Seasonal and spatial variations of ecological risk from potential toxic elements in the southern littoral zone of Izmir Inner Gulf, Turkey.

This study aims to investigate the ecological risk level of potentially toxic elements (PTEs) in Izmir Inner Gulf. Samples were taken from 16 stations selected in the southern littoral zone of the gulf for four seasons (winter, spring, summer, and autumn). Multi-element, total organic carbon, chlorophyll-a, biogenic silica and carbonate analyses were carried out. To determine contamination level and ecological risks, some indices (enrichment factor, modified hazard quotient and potential risk analysis, toxic risk index, etc.) were calculated. Mo and Pb show significant anthropogenic enrichment in the inner gulf. These are followed by Cu, Cd, and Zn with moderate accumulation. Risk assessment indices point out that Ni, Cr, and Cd have a serious potential to create risk for ecosystem, and these are followed by As, Hg, Pb, Zn, and Cu. According to the spatial distribution, land use maps, and factor analysis, the Cd, Zn, and Cr increases are localized at the mouth of the Poligon Stream. Pb and Cu accumulate at the mouth of four large streams feeding the eastern part of the gulf. Pb and Cu enrichment is associated with traffic and industrial discharges. While one of the sources of Hg is anthropogenic, another source is eutrophication resulting from benthic and planktonic diatom blooms. While Fe and Mn are added to the gulf via rivers as a result of rock and soil erosion, another source is sediment. Cr, As, and Ni come from anthropogenic and lithogenic sources and immobilized in sediment. CO3-2 source is marine (biogenic) and dilutes other immobilized PTEs. It is understood that the peripheral stations rich in allochthonous organic carbon and the stations close to the central area rich in autochthonous organic carbon contribute to the carbon source in question.

Ecological degradation and non-carcinogenic health risks of potential toxic elements: a GIS-based spatial analysis for Doganci Dam (Turkey).

This study was carried out to determine the ecological degradation and non-carcinogenic health risks at Doganci Dam, Bursa, Turkey. Potentially toxic element (PTE) concentrations (ppm) were as follows: Fe (55.030) > Al (27.220) > Mn (1053) > Cr (181) > Ni (180) > Zn (95) > Cu (62) > As (17) > Pb (11) > Cd (0.20) > Hg (0.108). As, Pb, Cd, and Hg were enriched anthropogenically, while other PTEs were of natural origin. The contamination severity index (CSI) indicated a moderate PTE contamination in the dam, mostly due to lithogenic effects. According to the modified hazard quotient (mHQ), ecological risk was identified at the level of extreme severity for Ni of lithological origin, of high severity for Cr of considerable severity for As of anthropogenic origin, and of moderate severity for Cu. According to the ecological contamination index (ECI), the dam had an ecological risk of a slight-to-moderate contamination. Health risk index showed no non-carcinogenic health risks in the dam. Mining, highways, and agricultural activities were identified as the primary anthropogenic drivers to be monitored. The ongoing anthropogenic activities in the Nilüfer Stream basin and natural factors affect the ecological degradation and non-carcinogenic health risk level of the dam.

Spatial distribution, environmental risk assessment, and source identification of potentially toxic metals in Atikhisar dam, Turkey.

The objective of this study was to determine the ecological risk created by metal contents of the surface sediments of Atikhisar dam, Çanakkale, NW Turkey. Enrichment factor (EF) and geoaccumulation index (Igeo) were calculated to determine anthropogenic effects. Ecological risk was assessed using the modified potential ecological risk index (mPER), with its levels being evaluated using the modified ecological risk index (mER). Toxic effects were determined using the toxic risk index (TRI). The ecological risk indices were mapped to provide their spatial distributions. Our findings indicate that enrichment was very high for Hg and significant for Pb, Tl, Cd, and As. The following mER pattern was detected: Hg > Cd > TI > As > Pb > Ni > Cr > Co > Zn > Mn > V. Hg and Cd exhibited extremely high and very high ecological risks, respectively, while TI and As had a significant ecological risk, with Pb exerting a medium ecological risk. Hg, Pb, Tl, Cd, As, Cr, Ni, Zn, and Cu were enriched via anthropogenic effects exceeding their natural concentration levels. Due to their high toxic effects, Hg, Cd, Tl, As, and Pb were identified as the very high risk elements. Mining, household wastes, agriculture, and natural mineral deposits were identified as the possible sources of the potential ecological risk.