Concentrations of Arsenic and Boron in Water, Sediment and the Tissues of Fish in Emet Stream (Turkey)

Critical knowledge gaps and relevant variables requiring consideration when performing aquatic ecotoxicity assays

The increasing diversity and complexity of contaminants released in the environment continuously lead to new challenges when applying ecotoxicity assays. This paper comprises a review concerning exposure assessment and highlights important variables that should be taken into account when investigating aquatic media toxicity under both laboratory or field conditions. Thus, to reflect as much as possible what occurs in nature, ecotoxicity assays must carefully consider these variables in their experimental design. This includes contaminant properties, the selected bioindicators and biomarkers, the dose mode/regime, concentration vs. load, exposure to single vs. multiple contaminants and exposure of single vs. multiple species. Many of these, however, are not usually taken into account, leading to critical knowledge gaps in this area, discussed in detail herein.

Spatial variation and quantitative screening level assessment of human risk from boron exposure in groundwater resources of western edge of the Lake Urmia, Iran

Boron is a ubiquitous element and exposure to high concentrations of boron in drinking water may lead to health outcomes. This study aimed to analyze boron in rural drinking water resources located at the west of Urmia Lake. An innovative risk matrix was developed for faster assessment of risk status and adaptation of mitigation approaches. The mean boron concentration in 121 drinking water sources from 301 villages obtained 1477 ± 1683 μg/L. In the west of Urmia lake and northwestern parts of the lake (east of Salmas city), boron concentrations were up to twice the World Health Organization (WHO) guidelines. Using regional screening levels calculator of the U.S. Environmental Protection Agency (US.EPA), as a deterministic risk assessment model, the total risks/Non-carcinogenic hazard index (HI) risks from exposure to 13,000 and 2600 μg/L of boron obtained 1.94E+00 and 3.91E-01, respectively. More investigations are recommended for better understanding of the extent of contamination in the study area.

Influence of arsenic and boron on the water quality index in mining stressed catchments of Emet and Orhaneli streams (Turkey)

Emet and Orhaneli stream basins are characterized by intense mining of colemanite, the main borate mineral in the area. Unlike other global borate deposits, the colemanite of this region contains arsenic minerals (realgar and orpiment). Undoubtedly, improper management of mine wastes causes pollution of water resources, affecting human life and biota. In the present study, spatial and temporal variation in water quality of Emet and Orhaneli streams was assessed. The water quality index (WQI) model was used to rate the overall status of the water, and geographical information systems (GIS) was used to aid the visualization of results. No significant differences in WQIs for the three-monitoring periods (March, July and October 2017) were noted. The WQI in the region is highly influenced by arsenic (As) and boron (B), with a strong positive correlation (p < 0.05, r² = 0.971). The As and B concentrations in Emet stream were 1.88-1907 μg/L and 0.01-1900 mg/L, respectively. Whereas for Orhaneli stream, respective As and B levels ranged from 5.17 to 116 μg/L and 0.01 to 5.45 mg/L. Globally, the As level in Emet stream basin is comparable to some of the words major contaminated regions such as Rapti River Basin (India) and Xieshui River (China). However, the uniqueness of this basin is seen in B and As trends, and input routes like active geothermal waters and weathering of the realgar (AsS) and orpiment (As₂S₃) from colemanite nodules. This paper demonstrates the influence of pollutants associated with basin geochemistry and exploration of mineral resources on WQI.

Accumulation of chemical elements in yellow-necked mice under a colony of great cormorants

This study represents the first investigation into the accumulation of chemical elements in small mammals inhabiting the territory of a great cormorant colony. Trapping was done in the Juodkrantė great cormorant colony, one of the largest colonies in Europe. The accumulation of 20 chemical elements in the bodies (muscle and bones) of yellow-necked mice (Apodemus flavicollis) was investigated using the energy-dispersive x-ray fluorescence equipment Spectro Xepos HE. Two groups of positively inter-correlated chemical elements (Mg, Al, P, Ca and Al, S, Cl, K) were identified. The concentrations of five elements differed significantly between mice trapped in different zones of the colony with differing intensities of cormorant influence: the values of K and Cu in A. flavicollis increased in line with an increase in the influence of the cormorants, while the concentrations of Rb and Pb decreased. The concentrations of Mn differed between zones, but were not related to the intensity of bird influence. Differences in the concentration of Zn (ANOVA F = 24.38; p < 0.001), Fe (F = 4.60; p < 0.05) and Mo (F = 4.47; p < 0.05) were related to the gender factor, all concentrations being higher in females. The concentrations of Zn were age-dependent, being highest in adult individuals (21.7 ± 4.5 μg g^-1) and exceeding those in subadult (19.4 ± 3.4 μg g^-1) individuals or juveniles (16.7 ± 1.3 μg g^-1). In general, the concentrations of accumulated elements in A. flavicollis from the territory of the cormorant colony were lower than in rodents from industrially polluted sites.

Vertical profile, contamination assessment of mercury and arsenic in sediment cores from typical intertidal zones of China

The vertical profiles, contamination levels, and potential ecological risks of mercury and arsenic were studied from the sediment cores of seven typical intertidal zones, including the Liaohe River Estuary, the Jianhe River Estuary, the Dagu River Estuary, Yancheng Shoal, the Dongtan Yangtze River Estuary, Hangzhou Bay, and the Pearl River Estuary. Marine sediment quality standards, the threshold effect level (TEL), and the probable effect level (PEL) were used as guidelines to evaluate sediment quality. In addition, the geo-accumulation index (I_geo) and potential ecological risk index ([Formula: see text]) were used to assess contamination and potential ecological risks from mercury and arsenic. The results showed that the Pearl River Estuary was moderately polluted by mercury and represented a high potential ecological risk, while other areas were uncontaminated or mildly contaminated with low or moderate potential ecological risks. The Pearl River Estuary was mildly polluted by arsenic and represented a mild potential ecological risk, while other areas were unpolluted and also posed a mild potential ecological risk.