Biogeochemical relationships of arsenic in the Haor Basin of Bangladesh

Biogeochemical relationships and the level of arsenic (As) contamination of groundwater and surface sediments in the Haor Basin of Bangladesh were assessed to see if surface sediments gave any indication of underlying As cycling. The Haor areas under study have been found to be affected with high As (up to 331 μg/L) in groundwater, with contamination of both shallow and deep aquifers. Highly significant relationships of As with Dissolved Organic Carbon (DOC) in groundwater and Total Carbon (TC) and Organic Carbon (OC) in sediments are indicative of reductive dissolution of iron (Fe) and/or manganese (Mn) oxides/oxyhydroxides coupled with biodegradation of organic matter as the dominant processes to release As in groundwater. This study also reveals that As geochemistry in the surface sediments has limited influence on As geochemistry in the groundwater of the Haor Basins. © 2012 Taylor & Francis Group.

Two species of caridean shrimps (Decapoda:Hippolytidae and Nematocarcinidae) newly recorded from hydrothermally vents on the Manus Basin, Southwestern Pacific.

Two species of caridean shrimps are newly recorded from hydrothermal vents on the Manus Basin, southwestern Pacific, at depths of 1540-1577m. Lebbeus manus, new species, is related to L.curvirostris Zarenkov, 1976, L.elegans Komai, Hayashi & Kohtsuka, 2004, L.longipes (Kobjakova, 1936), L.vicinus vicinus (Rathbun, 1902) and L.vicinus motereyensis (Wicksten & Mendez, 1982) because of the lack of strap-like epipods on the second and third pereopods; but characters of the rostrum, carapace and abdomen immediately distinguish the new species from the these five taxa. Subadult and juvenile specimens of Nematocarcinus are referred to N.sp.aff.exilis, but their definite identification is postponed until additional specimens become available for study. There are a few minor differences between the present Manus specimens and European specimens representing N.exilis (Bate, 1888), suggesting that the Manus population may indeed represent a separate species.