西南喀斯特流域土地利用对河流溶解无机碳及其同位素的影响

河流溶解无机碳(DIC)作为流域碳循环的重要部分一直备受关注,其稳定同位素(δ13CDIC)能够反映DIC来源和转化过程,而其受土地利用变化的影响的研究还较为缺乏.为了研究喀斯特河流水体DIC和δ13CDIC的影响因素,在典型喀斯特流域赤水河进行了河水样品采集与分析.赤水河流域上游主要分布碳酸盐岩而下游分布硅酸盐岩,且...     

“Degrowth” vs. Other Types of Growth: Labeling Affects Emotions but Not Attitudes

Questioning the compatibility of economic growth and environmental sustainability, some scholars and activists call for a degrowth strategy. This idea presents an attack on the economic growth paradigm, and it has thus raised considerable attention. Yet, although many agree with questioning economic growth, a debate continues as to whether the term “degrowth” is (dis)advantageous in wider public communications. This debate, however, lacks empirical evidence. Here, we present two studies on how “degrowth” is perceived compared to other relevant terms. In Study 1, we show that “degrowth” elicits more negative affective and emotional reactions compared to “post-growth” and “prosperity without growth.” In Study 2, we find that the effects of labeling on attitudes and voting intentions toward a sustainable economy are relatively small. These initial results suggest that “degrowth” may evoke somewhat more negative emotional reactions than similar terms, but this may not have significant consequences. We discuss the results and draw implications for communication and further research.     

Hexavalent chromium reduction kinetics in rodent stomach contents

Reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in the stomach prior to absorption is a well-recognized detoxification process thought to limit the toxicity of ingested Cr(VI). However, administration of high concentrations of Cr(VI) in drinking water cause mouse small intestinal tumors, and quantitative measures of Cr(VI) reduction rate and capacity for rodent stomach contents are needed for interspecies extrapolation using physiologically-based toxicokinetic (PBTK) models. Ex vivo studies using stomach contents of rats and mice were conducted to quantify Cr(VI) reduction rate and capacity for loading rates (1-400 mg Cr(VI) L⁻¹ stomach contents) in the range of recent bioassays. Cr(VI) reduction was measured with speciated isotope dilution mass spectrometry to quantify dynamic Cr(VI) and Cr(III) concentrations in stomach contents at select time points over 1 h. Cr(VI) reduction followed mixed second-order kinetics, dependent upon concentrations of both Cr(VI) and the native reducing agents. Approximately 16 mg Cr(VI)-equivalents of reducing capacity per L of fed stomach contents (containing gastric secretions, saliva, water and food) was found for both species. The second-order rate constants were 0.2 and 0.3 L mg⁻¹ h⁻¹ for mice and rats, respectively. These findings support that, at the doses that caused cancer in the mouse small intestine (?20 mg Cr(VI) L⁻¹ in drinking water), the reducing capacity of stomach contents was likely exceeded. Thus, for extrapolation of target tissue dose in risk assessment, PBTK models are necessary to account for competing kinetic rates including second order capacity-limited reduction of Cr(VI) to Cr(III).     

Levels and distribution of organophosphorus flame retardants and plasticizers in fishes from Manila Bay, the Philippines

Organophosphorus compounds (OPCs) and stable isotope ratios (δ¹³C and δ¹⁵N) were determined in 58 fishes belonging to 20 species collected from Manila Bay, the Philippines. OPCs were detected in most of the samples and found up to μg/g lw (lipid weight) level, suggesting their ubiquitous presence in the coastal marine environment of the Philippines. Higher levels (>1000 ng/g lw) of total OPCs were determined in yellowstriped goatfish, silver sillago, tripletail wrasse and bumpnose trevally indicates either their active uptake from ambient water or lower metabolic capacity of these species. Levels of triphenyl phosphate (TPhP) in demersal species showed a positive correlation with δ¹⁵N, indicating that TPhP was adsorbed onto the particle, settled down to the bottom sediment and accumulated through the benthic food web rather than the pelagic. Estimated dietary intake of OPCs in Manila Bay fishes were four to five orders of magnitude lower than the proposed reference dose (RfD).     

Contamination and source differentiation of Pb in park soils along an urban-rural gradient in Shanghai

Urban soil Pb contamination is a great human health risk. Lead distribution and source in topsoils from 14 parks in Shanghai, China were investigated along an urban-rural gradient. Topsoils were contaminated averagely with 65 mg Pb kg⁻¹, 2.5 times higher than local soil background concentrations. HCl-extracts contained more anthropogenic Pb signatures than total sample digests as revealed by the higher ^207/206Pb and ^208/206Pb ratios in extracts (0.8613 ± 0.0094 and 2.1085 ± 0.0121 versus total digests 0.8575 ± 0.0098 and 2.0959 ± 0.0116). This suggests a higher sensitivity of HCl-extraction than total digestion in identifying anthropogenic Pb sources. Coal combustion emission was identified as the major anthropogenic Pb source (averagely 47%) while leaded gasoline emission contributed 12% overall. Urbanization effects were observed by total Pb content and anthropogenic Pb contribution. This study suggests that to reduce Pb contamination, Shanghai might have to change its energy composition to clean energy.     

Assessment of atmospheric sulfur with the epilithic moss Haplocladium microphyllum: Evidences from tissue sulfur and δS analysis

The application of geochemical signals in mosses is more and more popular to investigate the deposition of atmospheric pollutants, but it is unclear whether records of atmospheric sulfur in mosses differ between their diverse habitats. This study aimed to investigate the influence of growing condition on tissue sulfur and δ³⁴S of Haplocladium microphyllum. Epilithic and terricolous mosses in open fields, mosses under different canopy conditions were considered. We found that tissue sulfur and δ³⁴S of mosses under different habitats were not consistent and could not be compared for atmospheric sulfur research with each other even collected at the same site, moss sulfur and δ³⁴S records would be distorted by subsoil and upper canopies in different degrees, which possibly mislead the interpretation of atmospheric sulfur level and sources. Consequently, mosses on open rocks can be used reliably to assess atmospheric-derived sulfur in view of their identical sulfur and δ³⁴S evidences.     

环境分子诊断技术在污染场地环境管理中的应用进展

环境分子诊断技术(EMDSs)是有机单体同位素分析和各种分子生物学技术的总称,将其应用于污染场地特征识别、修复方案可行性评估、监测和修复终止等污染场地环境管理过程中,探明土壤和地下水中污染物生物和非生物降解过程、降解速率及机制,确定不同污染来源,可弥补传统污染场地环境管理方法的不足,具有广阔的发展前景。文章综述了污染场地环境管理过程及传统方法的不足,介绍了有机单体同位素分析和各种分子生物学技术的基本原理和用途,并对各种技术的特点进行阐述和对比;介绍了EMDSs在污染场地环境管理中的实际应用,提出了EMDSs的发展趋势。     

燃煤电厂周边大气重金属污染特征及来源解析

为探究燃煤电厂周边大气环境中重金属的污染特征与来源,对广东某山区燃煤电厂周边地区环境和污染源的重金属进行测定,分析其污染特征,采用因子分析法和Pb同位素示踪法对环境中的重金属进行来源解析。结果表明,研究区域室内积尘中重金属浓度水平明显高于土壤重金属,污染空间分布与当地气象条件相关。环境空气TSP中重金属主要来自2个污染源,Cd、Pb、As主要来自电厂燃煤,Ca、Mn、Al、Mg主要来自土壤扬尘。TSP、降尘、积尘样品所含的Pb均与电厂采集的煤、炉渣、粉煤灰样品所含的Pb具有同源性,与其他污染源同源性不明显,说明研究区域大气中Pb污染主要来自电厂燃烧所排放的烟尘,其他污染源影响不大。     

液态锂铅合金残渣中微量氚的回收

氚提取的系统设计中,如何严格限制氚损失和减小其辐射风险是非常重要的问题.利用同位素交换法对模拟液态锂铅合金残渣中的微量氚进行回收.研究结果表明,同位素交换法对液态锂铅合金残渣中的氚回收是有效的;交换载带气的最佳组成为He 0.1% D2.载带气相同时,交换温度和交换次数对渣中氚的回收率有显著影响.温度越高、交换次数越多,氚回收率越高;823 K时,经过6次交换后的氚回收率接近80%.此外,依据气体与液态金属接触的动力学数学模型,推导出了锂铅合金滞留氚量释放的数学近似表达式.     

南昌市雨水和湖水硫同位素特征的研究

为探讨南昌市酸雨的硫源,研究了2006年南昌市区雨水、湖水的pH值、硫酸根离子浓度和硫同位素组成,并对市区用煤的δ34S值进行了测定。结果表明,雨水硫同位素组成的变化范围在-3.5‰~5.5‰之间,且具有夏季轻,冬、春季重的特点。湖泊水、赣江水的δ34S值变化范围在4.3‰~10.3‰之间。2006年南昌市酸雨污染较严重,冬春季时雨水的酸度较大。雨水中硫的来源是由生物成因硫、人为成因硫和海源硫综合贡献的,夏季生物硫贡献比重大,冬春季人为硫是主要贡献者,海源硫贡献可能很小。