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291.
William R. Cullen Qingqing Liu Xiufen Lu Anthony McKnight-Whitfor Hanyong Peng Aleksandra Popowich Xiaowen Yan Qi Zhang Michael Fricke Hongsui Sun X. Chris Le 《环境科学学报(英文版)》2016,28(11):7-27
Hundreds of millions of people around the world are exposed to elevated concentrations of inorganic and organic arsenic compounds, increasing the risk of a wide range of health effects. Studies of the environmental fate and human health effects of arsenic require authentic arsenic compounds. We summarize here the synthesis and characterization of more than a dozen methylated and thiolated arsenic compounds that are not commercially available. We discuss the methods of synthesis for the following14 trivalent(Ⅲ) and pentavalent() arsenic compounds: monomethylarsonous acid(MMA~Ⅲ), dicysteinylmethyldithioarsenite(MMA~Ⅲ(Cys)_2), monomethylarsonic acid(MMA~Ⅴ),monomethylmonothioarsonic acid(MMMTAⅤ) or monothio-MMA~Ⅴ, monomethyldithioarsonic acid(MMDTA~Ⅴ) or dithio-MMA~Ⅴ, monomethyltrithioarsonate(MMTTA~Ⅴ) or trithio-MMA~Ⅴ,dimethylarsinous acid(DMA~Ⅲ), dimethylarsino-glutathione(DMA~Ⅲ(SG)), dimethylarsinic acid(DMA~Ⅴ), dimethylmonothioarsinic acid(DMMTA~Ⅴ) or monothio-DMAⅤ, dimethyldithioarsinic acid(DMDTA~Ⅴ) or dithio-DMA~Ⅴ, trimethylarsine oxide(TMAO~Ⅴ), arsenobetaine(AsB), and an arsenicin-A model compound. We have reviewed and compared the available methods,synthesized the arsenic compounds in our laboratories, and provided characterization information. On the basis of reaction yield, ease of synthesis and purification of product, safety considerations, and our experience, we recommend a method for the synthesis of each of these arsenic compounds. 相似文献
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293.
Hallett Chris S. Hobday Alistair J. Tweedley James R. Thompson Peter A. McMahon Kathryn Valesini Fiona J. 《Regional Environmental Change》2018,18(5):1357-1373
Regional Environmental Change - Regions with a Mediterranean climate are generally predicted to become warmer and drier with climate change. Estuaries in these regions are influenced by a broad... 相似文献
294.
295.
Robin Naidoo L. Chris Weaver Richard W. Diggle Greenwell Matongo Greg Stuart‐Hill Chris Thouless 《Conservation biology》2016,30(3):628-638
Tourism and hunting both generate substantial revenues for communities and private operators in Africa, but few studies have quantitatively examined the trade‐offs and synergies that may result from these two activities. We evaluated financial and in‐kind benefit streams from tourism and hunting on 77 communal conservancies in Namibia from 1998 to 2013, where community‐based wildlife conservation has been promoted as a land‐use that complements traditional subsistence agriculture. We used data collected annually for all communal conservancies to characterize whether benefits were derived from hunting or tourism. We classified these benefits into 3 broad classes and examined how benefits flowed to stakeholders within communities under the status quo and under a simulated ban on hunting. Across all conservancies, total benefits from hunting and tourism increased at roughly the same rate, although conservancies typically started generating benefits from hunting within 3 years of formation as opposed to after 6 years for tourism. Disaggregation of data revealed that the main benefits from hunting were income for conservancy management and food in the form of meat for the community at large. The majority of tourism benefits were salaried jobs at lodges. A simulated ban on trophy hunting significantly reduced the number of conservancies that could cover their operating costs, whereas eliminating income from tourism did not have as severe an effect. Given that the benefits generated from hunting and tourism typically begin at different times in a conservancy's life‐span (earlier vs. later, respectively) and flow to different segments of local communities, these 2 activities together may provide the greatest incentives for conservation on communal lands in Namibia. A singular focus on either hunting or tourism would reduce the value of wildlife as a competitive land‐use option and have grave repercussions for the viability of community‐based conservation efforts in Namibia, and possibly other parts of Africa. 相似文献
296.
The role of automated feedback in training and retaining biological recorders for citizen science
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René van der Wal Nirwan Sharma Chris Mellish Annie Robinson Advaith Siddharthan 《Conservation biology》2016,30(3):550-561
The rapid rise of citizen science, with lay people forming often extensive biodiversity sensor networks, is seen as a solution to the mismatch between data demand and supply while simultaneously engaging citizens with environmental topics. However, citizen science recording schemes require careful consideration of how to motivate, train, and retain volunteers. We evaluated a novel computing science framework that allowed for the automated generation of feedback to citizen scientists using natural language generation (NLG) technology. We worked with a photo‐based citizen science program in which users also volunteer species identification aided by an online key. Feedback is provided after photo (and identification) submission and is aimed to improve volunteer species identification skills and to enhance volunteer experience and retention. To assess the utility of NLG feedback, we conducted two experiments with novices to assess short‐term (single session) and longer‐term (5 sessions in 2 months) learning, respectively. Participants identified a specimen in a series of photos. One group received only the correct answer after each identification, and the other group received the correct answer and NLG feedback explaining reasons for misidentification and highlighting key features that facilitate correct identification. We then developed an identification training tool with NLG feedback as part of the citizen science program BeeWatch and analyzed learning by users. Finally, we implemented NLG feedback in the live program and evaluated this by randomly allocating all BeeWatch users to treatment groups that received different types of feedback upon identification submission. After 6 months separate surveys were sent out to assess whether views on the citizen science program and its feedback differed among the groups. Identification accuracy and retention of novices were higher for those who received automated feedback than for those who received only confirmation of the correct identification without explanation. The value of NLG feedback in the live program, captured through questionnaires and evaluation of the online photo‐based training tool, likewise showed that the automated generation of informative feedback fostered learning and volunteer engagement and thus paves the way for productive and long‐lived citizen science projects. 相似文献
297.
Relative proportions of polycyclic aromatic hydrocarbons differ between accumulation bioassays and chemical methods to predict bioavailability 总被引:1,自引:0,他引:1
Jose L. Gomez-Eyles Chris D. Collins Mark E. Hodson 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):278-284
Chemical methods to predict the bioavailable fraction of organic contaminants are usually validated in the literature by comparison with established bioassays. A soil spiked with polycyclic aromatic hydrocarbons (PAHs) was aged over six months and subjected to butanol, cyclodextrin and tenax extractions as well as an exhaustive extraction to determine total PAH concentrations at several time points. Earthworm (Eisenia fetida) and rye grass root (Lolium multiflorum) accumulation bioassays were conducted in parallel. Butanol extractions gave the best relationship with earthworm accumulation (r2 ≤ 0.54, p ≤ 0.01); cyclodextrin, butanol and acetone-hexane extractions all gave good predictions of accumulation in rye grass roots (r2 ≤ 0.86, p ≤ 0.01). However, the profile of the PAHs extracted by the different chemical methods was significantly different (p < 0.01) to that accumulated in the organisms. Biota accumulated a higher proportion of the heavier 4-ringed PAHs. It is concluded that bioaccumulation is a complex process that cannot be predicted by measuring the bioavailable fraction alone. 相似文献
298.
Kimberly J. Reich Karen A. Bjorndal Michael G. Frick Blair E. Witherington Chris Johnson Alan B. Bolten 《Marine Biology》2010,157(1):113-121
To determine whether loggerhead turtles (Caretta caretta) nesting in southeastern USA exhibit polymorphic foraging strategies, we evaluated skin samples for stable isotopes of carbon
(δ13C) and nitrogen (δ15N) from 310 loggerheads from four locations on the east coast of Florida and epibionts from 48 loggerheads. We found a dichotomy
between a depleted δ13C cluster and an enriched δ13C cluster. Epibionts from oceanic/pelagic or neritic/benthic habitats were largely consistent with this dichotomy. The bimodal
distribution of δ13C could reflect a bimodal foraging strategy or—because of the potential for confounding among four gradients of δ13C in marine environments—a polymodal foraging strategy. We integrate our results with results from other stable isotope studies,
satellite telemetry, and flipper tags to evaluate potential foraging strategies. Understanding foraging strategies is essential
for development of management plans for this endangered species that has suffered a 43% population decline over the last decade. 相似文献
299.
Antimony speciation and contamination of waters in the Xikuangshan antimony mining and smelting area,China 总被引:3,自引:0,他引:3
Faye Liu X. Chris Le Anthony McKnight-Whitford Yunlong Xia Fengchang Wu Erika Elswick Claudia C. Johnson Chen Zhu 《Environmental geochemistry and health》2010,32(5):401-413
Water samples from Xikuangshan (China), the world largest antimony (Sb) mine with a Sb mining and smelting history of more
than 200 years, were analyzed. These water samples ranged from stream water in the vicinity of the mining and smelting area
that received seepage from ore residues to the underground mine-pit drainage. The concentrations of total Sb, Sb (III) and
Sb (V) of the samples were determined by HPLC-ICP-MS. In addition, water pH and concentrations of major cations and anions
were analyzed. All 18 samples demonstrated total Sb concentrations with ppm levels from 0.33 ppm to 11.4 ppm, which is two
to three orders of magnitude higher compared to the typical concentration of dissolved Sb in unpolluted rivers (less than
1 ppb). This is probably the first time that such high Sb contents have been documented with complete environmental information.
Distribution of total Sb and Sb species was investigated, taking into account the respective local environment (in the mining
area or close to the smelter, etc.). Sb (V) was the predominant valence in all 18 samples. Only trace levels of Sb (III) were
detected in 4 of the 18 samples. Geochemical speciation modeling showed the dominant species was Sb(OH)6−. It is also probably the first time that such high Sb contents have been documented in the natural environment with Sb speciation
distribution information. Several potential oxidation pathways are also discussed that might have facilitated the oxidation
of Sb (III) in the natural environment. Signs of intoxication were observed among local mine workers with extensive exposure
to different forms of Sb for a long period of time. 相似文献
300.
Rai Kookana Greg Holz Chris Barnes Ken Bubb Ray Fremlin Bob Boardman 《Journal of environmental management》2010,91(12):2649-2656
We studied the leaching and dissipation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1, 3, 5-s-triazine) and its two principal metabolites (desethylatrazine and desisopropylatrazine) for more than two years through soil profiles at five forestry sites across Australia (representing subtropical, temperate and Mediterranean climatic conditions with rainfall ranging from 780 to 1536 mm yr?1). Following atrazine applications at local label rates, soil cores were collected at regular intervals (up to depths of 90–150 cm), and the residues of the three compounds in soil were analysed in composite samples using liquid chromatography. Bromide was applied simultaneously with atrazine to follow the movement of the soil water. While bromide ion rapidly leached through the entire profile, in most cases the bulk of atrazine, desethylatrazine and desisopropylatrazine remained in the top 45 cm of the soil profile. However, a small fraction of residue moved deeper into the soil profile and at a subtropical site (Toolara) trace levels (ng L?1) of atrazine and one of its metabolites (DEA) were detected in perched groundwater located at a depth of 1.8 m. Data on the total residues of atrazine in soil profiles from all sites except the Tasmanian site fitted a first-order decay model. The half-life of atrazine in surface soils at the subtropical sites (Toolara and Imbil) ranged from 11 to 21 days. Four separate applications of atrazine at Toolara resulted in a narrow range of half-lives (16 ± 3.6 days), confirming relatively rapid dissipation of atrazine under subtropical conditions (Queensland). In contrast, a prominent biphasic pattern of initial rapid loss followed by very slow phase of degradation of atrazine was observed under the colder temperate climate of Highclere (Tasmania). The data showed that while its 50% (DT50) loss occurred relatively rapidly (36 days), more than 10% of herbicide residue was still detectable in the profile even a year after application (DT90 = 375 days). The rate of dissipation of atrazine at warm subtropical Queensland sites (Imbil and Toolara) was 2–3 times faster than sites located in colder climate of Tasmania. The marked contrast in DT50 values between subtropical and temperate sites suggest that climatic conditions (soil temperature) is one of the key factors affecting atrazine dissipation. At the Tasmanian site, the combination of leaching of the herbicide in subsoil and slower microbial activity at cooler temperatures would have caused a longer persistence of atrazine. 相似文献