基于网格划分的宜兴市区滨水区可达性评价

城市滨水区可达性不仅仅是空间距离的阻隔,还包括人们对滨水空间的需求及滨水区自身对公众的吸引力。依据潜能模型的概念,选取人口密度、滨水区综合质量和以土地利用表达的交通作为评价因子,借助ArcGIS93软件,建立了基于网格划分的滨水区可达性计算模型。该模型通过对研究区域进行等距网格划分以及定量计算网格内的人口密度、最小阻力成本和滨水区综合质量来进行滨水区可达性的定量评价。运用该模型评价了宜兴市中心城区居民至各滨水区的可达性水平,发现各滨水区平均可达性水平存在明显差异,最高的是团氿,最低的是蠡河;对每个滨水区而言,可达性从空间上均呈现出以滨水区为中心由内向外递减的趋势。评价结果可为城市滨水区合理建设格局的制定和居民享用滨水区的公平性提供决策参考     

江苏阳澄湖螺类群落的空间分布格局

2008年1月～2009年10月对江苏阳澄湖螺类群落结构进行了季节调查研究。共采集到螺类4科5属6种,优势种为铜锈环棱螺,次优种为长角涵螺。阳澄湖螺类平均密度为220±47 ind./m2,平均生物量为2331±469 g/m2,螺类密度和生物量在年际和季节间均无明显差异,但群落结构存在显著的空间变化,密度在东湖区和中华绒螯蟹围网养殖区较大、西湖区最小,生物量围网养殖区最高、西湖区最低;铜锈环棱螺密度围网养殖区最高、西湖区最低,长角涵螺密度东湖区最高、围网养殖区次之、入湖河流及其它湖区极低。中华绒螯蟹养殖未导致围网养殖区螺类数量下降,螺类（主要是铜锈环棱螺）的投放可能是该区螺类密度、生物量及铜锈环棱螺所占比例较高的主要原因之一。逐步回归分析表明,水深是影响螺类群落整体密度和生物量空间分布差异的主要因子;典型对应分析（CCA）表明,铜锈环棱螺主要分布在叶绿素a较高的水域,而长角涵螺和纹沼螺则主要分布在透明度较大的地方     

Effects of Exurban Development and Temperature on Bird Species in the Southern Appalachians

Land‐use dynamics and climatic gradients have large effects on many terrestrial systems. Exurban development, one of the fastest growing forms of land use in the United States, may affect wildlife through habitat fragmentation and building presence may alter habitat quality. We studied the effects of residential development and temperature gradients on bird species occurrence at 140 study sites in the southern Appalachian Mountains (North Carolina, U.S.A.) that varied with respect to building density and elevation. We used occupancy models to determine 36 bird species’ associations with building density, forest canopy cover, average daily mean temperature, and an interaction between building density and mean temperature. Responses varied with habitat requirement, breeding range, and migration distance. Building density and mean temperature were both included in the top occupancy models for 19 of 36 species and a building density by temperature interaction was included in models for 8 bird species. As exurban development expands in the southern Appalachians, interior forest species and Neotropical migrants are likely to decline, but shrubland or edge species are not likely to benefit. Overall, effects of building density were greater than those of forest canopy cover. Exurban development had a greater effect on birds at high elevations due to a greater abundance of sensitive forest‐interior species and Neotropical migrants. A warming climate may exacerbate these negative effects. Efectos del Desarrollo Exurbano y de la Temperatura sobre Especies de Aves en las Apalaches del Sur     

Distribution and persistence of carbaryl in some terrestrial and aquatic components of a forest environment

Abstract

An oil‐based formulation of carbaryl (1‐naphthyl N‐methyl‐carbamate) (Sevin‐2‐Oil) was applied twice by a fixed‐wing aircraft at a dosage rate of 280 g of A.I./ha/application to a coniferous forest near Allardville, New Brunswick. The highest concentrations of the chemical in fir foliage, litter and forest soil 1 h after application were respectively 4.20, 1.21 and 0.59 ppm (fresh weight). The residues dissipated rapidly and the DT50 values obtained from the depletion curves were 2.3 d for foliage and 1.5 d for litter and soil samples. Very low levels (<0.1 ppm) of carbaryl persisted in foliage and litter beyond the 10 d sampling period. The maximum residue level found in stream water was 0.314 ppm and more than 50% of it had dissipated within 1 h. Low but detectable levels (0.001 ppm) of the chemical persisted in water until the end of the 10 d sampling period. Sediment samples contained a maximum level of 0.04 ppm, which dissipated below the detection limit within 5 h. Brook trout and slimy sculpins captured in the stream 1 d after the spray contained on average about 0.04 ppm of carbaryl and none of it was found in 3 d postspray samples.     

氰化物测定机理的研究

研究了酒石酸-硝酸锌法提取易释放氰化物，磷酸-EDTA提取总氰的机理；对异烟酸-吡唑啉酮光度法测定氰化物的条件作了探讨。     

基于传热分析的林火蔓延特性研究

计算了水平流动的热烟气与大乔木、小乔木、灌木主干及大乔木树叶间的强制对流传热；垂直上升流动的热烟气与各类林木的纵向自然对流、纵向强制对流传热；以及烟气对各类林木的辐射传热。分别比较了它们的热流密度和总换热量。讨论了烟气流速、温度、林木尺寸等因素对换热的影响。在此基础上，对不同林木的火险特性进行了预测。     

Formation of polyester blends by a recombinant strain ofPseudomonas oleovorans: Different poly(3-hydroxyalkanoates) are stored in separate granules

WhenPseudomonas oleovorans (GPo1) is grown on sodium octanoate under ammonium limiting conditions, it is able to accumulate a copolyester consisting of medium chain length 3-hydroxyalkanoic acids (PHA_m). 3-Hydroxybutyrate is only incorporated in trace amounts. WhenP. oleovorans is equipped with the PHB biosynthetic genes ofAlcaligenes eutrophus (GPo1[pVK101::PP1]), it forms a polyester containing major amounts of 3-hydroxybutyrate. The resulting polymer however is a blend of PHA_m and PHB, rather than a copolymer of 3-hydroxybutyrate and medium chain length 3-hydroxyalkanoic acids [11]. To establish whether PHA_m and PHB molecules are stored in the same or separate granules by this recombinantP. oleovorans strain, we studied polymer forming cells by freeze-fracture electron microscopy. This approach is possible because previous freeze-fracture electron microscopy studies on PHA_m and PHB accumulating strains have shown that PHA_m and PHB granules can be distinguished from each other: PHA_m granules from mushroom-like structures, whereas PHB granules from needle structures during freeze-fracturing. In this paper we show that stationary phase cells of GPo1[pVK101::PP1] contained both mushroom and needle-like structures, indicating that PHA_m and PHB chains were stored in separate granules. To be able to determine whether the separation of PHA_m and PHB is complete, the respective granules were separated on sucrose gradients. A total cell extract of GPo1[pVK101::PP1] which was subjected to sucrose gradient centrifugation revealed two white bands of different densities: the upper band with a density of 1.05 g/mL consisted exclusively of PHA_m granules, while the lower band with a density of 1.19 g/mL consisted of PHB granules only. Thus, when bacteria synthesize both PHA_m and PHB, the resulting polymer chains are segregated completely and stored in separate granules.     

揭开武汉东湖蓝藻水华消失之谜

水华（亦称湖靛）是湖泊富营养化最恶劣的表征之一。武汉东湖７０年代至１９８４年间每年夏季出现蓝藻水华,１９８５年起突然消失,至今已有１４年没有重现,原因何在？通过三次设在湖里的围隔试验,证明鲢鳙的大量放养,是水华消失的决定性因素。     

川中丘陵区村级景观土壤有机碳密度和储量分析

本文综合运用了地理信息系统(GIS)、遥感(RS)和全球卫星定位系统(GPS)等技术手段,分析了人口密集的川中丘陵乡村区域土壤有机碳密度(SOCD)和储量(SOCS)的空间分布及影响因素。结果表明,区域内SOCD和SOCS平均值分别为5.58kg/m2和75.77×105g,SOCD随丘体高度的降低向四周逐渐增大,SOCS主要分布于旱地、水田等土地利用类型中。0~30cm土层和土体深度内,SOCD以冬水田最高,裸岩最低;SOCS则以丘脚旱地和轮作水田最高,裸岩最低。地形、土地利用和土地覆盖对SOCD、SOCS影响明显。     

环境物探技术在岩溶勘察中的应用及其效果

将高密度电阻率法及工程地震映像法两种环境物探技术同时应用于实际的地质灾害(岩溶)勘察中,结果表明:对于岩溶这样的地质灾害,单一环境物探技术虽然能清楚反映其埋深、规模和发育情况,但各有缺陷。而多种环境物探技术的综合使用,相互补充,将能大大提高岩溶勘察的准确性,提高勘察效果和效率。