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<正>Mercury is a global pollutant due to its widespread use,emission,and long-range transport(Blum,2013;Pacyna et al.,2010).It is considered a priority pollutant due to its neurological toxicity,persistence,and bioaccumulation(Pacyna et al.,2010;Sharma et al.,2015).Mercury pollution can occur when products that contain mercury are improperly disposed of and mercury is released into the air,water,and soil(Zhang and Wong,2007).An estimated 22%of the annual world usage of mercury is in electrical equipment such as batteries,thermometers,and discharge lamps,and electronic devices such as monitors and 相似文献
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Charita S. Kwan Hideshige Takada Kaoruko Mizukawa Maiko Torii Tatsuya Koike Rei Yamashita Rinawati Mahua Saha Evangeline C. Santiago 《Environmental science and pollution research international》2013,20(6):4188-4204
Polybrominated diphenyl ethers (PBDEs) are extensively used as flame retardants in many consumer products, and leachates from landfills have been identified as one of the possible sources of PBDEs in the environment. Meanwhile, the unprecedented economic and population growths of some Asian countries over the last decade have led to significant increases in the amount of waste containing PBDEs in that region. This study investigates the status of PBDEs in leachates from municipal solid waste dumping sites (MSWDS) in tropical Asian countries. A total of 46 PBDE congeners were measured, both in the adsorbed (n?=?24) and dissolved (n?=?16) phases, in leachate samples collected, from 2002 to 2010, from ten MSWDS distributed among the eight countries of Lao PDR, Cambodia, Vietnam, India, Indonesia, Thailand, the Philippines, and Malaysia. PBDEs were predominantly found in the adsorbed phase. Partitioning of PBDEs in the dissolved phase was associated with the presence of dissolved organic matter; the apparent organic carbon-normalized partition coefficients (K′oc) of the BDE congeners were lower by two to four orders of magnitude than the K oc predicted from the octanol–water partition coefficients (K ow). The total PBDE concentrations from mono- to deca-BDEs ranged from 3.7 to 133,000 ng/L, and showed a trend toward higher concentrations in the more populous and industrialized Asian countries. The congener profiles in the leachates basically reflected the composition of PBDE technical mixtures. The occurrence of congeners not contained, or in trace concentrations, in technical products (e.g., BDEs 208, 207, 206, 202, 188, 179, 49, 17/25, 8, 1) was observed in most of the leachate samples, suggesting the debromination of technical mixtures, including BDE-209, in the MSWDS of tropical Asian countries. Moreover, the temporal trend indicated the reduction of BDE-209 over time, with a corresponding increase in and/or emergence of lower brominated PBDE congeners. The results indicated that MSWDS of tropical Asian countries are potential sources of environmental PBDEs, which may be transported to the aquatic environment via dissolution with dissolved organic matter. MSWDS could be amplifiers of PBDE toxicity in the environment, possibly through debromination. 相似文献
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This study examines the marginalization process of rural communities, which is caused by the decline of community-based autonomy and various activities in relation to the decline and aging of their populations, based on the frameworks that describe the process in three stages. A field survey was conducted in five rural communities in Yurihonjo-shi in Akita Prefecture, Japan. These communities were selected based on their locations, population decline and aging rates, and population sizes and were categorized into two groups, the remote and the central communities. This survey was composed of two sections: (1) a questionnaire-based survey to households and (2) an interview survey with the chairperson of each community. In order to capture the multidimensionality of residents’ daily lives, sustainable development indicators, which are originally designed to capture the well-being of nations, were utilized to develop the questionnaire. The results demonstrated significant differences between the two groups of communities mainly on four aspects: (1) farming type, (2) visits and roles of out-migrated family, (3) self-evaluation of living conditions, and (4) residents’ future concerns. These findings suggest the current state of the remote community can be seen as that of the “marginalizing” community, for which a welfare-based approach is recommended to secure the living conditions of the residents. On the other hand, the current state of the central community is considered as that of the “sustaining” community for which a revitalization approach is recommended in order to rejuvenate the diminishing community functions. 相似文献
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Mochizuki M Sasaki R Yamashita Y Akinaga M Anan N Sasaki S Hondo R Ueda F 《Environmental monitoring and assessment》2002,77(2):155-161
The Mo contents and the relations between Mo and Cu or Crcontents were investigated in the organs of Japanese wild ducks(spotbill duck, pintail, wigeon, scaup and tufted duck). Thehighest Mo content in kidney and liver of the dabbling duckswere more than 30 g g-1 dry weight (g g-1 d.wt.), though that of diving ducks were less than 11 gg-1 d. wt. The contents were lower in the ducks migratingwithin Japan, Eurasia and North America than those in the birdsmigrating between Japan and Eurasia. The contents of liver inall species were more than 50 and less than 5 g g-1 d.wt. for Cu and Cr, respectively. Significant correlations werefound between Mo and both elements in pintail and scaup, and Moand Cr in tufted duck. These results suggest that thecontamination of wild ducks reflects the reproductive area, andnot the collected area. Mo contents closely correlated with theCu and/or Cr contaminations. 相似文献
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Nakata H Sakakibara A Kanoh M Kudo S Watanabe H Nagai N Miyazaki N Asano Y Tanabe S 《Environmental pollution (Barking, Essex : 1987)》2002,120(2):245-253
The effects of exposure to butyltin compounds (BTs: tributyltin; TBT, dibutyltin; DBT and monobutyltin; MBT) and non-ortho coplanar PCBs (IUPAC 77, 126 and 169) on marine mammals and human lymphocyte were evaluated. Peripheral blood mononuclear cells (PBMCs) isolated from Dall's porpoises (Phocoenoides dalli), bottlenose dolphins (Tursiops truncatus), a California sealion (Zalophus californianus), a larga seal (Phocoa largha) and humans (Homo sapiens) were exposed at varying concentrations of BTs and coplanar PCBs. Concanavalin A (Con A)-stimulated mitogenesis found significantly suppressed (P<0.01) when the cells were exposed at 300 nM (89 ng/ml) of TBT and 330 nM of DBT (77 ng/ml), while MBT showed little cytotoxicity at treatment levels of up to 3,600 nM (620 ng/ml). BTs concentrations in the liver of Dall's porpoises from Japanese coastal waters ranged between 81-450 ng/g for TBT and 200-1,100 ng/g (wet wt.) for DBTs, which is greater than the cytotoxic levels registered in this study. In contrast, non-ortho coplanar PCBs did not suppress cell proliferation at concentrations of up to 30 nM (10 ng/ml). The residue levels of coplanar PCBs in the blubber of Dall's porpoises were 0.12-1.3 ng/g, which were one order of lower than those levels that do cell proliferation. When cells were exposed to a mixture of TBT/DBTand coplanar PCBs, the proliferation was significantly reduced to 33 nM DBT plus 34 nM CB-77 and 33 nM DBT plus 28 nM CB-169 mixtures, respectively. The investigations relating the contaminant-induced immunosuppression in marine mammals have been focused on persistent organochlorines such as PCBs. pesticides and dioxin compounds. However, this study suggested the possibility of BTs could also pose a serious threat to the immune functions in free-ranging marine mammals and humans. 相似文献
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Tomoki Nakayama Rie Hagino Yutaka Matsumi Yosuke Sakamoto Masahiro Kawasaki Akihiro Yamazaki Akihiro Uchiyama Rei Kudo Nobuhiro Moteki Yutaka Kondo Kenichi Tonokura 《Atmospheric environment (Oxford, England : 1994)》2010,44(25):3034-3042
A highly sensitive cavity ring-down spectrometer (CRDS) was used to monitor the aerosol extinction coefficient at 532 nm. The performance of the spectrometer was evaluated using measurements of nearly monodisperse polystyrene particles with diameters between 150 and 500 nm. By comparing the observed results with those determined using Mie theory, the accuracy of the CRDS instrument was determined to be >97%, while the upper limit for the precision of the instrument was estimated to be 0.6–3.5% (typically 2%), depending on the particle number concentration, which was in the range of 30–2300 particles cm?3. Simultaneous measurements of the extinction (bext), scattering (bsca) and absorption (babs) coefficients of ambient aerosols were performed in central Tokyo from 14 August to 2 September 2007 using the CRDS instrument, two nephelometers and a particle/soot absorption photometer (PSAP), respectively. The value of bext measured using the CRDS instrument was compared with the sum of the bsca and babs values measured with a nephelometer and a PSAP, respectively. Good agreement between the bext and bsca + babs values was obtained except for data on days when high ozone mixing ratios (>130 ppbv) were observed. During the high-O3 days, the values for bsca + babs were ~7% larger than the value for bext, possibly because the value for babs measured by the PSAP was overestimated due to interference from coexisting non-absorbing aerosols such as secondary organic aerosols. 相似文献
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Linkages between phenology, pollination, photosynthesis, and reproduction in deciduous forest understory plants 总被引:2,自引:0,他引:2
Light availability in the understory of deciduous forests changes drastically within the growing season due to the foliage dynamics of canopy trees. Because flowering phenology, photosynthetic characteristics, and fruiting success respond to such strong seasonality in light availability, we hypothesized that understory plants in such ecosystems should describe distinct phenological groups or syndromes where "syndrome" is defined only as a set of characteristics that co-occur. To identify these phenological syndromes, we studied the flowering phenology, fruit or seed set, and photosynthetic characteristics for 18 perennial understory herbaceous species that differed in reproductive strategy over eight years in a deciduous forest in northern Japan. Three phenological groups emerged from this study: (1) spring bloomers, flowering and fruiting before the completion of canopy closure; (2) early-summer bloomers, flowering during the progress of canopy closure and fruiting after canopy closure; and (3) late-summer bloomers, flowering and fruiting after canopy closure. The spring bloomers had high photosynthetic rates and high fruiting abilities, but the flowering time varied considerably among years due to yearly fluctuations of snowmelt date. Bumble bee-pollinated species of spring bloomers showed variable seed-set success, while fly-pollinated species showed relatively stable seed sets over the years. The early-summer bloomers showed low fruiting abilities irrespective of pollination success, reflecting severe resource limitation with decelerating light availability during fruit development. Although the late-summer bloomers showed low photosynthetic rates under low-light conditions, high fruit-set success was attained if pollination was sufficient. These results support our hypothesis that phenological syndromes may be found in deciduous forest understory plants. Given that reproductive success of bee-pollinated spring bloomers is highly susceptible to seasonal fluctuation, climate change may have its strongest impacts on this group. 相似文献