Geochemical Evaluation of Surface Sediments in Niger Delta Mangrove, Nigeria

Mangrove surface sediments from Choba, Ogbogoro and Isaka along the New Calabar and Bonny rivers respectively in Niger Delta, Nigeria were sampled and analyzed to evaluate their geochemical compositions, inter-element relationships and potential ecological impact. Results show that the highest mean concentrations in parts per million (ppm) of Pb, Zn, Cu, Ni, Cr, Y, Nb, Th and Sc in Choba sediments were 36.2, 65.2, 19.6, 47.4, 121.6, 21.4, 23.0, 13.8 and 16.8; As, V, Sr, Zr, TS and F in Ogbogoro sediments were 6.4, 192.3, 70.0, 273.4, 14627.0 and 104.8 while Br, I and Cl in Isaka sediments were 27.4, 41.4 and 4189.6 respectively. Box plot of the elements show contrasting concentrations in different sampling locations. Compared to the upper continental crust (UCC), As and Ni are higher in Choba, Ogbogoro and Isaka. The abundance of Pb was found to be higher in Choba and Ogbogoro. Though Th and Sc are more concentrated in Choba and Ogbogoro relative to the UCC, they were found to be lower in Isaka. However, Zn, Cu, Cr, V, Sr and Zr concentrations in the UCC were found to be higher than the mean concentrations of these elements in Choba, Ogbogoro and Isaka mangrove sediments. Most of the trace elements correlated positively and strongly with Fe2O3. This implies that Fe2O3 is important in controlling metal concentrations in the area. The concentrations of As and Zn were either equal to or below the low effect level (LEL) and interim sediment quality guideline (ISQG). Pb, Cu and Ni were found to be higher than LEL and ISQG in Choba while Cr concentrations in Choba, Ogbogoro and Isaka all exceeded the LEL, ISQG and severe effect level (SEL) values but below probable effect level (PEL) value; thus indicating potentials for moderate to severe ecological harm. Keywords: Mangrove sediments, Geochemistry, Heavy metals, Sediment quality, Niger delt

Geochemical evaluation of land use at a medieval harbor site in Masuda City, Chugoku region, Japan

A large-scale Medieval harbor site has been recently discovered at Nakazu-Higashihara in Masuda City, Chugoku region, Japan. The Medieval harbor site is divided into north and south areas. The concentration of 22 elements in soil samples from the north of the harbor site was determined in order to identify the geochemical signatures of the Medieval harbor site. The evidence described in the north area is an example of identification of both natural and anthropogenic processes that lead to geochemical variations within the archaeological soils. The north area of the site contains silt and sandy soils characterized by highest concentration of Zr and relatively low levels of most other elements (except for Sr and TS). Negative or weak positive correlations between TiO2 and MnO, and CaO and P2O5 in the north area indicate that this association of elements represents an ancient anthropogenic signature, especially related to residential sites in all soil types. Correlation between TiO2 and Ni, Y, Nb, Zr, Th, and Fe2O3 did not reflect the anthropogenic history. However, these elements and their ratios can be used to identify sources, as well as to establish baseline concentration of other elements which are influenced by anthropogenic and detrital inputs

Evaluation of Present Lake Environment from Geochemistry of Bottom Sediment of Hartbeespoort Dam, North-West Province, South Africa

Present Lake Environment of Hartbeespoort Dam was evaluated from Geochemistry of bottom Sediment. Ten (10) bottom sediment samples were collected across the entire Lake. The geochemical composition of the sediment samples was determined using X-ray fluorescence (XRF); trace and major elements determined includes As, Pb, Zn, Cu, Ni, Cr, Fe2O3, TiO2, MnO, CaO and P2O5. The trace elements concentrations of the sediment were grouped into three zones base on their spatial distribution. The Western zone of the lake shows a remarkable enrichment in Nickel (Ni) and Chromium (Cr) and could be associated with geogenic source. However high enrichment of phosphate (P2O5) observed in the same zone could be attributed to anthropogenic source, due to agricultural activities on the catchment of Magalies River. Moderate enrichment of As, Zn, Cu, Cr and Pb was recorded in the central zone and could be ascribed to entrapment by fine-grained organic and Fe-rich clay deposit in the central part of the lake; this was showcased by the strong positive correlation between the trace elements and Fe2O3. As, Zn, Pb and Cu were highly enriched in the South – Eastern zone and anthropogenic source could be responsible for the enrichment due to the influence of the Crocodile River. The average concentration of As, Pb, Zn, Cu, Ni and Cr in the sediment were evaluated by comparison with the upper continental crust (UCC), Shale standard (Turekian and Wedepohl, 1961) and Sediment quality guidelines (SQG); the result indicates that As, Pb, Zn, Cu and Cr in the study area were above the lowest effect level (LEL) but below the severe affect level (SEL) which shows that the impact on biota is moderate. However, Nickel (Ni) was above the severe effect level and could therefore have severe effect on the aquatic environment. Keywords: aquatic environment, Bottom Sediment, Heavy Metals, Hartbeespoort Dam, X-ray fluorescence DOI: 10.7176/JEES/9-11-10 Publication date: November 30th 201