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.

Heavy metal pollution and spatial distribution in surface sediments of Mustafakemalpasa stream located in the world's largest borate basin (Turkey).

Mining activities in addition to the geology of Mustafakemalpasa catchment have for long been linked to its deteriorating water and sediment quality. This study assessed contamination levels of heavy metals and other major elements (Pb, As, B, Cd, Zn, Cr, Mo, Co, Ni, Cu, and Ag) in surface sediments of the area, and identified possible pollution sources. Sediment quality indicators, such as contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo) and sediment quality guidelines were used, in addition to multivariate statistical technics; Pearson Correlation Matrix (PCM), Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). The highest contamination (annual average > 110 mg kg-1) was revealed by B, Cr, Ni, Zn and As. Moreover, As, Cd and Ni levels exceeded their respective probable effect concentrations (PEC), posing a potential negative impact to biota. The highest Igeo values were recorded for Cr, B, Ni, As and Zn, and occurred near urban settlements and mining sites, particularly of coal and chromium. The present study also suggests use of site rank index (SRI) as an alternative to pollution load index (PLI), since the former is derived from the data of interest and eliminates arbitrary classifications. The sources of heavy metals in the sediments were attributed to fly ashes of coal-powered plants, urban waste leachate and weathering of sulfide ore minerals for Pb, Zn and Cu; urban-industrial wastes and mining wastes for Ni. Although Cr, As, Cd and B were ascribed to natural occurrence, their presences in river sediment is accelerated by mining.