考虑从众阈值和主体特征的人群疏散元胞自动机模型*

为研究从众行为对人群疏散效率的影响,建立考虑从众阈值和主体特征的人群疏散元胞自动机模型,通过引入从众阈值反映人群中不同个体的从众选择程度,耦合每个主体不同特征属性、不同人员认知能力导致的疏散从众选择差异,利用元胞自动机模拟人群运动状态及动态演化过程,探究从众行为对人群疏散过程的作用规律。结果表明:人群疏散中选择从众行为的人员比例与整体疏散效率存在对应关系,本模型原始工况下,当人群中约60%的人员做出从众选择时,疏散效率相对最优。     

淤地坝坝地淤积与侵蚀性降雨的灰色关联分析

水土流失是黄土高原地区重要的环境问题之一,淤地坝措施作为该区水土流失治理的重要工程措施之一发挥了巨大作用,但其淤积过程与水毁机理的研究较少.本文在全面调查黄土高原淤地坝的基础上,选取典型淤地坝,挖取剖面进行测量和分层取样,利用库容曲线和实测每个淤积层的淤积厚度求得每层淤积泥沙量,运用灰色关联分析法,系统地研究了侵蚀性降雨的4个指标(降雨侵蚀力R、降雨量P、最大30 min降雨强度,I30、平均降雨强度 I)与坝地泥沙淤积量之间的关联度.结果表明,降雨侵蚀力 R和坝地泥沙淤积量的发展趋势最为密切,呈幂函数关系;降雨量 P对淤积量的影响仅次于降雨侵蚀力,其关系呈指数型;最大30 min降雨强度,I30和平均降雨强度I对坝地泥沙淤积量的影响较小.     

异养硝化细菌Bacillus sp. LY脱氮性能研究

研究了异养硝化细菌Bacillus sp. LY的脱氮性能.结果表明,Bacillus sp. LY是1株具有脱氮能力的异养硝化细菌.在NH⁺₄-N浓度分别为40、80和120 mg/L 3种情况下,120 h反应后,氨氮的去除率分别是100%、85.7%、73.7%,总氮的去除率分别是76.6%、53.4%、64.8%,在菌液初始浓度相同的情况下,随着NH⁺₄-N浓度的增加,细菌的硝化速率以及脱氮速率呈现下降的趋势.有机物浓度是影响Bacillus sp. LY脱氮性能的重要因素,低的有机物浓度会阻碍细菌脱氮性能的发挥,中的有机物浓度会促进细菌脱氮性能的发挥,使体系的脱氮效果达到最佳,高的有机物浓度并不能再次提升细菌的脱氮性能.在Bacillus sp. LY作用下,有机氮经过氨化作用生成氨氮,通过2条可能的途径转化为氮气.1条途径是氨氮先硝化生成亚硝酸盐与硝酸盐,然后反硝化生成氮气.另1条途径是氨氮被氧化生成羟胺,然后脱氢生成氧化亚氮并进一步转化为氮气.这些研究可为开发新型高效生物脱氮工艺提供参考.     

水绵（Spirogyra）对蓝藻复苏及藻类群落结构的影响

通过采集富营养化水体中的底泥与上覆水,在自然光照条件下建立了模拟自然水体的实验装置,并设置了高（42mg.L-1）、低（21mg.L-1）、空白（0mg.L-1）3个水平的水绵添加量,研究了不同剂量的水绵对水华蓝藻（以微囊藻为主）复苏过程及藻类群落结构的影响,同时考察了充足的营养盐在实验中所起的作用.整个实验在藻类的复...     

粉煤灰对苯酚废水的吸附研究

在静态条件下研究了粉煤灰对苯酚的吸附性能,结果表明:平均粒径29.06μm,孔隙率64.0686%,在吸附时间50min,粉煤灰用量120 g/L,pH=7.45条件下,对75 mL浓度为30 mg/L的苯酚模拟废水,吸附效果最好,可达82.4%。粉煤灰吸附苯酚机理复杂,偏向于单分子层吸附的Langmuir吸附等温线模式:q=0.042Ce/(1+0.095Ce),吸附反应为一级反应,速率方程为lnC=-0.0096t+3.3097(C0=30 mg/L)。     

Bioaccumulation and translocation of cadmium in cole （Brassica campestris L.） and celery （Apium graveolens） grown in the polluted oasis soil, Northwest of China

A pot experiment was conducted to study the bioaccumulation and translocation of cadmium (Cd) in cole (Brassica campestris L.) and celery (Apium graveolens) grown in the Cd-polluted oasis soil, Northwest of China. The results showed that Cd in the unpolluted oasis soil was mainly bound to carbonate fraction (F2) and Fe-Mn oxide fraction (F3). However, marked change of Cd fractions was observed with increasing soil Cd concentrations, in which the concentration of Cd in F1 (exchangeable fraction), F2 and F3 increased significantly (p < 0.001 for F1, F2 and F3). The growth of cole and celery could be facilitated by low concentrations of Cd, but inhibited by high concentrations. The correlation analysis between the fraction distribution coefficient of Cd in the soil and Cd concentration accumulated in the two vegetables showed that Cd in F1 in the soil made the greatest contribution on the accumulation of Cd in the two vegetables. The high bio-concentration factor and the translocation factor of Cd in both cole and celery were observed, and Cd had higher accumulation in the edible parts of the two vegetables. Therefore, both cole and celery grown in Cd-polluted oasis soil have higher risk to human health. And the two vegetables are not suitable to be cultivated as vegetables consumed by human in the Cd-polluted oasis soil.     

Forest soil CO2 fluxes as a function of understory removal and N-fixing species addition

We report on the effects of forest management practices of understory removal and N-fixing species (Cassia alata) addition on soil CO2 fluxes in an Eucalyptus urophylla plantation (EUp), Acacia crassicarpa plantation (ACp), 10-species-mixed plantation (Tp), and 30-species-mixed plantation (THp) using the static chamber method in southern China. Four forest management treatments, including (1) understory removal (UR); (2) C. alata addition (CA); (3) understory removal and replacement with C. alata (UR+CA); and (4) control without any disturbances (CK), were applied in the above four forest plantations with three replications for each treatment. The results showed that soil CO2 fluxes rates remained at a high level during the rainy season (from April to September), followed by a rapid decrease after October reaching a minimum in February. Soil CO2 fluxes were significantly higher (P < 0.01) in EUp (132.6 mg/(m2·hr)) and ACp (139.8 mg/(m2·hr)) than in Tp (94.0 mg/(m2·hr)) and THp (102.9 mg/(m2·hr)). Soil CO2 fluxes in UR and CA were significantly higher (P < 0.01) among the four treatments, with values of 105.7, 120.4, 133.6 and 112.2 mg/(m2·hr) for UR+CA, UR, CA and CK, respectively. Soil CO2 fluxes were positively correlated with soil temperature (P < 0.01), soil moisture (P < 0.01), NO3?-N (P < 0.05), and litterfall (P < 0.01), indicating that all these factors might be important controlling variables for soil CO2 fluxes. This study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.     

优质发酵酒精生产酒糟废水回用技术研究

研究以控制优质发酵酒精贸易中二叶恶烷限量为目标,通过实验室模拟研究了不同水源做工艺拌料水时酒精中二叶恶烷含量对比,确定地下水为优质发酵酒精生产的工艺用水;研究了酒糟污水处理后SBR水对酒精发酵质量影响;将小试结论用于酒精生产的实际工艺,产品中二叶恶烷含量检测表明,60%SBR水40%地下水能够满足优质酒精的工艺用水要求。对SBR水反复回用3次后,酒精中二噁烷含量仍处于较低水平,能够满足优质酒精贸易中二叶恶烷限量的要求。     

中国可再生能源发展的环境影响及管理对策

可再生能源并不是“绝对的”清洁能源,其产业链的部分环节也会污染环境和破坏生态。环境管理不善是造成可再生能源项目生态环境破坏的重要原因之一．巨额投资对经济发展的带动作用导致其环保问题被忽视。未来我国可再生能源将持续快速发展,环境影响及生态破坏问题将有可能集中爆发,必须采取有效的管理措施,避免可再生能源环境污染及生态破坏问题,促进可再生能源产业全面均衡健康发展。     

典型河口底栖动物种类数、生物量及种群密度变化趋势的研究

根据2004～2008年每年5月和8月对黄河口、长江口及珠江口生态监控区底柄动物的监测结果,对以上三大河口底栖动物的种类数、生物量以及种群密度的现状进行了分析,并将数据与同地区、同季节的历史资料进行对比,分析变化趋势.结果表明,黄河口、长江口、珠江口底栖动物种类数均随时间变化呈明显减少趋势.黄河口春、夏两季底栖动物生物...