Investigation of saponification for determination of polychlorinated biphenyls in marine sediments

The effects of saponification conditions (temperature and water content of saponifying solution) on the determination of chlorinated biphenyls (CBs) in marine sediments were investigated. Although highly chlorinated biphenyls (nona- to deca-CBs) decomposed during high-temperature saponification, the degree of degradation was reduced by adding water to the ethanolic potassium hydroxide saponifying solution. Room-temperature saponification yielded quantitative recovery of highly chlorinated biphenyl surrogates but low extraction efficiencies of lightly chlorinated biphenyls (mono- to di-CBs). The same samples were analyzed by other extraction techniques, for example, pressurized liquid extraction, and analytical results were compared. The mono- and di-CB concentrations were correlated with the extraction temperatures of various extraction techniques. In particular, the concentrations of some CB congeners (CB11, CB14) were higher with saponification. The low degree of degradation of highly chlorinated biphenyls and the high recovery of lightly chlorinated biphenyls were compatible when room-temperature and high-temperature saponification were combined. Except for the anomalies of CB11 and CB14, the combined method gave satisfactory results for analysis of PCBs.     

Concentrations and compositions of organochlorine contaminants in sediments, soils, crustaceans, fishes and birds collected from Lake Tai, Hangzhou Bay and Shanghai city region, China

Contamination by persistent organochlorines (OCs), such as DDTs, hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene (HCB) and polychlorinated biphenyls (PCBs) were examined in sediments, soils, fishes, crustaceans, birds, and aquaculture feed from Lake Tai, Hangzhou Bay, and in the vicinity of Shanghai city in China during 2000 and 2001. OCs were detected in all samples analyzed, and DDT and its metabolites were the predominant contaminants in most sediments, soils and biota. Concentrations of p,p'-DDT and ratio of p,p'-DDT to SigmaDDTs were significantly higher in marine fishes than those in freshwater fishes. While the use of DDTs has been officially banned in China since 1983, these results indicate a recent input of technical DDTs into the marine environment around Hangzhou Bay. Comparison of organochlorine concentrations in fishes collected from Lake Tai and Hangzhou Bay suggests the presence of local sources of HCHs, chlordanes and PCBs at Lake Tai. Higher proportions of penta- and hexa-PCB congeners in fishes at Lake Tai may suggest the use of highly chlorinated PCB product, such as PCB(5), around this lake. To our knowledge, this is a first comprehensive study to examine the present status of organochlorine contamination in various environmental media, such as sediments, soils and wildlife, in China.     

Systematic analysis and overall toxicity evaluation of dioxins and hexachlorobenzene in human milk

A systematic method for analyzing dioxins (PCDDs, PCDFs and dioxin-like PCBs), hexachlorobenzene (HCB), heptachlor epoxide and beta-hexachlorocyclohexane (HCH) in human milk was developed to determine the residual amount of HCB in human milk and to evaluate the overall toxicity of both dioxins and HCB in human milk. The fractionation behavior of HCB on chromatography with silica gel, alumina, and activated carbon/silica gel, and the concentrated sulfuric acid decomposition method, which is widely used as a dioxin cleanup method, were studied in order to make the preprocessing operation for HCB measurement compatible with that for conventional dioxin measurement. HCB was found to be eluted in the 2% dichloromethane (DCM)/hexane 60 ml fraction from an alumina column. Heptachlor epoxide and a part of beta-HCH were eluted in the 10% DCM/hexane 50 ml fraction from a silica gel column, while the remaining beta-HCH was eluted in the 25% DCM/hexane 60 ml fraction from an activated carbon/silica gel column. Moreover, HCB showed significant correlation with dioxin congeners having high toxicity equivalence factors (TEFs). The results suggest that the exposure route to HCB and its accumulation behavior in the human body are similar to those of the dioxins.     

Feature of Dust Particles in the Spring Free Troposphere over Dunhuang in Northwestern China: Electron Microscopic Experiments on Individual Particles Collected with a Balloon-borne Impactor

Free tropospheric aerosol particles were collected using a balloon-borne particle impactor in August of 2002 and March of 2003 at Dunhuang in northwestern China (40°00′N, 94°30′E), and the morphology and elemental composition of the aerosol particles were analyzed in order to understand the mixing state of coarse dust particles (diameter >1 μm) over the desert areas in the Asian continent in spring. Electron microscopic experiments on the particles revealed that dust particles were major constituents of coarse mode particles in the free troposphere over the Taklamakan Desert in spring and summer. Si-rich or Ca-rich particles are major components of dust particles collected in the free troposphere over dunhuang and the values of [number of Ca-rich particles]/[number of Si-rich particles] differs markedly between spring and summer, being about 0.3 in the spring of 2003 and about 1.0 in the summer of 2002 at heights 3–5 km above sea level. It is likely that the condition of the ground surface and the strength of vertical mixing in source areas of Asian dust are potential factors causing the difference in the chemical types of dust particles. Comparison of the elemental compositions of these particles with those of particles collected over Japan strongly suggests that these particles were chemically modified during their long-range transport in the free troposphere. Analysis of wind systems shows that both the predominating westerly wind in the free troposphere and the surface wind strongly controlled by the geographical structure of the Tarim Basin are important in the long-range transport of KOSA particles originating in the Taklamakan Desert.     

用电子自旋探针研究水泥固化土壤中镉离子的反应

应用电子自旋探针（Ｅｌｅｃｔｏｒｏｎ ｓｐｉｎ ｐｒｏｂｅ，简ＥＳＰ）Ｍｎ＾２＋离子的超精细结构（ｈｙｐｅｒｆｉｎｅ ｓｔｒｕｃｔｕｒｅ，简称ｈｆｓ），揭示了水泥固化土壤中Ｃｄ＾２＋离子的化学反应，研究发现：由于水泥水化产生高的ＰＨ值，Ｃｄ＾２＋离子与ＯＨ＾－离子反应生成Ｃｄ（ＯＨ）２沉‘当有ＣＯ２气体存在时，Ｃｄ＾２＋离子会与ＣＯ２和水泥水化的ＯＨ＾－离子反应生成ＣｄＣＯ３、Ｃｄ（ＯＨ）２，这些     

Effects of process conditions on nano-dot array formation by thermal dewetting

In this paper, three kinds of self-organization processes for metal nano-dot array fabrication are compared; one is the conventional thermal dewetting, another is thermal dewetting of a grid patterned deposited metal layer, the other is thermal dewetting of a metal layer deposited on a patterned substrate. In these processes, nano plastic forming technique is utilized for patterning of groove grid. Effects of process conditions on nano-dot formation, such as substrate material, deposited metal, thickness of deposited layer, annealing condition, are experimentally studied. Also, effect of grid patterning on improvement of nano-dot array formation is studied. It is shown that grid patterning on a deposited metal layer is effective to improve alignment and configuration of nano-dot array.     

Factors affecting the interval between clutches in the hermit crab <Emphasis Type="Italic">Pagurus nigrivittatus</Emphasis>

Interval between reproductive events is an important factor for iteroparous animals because it determines the number of clutches throughout life. This study examined whether female size, clutch size, shell size and prenuptial molting affected the clutch interval in the hermit crab Pagurus nigrivittatus. Precopulatory guarding pairs of P. nigrivittatus were sampled in the field and kept in the laboratory until the female extruded eggs. The clutch interval of each female was assessed as one of two types of relatively “short” and “long” intervals by checking whether the guarded female had eggs and/or egg cases from the preceding brood or not when the guarding pair was collected. The clutch interval was longer in females with prenuptial molting than those without molting and these females usually grew larger at the prenuptial molt. This suggests that female P. nigrivittatus with a long interval might allocate energy into growth at the expense of the number of clutches during the current reproductive season. The allocation to growth is theoretically predicted to decrease with female size. Gastropod shell size is also known to affect the reproductive activity in hermit crabs. However, female size did not significantly affect the clutch interval in P. nigrivittatus, and the effect of gastropod shell size on clutch interval was not consistent with previous empirical studies. These results may be caused by differences in the gastropod species of shell occupied by the females of P. nigrivittatus.     

Evaluation of biological water purification functions of inland lakes using an aquatic ecosystem model

An effective measure to cope with eutrophication of lakes is to remove nutrients that can cause algal blooming by taking advantage of natural water purification processes. Here the term “purification” is defined, in a wide sense, as the potential role of a water body to contribute to the reduction of pollutants and thus controlling eutrophication. Also regarded as a kind of ecological regulating services, biological purification involves various processes concerning seasonal nutrient fixation, such as uptake by aquatic macrophytes, biofouling onto foliage substrates, feeding by organisms in higher trophic level, and eternal loss or removal of substance from the water. In order to evaluate the water purification ability, a numerical lake ecosystem model highlighting the role of macrophyte colonies in the shore zone was developed and applied to Lakes Suwa, Kasumi and Biwa, as well as five small lakes attached to Lake Biwa.