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161.
Soman is one of the most toxic nerve agents of the known chemical warfare agents. There is actually few knowledge on the behavior of soman in the event of an environmental contamination. It is in particular unknown whether soman remains on a given surface, evaporates into air, or degrades. Here, we studied the evaporation of soman deposited on silica sand using a laboratory-sized wind tunnel, thermal desorption, and gas chromatography. We also investigated the degradation of soman on silica sand by 31phosphorus solid state magic angle spinning nuclear magnetic resonance and gas chromatography–mass spectrometry. Results show that a drop of soman on silica sand spreads laterally while evaporating. The maximum vapor concentration was found when the spreading of the soman drop was maximum on the surface. Simultaneously, soman was absorbed gradually into the pore of sand and degraded to O-pinacolyl-methylphosphonic acid following a pseudo-first-order rate reaction over weeks. To our best knowledge, this is the first report on the fate of soman in a sandy environment. 相似文献
162.
Kit Yu Karen Chan Daniel Grünbaum Maj Arnberg Michael Thorndyke Sam T. Dupont 《Marine Biology》2013,160(8):2129-2135
Ocean acidification (OA), the reduction of ocean pH due to hydration of atmospheric CO2, is known to affect growth and survival of marine invertebrate larvae. Survival and transport of vulnerable planktonic larval stages play important roles in determining population dynamics and community structures in coastal ecosystems. Here, we show that larvae of the purple urchin, Strongylocentrotus purpuratus, underwent high-frequency budding (release of blastula-like particles) when exposed to elevated pCO2 level (>700 μatm). Budding was observed in >50 % of the population and was synchronized over short periods of time (~24 h), suggesting this phenomenon may be previously overlooked. Although budding can be a mechanism through which larval echinoids asexually reproduce, here, the released buds did not develop into viable clones. OA-induced budding and the associated reduction in larval size suggest new hypotheses regarding physiological and ecological tradeoffs between short-term benefits (e.g. metabolic savings and predation escape) and long-term costs (e.g. tissue loss and delayed development) in the face of climate change. 相似文献
163.
Marine reserves have become widely used in biodiversity conservation and are increasingly proposed as fisheries management tools. Previous modeling studies have found that reserves may increase or decrease yields, depending on local environmental conditions and on the specific life-history traits of the fishery species. Sex-changing (female-to-male) fish are targets of some of the most important commercial and recreational fisheries in the world. The potential for disproportionate removal of the larger, older sex of such species requires new theory to facilitate our understanding of how reserves will affect the yields of surrounding fisheries, relative to fishes with separate sexes. We investigated this question by modeling the effects of marine reserves on a non-sex-changing and a sex-changing population. We used demographic parameter estimates for the common coral trout as a baseline, and we conducted extensive sensitivity analyses to determine how sustainable yields of sex-changing species are likely to be affected by reserves across a broad range of life-history parameters. Our findings indicate that fisheries for sex-changing species are unlikely to receive the same yield-enhancing benefit that non-sex-changing fisheries enjoy from marine reserves, and that often reserves tend to reduce sustainable yields for a given overall population size. Specifically, the increased egg production and high fertilization success within reserves is more than offset by the reduced egg production and fertilization success in the fished areas, relative to a system in which fishing mortality is distributed more evenly over the entire system. A key reason for this appears to be that fertilization success is reduced, on average, when males are unevenly distributed among subpopulations, as is the case when reserves are present. These findings suggests that, for sex-changing populations, reserves are more suited to rebuilding overfished populations and sustaining fishery viability, rather than enhancing fishery yields. These results are robust over a range of sex-change regimes, stock-recruitment relationships, adult mortality rates, individual growth strategies, and fertilization-success functions. Our findings highlight the importance of considering the different contributions of males and females to population growth and fishery yields when evaluating the efficacy of marine reserves for enhancement of fished species. 相似文献
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167.
S. W. Chan C. C. Cheang C. W. Yeung A. Chirapart G. Gerung P. Ang 《Marine Biology》2014,161(4):785-795
Phylogeographical study of the brown macroalga, Sargassum aquifolium using nuclear internal transcribed spacer 2, plastidal RuBisCo spacer, and mitochondrial cytochrome oxidase subunit-III revealed the populations in Southeast Asia to be homogeneous. On the other hand, genetic differences were detected between populations from Southeast Asia and western Pacific Islands/Guam, suggesting the presence of genetic break between these regions. This further suggests that populations of S. aquifolium may have survived east of Sunda Shelf during the Last Glacial Maximum and recent recolonization led to homogeneity of the populations in the Sunda Shelf region. Recolonization could be facilitated by year-round reproduction of the populations and dispersal of germlings on floating thalli by coastal currents. Restricted current flow across Maluku Sea and directional equatorial current flows could have isolated the Pacific Island and Guam populations from those of Southeast Asia. Our results support the presence of multiple refugia as the source of different lineages of S. aquifolium populations with a lack of secondary contact in the post-glacial dispersal between Southeast Asia and western Pacific as the mechanisms behind the phylogeographical patterns observed. 相似文献
168.
北京大气PM2.5中微量元素的浓度变化特征与来源 总被引:24,自引:7,他引:17
为了解北京大气细粒子中微量元素的污染水平和来源,在车公庄和清华园进行了连续1年、每周1次的PM2.5采样和全样品分析.微量元素浓度的周变化大,尤以冬季为甚,相邻2周最大相差达1.6倍;但除冬季的平均浓度较高之外,其季节变化并不显著.微量元素的富集因子在春季最低,反映了频繁发生的沙尘天气的影响.Se、Br和Pb的浓度比来自于北京A层土壤中的含量要高出约1000~8000倍,表明它们主要来自于人为污染.其中Se的富集度最高,反映了北京细粒子来自于燃煤污染的特征.Pb的年均浓度(0.31μg·m-3)虽然未超过WHO的年均标准,但与洛杉矶和布里斯班相比处于较高的水平;与Br、Se的比较分析表明,燃煤可能是Pb除机动车排放之外的另一个重要来源. 相似文献
169.
Monitoring the toxicity of phenolic chemicals to activated sludge using a novel optical scanning respirometer. 总被引:3,自引:0,他引:3
This paper reports the development of optical scanning respirometer for determining the toxicity of chemicals to activated sludge. The respirometer is used to measure the dissolved oxygen concentration by monitoring the luminescence intensity of ruthenium dye immobilized in a polymer film in contact with the wastewater sample. The intensity is related to the extent of oxygen quenching of luminescence. The toxicity of chemicals can be evaluated by measuring the inhibition on respiration rate of microorganism using the scanning respirometer. The IC50 values (concentration of a chemical that exhibits 50% respiration inhibition) of various phenolic chemicals in activated sludge were determined. The performance of this method is compared with other toxicity methods. The experimental results indicate that the reproducibility and sensitivity of this respirometer are reasonably good. 相似文献
170.
Fozia Batool Shahid Iqbal Kim Wei Chan Muhammad Ilyas Tariq Afzal Shah Muhammad Mustaqeem 《Environmental Forensics》2015,16(1):1-6
Hair and nail samples from young Pakistani adults were separately analyzed for quantification of Cd, Cr, Cu, Ni, Pb, and Zn concentrations. The concentrations of these metals were also analyzed in commonly consumed local foods to evaluate potential correlation of hair and nail concentrations with diet. Pearson correlation coefficients ranged from 0.349 to 0.999, demonstrating diet to be a significant contributor for accumulation of heavy metals in humans. 相似文献