, probably due to the presence of chromite-bearing ultramafic rocks and/or of clastic deposits derived from older mafic magmatic rocks.…”

Risk Assessment of Metals in Urban Soils from a Typical Industrial City, Suzhou, Eastern China

“…This information is critical, considering the continuous exposure of urban residents, and especially children, to the metals in urban soils, whether through oral ingestion, inhalation, or dermal contact [ 2 , 3 , 4 , 5 , 6 ]. As in agricultural and industrial soils, urban soils are subject to metal inputs from atmospheric deposition, irrigation water, industrial activities, and natural sources [ 7 , 8 , 9 , 10 , 11 ]. Meanwhile, the pollution of urban soils with Pb, As, and Cr could also derive from vehicle exhaust and municipal solid waste [ 12 , 13 ].…”

The Cancer and Non-Cancer Risk of Santiago Island (Cape Verde) Population due to Potential Toxic Elements Exposure from Soils

“…The chemical composition of dust, soils, and groundwater may cause metabolic changes that may favor the occurrence of endemic diseases in humans [14][15][16][17][18][19][20]. The role of F, I, Se, and As concentrations in the health of human populations is well documented in the scientific literature [21][22][23][24][25][26].…”

“…The geochemistry of the major, trace, and rare earth elements (REEs) of soils of Santiago Island (Cape Verde) has been studied to characterize the soils developed on volcanic rocks and Quaternary sediments, contributing to the establishment of a geochemical atlas of the island [9,17,29,30].…”