【正文】 this suggests the need for and requires further investigations on the status of As contamination in groundwater on the island.. Arsenic in agricultural soils and miningenvironmentThe first article in this section (Saha and Ali, 2007 this volume) deals with the dynamics of arsenic in agricultural soils irrigated with Ascontaminated groundwater in Bangladesh. Arsenic concentrations in the soil layers of 12 rice fields located in four Asaffected areas and two unaffected areas in Bangladesh were monitored systematically. This study clearly shows enrichment of As in the top soil of rice fields irrigated with Ascontaminated groundwater (79–436 μg/L), pared to areas where irrigation water contained very lowAs (b1 μg/L).The study also revealed significant spatial and temporal variations of As concentrations in the contaminated rice field. Arsenic concentration of rice field soils increased significantly by the end of the irrigation season. About 71% of the As that was applied to the rice field with irrigation water accumulated in the top 0 to 75 mm soil layer. Most of this As was leached from the soil during the following wet season. It is very important that the observed spatial and temporal variability of As in rice field soils is taken into consideration in the future studies on As contamination of rice production.There are several hot spots in Poland where soils have very high concentrations of As, caused both by natural geochemical enrichment and longlasting ore mining and processing operations (Karczewska et al., 2004, 2005). Detailed investigations are therefore necessary to estimate the total concentrations of As in soils in such hotspotareas, its chemical fractionation, and potential solubility to evaluate the risks for mobilization of As. In the second article in this section (Krysiak and Karczewska, 2007this volume) an attempt has been made to assess the levels and environmental risk associated with possible increases in As mobility under changing pH and redox conditions in soils and waste material in two areas of former As mining and processing activities Zloty Stok (Zlote Mts.) and lezniak (Kaczawskie Mts.) in SW Poland. Arsenic concentrations were measured in twenty six soil samples collected from 12 sites, and represented a broad spectrum of soil properties and parent material origin, including natural soils, mine spoils, slags and tailings. Most soils in the area had extremely high concentrations of As (range 100?3,500 mg/kg), both of natural and anthropogenic origin. Sequential extraction techniques suggested that the main species of As in all soils were those bound to iron (Fe) oxides, whereas the contributions of mobile and specifically sorbed As forms were relatively low. In tailings and tailingaffected alluvial soils, As occurred mainly in residual forms, however these soils also had considerable amounts of mobile As. In all other soils, mobile As forms were very low.The last paper in this section (Eapaea et al., 2007this volume) discusses the dynamics of As in the mining sites of Pine Creek Geosyncline of Northern Territory of Australia. This study examined the mobility and retention of As in soil and sediments from five mine sites in the region, based on measuring the operationally defined forms of As in soils and other sediments using a modified sequential extraction procedure. The study revealed that As was present both in soluble and loosely bound forms, such as Al–As, Fe–As, Ca–As associations, Fe(OH)3 occluded As, organic bound As and residual As in sediment phases. Two general management principles were suggested for trapping the mine waste contaminants to minimize dispersion of As and heavy metals into the environment. These included prevention of direct discharge to creeks or water ways and discharges into constructed wetland with aquatic macrophytes to trap sediment that provides organic matter for arsenic and heavy metal retention.. Biogeochemistry of arsenicThis section contains three articles describing the aspects of biogeochemical interactions of As and toxicology. The first article deals with Arsenicicoccus bolidensis, a novel Asreducing actinomycete in contaminated sediments near the Adak mine (Routh et al., 2007). At Adak, a small mining town in the V228。 3) biogeochemistry of As and toxicity, and 4) remediation of Ascontaminated soils and sediments.. Arsenic in the groundwater environmentThis section has five articles. The first two contributions deal with the specific issues related to the occurrence of geogenic As in the alluvial aquifers of Bangladesh. The first paper (von Br246。 4) analytical techniques and speciation studies。 Fostner and Haase, 1998). Thus phytoremediation has the potential to bee an environmentally friendly and lowcost alternative remediation technique. It is well documented that some tropical and subtropical plant species can tolerate and uptake various inorganic and organic forms of As (Meharg and HartleyWhitaker, 2002). Mesquite is am plant that grows well in humid and desert environments that has been shown to absorb Cr(VI) and other metals such as Pb (Aldrich et al., 2004). Xray absorption spectroscopic (XAS) studies revealed that mesquite can bioreduce Cr(VI) to the less toxic Cr(III) (Aldrich et al., 2003). However, a significant gap of information exists on the ability of desert plant species to uptake As or other toxic elements.. Current researchResearch on As is currently very active and includes assessment of interactions at scales ranging from molecular bonding to subcontinental, As speciation in inorganic and organic materials through a wide variety of chemical and spectroscopic approaches, and an emerging understanding of the role of microbes and other biota in As cycling. A recent review on health impacts of As resulted in drinking water standards of 10 μg/L or even lower in some countries (Kapaj et al., 2006). These lowered standards are projected to greatly increase water supply co