Sequential impacts of Polynesian and European settlement on vegetation and environmental processes recorded in sediments at Whangapoua Estuary, Great Barrier Island, New Zealand

Whangapoua Estuary, Great Barrier Island, New Zealand, is central to a proposed Marine Reserve, and is currently managed for conservation by the Department of Conservation. This paper describes the sequential impacts of Maori and European people on the process of estuarine vegetation succession in time and space, and the rate of estuarine sedimentation. Multiple cores from one estuary gave confidence in assessing the temporal sequence of vegetation change, but bioturbation and other disturbance factors made it difficult to interpret ¹⁴C dates from the estuarine environment. The modern vegetation zonation pattern on the estuary is an active succession, which has been generated by rapid estuary in-filling, probably initiated as a consequence of erosion following Maori burning of the adjacent forest. European forest clearance for agriculture resulted in a further increase in estuarine sedimentation, and may have re-activated earlier sediments trapped in adjacent swamps. The combined effects of two phases of human exploitation have resulted in large-scale loss of nutrients and top-soil from catchments throughout Great Barrier Island. Conservation management of the estuary should take account of the anthropogenic impacts that have driven the plant succession and created the current vegetation zonation pattern. This pattern is neither static nor ‘natural’, but rather an on-going response to the changing human activities in the surrounding catchment.     

ALTERNATIVE DEMAND MODEL ESTIMATORS FOR BLOCK RATE PRICING1

ABSTRACT: Three alternative demand model estimators for water sold under block rate tariffs are examined. The models are conceptually discussed and empirically estimated using cross-section and time-series data from Tucson, Arizona. While all three techniques produce plausible elasticity estimates, the ordinary least squares and censored sample techniques are shown to produce statistically biased results.     

乌鲁木齐市烟尘控制区验收监测结果分析

通过对验收监测结果的分析，找出了乌鲁木齐市烟尘控制区的烟尘排放特点并提出了相应的建议。     

Macroalgal growth in nutrient-enriched estuaries: A biogeochemical and evolutionary perspective

Increased nutrient loading of a body of water leads to an increase in macroalgal growth. It is generally observed, however, that certain species thrive more than others, capitalising on the increased nutrient availability. These are usually small, fast-growing, ephemeral algae that often appear as nuisance blooms. This article discusses the correlation between nutrient increase and macroalgal bloom formation. From a historical perspective, the evolutionary history of nuisance macroalgae, and the habits available to them prior to anthropogenic influences on estuarine geochemistry are considered. The occurrence of macroalgal genera whose distribution is commonly related to estuaries with high nutrient loading is discussed, along with evidence suggesting that the ecophysiological traits of r-selected, ephemeral algae largely contribute to their ecological success and bloom-formation at nutrient-enriched sites.     

Cytogenetic Damage of Human Somatic Cells and Weeping Birch Cells in Voronezh Districts with Different Levels of Anthropogenic Pollution

Cytogenetic parameters (the mitotic rate and the frequency of pathological mitoses) of the seed offspring of weeping birch (Betula pendula Roth.) and the frequency of micronuclei in the buccal epithelium of children living in several raions (districts) of the city of Voronezh differing in environmental conditions were studied. Judging from these parameters, the environmental situation was the worst in the Sovetskii raion. A correlation was found between the frequency of pathological mitoses in the roots of birch seedlings and the frequency of micronuclei in the buccal epithelial cells of children. This indicates that the cytogenetic monitoring data obtained in plants may be extrapolated to man.     

我国煤矿安全生产领域构建保险体系的探讨

我国煤矿事故多发且后果严重,其安全生产形势严峻,而煤矿安全生产领域的工伤保险体制却存在着一些问题和不足。本文将我国煤矿现有的工伤保险与强制雇主责任保险相结合,提出了构建二元化的保险体系,即针对现有的工伤保险,结合煤矿安全生产的特点,建立主成分分析和聚类分析划分风险等级的模型,用来确定工伤保险费率,强调费率对企业安全状况的反馈,并充分利用工伤保险基金从技术上改进煤矿安全生产状况,同时引入强制雇主责任保险以便有效地转嫁矿难所带来的巨大风险。通过构建新的保险体系用来改善我国目前严峻的煤矿安全生产状况。     

依据VOC浓度变化优化场地SVE通风流量的研究

土壤气相抽提(SVE)中挥发性有机污染物(VOC)的扩散速度是确定SVE抽提流量的依据。为了优化场地SVE通风流量,结合试验现场土壤的土质条件和含水率,测试了污染物在不同均质土质中的扩散速度,绘制了污染物浓度随时间变化曲线。研究表明污染物的扩散在不同种土质和含水率的条件下,浓度的变化具有相似规律:快速上升阶段,出现拐点,浓度稳定阶段;在测试的压力场范围内,结合场地不同的抽提流量(Flow rate)的通风以及停止通风进行浓度恢复的试验,同样获取了场地污染物的浓度变化曲线,即场地污染物浓度平衡破坏和浓度平衡的恢复。测试数据显示,不同土质结构的场地内不同区域的污染物浓度恢复曲线和单一土质的污染物扩散具有相同的规律。因此可以采用扩散速度来求解抽提的通风流量。根据室内外的测试数据,文中给出了理论计算的场地优化通风速率建议。     

改进固相萃取预处理操作过程的探讨

结合固相萃取预处理技术原理和普遍操作流程,提出改进固相萃取预处理操作过程的方案.并以水中有机磷农药加标回收率为表征.进行对比实验分析.结果表明.操作过程优化对提高整个实验的准确性起非常关键的作用.而操作过程简化在保证实验效果的前提下提高实验效率.因此该改进方案可行.     

污染损失率法在土壤环境质量评价中的应用

根据污染损失模型的理论思想和实践应用,结合土壤环境污染的特征,尝试将污染损失率法应用于福州市郊菜区土壤环境质量评价中,并同时计算评价样本的密切值,发现污染损失率法与密切值法的评价结果基本一致,前者表现出对样本中超标较严重的污染因子有更强的分辨率。理论分析和实践应用证明,污染损失率法应用于土壤环境质量评价,物理意义明确,计算过程简便,评价结果合理精确。本研究拓展了污染损失率法的应用领域,也为土壤环境质量评价提供了新的思路和方法。     

添加硫酸根对燃煤电厂V2O5基脱硝催化剂性能的影响

采用浸渍法分别制得活性物质V2O5的含量均为1%和SO2-4的含量不同的催化剂,并通过实验研究了添加SO-24对燃煤电厂SCR法脱硝技术中V2O5基催化剂活性和热稳定性的影响.在固定床反应器上,在NH3/NOx物质的量比为1.0和模拟烟气流量为72 L·h-1条件下,对几种催化剂的活性进行了测试,结果显示,当负载加入5.01%的SO2-4或使用含有8.91%的SO-24载体制备催化剂时,催化剂的活性提高最为显著;在TGA 92热重.差热分析仪上对这两种催化剂进行了热重实验,结果表明,添加的硫酸根对催化剂的热稳定性也有一定提高,且不会影响电厂SCR催化剂的使用.