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81.
Experimental batch and miscible-flow cultures were studied in order to determine the mechanistic pathways of microbial Fe(III)
respiration in ferruginous smectite clay, NAu-1. The primary purpose was to resolve if alteration of smectite and release
of Fe precedes microbial respiration. Alteration of NAu-1, represented by the morphological and mineralogical changes, occurred
regardless of the extent of microbial Fe(III) reduction in all of our experimental systems, including those that contained
heat-killed bacteria and those in which O2, rather than Fe(III), was the primary terminal electron acceptor. The solid alteration products observed under transmission
electron microscopy included poorly crystalline smectite with diffuse electron diffraction signals, discrete grains of Fe-free
amorphous aluminosilicate with increased Al/Si ratio, Fe-rich grains, and amorphous Si globules in the immediate vicinity
of bacterial cells and extracellular polymeric substances. In reducing systems, Fe was also found as siderite. The small amount
of Fe partitioned to the aqueous phase was primarily in the form of dissolved Fe(III) species even in the systems in which
Fe(III) was the primary terminal electron acceptor for microbial respiration. From these observations, we conclude that microbial
respiration of Fe(III) in our laboratory systems proceeded through the following: (1) alteration of NAu-1 and concurrent release
of Fe(III) from the octahedral sheets of NAu-1; and (2) subsequent microbial respiration of Fe(III). 相似文献
82.
Yoko?YokouchiEmail author Takuya?Saito Hitoshi?Mukai 《Journal of Atmospheric Chemistry》2018,75(2):171-180
Dibromomethane (CH2Br2), a natural stratospheric ozone depleting substance, is mostly emitted from the ocean, but the relative importance of coastal (or macroalgae) and open ocean emissions is unknown. We made long-term high-frequency measurements of CH2Br2 concentrations at two remote coastal sites in Japan, on the subtropical Hateruma Island (poor in macroalgae) and at Cape Ochiishi (rich in macroalgae). CH2Br2 concentrations at Hateruma showed prominent seasonal variation, being lower in summer (around 0.94 ppt) than in winter (around 1.23 ppt). In contrast, CH2Br2 concentrations at Ochiishi were highly variable, often exceeding 2 ppt in the summer but with minimum baseline concentrations close to those from Hateruma; in the winter the concentrations were almost constant at about 1.3 ppt. Analysis of the data suggested that (1) emissions from macroalgae were not likely to extend offshore, but instead were localized near the shore, (2) strong macroalgal emissions of CH2Br2 were almost limited to the summer, but it was not reflected in the seasonality of the baseline concentrations of CH2Br2 in the atmosphere, and therefore (3) macroalgal or coastal emissions of CH2Br2 in the temperate zone might have a rather limited contribution to the global CH2Br2 sources. These findings are especially important for the understanding of the tropospheric and stratospheric bromine budget. 相似文献
83.
Kajiwara N Kunisue T Kamikawa S Ochi Y Yano S Tanabe S 《Marine pollution bulletin》2006,52(9):1066-1076
Blubber and liver samples were obtained for analysis of wide ranges of contaminants from killer whales (Orcinus orca) which were locked away in drifting sea ice on the coast of Rausu, the Shiretoko Peninsula in Eastern Hokkaido, Japan in February 2005. Among the organohalogen compounds analyzed, DDTs were the predominant contaminants with concentrations ranging from 28 to 220 microg/g on a lipid-weight basis followed by PCBs and other organochlorine pesticides. PBDEs levels were two or three orders of magnitude lower than those of PCBs and DDTs. 2,3,7,8-Tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) derived by WHO mammal-TEF in killer whales were in the range of 110-440 pgTEQ/g. Mono-ortho coplanar PCBs contributed to 75-98% of total TEQs, indicating coplanar PCBs are significant contaminants for risk assessment in this species. The fact that hepatic residue levels of butyltins (from 13 to 770 ng/g wet weight) were much higher than those of phenyltins may be reflecting extensive use of tributyltin as antifouling paint. 相似文献