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101.
D. Marc. Kilgour Liping Fang Keith W. Hipel 《Journal of the American Water Resources Association》1992,28(1):141-153
ABSTRACT: Game-theoretic models are developed for describing and analyzing the inspection and enforcement process, especially as it relates to environmental laws and regulations in North America. Based on these models, systems using irrevocable control orders can be compared to those relying on court determination of guilt and punishment. The cost-effectiveness of environmental enforcement can be systematically assessed in terms of factors such as the private gains for violators, the costs of inspection, penalties, and the social value of deterring violations. The policy implications of the analysis, especially with reference to environmental protection, are emphasized. 相似文献
102.
Qin Shao Machelle D. Wilson Christopher S. Romanek Keith A. Hobson 《Environmental and Ecological Statistics》2004,11(3):323-337
A temporal record of environmental conditions is often contained within accretionary biological tissue. These records can provide knowledge of the environmental conditions that existed at the time the tissue was formed. In this study, we look at trace element concentrations and isotopic ratios of carbon and nitrogen as contained in baleen from bowhead whales in the eastern and western Arctic Ocean. Time series techniques, including maximum likelihood method and likelihood ratio tests, are applied to analysis of data and inference about their mean structures. 相似文献
103.
Lars Bergström Keith W.T. Goulding 《Ambio-人类环境杂志》2005,34(4):277-281
在不污染环境的情况下生产足量的健康食品对未来世界农业是一个严重挑战.瑞典"21世纪的食物"研究计划已经研究了可持续耕作体系的经济的、环境的以及社会的各个方面,本文列举了瑞典"21世纪的食物"研究计划以及其它相关的国际研究计划中注重改善养分利用效率的一些研究,特别是氮和磷.它表明有许多可持续性解决养分利用效率的方法,有些很复杂,但有些就很简单.政府政策包括津贴、研究和技术以及公众对耕作方式的认可,所有这些都与制定这些解决方法结合在一起.需要知识转让的参与式途径,这样科学家、政策决策者、农场主、顾问以及消费者们可以交流信息,一起构建可持续的耕作体系. 相似文献
104.
Manganese oxide coatings on sand particles within filtration beds from a water treatment plant in Grampian, Scotland were
examined to determine their control on metal mobility. This study first sought to characterise the oxides, notably their mineralogy
and metal content, to provide a foundation for studies on the adsorption of dissolved metals from the treated water by the
oxides. The oxides were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and analysed by flame
atomic absorption spectrophotometry (AAS). These techniques showed the oxide coatings were amorphous but uniformly distributed
over each sand grain. The oxides were selectively removed from the sand grains prior to analysis by AAS using a hydroxylamine
hydrochloride selective leaching method. The compositional range of the extracts was 100–150 mg L−1 Mn; 30–55 mg L−1 Fe; 17–56 mg L−1 Ca; 4.6–7.0 mg L−1 Ni; 4.6–6.8 mg L−1 Zn and 1.3–5.7 mg L−1 Mg. When these results are expressed as mg of metal per mg of Mn, the metal content of the oxides is remarkably uniform:
0.25–0.37 mg Fe; 0.14–0.35 mg Ca; 0.035–0.042 mg Ni; 0.035–0.040 mg Zn; 0.01–0.04 mg Mg. The greatest metal concentrations
were consistently found in the upper 3 cm of the filtration bed, and these decrease with increasing depth. After the beds
are cleaned a more uniform distribution of metals occurs throughout the bed. The metals taken up by the manganese coating
are retained over a wide pH range with the exception of Ca and Mg which desorb to a significant extent. The percentage of
calcium and magnesium lost from the coating ranges from 30–94%, the amount being dependent on the final pH of the solution.
The presence of manganese oxide in the filtration beds appears to be advantageous in terms of removal of transition metals
from the treated water. 相似文献
105.
106.
Rocky Mountain bighorn rams use three distinct tactics in competition for mates. Two tactics (tending and blocking) feature
defense and cooperative mating over a relatively prolonged consort period (up to 3 days). In the coursing tactic, subordinate
rams fight dominants for temporary copulatory access (lasting seconds) to defended ewes. By combining population-wide genetic
(microsatellite) exclusion of paternity, behavioral data and a model of bighorn reproductive competition, we estimated that
coursing rams fathered 44% of 142 lambs assigned paternity in two natural populations. In one population, the probability
of successful defense against coursing was lowest among rams that had many female consorts and held highest dominance rank.
Even so, per capita annual male reproductive success was positively associated with social rank in both herds when measured
in terms of fall conceptions. The proportion of coursing versus defending ram matings in each population (0.36 and 0.39) was
similar to the corresponding fraction of lambs (0.43 and 0.47) fathered by coursing rams, suggesting that sperm competition
approximated a fair lottery. Male traits important in gaining social status and obtaining cooperative consorts with ewes were
different and potentially in conflict with those needed to defend against (and practise) coursing. Although the concussive
weapons (horns) of rams are less dangerous than, for example, the piercing weapons of other bovids, injury from falls and
horn blows during coursing brawls may cause death, handicap future mating competition or increase the risk of predation. Coursing
is a rare example of an unconventional alternative mating tactic that is high-gain and high-risk.
Received: 17 April 1996 / Accepted after revision: 15 March 1997 相似文献
107.
In Defense of the Epidemic Disease Hypothesis 总被引:2,自引:0,他引:2
108.
Spatial distribution of polybrominated diphenyl ethers and polybrominated biphenyls in lake trout from the Laurentian Great Lakes 总被引:11,自引:0,他引:11
Luross JM Alaee M Sergeant DB Cannon CM Whittle DM Solomon KR Muir DC 《Chemosphere》2002,46(5):665-672
Concentrations of two types of brominated flame-retardants (BFRs); polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) were determined in a single age class of lake trout (Salvelinus namaycush) collected from the Laurentian Great Lakes in 1997. Mean concentrations of total PBDE were highest in samples from Lake Ontario at 95+/-22 ng/g wet weight (ww) or 434+/-100 ng/g lipid weight (lw) while the lowest concentrations were observed in Lake Erie lake trout (27+/-8.6 ng/g ww, 117+/-37 ng/g lw). In all samples, the predominant PBDE congeners were 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and 2,2',4,4', 6-pentabromodiphenyl ether (BDE-100), which are the primary components of the commonly used penta-BDE formulation flame retardant. Lake trout collected from Lake Huron had the highest concentrations of PBBs (3.1+/-1.7 ng/g ww, 15+/-8.5 ng/g lw), while the lowest levels were detected in fish from Lake Superior (0.25+/-0.13 ng/g ww, 1.7+/-0.89 ng/g lw). In all lake trout samples, 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), a major constituent of the flame-retardant FireMaster BP-6, was the predominant PBB congener. 相似文献
109.
Concentration, size distribution, and dry deposition rate of particle-associated metals in the Los Angeles region 总被引:1,自引:0,他引:1
Jeong-Hee Lim Lisa D. Sabin Kenneth C. Schiff Keith D. Stolzenbach 《Atmospheric environment (Oxford, England : 1994)》2006,40(40):7810-7823
Daily averaged atmospheric concentrations and dry deposition fluxes of particulate metals were measured seasonally at six urban sites and one non-urban coastal site in the Los Angeles region using a conventional total suspended particulate matter (TSP) filter, surrogate surface deposition plates, and a Noll Rotary Impactor (NRI), which provides information about particle size distribution in four size ranges above 6 μm. With the exception of the non-urban site, particulate metal concentrations and deposition fluxes were remarkably uniform spatially and temporally. At all sites there were significant metal concentrations on particles greater than 10 μm, a commonly used upper limit for many air quality monitoring studies, and these large particles were estimated to be responsible for most of the deposited mass of metals. Annual averaged values of deposition rates measured with a surrogate surface were in good agreement with values estimated using theoretical deposition velocities in conjunction with measured size-segregated particle concentrations. Image analysis of particles deposited on NRI stage A, which collects all particles greater than 6 μm, indicated nighttime metal concentrations and deposition at the non-urban coastal site was higher than in the day time due to offshore advection of urban air associated with the diurnal land breeze. Measured enrichments of crustal elements and metals were correlated, indicating efficient mixing of natural and anthropogenic material from different sources, hypothesized to be the result of cyclical resuspension and deposition of dust by moving vehicles and wind. 相似文献
110.
Sanderson H Ingerslev F Brain RA Halling-Sørensen B Bestari JK Wilson CJ Johnson DJ Solomon KR 《Chemosphere》2005,60(5):619-629
A mixture of four tetracyclines; oxytetracycline (OTC), chlortetracycline (CTC), tetracycline (TC), and doxycycline (DC) was applied in fifteen 12000l outdoor microcosms at four treatment levels plus controls each with three replicates (n = 3). The dissipation times of parent compounds were monitored and half-lives (DT50) of 1-4 days, depending on treatment level were recorded. This is in accordance with half-lives from previous findings in bench-top experiments. Parent compound DT50, were determined using HPLC-UV. Furthermore, the samples were analyzed for ten different tetracycline products using LC/MS/MS. Two products were found for chlortetracycline; 4-epi-anh-chlortetracyline and the iso-chlortetracycline. Iso-forms were only found for CTC and only at the highest treatment (300 microg l(-1)). The half-lives, trajectories, and relative amounts of the products were analogous for all four tetracyclines. DT50 for products were less than 1.2 days. Formation of 4-epi-anh-tetracyclines, occurred at neutral to weak alkaline conditions. 相似文献