Plenary Speakers – ICOBTE / ICHMET 2023

Prof. Tanja Schwerdtle University of Potsdam, Germany

Prof. Tanja Schwerdtle

Title of the presentation: Toxicity of arsenic species: lessons learned from organisms, humans and the environment

Arsenic (As) is classified by WHO as one of the chemicals of major public health concern. In the environment, arsenic occurs in both organic and inorganic forms. For the general population, diet is the primary source for As. In terrestrial foods and drinking water, inorganic As is the predominant As species, whereas fish and seafood contain predominantly organic As.
Inorganic As is classified as human carcinogen owing to the increased incidence of cancer of the skin, lung, and urinary bladder observed in epidemiological studies primarily in population groups with elevated exposure to inorganic As via drinking water.
Following the EFSA 2009 As assessment maximum levels have been laid down for inorganic As for several food items including rice (Commission Regulation (EC) No 1881/20064). However, due to the application of sulphate fertilisers in rice S-containing methylated As species are formed, which are neither toxicologically characterized nor regulated.
Likewise for these recently identified S-containing As species, for most organic As species so far no risk characterization has been carried out. Organic lipid-soluble As species, so called arsenolipids, belong to the emerging As containing contaminants in fish and seafood. Overall, the studied endpoints so far show that arsenolipids exert a different toxicity as compared to inorganic As. In human cells As containing hydrocarbons exterted highest cellular toxicity, but in contrast to inorganic As no genotoxicity. Taken into account the investigations in nematodes (C. elegans), flies (Drosophila melanogaster) and mice, As containing hydrocarbons seem to be the most potent toxic arsenolipids studied so far.
Overall, these studies indicate the need for a differentiated hazard identification and exposure assessment for all As species / sub groups to assess whether the respective As species / sub groups pose a risk to the environment and human health.

Biography: Professor Dr Tanja Schwerdtle studied chemistry and food chemistry at the University of Karlsruhe, where she received her doctorate. After research positions in Karlsruhe and at Technical University (TU) Berlin, she held professorships in food chemistry first at the University of Muenster and then at the University of Potsdam. Her scientific work includes research into metal compounds, and their beneficial and toxic effects on the human organism. Here, among others, she currently coordinates as spokesperson the DFG funded research unit TraceAge. Moreover, she has strong expertise and research interest in the area of in vitro based testing strategies, genotoxicity testing as well as exposure and effect biomarkers. Since 2007, she has been involved as expert in EFSA working groups, since 2015, she has been Member of the EFSA Panel for Contaminants in the Food Chain. Since 2020, she is the Vice President of the German Federal Institute for Risk Assessment (BfR) and holds a professorship in food toxicology at the University of Potsdam.

Prof. Fang-Jie Zhao Nanjing Agricultural University, China

Prof. Fang-Jie Zhao

Title of the presentation: Cadmium biogeochemistry in paddy soils and strategies to reduce Cd accumulation in rice

Rice is a staple food for about half of the global population, for whom rice is also a major dietary source of the toxic trace metal cadmium (Cd). Contamination of paddy soils with Cd is a common problem in some areas of Asian countries, resulting in elevated intake of Cd and significant health risk for the local residents. It is therefore imperative to develop strategies to limit Cd accumulation in rice. The concentration of Cd in rice grain varies widely, from below the detection limits to several mg/kg. This wide variation is caused by the variations in the level of Cd contamination in the soil, soil properties and biogeochemical processes that affect Cd availability to plants, and the genetics that govern the uptake and distribution of Cd in rice plants. Paddy soil undergoes episodic flooding-draining cycles during the rice growing season, leading to wide fluctuations in the redox potential, a key factor controlling Cd availability in the soil. Cadmium availability decreases rapidly under anoxic conditions due the formation of insoluble cadmium sulphide; this process is reversed when paddy water is drained. The rate of cadmium remobilization after drainage of paddy water is controlled by factors such as the voltaic cell effect, production of free radicals, and pH-dependent sorption processes. These processes can be controlled to slow down the remobilization of Cd after drainage. There are large variations in Cd accumulation among different rice cultivars; the genetics underlying some of these variations have been elucidated in recent years. Several membrane transporters play important roles in the uptake, sequestration and distribution of Cd in rice plants, which are targets for manipulations to limit Cd accumulation in the grain. This knowledge has been used to enable breeding of ultra-low Cd accumulating rice cultivars.

Biography: Fang-Jie Zhao is a Professor of Environmental Science at Nanjing Agricultural University, China. He received his PhD at Newcastle University, U.K. Prior to taking up the current position in China, he worked at Rothamsted Research, U.K. for over 20 years, progressing from Higher Scientific Officer to Senior Principal Research Scientist. His research focuses on the biogeochemistry of essential trace elements and toxic metals/metalloids in soil-plant systems, molecular mechanisms of trace element uptake by plants, biofortification of essential micronutrients and bioremediation of contaminated soils. His research group adopts a multidisciplinary approach, employing research tools and methodologies in environmental chemistry, soil microbiology, plant genetics and molecular biology. His research goal is to enhance essential micronutrients and minimize toxic metals/metalloids in food crops for the benefit of human health and agricultural sustainability. He has co-authored two books and published over 360 peer-reviewed journal papers, which have been cited >38,000 times (H index = 110). He is a Highly Cited Researcher by Clarivate Analytics (2017 - 2021).

Prof. Donald L. Sparks University of Delaware, USA

Prof. Donald L. Sparks

Title of the presentation: Environmental Change Impacts on the Fate and Speciation of Metal(loid)s in Soil and Water

Environmental change, particularly the impact of climate change, is having a profound impact on humankind. Rising seas and temperatures, as well as other extreme events such as flooding, droughts, and fire, will increasingly impact the biogeochemical cycling of metal(loid)s in terrestrial and aquatic environments. The impact of these extreme events on redox active metal(loid)s e.g., As and Cr, play a significant role in controlling their fate and speciation in the environment. However, how the mechanistic processes will be impacted in our changing climate is not well understood. Employment of advanced analytical tools over a range of spatial and temporal scales could provide useful insights. Therefore, in this presentation, three field sites, in which the soils are heavily contaminated with As and Cr, will be featured to show how intensity of flooding, redox, and salinity affect the fate and speciation of the elements.

Biography: DONALD L. SPARKS is the Unidel S. Hallock du Pont Chair and Francis Alison Professor at the University of Delaware. He is internationally recognized for his research in the areas of kinetics of biogeochemical processes and surface chemistry of natural materials. His research has focused on fate and transport of trace metals in soil and water, soil remediation, water quality, and carbon sequestration in soils. He is the author of two textbooks, 12 edited books, and 360 refereed papers and book chapters. Dr. Sparks is a fellow of five scientific societies, and he has been the recipient of major awards and lectureships including the Geochemistry Medal from the American Chemical Society, the Liebig Medal from the International Union of Soil Sciences, Pioneer in Clay Science award from the Clay Minerals Society, an Einstein Professorship from the Chinese Academy of Sciences and the Philippe Duchaufour Medal from the European Geosciences Union. Dr. Sparks served as president of the Soil Science Society of America and the International Union of Soil Sciences and as chair of the U.S. National Academy of Sciences (NAS) Committee for Soil Sciences.

Prof. Nathalie Verbruggen Université Libre de Bruxelles (ULB), Belgium

Prof. Nathalie Verbruggen

Title of the presentation: Cadmium tolerance and detoxification in plants: what can we learn from Arabidopsis halleri?

Cadmium is one of the most toxic trace metals for living organisms and the highest concentrations have been found in plant cells. Cadmium accumulation in the environment is recognized as a worldwide concern. The accumulation pathway of cadmium in plants is crucial for phytoremediation applications, but also in breeding programmes to limit its consumption by crops. However, the different mechanisms used by Cd to enter, be transported and detoxified in plants remain unclear. In this presentation, the contributions made through the studies on Arabidopsis halleri will be outlined.
Arabidopsis halleri is a diploid perennial , self incompatible, and close relative to the plant model Arabidopsis thaliana. Arabidopsis halleri is considered as a model species for the study of metal homeostasis and detoxification. The species seems to constitutively hyperaccumulate zinc while cadmium accumulation is more variable. Some populations do however accumulate cadmium while others accumulate much less than A. thaliana.
A.halleri is a pseudometallophyte, able to grow on metal contaminated or non-contaminated soils. In Europe the species is distributed in several genetic units within which metallicolous populations seem to have been established from metallicolous populations. The comparative study of populations showed different mechanisms of cadmium detoxification but a genetic determinant of cadmium tolerance and accumulation that looks common.
In the presentation, contributions made to the understanding of cadmium accumulation and detoxification through studies on Arabidospis halleri will be outlined.

Biography: Full professor – Free University of Brussels (Université libre de Bruxelles), Belgium. Interest in the regulation of nutrition in plants, and their adaptation to extreme environments

Prof. Mak Saito Woods Hole Oceanographic Institution (WHOI), USA

Prof. Mak Saito

Title of the presentation: Marine biogeochemical cycling of bioactive metals from the Arctic to the Antarctic: A sea of change

Metals in the oceans have critical nutritional roles that intersect directly with the global carbon cycle. In recent years the global GEOTRACES sampling program has broadened our understanding of the distributions and processes of numerous trace elements. Human induced climate change is also affecting the distributions of these elements largely through changes in fluxes of metals from continental sources. Cobalt and zinc are extremely scarce yet critical micronutrients in the marine environment. Cobalt is used in vitamin B12 and both elements can be used in key enzymes such as carbonic anhydrase and alkaline phosphatase. Recent observations from the high latitudes reveal that Arctic and Southern Ocean cobalt inventories are changing. Moreover, incubation and metaproteomic analyses reveal the influence micronutrients on ocean microbial communities. For example, zinc and (cobalt-containing) vitamin B12 can be limiting of marine photosynthesis in Southern Ocean environments. These results will be discussed as well as perspectives on other potential environmental changes and resultant observational priorities.

Biography: Dr. Mak Saito is a Senior Scientist in the Marine Chemistry and Geochemistry Department of the Woods Hole Oceanographic Institution (WHOI) in Massachusetts USA. He received his PhD from the Massachusetts Institute of Technology-WHOI Joint Program and did postdoctoral research at Princeton University. For over twenty years the Saito laboratory has studied the biogeochemical cycling of metals in marine environments from Antarctica to the Arctic Ocean, including the metals Co, Fe, Zn, Mn, Ni, and Cu, applying analytical chemistry and proteomics techniques to unravel the interactions between life and metals in the oceans.

Prof. Jurate Kumpiene Luleå University of Technology, Sweden

Prof. Jurate Kumpiene

Title of the presentation: Iron amendments for immobilisation of metal(loid)s in soil – how confident are we about the long-term success of this approach?

Immobilization of metal(loid)s (also so-called trace elements, TE) and hence reduction of their mobility and bioavailability, can be achieved by changing TE chemical state using soil amendments that can promote TE precipitation, sorption, and complexation as well as the build-up of new minerals. Iron (Fe) and Fe-containing materials are often considered as suitable soil amendments to reduce TE mobility, bioavailability, and thus risks to human health and the environment. The treatment efficiencies can reach up to 99% in terms of reduced leaching of TE. Nevertheless, the question that has commonly been asked concerns not the immediate treatment success, but its long-term effectiveness.
An overview of studies where Fe amendments were used for soil stabilisation will be presented, focusing on field-scale studies, their duration and methods applied for the evaluation of the treatment success. Analysis of the documented research approaches to produce evidence on the long-term treatment success will be performed and presented during the conference.

Biography: Jurate Kumpiene, Professor at Luleå University of Technology, Sweden, is actively engaged in research and education in environmental engineering. She has ca 20 years experience in research and innovation in the area of soil remediation with particular focus on immobilization of soil contaminants and assessment of residual risks in remediated soil. In 2022, Kumpiene’s research on soil remediation has been selected by the Royal Swedish Academy of Engineering Sciences (IVA) to the year's list of top national research projects with the focus on technology in the service of humanity.