Bioaccumulation of arsenic in aquatic plants and animals near a municipal landfill

Arsenic pollution cycle, toxicity and sustainable remediation technologies: A comprehensive review and bibliometric analysis

Arsenic pollution and its allied impacts on health are widely reported and have gained global attention in the last few decades. Although the natural distribution of arsenic is limited, anthropogenic activities have increased its mobility to distant locations, thereby increasing the number of people affected by arsenic pollution. Arsenic has a complex biogeochemical cycle which has a significant role in pollution. Therefore, this review paper has comprehensively analysed the biogeochemical cycle of arsenic which can dictate the occurrence of arsenic pollution. Considering the toxicity and nature of arsenic, the present work has also analysed the current status of arsenic pollution around the world. It is noted that the south of Asia, West-central Africa, west of Europe and Latin America are major hot spots of arsenic pollution. Bibliometric analysis was performed by using scopus database with specific search for keywords such as arsenic pollution, health hazards to obtain the relevant data. Scopus database was searched for the period of 20 years from year 2003-2023 and total of 1839 articles were finally selected for further analysis using VOS viewer. Bibliometric analysis of arsenic pollution and its health hazards has revealed that arsenic pollution is primarily caused by anthropogenic sources and the key sources of arsenic exposure are drinking water, sea food and agricultural produces. Arsenic pollution was found to be associated with severe health hazards such as cancer and other health issues. Thus considering the severity of the issue, few sustainable remediation technologies such as adsorption using microbes, biological waste material, nanomaterial, constructed wetland, phytoremediation and microorganism bioremediation are proposed for treating arsenic pollution. These approaches are environmentally friendly and highly sustainable, thus making them suitable for the current scenario of environmental crisis.

Trophic transfer patterns of arsenic in freshwater ecosystem layers in arsenic-endemic Ganges Delta and its potential human health risk

Arsenic (As) is a toxic environmental contaminant with global public health concern. In aquatic ecosystems, the quantification of total As is restricted chiefly to the individual organisms. The present study has quantified the total As in different trophic layers (sediment-water-phytoplankton-periphyton-zooplankton-fish-gastropod-hydrophytes) of lentic freshwater ecosystems. As transfer pathways quantifying the transmission rate across trophic-level compartmental route were delineated using a novel model-based approach along with its potential contamination risk to humans. Lentic water bodies from Indo-Gangetic region, a core area of groundwater As, were selected for the present investigation. The study revealed that among the lower biota, zooplankton were the highest accumulator of total As (5554-11,564 µg kg-1) with magnification (rate = 1.129) of the metalloid, followed by phytoplankton (2579-6865 µg kg-1) and periphytic biofilm (1075 to 4382 µg kg -1). Muscle tissue of zooplanktivore Labeo catla is found to store higher As (80-115 µg kg-1 w.w.) compared to bottom-dwelling omnivore Cirrhinus mrigala (58-92 µg kg-1 w.w.). Whereas, Amblypharyngodon mola has accumulated higher As (203-319 µg kg-1 w.w.) than Puntius sophore (30-98 µg kg-1 w.w.) that raised further concern. The hepatic concentration indicated arsenic-mediated stress based on As stress index (threshold value = 1). Mrigal and Mola showed significant biomagnification among fishes while biodiminution was observed in Catla, Bata, Rohu and Punti. All the studied fishes were under the arsenic mediated stress. In the 'sediment-water-periphytic biofilm-gastropod' compartment, the direct grazing accumulation was higher (rate = 0.618) than the indirect path (rate = 0.587). Stems of edible freshwater macrophytes accumulated lesser As (32-190 µg kg-1 d.w.) than roots (292-946 µg kg-1 d.w.) and leaves (62-231 µg kg-1 d.w.). The target cancer risk (TCR) revealed a greater concern for adults consuming edible macrophyte regularly. Similarly, the varied level of target hazard quotient and TCR for adults consuming fishes from these waterbodies further speculated significant health concerns. The trophic transfer rate of environmental As in soil-water-biota level at an increasing trophic guild and consumer risk analysis have been unravelled for the first time in the Indo-Gangetic plains, which will be helpful for the strategic mitigation of As contamination.

A review on arsenic in the environment: bio-accumulation, remediation, and disposal

Arsenic is a widespread serious environmental pollutant as a food chain contaminant and non-threshold carcinogen. Arsenic transfer through the crops-soil-water system and animals is one of the most important pathways of human exposure and a measure of phytoremediation. Exposure occurs primarily from the consumption of contaminated water and foods. Various chemical technologies are utilized for As removal from contaminated water and soil, but they are very costly and difficult for large-scale cleaning of water and soil. In contrast, phytoremediation utilizes green plants to remove As from a contaminated environment. A large number of terrestrial and aquatic weed flora have been identified so far for their hyper metal removal capacity. In the panorama presented herein, the latest state of the art on methods of bioaccumulation, transfer mechanism of As through plants and animals, and remediation that encompass the use of physicochemical and biological processes, i.e., microbes, mosses, lichens, ferns, algae, and macrophytes have been assessed. Since these bioremediation approaches for the clean-up of this contaminant are still at the initial experimental stages, some have not been recognized at full scale. Nonetheless, extensive research on these primitive plants as bio-accumulators can be instrumental in controlling arsenic exposure and rehabilitation and may result in major progress to solve the problem on a worldwide scale.

A New Approach to Quantifying Bioaccumulation of Elements in Biological Processes

Simple Summary

The bioaccumulation of elements (e.g., heavy metals) in living organisms (e.g., animals) is vitally important from at least two points of view: the growth and development of the organisms themselves and remediation of the polluted environment. So far, bioaccumulation has been characterized by the bioaccumulation factor (BAF), which is the ratio between the concentration of elements in the organism to the concentration in the matrix (water, soil, etc.). This factor is a good measure of bioaccumulation in ecosystems in which an organism lives from the beginning of their lives to the moment of investigation. However, especially in laboratory experiments, when organisms at a given stage of development are introduced to the system and contain some non-zero concentration of an element, the BAF can lead to misinterpretation. Therefore, we propose a new measure called the bioaccumulation index (BAI), which is the relative increase in the concentration of a given element in the organism to its initial concentration after the experiment. We proved, on the basis of data published by other authors, that the BAI was much more valid for the interpretation of bioaccumulation in these cases.

Abstract

Bioaccumulation, expressed as the bioaccumulation factor (BAF), is a phenomenon widely investigated in the natural environment and at laboratory scale. However, the BAF is more suitable for ecological studies, while in small-scale experiments it has limitations, which are discussed in this article. We propose a new indicator, the bioaccumulation index (BAI). The BAI takes into account the initial load of test elements, which are added to the experimental system together with the biomass of the organism. This offers the opportunity to explore the phenomena related to the bioaccumulation and, contrary to the BAF, can also reveal the dilution of element concentration in the organism. The BAF can overestimate bioaccumulation, and in an extremal situation, when the dilution of element concentration during organism growth occurs, the BAF may produce completely opposite results to the BAI. In one of the examples presented in this work (Tschirner and Simon, 2015), the concentration of phosphorous in fly larvae was lower after the experiment than in the younger larvae before the experiment. Because the phosphorous concentration in the feed was low, the BAF indicated a high bioaccumulation of this element (BAF = 14.85). In contrast, the BAI showed element dilution, which is a more realistic situation (BAI = −0.32). By taking more data into account, the BAI seems to be more valid in determining bioaccumulation, especially in the context of entomoremediation research.

Genotoxicity and Oxidative Stress in Experimental Hybrid Catfish Exposed to Heavy Metals in a Municipal Landfill Reservoir

This study aimed to investigate the concentrations of Cr, Cd and Pb in the water, sediment and experimental hybrid catfish muscles, and to compare the genetic differentiation and the levels of oxidative stress biomarkers (malondialdehyde and protein carbonyl) between the catfish from the contaminated reservoir near a municipal landfill and the reference area after chronic exposure. The concentrations of all metals in the water and the concentration of Cd in the sediment exceeded Thailand's surface water quality and soil quality standards, respectively, whereas the concentrations of these metals in fish muscles did not exceed Thailand's food quality standards. Dendrogram results in terms of genetic similarity values of the catfish from the reference and the landfill areas were 0.90 to 0.96 and 0.79 to 0.86, respectively, implying that the genetic differentiation of the fish from the landfill was greater than of those from the reference area. The fish in the landfill reservoir had slightly increased protein carbonyl levels. The results indicate that chronic heavy metal exposure can cause genotoxicity of the hybrid catfish and induce protein carbonyl as an oxidative stress biomarker in the reservoir near a municipal landfill.

A Systematic Review on Arsenic Bio-Availability in Human and Animals: Special Focus on the Rice-Human System

The present systematic review synthesizes the diverse documentation of research on the occurrence of arsenic in soil-water systems and the human and animal bio-availability scenarios related to food chain contamination by arsenic. Humans and animals may drink arsenic-contaminated groundwater in addition to consuming foods that have been grown in arsenic-contaminated groundwater and soils. Rice grain is a potential arsenic carrier and the staple food in many parts of the world, particularly in Southeast Asian countries. Data have been summarized from 183 articles describing different aspects of arsenic flow in the food chain, that is, the soil-water-rice-human system and the water-crops-animals system and the bio-availability of arsenic to humans and animals. The phyto-availability of arsenic depends on the physicochemical and biological conditions of soil and water. In humans, the bio-accessibility of inorganic arsenic is 63-99%. Arsenic is more bio-available from rice than from other foods: different food materials differ in bio-accessible potential. Additionally, the review identifies trends in research on arsenic contamination and food chain flow considering arsenic species, toxicity assessment, and bio-accessibility studies. This systematic review provides a comprehensive assessment of the documented evidence to be used to guide future research on arsenic availability for the rice plant and subsequent availability to humans from cooked rice that can determine arsenic toxicity. The review also highlights how the focus of research on arsenic as a pollutant has changed in the past decades.

Assessment of red mud as sorptive landfill liner for the retention of arsenic (V)

The sorption of As^V on red mud (bauxite residue), produced in the ALCOA-San Cibrao factory (Spain), was assessed in view of its potential use as sorptive liner of landfills for the attenuation of As-rich leachates. The operating parameters evaluated, using batch-type procedures, comprised the effects of time, solution pH, As^V concentration (sorption isotherm) and presence of phosphate on the As^V sorption. The results showed that the red mud efficiently sorbed As^V. The sorption was fast, with a major fraction of initial As^V being removed in a few minutes or hours of contact, depending on As^V concentration. The kinetic process was well described by the pseudo-second order equation, which points to chemisorption is involved, whereas surface (film) diffusion chiefly governs the rate of As^V sorption for the red mud system. Sorption of As^V was strongly pH-dependent. Maximum removal (>98%) was observed at slightly acidic pH (pH_max = 5.5-6), while As^V sorption considerably decreased at both highly acidic and alkaline pH. The percentages of sorbed As^V decreased with the increasing solution As^V concentration, and the As^V sorption capacity (up to 43.5 mmol/kg) of the red mud was higher (∼4 -fold) at pH ∼6 than at pH ∼9.2 (natural pH of the red mud). The presence of P at equimolar or 1:10 As/P molar ratios reduced As^V sorption by ∼20% and 30%, respectively. Simulations of As^V migration taking into account the effects of dispersion and diffusion through an hypothetical red mud liner, using the sorption parameters and the geotechnical-hydraulic conductivity characteristics of the RM, predicted a deeper migration of As^V in the liner at pH∼9.2 than at pH∼6 and a minimum thickness of ∼90 cm and ∼20 cm, respectively, for a RM liner to decrease the solution As^V concentration from highly toxic 1 mM to a safe <0.133 μM (<10 μg/L) level, after a 35-years period.