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Arsenic Speciation

Title of Special Session: “Speciation of Arsenic in Environmental, Geological and Biological Systems: Occurrence, Release Kinetics, Transformation, Bioavailability and Remediation”

Session Proposer: Indika Herath, Jochen Bundschuh, Prosun Bhattacharya and Meththika Vithanage
University of Southern Queensland (USQ), Qld, Australia

Rationality of the Topic :
Environmental consequences of arsenic have become apparent over the recent decades. Relatively long history of global arsenic research has endeavored to understand its hazardous consequences in the environment. However, despite of advances in fundamental understanding of total arsenic, identification, characterization and quantification of different chemical forms of arsenic in environmental, geological and biological matrixes are still lacking or insufficient. Different chemical species of arsenic including, inorganic arsenites and arsenates, monomethylarsenate, dimethylarsonate, arsenosugars, dimethylarsenoethanol, dimethylarsenoacetate, inorganic and organic thioarsenic species, volatile species etc. play a vital role to better understand the geologic/geochemical mechanisms, mobility, bioavailability and toxicological effects of arsenic in the natural environment. Therefore, a comprehensive understanding of the formation, mobility, transformation, bioavailability and chemical analysis of toxic species of arsenic in environmental, geological and biological matrixes is crucial for determining and assessing their environmental fate and serious consequences.

Existence of toxic forms of arsenic in environmental, geological and biological suites such as geothermal fluids, deep groundwater, stratified lakes, organic-matter rich swamps, peat bogs, mangrove systems, paddy rice ecosystems and biological organisms is of global concern in terms of their hazardous consequences on human health as well as natural ecosystems. However, the definite chemical nature of most of arsenic species still remains a subject of debate and hence, it is urgently necessary to develop proper analytical protocols for resolving this dispute in order to understand mechanisms of As speciation and their geochemistry, mobility and bioavailability in the natural environment. Up to date, little information is available on the identification and quantification of inorganic and organic arsenic species in environmental and biological samples that may be due to their complexity and instability upon chemical analysis. In order to evaluate potential toxicological effects of As in the environment, it is necessary to identify and quantify a variety of arsenic species in natural samples. Accurate detection and quantification of arsenic species in different matrixes is entirely dependent on the analytical method selected in a certain analysis and state-of-the-art spectroscopic and chromatographic methods have been applied to propose/confirm the molecular structure of arsenic compounds and their quantification.

Improved knowledge on worldwide arsenic research regarding speciation, quantification and analytical instrumentation are crucial in order to establish a sustainable mitigation of arsenic on global scale. A collection of contributions on modern approaches to detect, characterize, quantify and remediate various arsenic species can reflect current thinking and awareness in the global scientific community involving cutting edge science in this field. This special session is particularly focused on emerging environmental issues, public concerns and global significance which are associated with high concentrations of toxic arsenic species in environmental, geological and biological systems. Hence, the session will provide a reasonable assessment of what is new, what is current, what needs to be known or what should be done in future research on the interdisciplinary topic of the occurrence of toxic arsenic specie in ground-surface-water, soils, biota and living organisms. Eventually, this special session will be a strong research showcase based on current knowledge for worldwide future research of arsenic speciation and its remediation strategies.

The proposed special session will take a holistic approach for interpreting human exposure to different species of arsenic through arsenic contaminated-ground-surface-water, soil, biota, and food due to predominantly geogenic sources. Naturally occurring processes by which the formation of a variety of arsenic species occurs in such systems will be discussed in relation to particular geological, geochemical, geographical, and climate conditions in different arsenic-affected counties/regions worldwide, such as Latin America, West Bengal (India), Bangladesh, etc. Moreover, this will be a strong research showcase for global scientific community to present their innovative findings/outcomes of arsenic speciation researches in relation to analytical instrumentation, sample preservation and remediation strategies which will allow gaining new insights for future research to identify, characterize and quantify more unknown arsenic species/complexes in environmental, geological and biological matrixes. Overall, this session will be a significant research showcase bringing ongoing global research of arsenic speciation and related aspects under one umbrella.

The following fields/areas will be covered by the special session through oral and poster presentations (Total arsenic and related aspects will not be discussed in this session).
1. Speciation of arsenic in environmental systems; Surface-ground-water, aquifer sediments, soils (paddy rice soil, mine soil, etc.)
2. Speciation of arsenic in geological systems; Geothermal springs, fluids, and waters, groundwater and aquifer sediments affected by geothermal systems
3. Speciation of arsenic in biological systems; human and animal cells/organisms, crop plants (rice, wheat, etc.) food  and other types of biota
4. Release or transformation kinetics of different species in various environments/suites and across respective borders
5. Toxicological effects of different species of arsenic in relation to volatility, bioavailability, and phytoavailability,
6. Identification, Characterization and quantification of unknown arsenic species/complexes in environmental, geological and biological samples
7. Chemical analysis and preservation techniques of arsenic species.
8. Remediation strategies for the immobilization of arsenic species; Application of low cost and environmental friendly materials (activated charcoal, biochar, biomasses, etc.) naoparticals and other related methods.

Note: An extended abstract which is a contribution concisely describing original research work, including abstract, introduction, analytical methods, results, discussion and conclusion should be submitted before the deadline displayed on the AS2018 homepage. Submitted abstracts will be subjected to a peer review by the experts in this field and accepted based on the quality, depth of scientific information and novelty for either oral or poster presentations at the conference premises.

Medical Geology of Arsenic

Title of Special Session: Medical Geology of Arsenic

Session Proposer: Debapriya Mondal (UK), Ashok Ghosh (India) & Prosun Bhattacharya (Sweden/Australia)

Arsenic contamination is a serious threat to global population and the potential for medical geology interventions is enormous and the scope is global. The health effects of chronic arsenic exposure are well studied in countries with high levels of arsenic in their drinking water. However, little has been explored in populations exposed to low arsenic and most importantly whether consumption of arsenic in drinking water at the current WHO limit of 10 ppb results in an increased incidence of cancer or non-cancer effects. Therefore, research efforts are urgently needed to better understand the health risks from chronic exposure to low levels of arsenic, as well as studies to better define the distribution of arsenic in the natural environment, food, and other sources of exposure.

The primary aim of the special session is to bring together, at the global scale, scientists working in countries with low and/or emerging arsenic exposure, stressing the importance of geoscientific factors that affects the human health

Co-occurring Geogenic Contaminants

Title of Special Session:
Arsenic, Manganese and other co-occurring geogenic contaminants in aquifer system - Coupled biogeochemical cycling and constraints on mobility, toxicity and treatment.

Session Convenors: Saugata Datta, Prosun Bhattacharya, Mohammad Alauddin, Manish Kumar.

The importance of biogeochemical cycling of arsenic and co-occurring elements in the environment has long been recognized; both from the aspect of toxicity to organisms and also owing to their presence that are critical trace nutrients in the environment. Lesser attention was directed towards understanding the biogeochemistry of coupled geochemical behavior of multiple dissolved elements in the environment. A number of extensive environmental poisoning events have drawn widespread attention to co-occurrence of arsenic and manganese in aqueous environments, and in particular, helped to underscore the necessity of an improved understanding of their biogeochemistry.  Surely in this aspect one of the examples is the mass poisoning of tens of millions of people in Bangladesh and West Bengal, India, owing to the consumption of drinking water with elevated As concentrations. In addition, high levels of dissolved Mn at the similar depths of an aquifer with high arsenic is causing to raise the alarm much higher. In addition to this a proper understanding of the interaction of these elements in nature as well as for designing their efficient drinking water treatment systems are needed. Likewise other co-occurring suite of contaminants in groundwater and their interactions also significantly affect human health and there is a substantial knowledge gap needs to be narrowed by the research community. Recent findings target aquifers that might be safer with respect to low levels of As but showing increasing trends of dissolved Mn. Understanding the biogeochemical cycling of both these arsenic and manganese has proved to be a one most essential topic even in the recent past. Even arsenic and manganese are important biologically. Understanding both the geochemistry and geomicrobiology of coupled arsenic and manganese is critical to unraveling their biogeochemical cycles in the environment. We seek contributions that target and link novel geochemical, tracer and geomicrobiological techniques towards enhancing the understanding of the mobilities of these elements in the environment. Studies involving molecular level exploration using high-energy X-ray spectroscopic techniques and genetic/enzymatic markers as well as metal/metalloid speciations, environmental characterization, biogeochemical modeling, and biomineralization processes are encouraged.