Arsenic species uptake and translocation in Elodea canadensis

Elevated Urbanization-Driven Plant Accumulation of Metal(loid)s Including Arsenic Species and Assessment of the Kłodnica River Sediment Contamination

The impact of water and bottom sediment pollution of a river subjected to a strong industrial anthropogenic pressure of metal(loid) (including arsenic and its species) accumulation in riverbank plants such as Solidago virgaurea L., Phragmites L. and Urtica dioica L. was investigated. The high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) technique was used to study organic and inorganic arsenic species in selected plants and their response to heavy metal and arsenic contamination. The modified BCR extraction results showed that arsenic was mainly bound to the mobile reducible and organic-sulfide fractions in the Kłodnica River bottom sediments. Research has shown that the bottom sediments of the Kłodnica River are contaminated with metals, including Pb, Zn, Ni, As, and among arsenic species, the As(V) form dominated quantitatively, with its highest concentration being 49.3 mg kg^-1 and the organic species occurred extremely rarely. The highest concentration of arsenic, among the tested plants, occurred in Phragmites communis L. The evaluation of the bottom sediment pollution was performed using Sb/As factor, geoaccumulation index (I_geo), enrichment factor (EF) and pollution load index (PLI). The ability of the plant to assimilate metals from the substrate was studied by calculation of the bioaccumulation factor (BAF). Values of the I_geo change in a wide range from class 1 (uncontaminated to moderately polluted for Cu and Zn) at the first sampling point, to 5 (highly to extremely polluted for Ba and Fe) at the K4 sampling point. The I_geo results show an increase in the contamination with elements toward the runoff of the Kłodnica River.

Water and soil contaminated by arsenic: the use of microorganisms and plants in bioremediation

Owing to their roles in the arsenic (As) biogeochemical cycle, microorganisms and plants offer significant potential for developing innovative biotechnological applications able to remediate As pollutions. This possible use in bioremediation processes and phytomanagement is based on their ability to catalyse various biotransformation reactions leading to, e.g. the precipitation, dissolution, and sequestration of As, stabilisation in the root zone and shoot As removal. On the one hand, genomic studies of microorganisms and their communities are useful in understanding their metabolic activities and their interaction with As. On the other hand, our knowledge of molecular mechanisms and fate of As in plants has been improved by laboratory and field experiments. Such studies pave new avenues for developing environmentally friendly bioprocessing options targeting As, which worldwide represents a major risk to many ecosystems and human health.

Arsenic acquisition, toxicity and tolerance in plants - From physiology to remediation: A review

Globally, environmental contamination by potentially noxious metalloids like arsenic is becoming a critical concern to the living organisms. Arsenic is a non-essential metalloid for plants and can be acclimatised in plants to toxic levels. Arsenic acquisition by plants poses serious health risks in human due to its entry in the food chain. High arsenic regimes disturb plant water relations, promote the generation of reactive oxygen species (ROS) and induce oxidative outburst in plants. This review evidences a conceivable tie-up among arsenic levels, speciation, its availability, uptake, acquisition, transport, phytotoxicity and arsenic detoxification in plants. The role of different antioxidant enzymes to confer plant tolerance towards the enhanced arsenic distress has also been summed up. Additionally, the mechanisms involved in the modulation of different genes coupled with arsenic tolerance have been thoroughly discussed. This review is intended to present an overview to rationalise the contemporary progressions on the recent advances in phytoremediation approaches to overcome ecosystem contamination by arsenic.

Insights into conventional and recent technologies for arsenic bioremediation: A systematic review

Arsenic (As) bioremediation has been an economical and sustainable approach, being practiced widely under several As-contaminated environments. Bioremediation of As involves the use of bacteria, fungi, yeast, plants, and genetically modified organisms for detoxification/removal of As from the contaminated site. The understanding of multi-factorial biological components involved in these approaches is complex and more and more efforts are on their way to make As bioremediation economical and efficient. In this regard, we systematically reviewed the recent literature (n=200) from the last two decades regarding As bioremediation potential of conventional and recent technologies including genetically modified plants for phytoremediation and integrated approaches. Also, the responsible mechanisms behind different approaches have been identified. From the literature, it was found that As bioremediation through biosorption, bioaccumulation, phytoextraction, and volatilization involving As-resistant microbes has proved a very successful technology. However, there are various pathways of As tolerance of which the mechanisms have not been fully understood. Recently, phytosuction separation technology has been introduced and needs further exploration. Also, integrated approaches like phytobial, constructed wetlands using As-resistant bacteria with plant growth-promoting activities have not been extensively studied. It is speculated that the integrated bioremediation approaches with practical applicability and reliability would prove most promising for As remediation. Further technological advancements would help explore the identified research gaps in different approaches and lead us toward sustainability and perfection in As bioremediation.