Casado-Martinez pp. 1-8
Models that explain the uptake and bioaccumulation of an element in an aquatic ecosystem are valuable for predicting its potential ecotoxicity in coastal areas. Arsenic is a toxic element that is strongly adsorbed to sediments, offering a potential risk to deposit-feeding invertebrates, and ultimately to consumers higher up coastal food chains. This study uses biodynamic modelling to predict the uptake and accumulation of arsenic from water and sediment in a deposit-feeding polychaete worm that is a major source of food to fish and wading birds in estuaries.
Chariton pp. 9-18
Arsenic concentrations and species were determined in seagrass ecosystems where the food web was established using carbon and nitrogen isotopes. There was a clear increase in the proportion of arsenobetaine in tissues of higher trophic level organisms, which is attributed to an increasing arsenobetaine content of the diet and the more efficient assimilation and retention of arsenobetaine over other arsenic species. The results provide an explanation for the prominence of arsenobetaine in higher marine animals.
Tanabe pp. 19-29
Although among higher marine animals, relatively high concentration of arsenic and unique distribution of arsenic compounds are found in green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata), the accumulation mechanism remains unknown. We examined the accumulation of arsenicals in two turtles from the standpoint of short- and long-term intake and excretion and found that prey items might be important for the arsenic accumulation. This study can provide useful information on the accumulation pattern of arsenic speciation in sea turtles.
Feldmann pp. 30-43
Seaweeds hyperaccumulate the toxic metalloid arsenic, but seemingly achieve detoxification by transformation to arsenosugars. The edible seaweed hijiki is a notable exception because it contains high levels of toxic arsenate and arsenite. Terrestrial plants detoxify arsenic by forming arsenite–phytochelatin complexes. The hypothesis that seaweeds also synthesise phytochelatins to bind arsenite as a means of detoxification before arsenosugar synthesis is tested in this investigation.
Francesconi pp. 44-51
Despite high levels of complex organoarsenic compounds in marine organisms, arsenic in seawater is present almost entirely as inorganic species. We examine the arsenic products from a marine alga allowed to decompose under simulated natural coastal conditions, and demonstrate a multi-step conversion of organic arsenicals to inorganic arsenic. The results support the hypothesis that the arsenic marine cycle begins and ends with inorganic arsenic.
Feldmann pp. 52-61
Risk identification and characterisation of As-bearing sulfide minerals, the most important natural source of arsenic pollution, is significant in pollution control and risk management at mine sites. Bioassays constitute a cost-efficient approach to toxicity testing because they give an integrated picture of the biologically available fraction thereby allowing predictions of the potential combined effects of contaminants in testing mixtures.
Mortazavi pp. 62-73
Recent research has been directed towards the exchange of microorganisms and chemical compounds between snow and air. We investigate how microorganisms and chemical species in snow from the Arctic and temperate regions are transferred to the atmosphere and altered by the sun's energy. Results suggest that snow photo-biochemical reactions, in addition to physical-chemical reactions, should be considered in describing organic matter in air–snow exchanges, and in investigations of climate change.
Sciare pp. 74-90
Megacities are huge hotspots of pollutants that have an impact on atmospheric composition on local to larger scales. This study presents for the first time detailed results of measurements of volatile organic compounds in Paris and shows that, whereas non-methane hydrocarbons are mainly of local and regional origin associated with traffic emissions, a significant part of oxygenated volatile organic compounds originates from continental import. This highlights the importance of measuring volatile organic compounds instead of non-methane hydrocarbons alone in source classification studies.
Sciare pp. 91-103
Volatile organic compounds are key compounds in atmospheric chemistry as precursors of ozone and secondary organic aerosols. To determine their impact at a megacity scale, a first important step is to characterise their sources. We present an estimate of volatile organic compound sources in Paris based on a combination of measurements and model results. The data suggest that the current emission inventory strongly overestimates the volatile organic compounds emitted from solvent industries, and thus needs to be corrected.