Application of microcosm and species sensitivity distribution approaches in the ecological hazard assessment of 4-tert-butylphenol

In order to evaluate the ecological hazard of 4-tert-butylphenol (4-TBP), species abundances and physicochemical properties were monitored for 63 days in a microcosm system containing planktonic algae, rotifers, shrimps and Daphnia. The 63 days-NOEC (no observed effect concentration) of 4-TBP for this system was calculated. At the same time, species sensitivity distribution curves were constructed based on the toxicity data of EC₁₀, EC₅₀ and NOEC derived from laboratory single-species toxicity tests, which further gives no obvious hazard concentrations for 95% species in the ecosystem (HC₅). In both the microcosm and the single-species tests, the shrimp (Neocaridina sp.) was the most sensitive species to 4-TBP exposure, while most algae species were relatively insensitive compared to the zooplankton. For the microcosm exposed to 4-TBP, significant changes occurred to the community structure instead of the community function, resulting in a NOEC_microcosm of 265.38?μg?L^–1 which approached the EC₁₀-based HC₅ (0.376?mg?L^–1). Nevertheless, EC₅₀-based HC₅ was higher than the NOEC_microcosm, and the NOEC-based HC₅ was lower. The data showed that the EC₁₀-based HC₅ was protective at the similar level with the result of microcosm for 4-TBP, providing supportive data for chemical risk assessment.     

煤粒筛分现象与粒度分布特性的试验研究

在求解煤的物性参数时,为探究煤粒平均粒径对参数求解的影响,以5种不同粒级的煤粒为研究对象,系统研究筛分现象和粒度分布;以煤粒瓦斯扩散系数求解为例,分析算术平均值、体积加权平均体积粒径对计算结果的影响.研究结果表明:煤颗粒在筛分过程中会出现特殊分选现象,目标粒级粒度分布仅占真实粒度分布的33.37％～49.32％;算术平...     

三株产甲烷细菌表面层研究

用电子显微镜的负染色技术,对史氏甲烷短杆菌Ｈ１３（ Ｍｅｔｈａｎｏｂｒｅｖｉｂａｃｔｅｒｓｍｉｔｈｉｉ Ｈ１３）、嗜热甲酸甲烷杆菌ＣＢ１２（ Ｍｅｔｈａｎｏｂａｃｔｅｒｉｕｍ ｔｈｅｒｍｏｆｏｒｍｉｃｉｃｕｍ ＣＢ１２） 、拉布雷甲烷粒菌Ｚ（ Ｍｅｔｈａｎｏｃｏｒｐｕｓｃｕｌｕｍ ｌａｂｒｅａｎｕｍ Ｚ） 的表面结构观察比较结果表明：史氏甲烷短杆菌Ｈ１３ 和嗜热甲酸甲烷杆菌ＣＢ１２ 的表面层由规则排列的四边形亚单位组成;前者每个亚单位直径为５～７ ｎｍ ,亚单位之间的中心距离为５ ～８ ｎｍ ,后者亚单位直径为９～１２ ｎｍ ,亚单位之间的中心距离为１１～１４ ｎｍ ．拉布雷甲烷粒菌Ｚ的表面层是条纹和颗粒状或丝状组成的网状结构．每根条纹宽３～４ ｎｍ ,条纹之间的距离为６～８ ｎｍ ．３ 株产甲烷细菌的表面层各不相同,其中嗜热甲酸甲烷杆菌ＣＢ１２ 和拉布雷甲烷粒菌Ｚ的表面层结构十分独特,明显不同于已报道的产甲烷细菌和古细菌的表面层结构．     

13种樟科植物叶油细胞和粘液细胞的分布和结构的比较研究

利用组织透明法、石蜡制片法和薄切片法比较研究了樟科５属１３种植物叶片中油细胞和粘液细胞的分布和结构．结果表明：５属１１种植物叶片中有油细胞分布,其形状多为圆形,体积较小且大小基本一致,ｄ３０～４５μｍ;４属８种植物叶片中有粘液细胞分布,其形状多为椭圆形,体积较大,ｄ６０～１００μｍ．根据透明叶片观察,不同植物油细胞的分布密度不同;从叶片横切面观察,有些种油细胞分布于整个叶肉中,有的分布于栅栏组织与海绵组织之间及海绵组织中,有的仅分布于栅栏组织内．粘液细胞有些种分布于整个叶肉,而有的仅分布于栅栏组织中．因此,叶片内油细胞的分布密度、油细胞和粘液细胞的分布位置及其大小在种与种之间存在明显的差异,此种结构特征具有分类学上的意义     

Estimation of Normal Variance Based on Balanced and Unbalanced Ranked Set Samples

In this paper we address the problem of estimation of the variance of a normal population based on a balanced as well as an unbalanced ranked set sample (RSS), which is a modification of the original RSS of McIntyre (1952).We have proposed several methods of estimation of variance by combining different unbiased between and within estimators, and compared their performances     

Effects of Recent Volcanic Eruptions on Aquatic Habitat in the Drift River, Alaska, USA: Implications at Other Cook Inlet Region Volcanoes

/ Numerous drainages supporting productive salmon habitat are surrounded by active volcanoes on the west side of Cook Inlet in south-central Alaska. Eruptions have caused massive quantities of flowing water and sediment to enter the river channels emanating from glaciers and snowfields on these volcanoes. Extensive damage to riparian and aquatic habitat has commonly resulted, and benthic macroinvertebrate and salmonid communities can be affected. Because of the economic importance of Alaska's fisheries, detrimental effects on salmonid habitat can have significant economic implications. The Drift River drains glaciers on the northern and eastern flanks of Redoubt Volcano. During and following eruptions in 1989-1990, severe physical disturbances to the habitat features of the river adversely affected the fishery. Frequent eruptions at other Cook Inlet region volcanoes exemplify the potential effects of volcanic activity on Alaska's important commercial, sport, and subsistence fisheries. Few studies have documented the recovery of aquatic habitat following volcanic eruptions. The eruptions of Redoubt Volcano in 1989-1990 offered an opportunity to examine the recovery of the macroinvertebrate community. Macroinvertebrate community composition and structure in the Drift River were similar in both undisturbed and recently disturbed sites. Additionally, macroinvertebrate samples from sites in nearby undisturbed streams were highly similar to those from some Drift River sites. This similarity and the agreement between the Drift River macroinvertebrate community composition and that predicted by a qualitative model of typical macroinvertebrate communities in glacier-fed rivers indicate that the Drift River macroinvertebrate community is recovering five years after the disturbances associated with the most recent eruptions of Redoubt Volcano. KEY WORDS: Aquatic habitat; Volcanoes; Lahars; Lahar-runout flows; Macroinvertebrates; Community structure; Community composition; Taxonomic similarity     

Change in Fish Fauna as Indication of Aquatic Ecosystem Condition in Río Grande de Morelia–Lago de Cuitzeo Basin, Mexico

Chirostoma charari and C. compressum, and they are presumed extinct. Twelve (63%) of the remaining species had declines in distribution. Sixteen (80%) of the 20 localities sampled had lost species. The greatest declines occurred in Lago de Cuitzeo proper and in the lower portion of the Río Grande de Morelia watershed. Species losses from the lake were attributable to drying and hypereutrophication of the lake because of substantial reductions in the amount and quality of tributary inputs, whereas losses from the Río Grande de Morelia watershed were the result of pollution from agricultural, municipal, and industrial sources, especially in the region around the city of Morelia. Three localities in the upper portion of the Río Grande de Morelia watershed—Cointzio reservoir, La Mintzita spring, and Insurgente Morelos stream—contained most of the remaining fish species diversity in the basin and deserve additional protection. Fish faunal changes indicated major declines in the health of aquatic ecosystems in the Morelia–Cuitzeo basin.     

90锶在核排污水域中的分布与监测

本文报告了川江上游核排污水环境中９０ Ｓｒ 的监测结果。表明：９０ Ｓｒ 在河水和底泥中的含量与排污距离密切相关,在不同水生物种之间的蓄积分布有显著性差异,其中底泥和含钙高的生物对９０ Ｓｒ 有较强的浓集作用。所以,选用指示性物种能提高９０ Ｓｒ 监测灵敏度,是核污染监测的较好方法。     

基于景观结构的区域生态风险分析

以深圳市龙华镇为中心的324km²正方形区域为例,以1988～1996年期间的5幅景观遥感解译图为基本信息源,根据不同时段景观元素的结构特征,构造一个综合性生态风险指数,利用系统空间采样方法对生态风险指数进行变量空间化．通过对生态风险指数采样结果进行半变异函数分析和空间插值,可以解释生态风险的空间特征和内在形成机制．结果表明,1988～1996年,工作区内的生态风险强度不断增加,区域分布的不均匀性增大;南北方向为景观人为改造活动的主方向;沿梅澜和石龙两条高速公路沿线形成两条带状高生态风险区域,其中龙华镇中心及周围地区是急需采取保护性措施的重点区域．     

活性炭纤维的表面结构及其吸附模式

迄今的吸附模式,Henry定律、Langmuir模型、BET模型、D-R方程、D-A方程都分别适用于不同的表面结构,对于活性炭纤维（Activated Corbon Fiber,ACF）这种特殊的炭吸附材料适用于哪种吸附模型,未见有文献专题论述。本论文在对ACF材料进行了大量表面结构研究的基础上,对ACF的表面结构与颗粒活性炭（GranularActivated Carbon,GAC）的表面进行了对比,并尝试性地对适用于ACF的吸附模式进行了计算和比较,得到了一些有价值的结论。