氮肥种类及用量对赤红壤pH和可溶性盐的影响

为了探讨施用氮肥对赤红壤性土壤pH和可溶性盐的影响,以赤红壤上发育的水稻土为供试土壤,以油麦菜(Lactucasativa L)为栽培作物,采用盆栽试验,研究了在施等量的磷(P2O5 0.08 g·kg-1)、钾(K2O 0.16 g·kg-1)条件下,尿素、硫酸铵、氯化铵、硝酸铵4个氮肥品利吸其不同用量水平(0、0.08、0.16、0.24和0.32 g·kg-1)下土壤的pH和可溶性盐的变化情况.结果表明,施用氮肥的利,类及用量对赤红壤性土壤的pH、可溶性盐及K 、Na 、Ca2 和Mg2 的质量分数有显著影响;随着氮肥用量的增加,土壤pH显著降低,而可溶性盐及K 、Na .、Ca2 和Mg2 的质量分数则升高;在各施氮水平下,(NH4)2SO4、NH4Cl对土壤pH、可溶性盐及K 、Na 、Ca2 和Mg2 的质量分数的影响总体上明显大于CO(NH2)2、NH4NO3.     

不同温度与威百亩联合时对线虫的杀灭效果评价

通过设定不同温度、培养时间及其与熏蒸剂威百亩结合,对青岛、固安、北京三地线虫的杀灭效果进行了测定.结果表明,不添加熏蒸剂时,线虫在50℃、55℃、25℃处理187 h,死亡率分别为100%、100%、10%左右.说明50℃以上不利于线虫的生存.当用威百亩8.4 mg·kg-1处理土壤,在40℃、50℃、25℃培养168 h或威百亩12.8 mg·kg-1处理土壤培养24 h,线虫死亡率分别为100%、100%、60%左右.由此可见,在不利线虫生长的环境条件下,添加少量的熏蒸剂,可显著提高熏蒸剂的杀线虫效果.     

基于主成分分析的全国建设用地集约度评价

建设用地的集约利用是一个基于时空尺度的动态概念.首先了解了1996-2005年期间全国建设用地变化的大背景,然后以全国各省、市、自治区2005年建设用地数据、各种社会经济数据为基础,在总结前人研究的基础上,构建了全国建设用地集约利用评价体系,采用主成分分析的方法,确定了各省、市、自治区建设用地的集约分值,根据标准确定了各自的集约度水平,结合ArcGis将评价结果空间化,进一步分析了集约度的空间差异.针对不同的集约度区域提出了针对性的意见,为区域建设用地集约利用提供指导,促进经济发展.研究结果表明,(1)全国建设用地数量在持续上升,增长率呈现波浪状;(2)建没用地的集约度在空间上存在差异,东部沿海地区的集约度水平要高于中部和西部地区;(3)环境的可持续发展指标是考核建设用地集约利用的重要因素;(4)利用主成分分析的方法在结果评价时比较客观、全面,同时可以很方便地确定权重系数.     

红树林生态系统微生物学研究进展

红树林生态系统是复杂而独特的生态系统,是目前环境科学和生态学研究的热点领域,而对红树林生态系统微生物学的研究也越来越受到重视,目前研究的热点主要集中在红树林生态系统微生物的物种多样性、生理活性物质多样性以及环境修复功能上.未来的研究,除了现有的研究基础要加强,研究手段与方法要采用新技术外,还应该在探索红树林生态系统微生物与物质和能量平衡、微生物与其它生物及其与气候的关系等方面进一步深入研究.     

Biodiversity mediates productivity through different mechanisms at adjacent trophic levels

Biodiversity may enhance productivity either because diverse communities more often contain productive species (selection effects) or because they show greater complementarity in resource use. Our understanding of how these effects influence community production comes almost entirely from studies of plants. To test whether previous results apply to higher trophic levels, we first used simulations to derive expected contributions of selection and complementarity to production in competitive assemblages defined by either neutral interactions, dominance, or a trade-off between growth and competitive ability. The three types of simulated assemblages exhibited distinct interaction signatures when diversity effects were partitioned into selection and complementarity components. We then compared these signatures to those of experimental marine communities. Diversity influenced production in fundamentally different ways in assemblages of macroalgae, characterized by growth-competition trade-offs, vs. in herbivores, characterized by dominance. Forecasting the effects of changing biodiversity in multitrophic ecosystems will require recognizing that the mechanism by which diversity influences functioning can vary among trophic levels in the same food web.     

络合剂和酸度控制对土壤铬电动过程的影响

研究了添加络合剂和控制阴极池溶液酸度对铬在黄棕壤中电动过程的影响.结果表明,EDTA 柠檬酸和乳酸的加入明显改变了电动过程中电渗流的大小和铬在土柱中的分配,其中柠檬酸因可与土壤中的 Cr(III)发生较强的络合作用而显著增加了土壤总铬的去除率(29.8%);改变阴极池溶液酸度不仅影响了电动过程中电流、电渗流的大小和铬在土柱中的分配,同时也显著改变了总铬的去除率.其中在 pH 6.0 和pH 10.0 时,总铬的去除率分别达 25.3%和 24.0%,较 pH 4.0 和 pH 8.0 时增高近 1 倍.所有电动处理以后土壤中剩余的六价铬浓度均显著减少,约降低 80%,表明电动处理对土壤中六价铬(铬的主要有毒形态)的去除是非常有效的.     

改进密切值法在地面水环境质量评价中的应用

密切值法(OsculatingMethod)作为一种多目标优选方法,在水环境质量评价中具有一定的应用。经过改进,将环境标准作为评价样本,参与到地面水环境样本的矩阵中,可以分析出各个监测断面的水质优劣排序,并使其与各级环境标准的关系一目了然。引入层次分析法,对各评价指标的贡献程度加以确定,保证了地面水环境质量评价的科学性。     

Anaerobic co-digestion of kitchen waste and fruit/vegetable waste: Lab-scale and pilot-scale studies

The anaerobic digestion performances of kitchen waste (KW) and fruit/vegetable waste (FVW) were investigated for establishing engineering digestion system. The study was conducted from lab-scale to pilot-scale, including batch, single-phase and two-phase experiments. The lab-scale experimental results showed that the ratio of FVW to KW at 5:8 presented higher methane productivity (0.725 L CH₄/g VS), and thereby was recommended. Two-phase digestion appeared to have higher treatment capacity and better buffer ability for high organic loading rate (OLR) (up to 5.0 g (VS) L^?1 d^?1), compared with the low OLR of 3.5 g (VS) L^?1 d^?1 for single-phase system. For two-phase digestion, the pilot-scale system showed similar performances to those of lab-scale one, except slightly lower maximum OLR of 4.5 g (VS) L^?1 d^?1 was allowed. The pilot-scale system proved to be profitable with a net profit of 10.173 $/ton as higher OLR (?3.0 g (VS) L^?1 d^?1) was used.     

Assessment of Pb and pyrene accumulation in Scirpus triqueter assisted by combined alkyl polyglucoside and nitrilotriacetic acid application

Environmental Science and Pollution Research - To understand the accumulation and uptake of polycyclic aromatic hydrocarbons (PAHs) and heavy metals by plants is an important part of the assessment...     

Influence of surface properties of RO membrane on membrane fouling for treating textile secondary effluent

Environmental Science and Pollution Research - Reverse osmosis (RO) is a promising technology for treating and reusing textile secondary effluent (SE). To better understand the effect of membrane...