【正文】 sterbotten district of Northern Sweden, highAs concentrations are encountered in surface and groundwater, sediments, and soil. In spite of the oxic conditions, Asrich surface and ground water samples indicate a predominance of As(III) species (up to 83%). Several microorganisms potentially involved in As cycling were isolated from the sediment enrichment cultures (Routh et al., 2007this volume). Results from laboratory investigations show that A. bolidensis (a novel grampositive, facultatively anaerobic, coccusshaped actinomycete) actively reduced As(V) to As(III) in aqueous media. The second article (Chen et al., 2007this volume) reveals that arbuscular mycorrhizal fungi (AMF) may play an important role in protecting plants against As contamination. However, little is known about the direct and indirect involvement of AMF in detoxification mechanisms. A partmented pot cultivation system (‘crosspots’) investigated the roles of AMF Glomus mosseae in plant phosphorus (P) and As acquisition bym Medicago sativa, and P–As interactions. The results indicate that fungal colonization dramatically increased plant。Shea et al. (2007this volume), discuss about the source of naturally occurring As in a coastal sand aquifer of eastern Australia. The study suggests that As is regionally derived from erosion of Asrich stibnite(Sb2S3) mineralisation present in the hinterland. Fluvial processes have transported the eroded material over time to deposit an aquifer lithology elevated in As. The findings of this study indicate that any aquifer containing sediments derived from mineralised provenances may be at risk of natural As contamination. Groundwater resource surveys should thus incorporate a review of the aquifer source provenance when assessing the likely risk of natural As occurrence in an aquifer. In the next paper (Jakariya et al., 2007this volume) analytical results of field test kits and laboratory measurements by AAS as a “gold standard” for As in water for 12,532 TWs in Matlab Upazila in Bangladesh were pared. The study indicated that the field kit correctly determined the status of 87% of the As levels pared to the Bangladesh Drinking Water Standard (BDWS) of 50 μg/L, and 91% of the WHO guideline value of 10 μg/L. However, due to analytical and human errors during the determination of As by the field test kits, there were considerable discrepancies in the correct screening of As concentrations between 10– μg/L and 50– μg/L. Proper training of the field personnel, verification of the field test kit results with laboratory analyses, and further development of the field test kits, will improve the accuracy of As measurements at low concentrations.The concluding short contribution in this section (Vuki et al., 2007this volume) deals with a study on the speciation of As in spring waters located along Tumon Bay in the small island of Guam in Western Pacific Ocean. Earlier investigation conducted by the Guam Environmental Protection Agency (GEPA, 2002) on total concentrations of As in groundwater springs and seepages at Guam indicated concerns over As contamination resulting predominantly from anthropogenic sources. Although more detailed studies are required for a detailed evaluation of the extent of As contamination in Guam. The results of this study show that total As concentrations in the spring water samples ranged from – μg/L with inorganic arsenate As(V) the dominant species. The low concentrations of dissolved As are also consistent with the values recorded for the groundwater wells in the northern part of Guam (GWA, 2003). These concentrations are much lower than the previously reported values, probably due to a much more rigorous methodological approach。mssen et al., 2007this volume) targets lowarsenic aquifers in areas with high concentrations of geogenic As in groundwater with a case study from Matlab Upazila in Southeastern Bangladesh. The local drillers are constructing deeper tubewells than in the recent past (60 m instead of 30 m), primarily because of low concentrations of dissolved Fe and As (von Bromssen et al., 2005。 2) arsenic in agricultural soils and mining environment。 5) remediation and management of Ascontaminated soils and groundwater。 3) prediction of the fate of As in natural environments in response to geochemical, hydrologic, and biologic changes。 Bhattacharya et al., 2007). Considering the seriousness of this global As problem, a twoday symposium was organized to facilitate a thorough discussion on a broad range of interdisciplinary issues that are related to the research on As in the environment. These include understanding the natural and anthropogenic processes which accelerate or control human exposure to As and different aspects of remediation. The outline of the symposium and the subsequent publications are described below.2. Theme of the Special SymposiumThe Special Symposium (SYP4) “Arsenic in the Environment: Biology and Chemistry” was organized as part of the 8th International Conference on Biogeochemistry of Trace Elements (ICOBTE) in Adelaide, Australia during April 2005. This Special Symposium attracted a wide range of contributions from a large number of multidisciplinary As researchers, that covered major themes, such as: 1) sources and characterization of As in groundwater environment。 Vithanage et al., 2006), but there is a pressing need to develop these methods further and in a costeffective way. The concept of phytoremediation of Ascontaminated sites was proposed over twenty years ago (Chaney, 1983). Phytoremediation has an advantage over conventional remediation of Ascontaminated soils that include burial and chemical stabilization, which may pose longterm health threats due to leakage or chemical instability (Allen, 2001。 Islam et al., 2004).. RemediationSeveral technologies are currently available for As removal, ranging from simple and effective coagulation– flocculation, to sophisticated technologies such as ion exc