Potentially toxic elements contamination in surface sediment and indigenous aquatic macrophytes of the Bahmanshir River, Iran: Appraisal of phytoremediation capability.

Groundwater geochemistry, quality, and pollution of the largest lake basin in the Middle East: Comparison of PMF and PCA-MLR receptor models and application of the source-oriented HHRA approach.

Groundwater geochemistry, quality, and pollution of the largest lake basin in the Middle East: Comparison of PMF and PCA-MLR receptor models and application of the source-oriented HHRA approach

The evaluation of trace elements (TEs) in sediments of dam lakes is crucial for maintaining ecosystem health. Therefore, it is very important to determine their concentrations, pollution status, sources, controlling factors and ecological risks in these ecosystems. Here, for the first time, we analyzed 14 TEs (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg and Pb) and sediment properties (organic matter (OM) and pH) in sediments from four dam lakes (Erfelek, Derbent, Suat Uğurlu and Saraydüzü) in the Black Sea Region of Turkey, which are used for different purposes and located on the different rivers or streams with different pollution levels. The results indicated that Al, V, Mn, Fe, Cu, Zn, As, Pb and Sb concentrations were lower in the Erfelek Dam Lake which has been used for drinking water supply, indicating that it is more protected than other dam lakes. However, Al, V, Mn, Fe, Co, Cu and Sb concentrations were higher in the Suat Uğurlu Dam Lake on the Yeşilırmak River which is moderately polluted. According to sediment contamination indices, there was low contamination in the sediments of all dam lakes. Similarly, the assessment of ecological risk posed by TEs indicated low eclogical risk in the dam lakes. Sediment OM and pH were found to be important control factors affecting the distribution of TEs in the dam lakes sediments. Correlation and factor analyses suggested that all TEs in the sediments of dam lakes mainly originated from geogenic sources. 

Ecological risks and controlling factors of trace elements in sediments of dam lakes in the Black Sea Region (Turkey)

The present study aimed to evaluate the sources of pollution and the potential human and ecological risks of hazardous elements (HEs) in 40 hotspot sites of the agricultural soil around the Arvand River, Iran. The mean concentrations of As, Cd, Co, Cr, Ni, Pb, Zn, and Hg were measured to be 7.2, 0.8, 14.0, 67.9, 69.5, 63.0, 296, and 0.66 (mg kg−1), respectively. With the exception of Ni, the mean concentrations of all the elements were found to be higher than those in the background. The spatial distribution of HEs in the study area indicated an increasing trend of contamination from the north to the south. Pb, Zn, and Hg were the most enriched elements, resulting in a high pollution load. Moreover, the agricultural soil of the study area was threatened by a very high ecological risk due to the contribution of Hg, Cd, and Pb. Multivariate statistical analyses determined that the pollution sources are specified by the oil refinery emissions and effluents, irrigation with polluted water, fertilizers, dust storms, and airport emissions. The carcinogenic risk of HEs in both adults and children revealed an acceptable level; however, children faced a great chance of non-carcinogenic risk. The results provide a scientific basis for monitoring HEs and managing health risks via effective methods in the agricultural areas of the Arvand River basin.

Spatial distribution and risk assessment of agricultural soil pollution by hazardous elements in a transboundary river basin

Rivers are one of the main sources to supply sand and gravel for construction projects. Depending on river morphology and hydraulic characteristics, its sediment transport capacity, and mining operation method, the extraction of river bed materials may affect its ecosystem through bank and bed erosion. To advance the mechanisms of river pit infilling, the effects of various parameters (i.e., the distance between pits, the pit plan shape, the pit depth, sediment size, and approaching flow velocity) on pit infilling volume are investigated in this research. The results of this research show that infilling volume of upstream pit is insignificantly affected by the distance between the pits, and it is completely refilled for different distances. However, the infilling volume of downstream pit decreases by increasing the distance between the pits. In addition, by reducing the ratio of pit length to its width (pit shape extension in spanwise direction), the pits can be excavated in a shorter distance from each other; when this ratio decreases by 15%, the infilling volume increases up to 30%. Subsequently, as a cost-effective option, the pit distance can be reduced up to 50% in these conditions. According to the obtained results, although the sediment size has negligible effect on infilling volume in the studied range, the infilling volume increases up to 20% by an increase of 8% in the approaching flow velocity. Increasing the ratio of pit length to its width (pit shape extension in streamwise direction) highlights the effectiveness of smaller depths, so that the infilling volume increases up to 20% by a decrease of 20% in the pit depth. In this regard, it is recommended that the pit depth be restricted to 70% of the channel flow depth to have a complete pit refilling.

Evaluation of infilling and replenishment of river sand mining pits

Rivers are considered as beneficial sources to provide gravel and sand for projects, but it creates many negative hydraulic, physical and environmental effects. As the amount of infilling and appropriate location for better pit filling play important roles in scheduling the mining program and returning of the river to its stable condition, in this research through an experimental study, the effect of distance and locating the material pits for their infilling and mining management, is investigated. According to the results, getting the distance of the downstream pit does not significantly affect upstream pit filled volume and its migration, but the sedimentation rate in the downstream pit and its migration are decreased. Also when the pit approaches the river wall, the infilling volume of the upstream pit is reduced up to 25% compared to that of the channel center. On the other hand, by locating the downstream pit up to 14 times the flow depth, firstly the infilling volume is increased and later on decreased. The best infilling rate and migration of the pits occurs when they are excavated in the channel center and the downstream pit is excavated in a distance equal to 8 times the flow depth.

Hamed Haghnazar

Papers

Potentially toxic elements contamination in surface sediment and indigenous aquatic macrophytes of the Bahmanshir River, Iran: Appraisal of phytoremediation capability.

Spatial distribution and risk assessment of agricultural soil pollution by hazardous elements in a transboundary river basin

Evaluation of infilling and replenishment of river sand mining pits

Impacts of pit distance and location on river sand mining management

Experimental Study on the Effect of Single Spur-dike with Slope Sides on Local Scour Pattern