M-Triad: An improvement of the sediment quality triad

Univariate or multivariate approaches for histopathological biomarkers in the context of environmental quality assessments?

Although the simplification of multivariate histopathological data into univariate indices can be useful for the assessment of environmental quality, this implies a great loss of information. The objective of the present study was to evaluate the effectiveness, in the context of environmental quality assessment, of an approach that integrates individual histopathological responses in a discriminated manner with the results of contaminants by means of multivariate analyses. This analysis was compared to the diagnosis of environmental quality provided by the use of the univariate Bernet histopathological index. Contaminant loads (sediments and fish) and the liver histopathology of Cathorops spixii were integrated through multivariate analysis. Integrated individual histopathological responses allowed classifying environmental quality from more to less impacted sites, while the univariate index showed some inconsistencies with chemical loads and allowed identifying only the most impacted site.

Revisited a sediment quality triad approach in the Korean coastal waters: Past research, current status, and future directions

We present a comprehensive review of the sediment quality triad (SQT) assessment studies in Korea. The bibliographic analysis was applied to evaluate how approaches in sediment assessment have evolved. A meta-analysis was performed, to evaluate potential risks of sedimentary persistent toxic substances (PTSs) reported in Korean coastal waters. Within the framework, we identified and discussed current status and spatiotemporal trends in contamination of both classic and emerging PTSs over the recent decadal period. Out of 26 target regions in Korea, five hotspots (Sihwa, Masan, Ulsan, Taean, and Gwangyang) of concern could be identified. Four of those regions have been designated as Specially-Managed Sea Area under the implementation of Total Pollution Load Management System in Korea, except for Taean coast (oil spill site). Meantime, we could identify three stepwise research phases based on a bibliographic analysis; Phase 1 (1995-2008), Phase 2 (2009-2015), and Phase 3 (2016-2020). It is noteworthy that a technical evolution of the SQT assessment by the phase was featured. It was also evidenced that in-depth studies adopting multiple lines of evidence (LOEs) became prevailed upon approaching Phase 3. In a quantitative manner, the toxicity explanatory power of target PTSs increased by about 10% in Phase 3 compared to the earlier phases. The meta-analysis using ratio-to-mean value method applied for the data set having all three LOEs indicated general improvement of sediment qualities in the hotspots. However, their associations quite varied across regions and years, reflecting a dynamicity in oceanographic settings and/or heterogeneity in toxicological effect or benthic community response. At present, SQT assessment adopting the increased LOEs generally supports better assessment. In conclusion, we suggest that future SQT studies globally should reaffirm the utility of the "multiple LOEs approach", focusing on the identification and management of causative toxicants that driving negative ecological impacts on marine ecosystems.

Sediment Assessment of the Pchelina Reservoir, Bulgaria

The temporal dynamics of anthropogenic impacts on the Pchelina Reservoir is assessed based on chemical element analysis of three sediment cores at a depth of about 100-130 cm below the surface water. The ¹³⁷Cs activity is measured to identify the layers corresponding to the 1986 Chernobyl accident. The obtained dating of sediment cores gives an average sedimentation rate of 0.44 cm/year in the Pchelina Reservoir. The elements' depth profiles (Ti, Mn, Fe, Zn, Cr, Ni, Cu, Mo, Sn, Sb, Pb, Co, Cd, Ce, Tl, Bi, Gd, La, Th and U_nat) outline the Struma River as the main anthropogenic source for Pchelina Reservoir sediments. The principal component analysis reveals two groups of chemical elements connected with the anthropogenic impacts. The first group of chemical elements (Mn, Fe, Cr, Ni, Cu, Mo, Sn, Sb and Co) has increasing time trends in the Struma sediment core and no trend or decreasing ones at the Pchelina sampling core. The behavior of these elements is determined by the change of the profile of the industry in the Pernik town during the 1990s. The second group of elements (Zn, Pb, Cd, Bi and U_nat) has increasing time trends in Struma and Pchelina sediment cores. The increased concentrations of these elements during the whole investigated period have led to moderate enrichments for Pb and U_nat, and significant enrichments for Zn and Cd at the Pchelina sampling site. The moderately contaminated, according to the geoaccumulation indexes, Pchelina Reservoir surface sediment samples have low ecotoxicity.

Pollution Assessment of Potentially Toxic Elements (PTEs) in Soils around the Yanzhuang Gold Mine Tailings Pond, Pinggu County, Beijing, China

The accumulation of tailings from gold mining and smelting may result in PTE pollution. We investigated PTE contamination from a large amalgamated gold mine tailings pond in Pinggu County, Beijing. In November 2017, 30 soil samples were collected around the tailings pond. The concentrations and pollution degree of PTEs in the samples and the sources of Sb, As, Cd, Cu, Pb, Zn and Hg were analyzed. The average concentration of these elements in soil samples near the tailings pond (16.24, 28.29, 0.99, 171.04, 263.25, 99.73, 0.72 mg/kg, respectively) were higher than their corresponding standard values and background values of the study area. The geoaccumulation index showed that the pollution degree of As, Pb and Hg was moderate, while Sb and Cu present non-pollution to moderate pollution. The average EF values of the elements were Sb (38.31), As (4.23), Cd (0.71), Cu (3.68), Pb (21.24), Zn (0.82) and Hg (5.29), respectively. The environmental risk assessment developed throughout the PERI method indicated that Sb, As, Hg and Pb were the main pollutants in the study area. The three quantitative risk indicators (RI, Igeo and EF) were positively correlated, and all of them indicated that PTEs had significant pollution to the local area. Thus, Sb, As, Pb, Cu, and Hg pollution should be highly concerning. Multivariate statistical analysis shows that the pollution of PTEs was mainly caused by the accumulation of tailings ponds after gold mining and smelting. The research result is of great significance for the prevention and control of soil pollution of PTEs near the tailings pond.