Geochemical Baseline and Contamination Level Assessment of Antimony (Sb) in Sediment around Agbaou Gold Mine, Côte d’Ivoire

Agbaou is one of the most recent gold mine exploitation sites in Côte d’Ivoire. Little studies are discussed on the geochemical baseline concentration of trace metals in the wetland sediments around Agbaou gold mine. The main objectives of this study were to establish geochemical baseline values and to assess the pollution status of antimony (Sb). The geochemical baseline concentration of Sb (GBCSb) was estimated using linear regression method. In this study, total Sb concentration was analysed in sediment (10 sediment samples) collected around Agbaou gold mine site. The average Sb concentration was 5.63 ± 2.50 µg.g-1 ranging from 2.50 to 11.3 µg.g-1. The spatial distribution of Sb showed a tendency to accumulate near gold mine site. Moreover, the GBCSb (5.72 µg.g-1) was slightly higher than the average concentration found in sediments. GBC of Sb was used to calculate the anthropogenic contribution rate (R) which exhibited a positive value (R > 0) for all samples, indicating that the sediments were influenced by gold mining activities. Due to lack of local baseline value in the study area, the GBCSb obtained could be used as reference value for Sb contamination level assessment in the sediments.

Evaluation of Sodium Omadine for Short-Term Preservation of Nitrate-N and Orthophosphate in Water Samples

Maintaining nitrate-N and orthophosphate (dissolved reactive phosphorus) concentrations in a water sample over time is critical for water quality research. This study investigated the ability of current preservation methods to maintain nitrate-N and orthophosphate concentrations in environmental water samples over a period of up to 14 days. The United States Environmental Protection Agency (US EPA) currently recommends adding sulfuric acid for nitrate-N and filtering the water sample at the time of collection for orthophosphate. This study compared these recommended methods to baseline control concentrations in subsurface tile drainage water, pond water, and stream water. In addition, sodium omadine was tested as a potential alternative preservative. Across the three sources of water tested, sulfuric acid was the most reliable preservation method for both nitrate-N and orthophosphate, with percent changes from the baseline concentrations on Day 14 ranging from 2.30–3.27% for nitrate-N and 1.94–8.48% for orthophosphate. The control samples also maintained the baseline concentrations quite well, with percent changes on Day 14 ranging from 0.09–6.68% for nitrate-N and 2.63–11.87% for orthophosphate. When sodium omadine was added to the water samples, the nitrate-N concentrations had percent changes of 0.13–6.10% from the baseline concentration on Day 14. In contrast, sodium omadine was less effective for maintaining orthophosphate concentrations, with percent changes of 8.86–13.06% from the baseline concentration on Day 14. However, there were no significantly different orthophosphate concentrations when sodium omadine was added to stream water, showing a promising alternative for this scenario. Depending on the objective, researchers may need to consider the source water and length of storage of water samples to determine what, if any, preservative is necessary.

Temporal and spatial variability of heavy metals in Marudu Bay, Malaysia

The current study was conducted to estimate the baseline concentration of heavy metals in the surface sediment of Marudu Bay. Environmental parameters were measured at the seafloor and samples of the surface sediment were collected at monthly intervals for the period of 12 months. The organic content, total N, total P and concentration of 16 trace metals in the surface sediment were analyzed. The baseline concentration of metals was estimated by geochemical normalization. Anthropogenic inputs of metals were then estimated by calculating the enrichment factor for each element. The result demonstrated that the C/N ratio of sediment at Marudu Bay varies from 15 to 342, which indicates the dominance of terrestrial organic matter. The baseline concentration of V, Fe, Mn, Zn, Ti, Rb and Sr were 26.74 mg kg