Evaluating water quality and ecotoxicology assessment techniques using data from a lead and zinc effected upland limestone catchment

Assessing Heavy Metal Contamination Risk in Soil and Water in the Core Water Source Area of the Middle Route of the South-to-North Water Diversion Project, China

The Middle Route Project of China’s South-to-North Water Diversion Project (SNWDP) is a national-level water source protection zone and the ecological safety of its water quality and surrounding soil is of great significance. In this study, heavy metals in the surface water and topsoil in the core water source area were quantitatively analyzed using a geographic information system (GIS) and geostatistical techniques combined with environmental pollution and ecological risk assessment models to determine their environmental contamination levels, ecological risk levels, and spatial distribution patterns. Cd was identified as an essential factor responsible for the overall slight heavy metal pollution in the topsoil layer. Heavy metal contamination in surface water was primarily driven by alert-level concentrations of Hg and was consistently distributed in areas with high concentrations of Hg in the topsoil. Applying the potential ecological risk index (RI) revealed two key results. First, surface water showed no ecological risk. The concentrations of heavy metals in surface water met the goals set by relevant authorities in China. Second, overall, the topsoil was at low ecological risk, with a spatial pattern primarily influenced by Cd and Hg. Some heavy metals might have similar pollution sources and originate from human activities such as industrial activities, mining and smelting, and pesticide and chemical fertilizer applications. The study is important for improving the soil and water ecology in the reservoir area and ensuring the northward diversion of high-quality water. In addition, it provides a sound basis for making decisions about local heavy-metal remediation and treatment projects.

Seasonal variations, risk assessment and multivariate analysis of trace metals in the freshwater reservoirs of Pakistan

Water samples were collected from three freshwater reservoirs of Pakistan during three seasons (pre-monsoon, monsoon and post-monsoon). The collected samples were examined for the concentrations of selected trace metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr and Zn) and physicochemical parameters (pH, T, EC, TDS, DO, Cl^-). Among the metals, Co, Pb and Sr revealed relatively higher concentrations while Cd, Mn and Zn exhibited fairly lower contents. Most of the metals (except Co) revealed considerably higher contributions in the pre-monsoon period. The average levels of Cr, Co, Cd, Pb and Ni exceeded the national/international guideline limits. Pollution assessment highlighted significant pollution; mainly by Cd, Cr, Ni and Pb. Evaluation of health risk indicated that Cr, Cd, Co, Pb and Ni were associated with high risks (HQ_ing > 1), especially for the children. Principal component analysis showed anthropogenic contributions of Cd, Cr, Co, Pb and Ni, while significant spatial variability was shown by cluster analysis. The highest metal pollution was found at sites near to the entrances of the reservoirs and/or near to the urbanized areas. This study revealed that priority pollutants of concern were Cr, Cd, Co, Pb and Ni; therefore, immediate remedial measures should be implemented for sustaining the healthy aquatic ecosystems.

Controls on accumulation and soil solution partitioning of heavy metals across upland sites in United Kingdom (UK)

A significant body of knowledge suggests that soil solution pH and dissolved organic carbon (DOC) strongly influence metal concentrations and speciation in porewater, however, these effects vary between different metals. This study investigated the factors influencing soil and soil solution concentrations of copper (Cu), lead (Pb), nickel (Ni) and zinc (Zn) under field conditions in upland soils from UK having a wide range of pH, DOC and organic matter contents. The study primarily focussed on predicting soil and soil solution metal concentrations from the data on total soil metal concentrations (HNO₃ extracts) and soil and soil solution properties (pH, DOC and organic matter content). We tested the multiple regression models proposed by Tipping et al. (2003) to predict heavy metal concentrations in soil solutions and the results indicated a better fit (higher R² values) in both studies for Pb compared to the Zn and Cu concentrations. Both studies observed consistent negative relationships of metals with pH and loss on ignition (LOI) suggesting an increase in soil solution metal concentrations with increasing acidity. The positive relationship between Pb concentrations in porewater and HNO₃ extracts was similar for both studies, however, similar relationships were not found for the Zn and Cu concentrations because of the negative coefficients for these metals in our study. The results of this study conclude that the predictive equations of Tipping et al. (2003) may not be applicable to the field sites where the range of DOC and metal concentrations is much lower than their study. Our study also suggests that the extent to which metals are partitioned into soil solution is lower in soils with a higher organic matter contents due to binding of these metals to soil organic matter.