1997～2008年京杭大运河扬州段水质状况研究

研究京杭大运河水污染变化趋势及主要影响因子,对于更有效提高京杭大运河水质、更大的发挥其功能、保证南水北调工程具有重要战略意义和长远环境效益。依据1997～2008年京杭大运河扬州市区段水质监测数据,以内梅罗水污染指数为评估指标,采用方差分析方法,对京杭大运河扬州市区段水质现状进行了分析。结果表明:京杭大运河扬州市区段主要污染物是氨氮、挥发酚和石油类;氨氮年均浓度变化趋势较为平缓,在Ⅲ和IV类水质指标间浮动;挥发酚年均浓度变化较为活跃,总体有上升趋势,呈V类水质指标;石油类年均浓度在1998年至2001年间污染较为严重,超标达3倍以上,其它年份浓度维持在0.05mg/L左右;1998～2001年间京杭大运河扬州市区段水质处于污染状态,其余年份较好。该文研究成果为扬州市水资源分配和利用提供了科学依据。     

某BAF污水处理厂的数据统计分析及运行建议

采用平均值法和累积频率法对某曝气生物滤池（BAF）污水处理厂的COD、SS、氨氮和总氮运行数据进行了分析比较,以考察BAF运行的高效性和稳定性。结果表明,当数据波动性较小时,平均值法和累积频率法均可较为合理地反映BAF的处理能力,平均值法数据处理较累积频率法方便易行;但当数据波动性较大时,累积频率统计方法则能更好地反映BAF的处理能力和处理效果。综合运行数据和实际经验,对BAF运行时存在的主要问题进行了总结,并从强化BAF预处理、优化BAF反冲洗和提升运行效果等方面提出了相应的运行建议。     

层流环形通道热泳脱除可吸入颗粒物技术研究

依据热泳基本原理 ,设计了一种新型层流方环形双壁冷却式通道。经过计算 ,该类型通道比一般管通道有着较高的脱除可吸入颗粒物的效率。同时 ,在不同的气流进口温度下 ,利用速度温度充分发展流与速度温度正在发展流的有不同热泳沉积效率工况 ,可以达到较高的沉积效率。通过结构设计 ,可以达到较高的可吸入颗粒物脱除效率 ,是值得进一步探索的新路子。     

三江源河岸带植物群落空间分布特征及其驱动因子解析

三江源独特的地理与气候条件孕育了特色鲜明的植物种类和植被类型,为揭示三江源河岸带植物群落和土壤生境的空间分布规律及其影响机制,设置了14个调查样地（长江源10个,澜沧江源2个,黄河源2个）,定量分析了土壤养分特征（尤其是土壤磷形态）、 气候因子和河流地形地貌等环境因子对植物群落特征的影响.结果表明,三江源河岸带植物群落组成以多年生草本植物为绝对优势（72.2%）,其次为一年生草本植物（20.4%）和灌木（7.4%）. 优势植物主要有紫花针茅、 圆穗蓼、 高山嵩草、 蕨麻和麻花艽等. 植物盖度、 Shannon-Wiener指数和Pielou均匀度指数均值分别为（64.4% ±23.6%）、 （1.31 ±0.42）和（0.84 ±0.08）. 长江源植物群落多样性指数最高,澜沧江源次之,黄河源最小. 长江源河岸带土壤pH显著大于澜沧江源,而土壤有机质、 全氮和铁铝结合态磷含量均值显著低于澜沧江源. 钙镁结合态磷为河岸带土壤磷的主要形态（63.89%）. 气温、 土壤有机磷含量和pH值对三江源河岸带植物群落结构的影响显著,而土壤钙镁结合态磷含量对植物群落多样性的影响显著. 研究结果可加深三江源河岸带植物群落演变趋势及其成因机制的科学认知.     

Adaptive two-stage one-per-stratum sampling

We briefly describe adaptive cluster sampling designs in which the initial sample is taken according to a Markov chain one-per-stratum design (Breidt, 1995) and one or more secondary samples are taken within strata if units in the initial sample satisfy a given condition C. An empirical study of the behavior of the estimation procedure is conducted for three small artificial populations for which adaptive sampling is appropriate. The specific sampling strategy used in the empirical study was a single random-start systematic sample with predefined systematic samples within strata when the initially sampled unit in that stratum satisfies C. The bias of the Horvitz-Thompson estimator for this design is usually very small when adaptive sampling is conducted in a population for which it is suited. In addition, we compare the behavior of several alternative estimators of the standard error of the Horvitz-Thompson estimator of the population total. The best estimator of the standard error is population-dependent but it is not unreasonable to use the Horvitz-Thompson estimator of the variance. Unfortunately, the distribution of the estimator is highly skewed hence the usual approach of constructing confidence intervals assuming normality cannot be used here.     

Quantifying the conservation gains from shared access to linear infrastructure

The proliferation of linear infrastructure such as roads and railways is a major global driver of cumulative biodiversity loss. One strategy for reducing habitat loss associated with development is to encourage linear infrastructure providers and users to share infrastructure networks. We quantified the reductions in biodiversity impact and capital costs under linear infrastructure sharing of a range of potential mine to port transportation links for 47 mine locations operated by 28 separate companies in the Upper Spencer Gulf Region of South Australia. We mapped transport links based on least‐cost pathways for different levels of linear‐infrastructure sharing and used expert‐elicited impacts of linear infrastructure to estimate the consequences for biodiversity. Capital costs were calculated based on estimates of construction costs, compensation payments, and transaction costs. We evaluated proposed mine‐port links by comparing biodiversity impacts and capital costs across 3 scenarios: an independent scenario, where no infrastructure is shared; a restricted‐access scenario, where the largest mining companies share infrastructure but exclude smaller mining companies from sharing; and a shared scenario where all mining companies share linear infrastructure. Fully shared development of linear infrastructure reduced overall biodiversity impacts by 76% and reduced capital costs by 64% compared with the independent scenario. However, there was considerable variation among companies. Our restricted‐access scenario showed only modest biodiversity benefits relative to the independent scenario, indicating that reductions are likely to be limited if the dominant mining companies restrict access to infrastructure, which often occurs without policies that promote sharing of infrastructure. Our research helps illuminate the circumstances under which infrastructure sharing can minimize the biodiversity impacts of development.     

Joint versus separate estimation of state and change in category frequencies from repeat stratified two-phase sampling with a fallible classifier

Joint maximum likelihood estimates (JML) of category frequencies and change from repeat stratified two-phase samplingsurveys with a fallible classifier are often seriously biased andhave large root mean square errors when they are obtained for small populations (<5000) with three or more categories and amoderate to small phase II sample size (<1000). JML estimates of state also depend on antecedent or posterior data, a recipe for inconsistency. In these situations, a separate maximum likelihood estimation (SML) of category frequenciesat each survey date appears preferable. SML estimates of net change are obtained as the difference in states. SML standard errors of change are obtained via an estimate of the temporal correlation and variances of state. A bivariate binarylogistic model of change provided the estimate of temporal correlation. SML generally outperformed JMLsignificantly in terms of bias and root mean square errors in eight case studies.     

Northern Rivers Ecosystem Initiative: Context and Prevailing Legacy

The Northern River Ecosystem Initiative (NREI), 1997–2004, has provided new scientific knowledge in response to specific recommendations from its predecessor, the Northern River Basins Study (NRBS), 1990–1996. The two initiatives together provide a remarkable body of science which is, and will continue to be, used by resource managers responsible for economic and environmental sustainability in the northern watersheds of Alberta. The NREI focused its investigative efforts on improving our understanding related to ecological considerations of changes in river flow, effect of climate change on flow, ecological responses to pollution and cumulative effects, vulnerability of drinking water quality, and to a lesser degree, wildlife (birds) response to large scale changes within the watersheds. Key findings are briefly presented in this paper and discussed in greater detail in the other NREI papers included in this. Commensurate with the undertakings of NREI, provincial and territorial governments, First Nation and Métis communities, and other administrative organizations such as the Mackenzie River Basin Board, undertook policy, regulatory, and watershed initiatives towards achieving sustainability and providing reliable drinking water quality.