Ecological risk assessment of heavy metal pollution in sediments of Nile River, Egypt

Oral and dermal exposure to natural radionuclides and heavy metals in water and sediments of Nile River, Qena, southern Egypt

This study assessed the levels of natural radionuclides (226Ra, 232Th, and 40K) and heavy metals (Hg, Fe, Cr, As, Zn, Cu, Cd, and Pb) in surface water and sediment samples from the Nile River in Qena Governorate, southern Egypt, using a gamma-ray spectrometer, 3" NaI (Tl) scintillation detector coupled with 1024 multi-channel analyzer, and an atomic absorption spectrometer. In surface water and sediments, the average activity concentrations of natural radionuclides were 40K (4.73 Bq L-1; 395.76 Bq kg-1) > 226Ra (0.41 Bq L-1; 18.14 Bq kg-1) > 232Th (0.30 Bq L-1; 17.98 Bq kg-1). The average heavy metal concentrations in surface water in µg L-1 were Fe (121.0) > Zn (33.80) > Cr (28.0) > Cu (8.62) > Pb (8.35) > As (1.19) > Hg (0.81) > Cd (0.12). In Nile sediments the concentrations in mg kg-1 were Fe (1670.0) > Zn (207.0) > Cr (29.40) > Cu (16.20) > Pb (4.32) > Hg (0.41) > Cd (0.31) > As (0.14). The heavy metal evaluation index (HMEI) calculations for water samples revealed that 31% of the samples were suitable for domestic use, while 69% were not. The geo-accumulation index, enrichment factor, and ecological risk factor for sediments were estimated, showing extreme enrichment for Hg and Zn with high ecological risk for Hg. Health risks for adults were evaluated due to oral and dermal exposure to Nile surface water and sediments from the study area, indicating minimal radiological risks and potential carcinogenic and non-carcinogenic risks from the metals.

Ecological footprint model of heavy metal pollution in water environment based on the potential ecological risk index

Social heavy metal pollution poses a significant threat to aquatic ecosystems. Heavy metals are easily adsorbed by sediments and have cumulative effects on aquatic organisms, which is different with the hypothesis of the conventional ecological footprint model that the pollutants are independently degraded by water bodies. To solve this problem, an ecological footprint for heavy metal pollution (EFHM) is constructed based on the potential ecological risk index (PERI). EFHM is defined as the sediment area to control the cumulative ecological risk of heavy metals within the allowable limit. And then, EFHM uses ecological footprint index (EFI) and ecological footprint contribution rate (EFCR) to quantify the hazard of social heavy metal load and recognize the key risk factor. EFHM is applied for assessing the heavy metal pollution of Central China. The results show that (i) the EFHM model can effectively evaluate the cumulative ecological hazards of heavy metals in sediment. (ii) The EFHM values of Central China in 2015 and 2020 are 20,764.56 and 17,358.59 km2, respectively. (iii) Compared with 2015, the EFI values of Hunan Province and Jiangxi Province in 2020 decrease from 1.53 to 0.87 to 1.23 and 0.39, respectively, both of which are improved by one grade. The EFI values of Hubei Province increases from 0.42 to 1.34, which is deteriorated by one grade. (iv) In 2020, both of the key risk factors of Hunan Province and Hubei Province are Hg, and the crucial hazard source of Jiangxi Province is Cd. (v) The mine pollution control in Central China should be further consolidated, and the wastewater treatment of electronics and machinery industries should be strengthened.

Anatase-cellulose acetate for reinforced desalination membrane with antibacterial properties

This study aimed to prepare antifouling and highly mechanical strengthening membranes for brackish and underground water desalination. It was designed from cellulose acetate (CA) loaded anatase. Anatase was prepared from tetra-iso-propylorthotitanate and carboxymethyl cellulose. Different concentrations of anatase (0.2, 0.3, 0.5, 0.6, 0.7, and 0.8)% were loaded onto CA during the inversion phase preparation of the membranes. The prepared membranes were characterized using Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM & EDX), mechanical properties, swelling ratio, porosity determination, and ion release. The analysis confirmed the formation of anatase on the surface and inside the macro-voids of the membrane. Furthermore, anatase loading improved the CA membrane's mechanical properties and decreased its swelling and porosity rate. Also, CA-loaded anatase membranes displayed a significant antibacterial potential against Gram-positive and Gram-negative bacteria. The results showed that the salt rejection of the CA/anatase films as-prepared varies considerably with the addition of nanomaterial, rising from 46%:92% with the prepared membranes under the 10-bar operation condition and 5 g/L NaCl input concentration. It can be concluded that the prepared CA-loaded anatase membranes have high mechanical properties that are safe, economical, available, and can stop membrane biofouling.

Taxonomic and functional structure of macrobenthic invertebrate communities and their response to environmental variables along the subbranches of the Nile River (rayahs), Egypt

Macrobenthic invertebrate communities serve as markers of anthropogenic stress in freshwater ecosystems. In this study, 17 sampling sites were selected from two Nile river subbranches (El-Rayah El-Behery and El-Rayah El-Nassery) and subjected to different anthropogenic influences to explore the ecological environment and characteristics of macrobenthos communities. Macrobenthos were studied using taxonomic diversity and biological trait analysis to investigate how human activity and variation in water quality affect their structure and function. A total of 37 taxa represented by 43,389 individuals were recognized. The communities are composed chiefly of Oligochaeta and aquatic insects. Multivariate statistical analyses found that the most influential environmental variables in the structural and functional community were sodium, dissolved oxygen, silicate, pH, calcium, and cadmium. At high levels of pollution, notably sewage and industrial pollution in the northern part of El-Rayah El-Behery, characteristics such as larger body size, detritus feeders, burrowers, and high tolerance to pollution predominated, whereas at low levels of pollution, features such as small body sizes, scraper and predator feeders, intolerant and fairly tolerant of pollution, and climber and swimmer mobility are predominant. The results confirm our prediction that the distribution of macroinvertebrate traits varies spatially in response to environmental changes. The diversity-based method distinguished impacted sewage and industrial sites from thermal effluent sites, while the trait-based approach illustrated an apparent variance between the ecological status of contaminated regions. Therefore, the biological features should be employed in addition to structural aspects for assessing the biodiversity of macroinvertebrate communities under environmental stressors.

Heavy metal profile, mobility, and source characterization in size-fractionated bed-sediments of River Ganga, India

Sediment quality assessment is vital while assessing the quality of rivers since sediments can alter the water quality depending on pH, redox conditions, and other physico-chemical characteristics. The present study aims to assess the heavy metal concentration in the size-fractionated sediments of River Ganga, and ascertain the sources of contamination in upper Himalayan stretch of around 300 km. The bed sediments of River Ganga were collected from Gomukh, Bhojwasa, Gangotri, Jhala Bridge, Chinyalisaur, Devaprayag, and Rishikesh; and these were size-fractionated in the range of 0-75, 75-150, 150-200, 200-250, 350-300, 300-450, 450-600 μm particle size to determine the concentration of heavy metals associated with each range of particle size using Atomic Absorption Spectrophotometer (AAS). The mean concentration of the metals in the sediments varied in the order Al (126 g/kg) > Fe (68 g/kg) > Cr (79 mg/kg) > Zn (67 mg/kg) > Pb (59 mg/kg) > Ni (38 mg/kg) > Cu (36 mg/kg) > Cd (2 mg/kg), and representing more affinity of metals with finer particle size of sediments. Contamination Factor and Metal Enrichment Factor indicated that sediments in the lower stretch were contaminated and enriched with many toxic metals. Geo-accumulation index, Sediment Pollution Index, and Pollution Load Index revealed that the sediments of Chinyalisaur, Devaprayag, and Rishikesh were moderately to strongly polluted and are progressively getting deteriorated by metals, thus, classifying these locations as hotspots of contamination. The major sources of Al and Fe were found to be natural; whereas Cr, Zn, Pb, Ni, Cu and Cd were mainly contributed by anthropogenic sources. The study stresses for immediate interventions to control further contamination by restricting addition of wastewater directly to River Ganga, or through other streams in Ganga basin.

Development of a Social Impact Assessment for the Water Environment: A Professional Perspective

Climate change and population growth are increasing the frequency of flooding and drought, resulting in conflict over water resources. Social impact assessments (SIA) of the allocation and management of water resources provide a way of reducing and resolving such conflicts. This article first explores the nature of SIA for water environments through an inductive analysis of the cases mentioned in more than 30 papers. Next, it identifies important advantages of SIA over integrated water resources management (IWRM) practices and indicates that while IWRM solves water-related issues to improve social well-being, it cannot entirely grasp the overall social impact of planned interventions. Following this, it analyzes the water environment governance structures in Taiwan, using questionnaire responses from water environment management professionals to discuss challenges of effectively implementing water environment SIA. The questionnaire covers 26 detailed tasks of SIA advocated by Vanclay et al. This research is the first to have evaluated the difficulty of the tasks. The survey results can be used as a reference for the implementation of SIA in other regions. The results show that (1) the water environment SIA is indeed necessary; (2) Taiwan’s water environment professionals need to improve from their current lack of understanding of SIA; (3) it is difficult to implement the water environment SIA; (4) it is necessary for SIA to clarify and integrate the authorities and responsibilities of relevant government departments; (5) the professionals believe the myth of quantification of SIA; and (6) water environment SIA must be integrated with the existing IWRM. Finally, we emphasize the need to integrate SIA and IWRM in a mutually complementary way, and illuminate the need for an integrated SIA framework for water environment management.