Alarming carcinogenic and non-carcinogenic risk of heavy metals in Sabalan dam reservoir, Northwest of Iran

Toxic phytoplankton in the aquatic ecosystems are dynamic, affecting water quality. It remains unclear as to how possible toxic phytoplankton assemblages vary vertically and temporally in Swakoppoort and Von Bach dams, located in a dry subtropical desert region in central Namibia. The following variables were analyzed: pH, Secchi depths, turbidity, water temperature, total phosphorus, orthophosphate, chlorophyll-a, phytoplankton cells, and water depths. Cyanobacteria dominated the phytoplankton community in the autumn, winter and spring (dry) and summer (wet) seasons, at all the depth ranges in both dams. Microcystis dominated the vertical and temporal dynamics, followed by Dolichospermum. In the dry seasons, higher cyanobacteria cell numbers were observed in comparison to the rainy season in both dams. Spring blooms of cyanobacteria were evident in the Von Bach Dam while autumn and spring cyanobacteria blooms were observed in the Swakoppoort Dam. In the Swakoppoort Dam, the preferable depth ranges for toxic cyanobacteria species were at 5 to 10 m while in the Von Bach Dam at 0 to 5 m range. The findings of the current study indicate that the traditional selective withdrawal of water in the two dams should be performed with vertical and temporal dynamics of possible toxic cyanobacteria accounted for to aid the abstraction of water with the lowest possible toxic phytoplankton numbers, which could lower the public health risk.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Assessment of Phytoplankton Dynamics in Two Reservoirs in Southern Africa with Special Reference to Water Abstraction for Inter-Basin Transfers and Potable Water Production

Sirunda

Oberholster

Wolfaardt

et al. 2021

“…The hydrochemical concentrations of ions, such as As; K + , Na + , Ca 2+ , Mg 2+ , Cl − , SO 4 2− , HCO 3 − , F − and Br − , the total alkalinity, and total acidity were determined at the Laboratory of the China Geological Survey, Nanjing Center. The arsenic concentration in the groundwater was determined by atomic fluorescence spectrometry.…”

Section: Sampling and Methodsmentioning

confidence: 99%

“…The recommended limit of As concentration in drinking water is 10 µg/L, according to the guidelines for drinking-water quality by the World Health Organization (WHO) [3]. According to the United States Environmental Protection Agency (EPA) and the National Research Council (NRC), the long-term consumption of water with As concentrations as low as 5 µg/L, or even 3 µg/L, might cause adverse chronic health effects on humans, especially cancer [4,5]. Drinking arsenic-rich groundwater is the main route for human exposure to this element.…”

Section: Introductionmentioning

confidence: 99%

Hydrogeochemical Processes and Potential Exposure Risk of Arsenic-Rich Groundwater from Huaihe River Plain, China

Gong

Tao

et al. 2022

Arsenic poses a danger to environmental health, and arsenic-rich groundwater is a key exposure risk for humans. The distribution, migration, and enrichment of arsenic in groundwater is an important environmental and public health problem. Currently, the Huaihe River Basin is identified as a region of arsenic-rich groundwater in China. This study aims to assess arsenic-rich groundwater potential pollution risk, analyze the hydrogeochemical processes, and trace the ion source based on an analysis of groundwater hydrogeochemical data. The results show that arsenic is the main inorganic chemical substances affecting the water quality in the study area, which presents a high exposure risk for public health. The arsenic concentration of groundwater was f 5.75 ± 5.42 μg/L, and 23% of the considered samples exceeded the drinking water standards of the World Health Organization. The groundwater in the study area underwent evaporation, halite dissolution, and ion exchange processes. The total alkalinity (HCO3−) of the arsenic-rich groundwater mainly ranged between 400–700 mg/L, and the chemical type was mainly of HCO3-Na. In an alkaline environment, the oxidative dissolution and reductive dissolution of arsenic bearing minerals might be the formation mechanism of arsenic-rich groundwater.

“…Since the 1990s, health risk assessment (HRA) has become a hot topic with a crucial guiding function in determining whether contaminants pose adverse risks to health and whether groundwater can be drunk directly [28,29]. In recent years, human health risk assessment has been developed and widely used in many countries to determine the adverse effects of chemicals taken from groundwater in different populations [30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Groundwater Suitability for Irrigation and Drinking Purposes in an Agricultural Region of the North China Plain

Guo

Wang

et al. 2021

Groundwater is an irreplaceable resource for irrigation and drinking in the North China Plain, and the quality of groundwater is of great importance to human health and social development. In this study, using the information from 59 groups of groundwater samples, groundwater quality conditions for irrigation and drinking purposes in an agricultural region of the North China Plain were analyzed. The groundwater belongs to a Quaternary loose rock pore water aquifer. The depths of shallow groundwater wells are 20–150 m below the surface, while the depths of deep groundwater wells are 150–650 m. The sodium adsorption ratio (SAR), sodium percentage (%Na), residual sodium carbonate (RSC), magnesium hazard (MH), permotic index (PI) and electrical conductivity (EC) were selected as indexes to evaluate the shallow groundwater suitability for irrigation. What’s more, the deep groundwater suitability for drinking was assessed and the human health risk of excessive chemicals in groundwater was studied. Results revealed that SAR, Na% and RSC indexes indicated the applicability of shallow groundwater for agricultural irrigation in the study area. We found 57.1% of the shallow groundwater samples were located in high salinity with a low sodium hazard zone. The concentrations of fluorine (F−) in 79.0% of the deep groundwater samples and iodine (I−) in 21.1% of the deep groundwater samples exceeded the permissible limits, respectively. The total hazard quotient (HQ) values of fluorine in over half of the deep groundwater samples exceeded the safety limits, and the health risk degree was ranked from high to low as children, adult females and adult males. In addition to natural factors, the soil layer compression caused by groundwater over-exploitation increased the fluorine concentration in groundwater. Effective measures are needed to reduce the fluorine content of the groundwater of the study area.