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741.
Research in political economy has traditionally sought to disentangle the effects of legislative ideology and constituent interest in explaining policy decisions. Frequently, proxy variables are used to measure constituent interest. However, these measures do not adequately reflect true constituent interest, which is based upon the costs and benefits of the policies under consideration, incorporating the scope of the policies. Using Haiku, a detailed model of the US electricity sector, and TAF, an integrated assessment model of pollution pathways and valuation, I construct economic measures of constituent interest at the state level as well as for federal policy. I then use these measures to analyze state adoption of more stringent green electricity policies and congressional roll-call voting on federal environmental policy. Previous studies that use proxy measures of constituent interest typically find that the legislator ideology matters more, while my study shows that both ideology and constituent interest are significant factors.  相似文献   
742.
Nest predation imposes a major cost to reproductive females, who should therefore take measures to avoid encounters with predators. However, when predators are conspecifics, avoidance can be more difficult and may be a consequence of social or aggregative behaviors. In this study, we measured the consequences of conspecific egg cannibalism on hatching success in the maritime earwig (Anisolabis maritima), which occasionally form aggregations. We hypothesized that conspecific egg cannibalism is a byproduct of aggregation, and that cannibalism rates would increase with aggregation density; however, our results do not support this. We combined field data with a lab experiment to test the effectiveness of maternal nest defense in protecting nests from a conspecific. Nests with a guard had higher hatching success and lower rates of cannibalism than unattended nests in the presence of a conspecific. We also measured body and forcep size to see whether the outcome of contests was determined by relative size. Female guards who were larger relative to the invading conspecific maintained their nest and had higher hatching success than females who were relatively smaller, suggesting that the maritime earwig is under directional selection for larger body and/or forcep size.  相似文献   
743.
Several physiologically based extraction procedures have been proposed to estimate the fraction of the potentially toxic element content that would be bioaccessible in the human gastro-intestinal tract following accidental ingestion of soil. Many of these procedures are complex, they have been applied to a very limited range of soils, and most work has focussed on arsenic and lead. In the present study, a simplified, two-stage extraction, simulating the human stomach and intestine, was developed and applied to urban soil samples from ten public-access areas in the City of Torino, Italy. The human oral bioaccessibility of chromium, copper, nickel, lead and zinc was estimated. Lead and zinc bioaccessibilities were found to be higher in the stomach, but chromium was more bioaccessible in the intestine. Analyte concentrations were higher in roadside soils than in soils from parks. A higher proportion of the soil metal content was found in bioaccessible forms at roadsides than in parks. Comparison of the current findings with results of earlier work involving sequential extraction of the same soils indicated that the sequential procedure gave a relative, but not an absolute, indication of bioaccessibility. Calculations based on the bioaccessible analyte concentrations suggest that ingestion of only 2–3 g of some of the roadside soil samples from Torino could deliver the tolerable daily oral intake of chromium, nickel and lead to a 20-kg child. The developed procedure is useful for preliminary screening of soils and prediction of whether their bioaccessible metal contents are likely to pose a risk to human health.  相似文献   
744.
This study evaluated changes in oyster tissue contaminant levels following North Atlantic tropical cyclones to determine if changes in contaminant concentrations were predictable. The basis for this study was analysis of coastal chemical contaminant data from the National Oceanic and Atmospheric Administration's (NOAA) National Status and Trends Mussel Watch Program and NOAA's National Weather Service storm track data. The tendency for contaminant (metals and organic compounds) body burdens to increase or decrease in oyster tissue after a storm was assessed using contingency and correspondence analyses. Post-storm contaminant levels in oysters revealed a consistent pattern of distribution, which could be described as follows: (1) most of the organic contaminants stay within their long-term concentration ranges, (2) very few organic contaminants decreased, and (3) metals overwhelmingly tend to increase.  相似文献   
745.
Bermuda is a densely populated coral 'atoll' located on a seamount in the mid-Atlantic (Sargasso Sea). There is no national sewerage system and the ~20 × 10(6)?L of sewage generated daily is disposed of via marine outfalls, cess pits/septic tanks underneath houses and through waste disposal (injection) wells. Gastrointestinal (GI) enterococci concentrations were measured in surface seawater samples collected monthly at multiple locations across the island over a 5-year period. According to the EU Bathing Water Directive microbial classification categories, 18 of the sites were in the 'excellent' category, four sites in the 'good', five sites were in the 'sufficient' and three sites in the 'poor' categories. One of the sites in the 'poor' category is beside a popular swimming beach. Between 20-30% of 58 sub tidal sediment samples collected from creeks, coves, bays, harbours and marinas in the Great Sound complex on the western side of Bermuda tested positive for the presence of the human specific bacterial biomarker Bacteroides (using culture-independent PCR-based methods) and for the faecal biomarker coprostanol (5β-cholestan-3-β-ol, which ranged in concentration from <0.05-0.77?mg?kg(?-?1). There was a significant statistical correlation between these two independent techniques for faecal contamination identification. Overall the microbial water quality and sedimentary biomarker surveys suggest sewage contamination in Bermuda was quite low compared with other published studies; nevertheless, several sewage contamination hotpots exist, and these could be attributed to discharge of raw sewage from house boats, from nearby sewage outfalls and leakage from septic tanks/cess pits.  相似文献   
746.
Loss of ecological integrity due to excessive suspended sediment in rivers and streams is a major cause of water quality impairment in the USA. Current assessment protocols for development of sediment total maximum daily loads (TMDLs) lack a means to link temporally variable sediment transport rates with specific losses of ecological functions as loads increase. In order to accomplish this linkage assessment, a functional traits-based approach was used to correlate site occurrences of 17 fish species traits in three main groups (preferred rearing habitat, trophic feeding guild, and spawning behavior) with suspended sediment transport metrics. The sediment transport metrics included concentrations, durations, and dosages for a range of exceedance frequencies; and mean annual suspended sediment yields (SSY). In addition, this study in the Northwestern Great Plains Ecoregion examined trait relationships with three environmental gradients: channel stability, drainage area, and elevation. Potential stressor responses due to elevated suspended sediment concentration (SSC) levels were correlated with occurrences of five traits: preferred pool habitat; feeding generalists, omnivores, piscivores, and nest-building spawners; and development of ecologically based TMDL targets were demonstrated for specific SSC exceedance frequencies. In addition, reduced site occurrences for preferred pool habitat and nest-building spawners traits were associated with unstable channels and higher SSY. At an ecoregion scale, a functional traits assessment approach provided a means to quantify relations between biological impairment and episodically elevated levels of suspended sediment, supporting efforts to develop ecologically based sediment TMDLs.  相似文献   
747.
The European Union’s Restriction on the Use of Certain Hazardous Substances (Directive 2002/95/EC) targeted at electronic products took effect in 2006. In contrast, the USA has no comparable national policy on these products. To understand corporate responses to policy differences across jurisdictions, we conducted a structured-questionnaire survey of individuals in 109 companies that are representative of the US electronics industry. The results reveal that 70% of these companies have already adopted lead-free solder for electronics with 49% of the total preferring the SnAgCu formulation, despite uncertainties associated with environmental impacts of this alternative alloy. We use a modified life cycle impact assessment method based on endpoint modeling approach to derive weighting factors that represent the respondents’ value system for tradeoffs among environmental impacts. We use a modified fuzzy Technique for Order Preference by Similarity to Ideal Solution approach to evaluate technical criteria dominance in declared preferences. A statistical model of corporate behavior is also presented. The results provide the first systematic framework that accounts for environmental impact, technological challenge, and business strategy concurrently toward formulating a comprehensive national policy for materials selection in electronic products.  相似文献   
748.
Salts of 2,2-dichloropropionic acid, such as dalapon, are well known as herbicides and are regulated as such in potable water in Australia and elsewhere. It is also an identified disinfection by-product (DBP), but little is known about the compound's formation and typical levels from this source. This work presents results from a sampling campaign where 2,2-dichloropropionate was found at levels between 0.1 and 0.5 μg l(-1) in potable water samples from a major treatment plant in South East Queensland, Australia. However, levels were below the reporting limit (0.01 μg l(-1)) in the immediate source water for the plant. Also, temporal trends in 2,2-dichloropropionate observed in treated water during sampling mirrored those of trihalomethanes albeit at much lower concentrations, suggesting that the occurrence is due to in situ formation as a DBP. This could present a regulatory dilemma in some jurisdictions.  相似文献   
749.
Rice is elevated in arsenic (As) compared to other staple grains. The Bangladeshi community living in the United Kingdom (UK) has a ca. 30-fold higher consumption of rice than white Caucasians. In order to assess the impact of this difference in rice consumption, urinary arsenicals of 49 volunteers in the UK (Bangladeshi n = 37; white Caucasians n = 12) were monitored along with dietary habits. Total urinary arsenic (As(t)) and speciation analysis for dimethylarsinic acid (DMA), monomethylarsonic acid (MA) and inorganic arsenic (iAs) was conducted. Although no significant difference was found for As(t) (median: Bangladeshis 28.4 μg L(-1)) and white Caucasians (20.6 μg L(-1)), the sum of medians of DMA, MA and iAs for the Bangladeshi group was found to be over 3-fold higher (17.9 μg L(-1)) than for the Caucasians (3.50 μg L(-1)). Urinary DMA was significantly higher (p < 0.001) in the UK Bangladeshis (median: 16.9 μg DMA L(-1)) than in the white Caucasians (3.16 μg DMA L(-1)) as well as iAs (p < 0.001) with a median of 0.630 μg iAs L(-1) for Bangladeshi and 0.250 μg iAs L(-1) for Caucasians. Cationic compounds were significantly lower in the Bangladeshis (2.93 μg L(-1)) than in Caucasians (14.9 μg L(-1)). The higher DMA and iAs levels in the Bangladeshis are mainly the result of higher rice consumption: arsenic is speciated in rice as both iAs and DMA, and iAs can be metabolized, through MA, to DMA by humans. This study shows that a higher dietary intake of DMA alters the DMA/MA ratio in urine. Consequently, DMA/MA ratio as an indication of methylation capacity in populations consuming large quantities of rice should be applied with caution since variation in the quantity and type of rice eaten may alter this ratio.  相似文献   
750.
We studied the effect of high ozone (O(3)) concentration (110-490 nmol mol(-1)) on regenerating aspen (Populus tremuloides) and maple (Acer saccharum) trees at an open-air O(3) pollution experiment near Rhinelander WI USA. This study is the first of its kind to examine the effects of acute O(3) exposure on aspen and maple sprouts after the parent trees, which were grown under elevated O(3) and/or CO(2) for 12 years, were harvested. Acute O(3) damage was not uniform within the crowns of aspen suckers; it was most severe in the mature, fully expanded photosynthesizing leaves. Young expanding leaves showed no visible signs of acute O(3) damage contrary to expectations. Stomatal conductance played a primary role in the severity of acute O(3) damage as it directly controlled O(3) uptake. Maple sprouts, which had lower stomatal conductance, smaller stomatal aperture, higher stomatal density and larger leaf surface area, were tolerant of acute O(3) exposure. Moreover, elevated CO(2) did not ameliorate the adverse effects of acute O(3) dose on aspen and maple sprouts, in contrast to its ability to counteract the effects of long-term chronic exposure to lower O(3) levels.  相似文献   
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