绿道网规划建设与管理进展分析

绿道是将大量自然、经济、社会的景点、集聚地和示范点连接在一起的,兼具生态、体育、休闲、文化和通行功能的,彰显绿色、智慧、创新、务实和人本理念的线性生态开敞空间。经历了一百多年的发展后,绿道建设已成为一项全球性运动。绿道建设对促进城市质量提高,推动低碳生态城市建设具有重要意义。西方国家和部分亚洲国家和地区的绿道已发展到了较为成熟的阶段。我国内地引入绿道的时间较晚,但建设步伐快,发展迅速,尤其是珠三角绿道建设更为迅速。国内外在绿道网建设过程中积累了一定的经验,也存在一定的问题,为更好地推进我国绿道网建设,提高绿道网管理水平,非常有必要对国际绿道网和我国珠三角绿道网的进展状况进行分析。本文系统地介绍了绿道的发展历程,并从规划设计、建设实践、科学研究与管理等方面对绿道建设状况进行了深入分析。在总结、分析国内外绿道网建设经验与存在问题基础上,提出了我国绿道网建设对策,主要包括：（1）因地制宜,科学规划;（2）加快完善标识系统建设;（3）尽快探讨绿道网经营模式;（4）建立绿道监测与评估机制等。     

Ag(I)对大肠杆菌抑制作用影响因素的分析

通过测定在各种条件下Ag(I)对大肠杆菌Escherichia coli的生长的抑制作用,系统分析了各参数对Ag(I)毒性的影响.结果表明:好氧、厌氧状态下,Ag(I)对E.coli的抑制能力基本相同;在LB培养基、氨基酸基本培养基和标准基本培养基中Ag(I)开始抑制E.coli生长的浓度差异较大,分别为10、0.5、0.1μmol/L; LB组分中的酵母粉的加入完全消除了Ag(I)对E.coli的抑制作用;此外,菌体浓度越高抑制其生长所需的Ag(I)浓度也越高.因此Ag(I)对E.coli生长的抑制作用与氧化应激无关,而与培养基种类、培养基组分及菌体浓度高度相关.     

典型菜地土壤汞在小白菜和胡萝卜可食部位的富集规律

对广东省蔬菜种植面积较大的10个城市典型菜地土壤和蔬菜（小白菜和胡萝卜）对应采样,分析217个蔬菜可食部位中重金属汞（Hg）质量分数及对应土壤中Hg全量和有效态质量分数,研究大田条件下小白菜和胡萝卜可食部位富集Hg的规律。结果表明,广东省菜地土壤存在一定的Hg污染,约20％的土壤超过国家土壤环境质量标准（GBl5618－1995）中二级标准值,但小白菜和胡萝卜中Hg质量分数较低,均值分别为0．0012和0．0013mg·kg-1,仅2个小白菜样品Hg质量分数超过国家食品卫生标准《食品中污染物限量》（GB2762-2005）中的限值0．01mg·kg-1。TGA提取的土壤有效态Hg质量分数与土壤Hg全量显著正相关,TGA提取Hg量仅占土壤总Hg质量分数的3％-4％。小白菜和胡萝卜对Hg的富集系数分别为0．90％和0．94％,表明土壤中绝大部分的Hg不易转化迁移、为蔬菜吸收。小白菜和胡萝卜可食部位Hg质量分数与土壤中Hg全量和有效态质量分数均存在显著的线性关系,其中蔬菜与土壤Hg有效态质量分数的关系优于其与土壤Hg全量的关系。依据国家食品卫生标准,通过拟合回归方程计算出的保障小白菜和胡萝b质量安全的菜地土壤Hg有效态质量分数临界值分别为O．038和0．063mg·kg-1。计算出的土壤Hg全量临界值远大于我国现行土壤环境质量标准的二级标准值,表明该标准值对于保障广东省小白菜和胡萝b质量安全来说可能过于严格。     

大肠杆菌植酸酶的原核表达及酶学性质

将大肠杆菌植酸酶appA摹因重组于表达载体pET32a中,导人大肠杆菌Origami(DE3)构建工程菌Origami(DE3)-pET32aappA.对表达的appA重组植酸酶经Ni柱亲和纯化、SDS-PAGE分析表明,纯化后条带单一,酶的纯度较高.对其酶学性质的研究表明,该酶反应的比活力为3.36×106 U/mg;最适pH为4.5;最适温度为60℃ ;在80℃和85℃的耐干热能力超过耐湿热能力;在37℃下,Mg2+、Ca2+、Mn2+对酶活性有促进作用,CO2+、Cu2+、K+对酶活性有不同程度的抑制作用,而Fe3+和Zn2+对酶活性有强烈的抑制作用;此外,该酶还具有非常好的抗胃蛋白酶水解的能力和部分抗胰蛋白酶水解的能力.图8表1参21     

几种挺水植物对重金属锌的抗性能力及其影响因素

水生植物已被用于重金属污染水体的生态修复,但不同水生植物对重金属的抗性能力存在差异,选择对重金属抗性和吸收能力强的植物有利于提高污水生态修复效果.以4种挺水植物为材料,通过室内培养实验研究挺水植物对重金属锌的抗性能力及其影响因素,结果表明:挺水植物地上部分铁含量显著(p<0.05)低于根和根表铁氧化物胶膜上铁含量,铁主要积累在挺水植物地下部分.加入高浓度锌时,灯心草(Jancus effuses)和菖蒲(Acorus gramineus)对锌的抗性能力较强,而茭白(Zizania ceduciflora)和美人蕉(Canna indica)则较弱.挺水植物对锌的抗性能力与其根表铁氧化物胶膜含量和地上部分铁含量有关,铁氧化物胶膜可作为一个障碍层,而降低锌对植物的毒害,而植物地上铁与锌竞争植物叶中的代谢性敏感位点而降低锌对植物的毒害.灯心草对锌的抗性能力比较强与其根表铁氧化物胶膜和地上部分铁含量较高有关,灯心草可作为一种工程植物用于锌污染水体的植物修复.     

Migration of manganese and iron during the adsorption-regeneration cycles for arsenic removal

Fe-Mn binary oxide incorporated into porous diatomite (FMBO-diatomite) was prepared in situ and regenerated in a fixed-bed column for arsenite [As(III)] and arsenate [As(V)] removal. Four consecutive adsorption cycles were operated under the following conditions: Initial arsenic concentration of 0.1 mg·L^-1, empty bed contact time of 5 min, and pH 7.0. About 3000, 3300, 3800, and 4500 bed volumes of eligible effluent (arsenic concentration≤0.01 mg·L^-1) were obtained in four As(III) adsorption cycles; while about 2000, 2300, 2500, and 3100 bed volumes of eligible effluent were obtained in four As(V) adsorption cycles. The dissection results of FMBO-diatomite fixed-bed exhibited that small amounts of manganese and iron were transferred from the top of the fixed-bed to the bottom of the fixed-bed during As(III) removal process. Compared to the extremely low concentration of iron (<0.01 mg·L^-1), the fluctuation concentration of Mn²⁺ in effluent of the As(III) removal column was in a range of 0.01–0.08 mg·L^-1. The release of manganese suggested that manganese oxides played an important role in As(III) oxidation. Determined with the US EPA toxicity characteristic leaching procedure (TCLP), the leaching risk of As(III) on exhausted FMBO-diatomite was lower than that of As(V).     

Practical performance and its effciency of arsenic removal from groundwater using Fe-Mn binary oxide

A treatment unit packed by granular adsorbent of Fe-Mn binary oxide incorporated into diatomite (FMBO(1:1)-diatomite) was studied to remove arsenic from anaerobic groundwater without any pre-treatment or post-treatment. The raw anaerobic groundwater containing 35-45 μg/L of arsenic was collected from suburb of Beijing. Arsenic(III) constituted roughly 60%-80% of the total arsenic content. Approximately 7,000 bed volumes (ratio of efluent volume to adsorbent volume) treated water with arsenic concentration b...     

Concentrations of heavy metals and polycyclic aromatic hydrocarbons in needles of Masson pine (Pinus massoniana L.) growing nearby different industrial sources

Emissions from industrial activities pose a serious threat to human health and impose the need for monitoring both inorganic and organic pollutants in industrial areas.We selected Masson pine (Pinus massoniana L.) as potential biomonitor and collected the current (C) and previous year (C+1) needles from three industrial sites dominated by petrochemical,ceramics manufacturing,and iron and steel smelting plants and one remote site to determine heavy metals (Cu,Cd,Pb,Zn,Cr,Ni and Co) and polycyclic aromatic hydrocarbons (PAHs) in unwashed and water-washed needles.Both unwashed and washed C+1 needles showed generally higher concentrations of heavy metals and PAHs than C needles,although the washed needles more clearly spotlighted the accumulation effect of PAHs over exposure time.Water-washing resulted in a significant decrease in needle PAH concentrations with more significant effects shown in C needles.By contrast,needle heavy metal concentrations were much less affected by washing.Although heavy metals and PAHs might differ in adsorption and uptake strategies,their higher concentrations in the needles at the industrial sites indicated conspicuous contamination due to industrial emissions there,The PAH distribution patterns in pine needles accorded with the real types of energy consumption in the study sites and were efficiently used for pinpointing local pollutant sources.     

地震作用下三维抗滑桩加固土质边坡稳定性分析∗

基于三维抗滑桩加固边坡稳定性极限分析法,采用拟静力法分别对水平地震作用和竖向地震作用下的三维抗滑桩加固边坡稳定性进行了分析,得到以下结论:在水平地震力作用下,边坡的三维效应(限制宽度B/H)对抗滑桩的最有效位置几乎没有影响,但在较大水平地震强度下,最有效的桩位置更靠近边坡顶部;竖向地震力方向向下时(kv0),竖向地震强度绝对值|kv|越大,边坡临界滑动面会变浅,坡顶的破坏区域变小,最有效的桩位置随宽高比B/H的减小而越来越远离坡顶,但当竖向地震力方向向上时(kv0),竖向地震强度绝对值|kv|越大,边坡临界滑动面会变深,坡顶的破坏区域变大,最有效的桩位置随宽高比B/H的减小而越来越接近坡顶,并且三维边坡的安全系数要远大于二维解。     

黄河口径流变化对生态系统净生产力的影响研究

针对水文过程变化对河口生态系统整体平衡的重要作用,利用开放水体溶氧曲线法,分析了黄河口径流变化对生态系统净生产力的影响.径流显著变化的4月至9月期间,黄河口生态系统净生产力变化范围约为-5.32-4.84mg·L-1·d-1,且呈现显著的时空差异性.上河口区和中河口区比远河口区异养;丰水期8月至9月比枯水期5月至6月异...