Modified heavy metal Pollution index (m-HPI) for surface water Quality in river basins, India

Biochar applications for treating potentially toxic elements (PTEs) contaminated soils and water: a review

Environmental pollution with potentially toxic elements (PTEs) has become one of the critical and pressing issues worldwide. Although these pollutants occur naturally in the environment, their concentrations are continuously increasing, probably as a consequence of anthropic activities. They are very toxic even at very low concentrations and hence cause undesirable ecological impacts. Thus, the cleanup of polluted soils and water has become an obligation to ensure the safe handling of the available natural resources. Several remediation technologies can be followed to attain successful remediation, i.e., chemical, physical, and biological procedures; yet many of these techniques are expensive and/or may have negative impacts on the surroundings. Recycling agricultural wastes still represents the most promising economical, safe, and successful approach to achieving a healthy and sustainable environment. Briefly, biochar acts as an efficient biosorbent for many PTEs in soils and waters. Furthermore, biochar can considerably reduce concentrations of herbicides in solutions. This review article explains the main reasons for the increasing levels of potentially toxic elements in the environment and their negative impacts on the ecosystem. Moreover, it briefly describes the advantages and disadvantages of using conventional methods for soil and water remediation then clarifies the reasons for using biochar in the clean-up practice of polluted soils and waters, either solely or in combination with other methods such as phytoremediation and soil washing technologies to attain more efficient remediation protocols for the removal of some PTEs, e.g., Cr and As from soils and water.

Detrimental influence of industrial effluents, especially heavy metals, on limnological parameters of water and nutritional profile in addition to enzymatic activities of fish, Sperata seenghala (Sykes, 1839) from diverse Ramsar sites, India (Punjab)

The present research was designed to determine the nutritive value of the liver and intestine of fish, Sperata seenghala, the impact of effluence load on limnological parameters of water and proximate composition of fish organs, especially on fatty acids, liver enzymatic activities, seasonal variations in the nutritional profile of fish, and to check and compare the pollution status of Ramsar sites in Punjab by calculating the water quality index, heavy metal pollution index, and metal index from June 2018 to August 2020. WQI of Harike wetland was found to be 53.95, which depicts that water quality in this region is "poor". At Nangal wetland, water quality index was reported to be "excellent" quality water and fit for the whole ecological unit. Overall heavy metal pollution index for Harike wetland was reported 174.569, whereas for Nangal wetland it was 5.994, depicting massive contaminant loads in a polluted region. MI value was also recorded as being higher (6.9336) in polluted habitat than in control habitat (0.8175). In fish liver, significant (p < 0.05) higher mean total lipids (6.73%), total proteins (3.98%), moisture (77.69%), ash (3.56%), and carbohydrates (3.79%) were observed in the samples from Nangal wetland than Harike wetland. A similar trend was reported in all biochemical contents of the fish intestine. Enzyme activities such as aspartate-aminotransferase and alanine-aminotransferase were significantly elevated (p < 0.05) in the specimens collected from the polluted region. The mean total n-3 (except in spring), n-6 polyunsaturated fatty acids (except in winter), and average monounsaturated and saturated fatty acids diminished significantly (p < 0.05) in the liver of fish from contaminated habitat than control site. In the intestine of fish collected from the polluted region, significant reductions in the mean total n-3 (except in autumn as well as summer), total n-6 PUFAs (in autumn and winter), and total SFAs were reported than control site.

Mangrove (Avicennia marina) parts as proxies in marine pollution of Nizampatnam Bay, East Coast of India: An integrated approach

This study focuses on the assessment of heavy metals (HM) concentration and pollution status of the Nizampatnam Bay, east coast of India, from mangrove plant parts (roots and leaves) and sediment samples. This is the first of its kind work (comparison of data from both mangrove and sediment samples) from the third largest mangrove ecosystem in India. To carry out this work, plant (Avicennia mariana) and sediment samples were collected from five stations. The collected samples were carefully subjected to the laboratory methods and heavy metal concentrations were determined by using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The obtained results were juxtaposed with the optimal values of world surface pollution rock averages, and noticed heavy metals such as Cd and Cu exceed the optimal values. To know the contamination levels and the chemical elements that contribute to the pollution, various environmental indices, viz., contamination factor, enrichment factor, geoaccumulation index, and pollution load index were, carried out on the sediment sample data. To ascertain the mangrove plant's capacity (in the study area) for accumulation and translocation of heavy metals in different parts of the plants, factors such as bio-concentration and translocation were calibrated.

Concentration, Health Risk, and Hydrological Forcing of Heavy Metals in Surface Water Following Water-Sediment Regulation of the Xiaolangdi Dam in the Yellow River

Water and sediment regulation aimed at aquatic ecosystems and preserving reservoir capacity to minimize the negative consequences of dams can fundamentally change the distribution of heavy metals (HMs) in the reservoir and downstream reaches. However, the effects of water and sediment regulation on variation in HMs are still poorly understood. In this study, the variations in concentration, contamination, human health risk, potential sources, and influencing factors of the metalloid As and HMs (Cr, Hg, Ni, Pb, and Zn) in surface water in the reservoir and the downstream reach of the Xiaolangdi Dam (XLD) following the operation of the water-sediment regulation scheme (WSRS) were determined. These results indicate that HM concentrations in the two post-WSRS seasons were much lower than the water quality standards, but were significantly increased over time due to the trapping effects of the XLD (p < 0.05, except for Zn). However, As concentration in the reservoir was significantly lower than that observed in downstream reaches, likely due to anthropogenic input from agricultural activities. Meanwhile, HM concentrations varied with distance to the dam, which displayed a distinct accumulation closer to the dam in the post-WSRS II season. The contamination of HMs, the carcinogenic risk of exposure to As, and the noncarcinogenic risks associated with exposure to Hg, Ni, Pb, and Zn via the direct ingestion pathway of drinking water were all within acceptable levels following the WSRS, but increased over time. The carcinogenic risk of Cr in the post-WSRS II season was at an unacceptably high level, particularly at sites near the dam. Hydrological characteristics (water level and flow rate) were the dominant factors in determining the distribution of HMs. These results can provide new insight for a better understanding of the variations in HMs following the water and sediment regulation practices, and guide future management in regulating the trapping effects of dams.

Impact of industrial effluents on physico-chemical parameters of water and fatty acid profile of fish, Labeo rohita (Hamilton), collected from the Ramsar sites of Punjab, India

In this contemporary era, wetlands and the entire aquatic diversity are suffering from major pollution problem. Not only the aggregation of higher population in metropolitan causes the production of plenty of solid, liquid and gaseous wastes, but also the high-technological industries contribute to a mammoth of wastes in the ecosystem. During the process of industrial effluent discharge into the water bodies, the toxic substances available in these wastes can affect the aquatic flora and fauna, resultantly disturbing the entire system and constituting human health hazards indirectly or directly. The objective of this study was to estimate the nutritional value of the liver and intestine of fish which is being discarded as waste during fish processing and pollution status by calculated water quality index (WQI) and comparison of both wetlands during diverse seasons. WQI of Harike Wetland was observed to be 56.68 which indicates that water quality in this wetland is "poor", while at Nangal Wetland WQI was calculated to be 39.54 and comes under "good" water quality and safe for the entire ecosystem. HPI (heavy metal pollution index) for Harike Wetland was observed 144.9 and for Nangal Wetland was 3.12, indicating heavy load of heavy metal pollution at test sample site. MI (metal index) value was also detected higher at test sample site (4.76) as compared to that at control site (0.22). The mean total n-3 and n-6 polyunsaturated fatty acids (PUFAs) declined in the liver of test fish samples (Harike Wetland) as compared to control fish (Nangal Wetland) samples except in winter season. Similarly, mean total saturated fatty acids (SFAs) were also found to decline significantly (p<0.05) in the liver of test fish sample as compared to control fish sample during autumn and winter seasons. Significant (p<0.05) decline of mean total n-3 PUFAs (except winter) and total n-6 PUFAs (except rainy) in the intestine of test fish sample was observed during all the seasons when compared to control fish samples. However, total SFAs were found to increase in the intestine of test fish samples as compared to control fish samples during all the studied seasons. In the present investigation, fluctuations recorded in the water quality parameters and major groups of FAs in the tissues were due to the geographical location and pollution load in the fish samples taken from Harike Wetland.

Drinking water elements constituent profiles and health risk assessment in Wuxi, China

Water elements pollution has attracted public attention globally. Wuxi is located in East China, and its water source, Taihu Lake, has been severely polluted since 2007. Studies of elemental pollution profiles have yet to be conducted in this area. In this study, 56 water samples were collected in 2018, and 33 elements were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The results showed that the levels of 33 elements ranged from 1.35 × 10^-3 μg/L(Tl) to 101 mg/L(Ca), with Sr, Al, Fe, B, Ti, Ba, and Zn levels being relatively higher. A comprehensive literature review showed spatial distribution of conspicuous elements in drinking water worldwide. Meanwhile, Monte Carlo simulations were applied to evaluate exposure health risks. The total hazard index(HI) for 14 non-carcinogens and the average incremental lifetime cancer risk (ILCR) of As and Pb exposure through drinking water were found acceptable. Sensitivity analyses suggested that Sb and As in the drinking water represent an increasing risk to human health. The results of this study provide key data on local metal pollution characteristics, help identify potential risk factors, and contribute to the development of effective environmental management policies for Taihu Lake.

Accumulation and risk assessment of heavy metals employing species sensitivity distributions in Linggi River, Negeri Sembilan, Malaysia

The constant increase of heavy metals into the aqueous environment has become a contemporary global issue of concern to government authorities and the public. The study assesses the concentration, distribution, and risk assessment of heavy metals in freshwater from the Linggi River, Negeri Sembilan, Malaysia. Species sensitivity distribution (SSD) was utilised to calculate the cumulative probability distribution of toxicity from heavy metals. The aquatic organism's toxicity data obtained from the ECOTOXicology knowledgebase (ECOTOX) was used to estimate the predictive non-effects concentration (PNEC). The decreasing sequence of hazardous concentration (HC₅) was manganese > aluminium > copper > lead > arsenic > cadmium > nickel > zinc > selenium, respectively. The highest heavy metal concentration was iron with a mean value of 45.77 μg L^-1, followed by manganese (14.41 μg L^-1) and aluminium (11.72 μg L^-1). The mean heavy metal pollution index (HPI) value in this study is 11.52, implying low-level heavy metal pollutions in Linggi River. The risk quotient (RQ) approaches were applied to assess the potential risk of heavy metals. The RQ shows a medium risk of aluminium (RQ_m = 0.1125) and zinc (RQ_m = 0.1262); a low risk of arsenic (RQ_m = 0.0122) and manganese (RQ_m = 0.0687); and a negligible risk of cadmium (RQ_m = 0.0085), copper (RQ_m = 0.0054), nickel (RQ_m = 0.0054), lead (RQ_m = 0.0016) and selenium (RQ_m = 0.0012). The output of this study produces comprehensive pollution risk, thus provides insights for the legislators regarding exposure management and mitigation.

Use of Heavy Metal Content and Modified Water Quality Index to Assess Groundwater Quality in a Semiarid Area

Groundwater is a major source of drinking and agricultural water supply in arid and semiarid regions. Poor groundwater quality can be a threat to human health especially when it is combined with hazardous pollutants like heavy metals. In this study, an innovative method involving entropy weighted groundwater quality index for both physicochemical and heavy metal content was used for a semiarid region. The entropy weighted index was used to assess the groundwater’s suitability for drinking and irrigation purposes. Thus, groundwater from 19 sampling sites was used for analyses of physicochemical properties (electrical conductivity—EC, pH, K+, Ca2+, Na+, SO42−, Cl−, HCO3−, TDS, NO3−, F−, biochemical oxygen demand—BOD, dissolved oxygen—DO, and chemical oxygen demand—COD) and heavy metal content (As, Ca, Sb, Se, Zn, Cu, Ba, Mn, and Cr). To evaluate the overall pollution status in the region, heavy metal indices such as the modified heavy metal pollution index (m-HPI), heavy metal evaluation index (HEI), Nemerow index (NeI), and ecological risks of heavy metals (ERI) were calculated and compared. The results showed that Cd concentration plays a significant role in negatively affecting the groundwater quality. Thus, three wells were classified as poor water quality and not acceptable for drinking water supply. The maximum concentration of heavy metals such as Cd, Se, and Sb was higher than permissible limits by the World Health Organization (WHO) standards. However, all wells except one were suitable for agricultural purposes. The advantage of the innovative entropy weighted groundwater quality index for both physicochemical and heavy metal content, is that it permits objectivity when selecting the weights and reduces the error that may be caused by subjectivity. Thus, the new index can be used by groundwater managers and policymakers to better decide the water’s suitability for consumption.