Geo-Temporal Signatures of Physicochemical and Heavy Metals Pollution in Groundwater of Khulais Region—Makkah Province, Saudi Arabia

Seawater has intruded into many of Saudi Arabia’s Red Sea coastal aquifers, with varying degrees of extension depending on location, hydrogeology, and population density. This study aimed to evaluate and comprehend the processes that influence the hydrogeochemical characteristics of the coastal aquifer in Saudi Arabia’s Khulais region. Groundwater samples were taken from nineteen locations during the winter and summer of 2021, and data from major ions and trace elements were examined and interpreted using ArcGIS software. The total dissolved solids (TDS) concentrations ranged between 480 and 15,236 mg/L and 887–18,620 mg/L in winter and summer, respectively. Groundwater TDS concentration was observed to be influenced by groundwater flow, lithogenic, anthropogenic, and seawater intrusion in this study (2021) when compared to 2016. The concentration of nitrate (NO3−) and strontium (Sr) in most samples exceeds the drinking guidelines. The occurrence of high concentrations of bromide (Br), Fluoride (F), Iron (Fe) (winter and summer) and Aluminum (Al), Boron (B), Chromium (Cr), Nickel (Ni), lead (Pb), cadmium (Cd), cobalt (Co), copper (Cu) and manganese (Mn) (winter) was also exhibited and observed up to more than drinking and irrigation limits. The central part of the study area was affected by seawater intrusion. The hydraulic conductivity of the topsoil was measured, and it ranged from 0.24 to 29.3 m/day. Based on electrical conductivity (EC) and sodium absorption ratio, most aquifer samples were unsuitable for irrigation (SAR).

Phytoremediation of Heavy Metals in Contaminated Soils: A Review

Heavy metals represent a major threat to public health and the environment if they are intentionally or unintentionally introduced into the soil. They are elements that cannot be degraded and can be teratogenic, mutagenic, and endocrine-disrupting. Carcinogens and toxins in humans can be caused by heavy metals, which are difficult to regulate. Phytoremediation has been recommended as an alternative to classic physicochemical remediation methods since it is more efficient for combating heavy metals pollution in soil or water bodies and ecologically friendly. Biomass produced as a result of phytoremediation can be utilised for cogeneration of energy and/or the creation of biofuels, all of which contribute to health, the environment, and cost-effectiveness. In order to improve the usage of phytoremediation in the coming years, a deeper understanding of the technique's potential is necessary. Additionally, this study provides information on the use of herbaceous and woody plants for phytoremediation in soils affected by heavy metals.

Dataset-Based Assessment of Heavy Metals Pollution in Taihu Lake Fish and Their Health Risk

The ecological risks and health hazards of heavy metals pollution in Taihu Lake have received widespread concern. This study has developed a nationwide dataset on pollutant loads in species, and the dataset records 55,297 data from 310 articles, covering 778 species and 537 pollutants. In this paper, we extract and systematically integrate data on heavy metals concentrations in Taihu fish from the dataset. The Pi (single pollution index) and MPI (metal pollution index) models were used to assess the level of contamination in fish and the THQ (target hazard quotient) and ILCR (incremental lifetime cancer risk) models were used to assess the health hazards of fish consumption. The contamination levels varied in a feeding habit and living habit dependent manner. The risk of non-cancer health is the highest in omnivorous fish, then in carnivorous fish and herbivorous fish. ILCR model predicted that the values of As and Cd in omnivorous fish for children exceeded the risk threshold limits set by the EPA, and the ILCR values of As in omnivorous fish and Cd in carnivorous fish for adults also exceeded the risk threshold limits. In all, this study provided a comprehensive understanding of the risk of heavy metals in Taihu.

Temporal changes in metal concentrations in a polluted urban basin: the contribution of multivariate techniques to the evaluation of their recovery

In urban rivers in many fast-growing cities, heavy metals pollution is one of the major quality issues. Quantifying its recovery success seems to be a difficult but necessary challenge, in part, because a complex database is generally needed to assess water quality. The overall goal of this work was to evaluate temporal changes in metal concentrations in a polluted basin applying the AEM method and to determine the physicochemical and meteorological parameters associated with these changes using the RDA. We analyzed temporal changes of 15 sites located in the Matanza Riachuelo River Basin, one of the most polluted basins in the word. For this, we collected data of metal concentrations in surface water, physicochemical parameters of water and meteorological factors of eight years (2008 to 2015) in each site. The results of this work allowed make evident temporal patterns (at different scales) in metal concentrations and several factors associated with these patterns. Also, we found that the effects of physicochemical and meteorological factors in metal concentrations were dependent of each site, possibly related to the presence of different sources of pollution or characteristics of the river. Our study showed that the combination of AEM and RDA multivariate techniques is a useful tool for both detecting temporal trends in the concentrations of environmental pollutants, which are not easily detectable in highly degraded environments, and for evaluating factors associated with these changes. These techniques could be applied to different scenarios (aquatic and terrestrial) affected by the continuous advance of human activities.

The effectivity of Biduri combined with indigenous bacteria in mercury absorption

Heavy metals pollution, especially Mercury (Hg), is one of the most serious environmental problems. The presence of excessive Hg will cause soil degradation and threaten the life of the ecosystem, for that remediation is necessary. Biduri is known to be able to absorb heavy metals, but there is no research on the ability of Biduri in absorb Hg. The use of indigenous bacteria is expected to increase the absorption of Mercury by Biduri. The purpose of this study was to determine the potential of Biduri combined with indigenous bacteria and Agrobacterium sp I37 in absorbing of Hg in the soil. The experimental was designed as factorial with completely randomized design, consisting of 2 factors namely Bioremediation agent (A0: without bioremediation agent, A1: indigenous bacteria, A3: Agrobacterium sp I37) and Hg dosage (D0: without Hg, D1: Hg 0.3 µg.g-1, D2: Hg 0.51 µg.g-1). The results showed that the combination of Biduri with indigenous bacteria + 0.3 µg.g-1 Hg shows highest absorption of Hg at 57.19 µg (99.24% higher than control) and reduce soil Hg levels by 0.09 µg.g-1. Biduri is a hyperaccumulator plant because it is able to absorb more than 10 µg.g-1 of mercury.