The problem of using fixed-area subsampling methods to estimate macroinvertebrate richness: a case study with Neotropical stream data

Subsampling has been widely applied in the laboratory to process freshwater macroinvertebrate samples. Currently, many governmental agencies and research groups apply the fixed-count approach, targeting a number of individuals per sample, and at the same time keeping track of the number of quadrats (fraction of the sample) processed. However, fixed-area methods are still in use. The objective of this paper was to evaluate the reliability of macroinvertebrate taxonomic richness estimates developed from processing a standard number of subsampling quadrats (i.e., fixed-area approaches). We used a dataset from 18 tropical stream sites experiencing three different levels of human disturbance (most-, intermediate-, and least-disturbed). With 12 quadrats processed (half the sample), the collection curves started to stabilize, and for more than half of the sites studied, it was possible to sample at least 80 % of the total taxonomic richness of the sample. However, we observed that the minimum number of quadrats to achieve 80 % of taxonomic richness was strongly negatively correlated with the number of individuals collected in each site: the fewer the individuals in a sample, the greater the processed proportion of that sample needed to represent it properly. Thus our results indicate that for any given areal subsampling effort (any fixed fraction of the sample), samples with different numbers of individuals will be represented differently in terms of the proportion of the total number of taxa of the whole samples, those with greater numbers being overestimated and those with fewer numbers being underestimated. Therefore, we do not recommend the use of fixed-area subsampling methods alone if the main purpose is to measure and analyze taxonomic richness; instead, we encourage researchers to use fixed-count approaches for this purpose.     

Emissions Control and Ambient Air Quality at a Secondary Steel Production Facility

Steel production from electric arc furnaces has been continuously rising over the past few years. The trend is expected to continue due to both the anticipated increase in demand for steel, and to the replacement of obsolete open hearth furnaces. In 1972 steel produced in electric arc furnaces, which makes up 25 to 30% of the annual United States steel production, was produced primarily from recycled scrap steel in approximately 300 electric arc furnaces operated by 99 companies at 121 locations.¹ Over half of these furnaces are smaller than 50 tons, and many are located in small bar mills producing a variety of merchant steel products.     

What’s the Problem? River Management,Education, and Public Beliefs

This paper invokes the theory of planned behavior (TPB) as a diagnostic tool to explain an existing public education program's limited success at improving river water quality in the City of Perth, Western Australia. A reflective, client-driven research approach was used. A facilitated expert workshop defined an environmental problem (excess nutrients leaving gardens and entering waterways) and a desired behavior (residents purchasing environmentally sensitive fertilizer) to address the problem. A TPB-based belief elicitation survey captured respondents' beliefs regarding the desired behavior. The findings suggest respondents were aware of the links between purchasing environmentally sensitive fertilizer and river water quality. However, this behavior is compromised by the challenges in identifying appropriate products, product quality concerns, and cost. Viewing the content of a public education program through the lens of the TPB reveals insights into how and why the program fell short in achieving one of its key behavioral change goals.     

Biotic, temporal and spatial variability of tritium concentrations in transpirate samples collected in the vicinity of a near-surface low-level nuclear waste disposal site and nearby research reactor

The results of a 21 month sampling program measuring tritium in tree transpirate with respect to local sources are reported. The aim was to assess the potential of tree transpirate to indicate the presence of sub-surface seepage plumes.Transpirate gathered from trees near low-level nuclear waste disposal trenches contained activity concentrations of ³H that were significantly higher (up to ∼700 Bq L⁻¹) than local background levels (0-10 Bq L⁻¹). The effects of the waste source declined rapidly with distance to be at background levels within 10s of metres. A research reactor 1.6 km south of the site contributed significant (p < 0.01) local fallout ³H but its influence did not reach as far as the disposal trenches.The elevated ³H levels in transpirate were, however, substantially lower than groundwater concentrations measured across the site (ranging from 0 to 91% with a median of 2%). Temporal patterns of tree transpirate ³H, together with local meteorological observations, indicate that soil water within the active root zones comprised a mixture of seepage and rainfall infiltration. The degree of mixing was variable given that the soil water activity concentrations were heterogeneous at a scale equivalent to the effective rooting volume of the trees. In addition, water taken up by roots was not well mixed within the trees. Based on correlation modelling, net rainfall less evaporation (a surrogate for infiltration) over a period of from 2 to 3 weeks prior to sampling seems to be the optimum predictor of transpirate ³H variability for any sampled tree at this site.The results demonstrate successful use of ³H in transpirate from trees to indicate the presence and general extent of sub-surface contamination at a low-level nuclear waste site.     

基于RS/GIS的伊犁河谷生态环境模糊综合评价

土地利用/土地覆盖是生态环境系统的组成部分,它的变化是区域生态环境演变的直接反映和结果,它是区域生态环境演变的一个重要因素。运用RS/GIS技术,采用土地利用类型覆盖率作为评价因子,参考国际和国内各省的土地利用类型覆盖率制定评价标准,对伊犁河谷生态环境进行模糊综合评价。得出伊犁河谷生态环境质量属"优"的面积覆盖率占伊犁河谷总面积的73.2%;生态环境质量为"良"的县市面积覆盖率占伊犁河谷的26.3%。伊犁河谷生态环境总体较好,局部较差。伊犁河谷各县市的耕地面积覆盖率、建设用地覆盖率和草地面积覆盖率是各县市生态环境状况差异的主要原因。该方法与其他方法比较,所得的评价结果比较一致,结论符合实际状况,且有计算简便快捷等优点,方法可行,具有一定的可靠性和理论价值。     

Generating sustainable towns from Chinese villages: a system modeling approach

The great majority of China's developing towns will be extensions of already existing villages. With the prospect of hundreds of millions of Chinese farmers projected to leave their villages to become industrial workers in new and expanded towns within the next few years, new challenges will be faced. As expansion and modernization progress, this development moves from the traditional village model that operates not far from resource sustainability to increasingly unsustainable patterns of commerce, urban development, and modern life. With such an unprecedented mass migration and transformation, how can Chinese culture survive? What is to become of the existing million plus agricultural villages? How can these massively unsustainable new industrial towns survive? In the European Commission sponsored research program SUCCESS, researchers worked from the scale of the Chinese village to find viable answers to these questions.     

阿尔泰山湿地生态系统服务功益与可持续利用

阿尔泰山湿地是新疆干旱区最大的山区湿地生态系统之一,在对该湿地进行实地考察、遥感分析、实验室分析的基础上,认为该湿地具有提供水源、调蓄洪水、调节局部气候、维持生物多样性、净化水质、提供体闲旅游、文化科研教育等多种生态系统服务功益。鉴于目前对阿尔泰山湿地生态系统服务功益的片面理解和不合理利用问题,对湿地生态系统服务功益的可持续利用现状进行了分析,提出了湿地生态系统服务功益可持续利用的科学对策。     

Single and double metallothionein knockout in the nematode C. elegans reveals cadmium dependent and independent toxic effects on life history traits

The genome of the nematode Caenorhabditis elegans contains two metallothionein genes, both involved in metal homeostasis and/or detoxification. Single metallothionein knockout mutants have been created and now, for the first time, a double mutant has been isolated. Life history studies in the presence or absence of cadmium showed that all metallothionein mutants are viable. Although cadmium did not influence longevity, a dose dependent reduction in total brood size and volumetric growth was observed in wild type animals, which was magnified in single knockouts and further exacerbated in the double knockout. However, the metallothionein deletion caused two effects that are independent of cadmium exposure, namely all knockout strains displayed a reduced total brood size and the deletion of both metallothionein loci caused a significant reduction in volumetric growth. In summary, metallothionein is undoubtedly an important player in cadmium detoxification, but evidently also an important factor in cadmium independent pathways.     

新疆艾比湖湿地自然保护区建设及效益分析

艾比湖是典型的干旱区湖泊,具有特殊湿地的干旱生态系统.晚更新世晚期开始,由于气候逐渐变干,艾比湖不断萎缩.20世纪50年代至80年代末,由于湖区人口的激增及其对水土资源的不合理开发利用,加速了湖泊干缩的进程,80年代后期至今,随着新疆北部的气候向暖湿转变,以及湖区人口和耕地增长趋缓,艾比湖湖面出现波动扩张态势.本文对艾比湖湿地自然保护区的建设及效益情况进行了阐述.     

阿图什市2006年"3·12"特强沙尘暴重污染过程分析

分析了2006年3月12日新疆南疆地区特强沙尘暴的形成原因及机理,着重研究阿图什市空气重污染的变化特征及其与气象条件的关系,并从气象特点、局地影响因子等方面的变化分析空气重污染的成因,进一步研究造成重污染的机制,以期为改善阿图什地区城市大气污染状况提供科学依据与建议.