土地利用方式和施肥管理对黑土物理性质的影响

为了探讨东北黑土区土壤水分的调控能力及其影响因素以及土壤水分对降水和不同植被覆盖的响应,以海伦农田生态系统国家野外科学观测研究站内的长期定位试验为基础,利用中子水分仪测定土壤体积含水量,研究裸地、休闲地以及包括单施有机肥、化肥+秸秆还田、单施化肥和不施肥4种处理的农田耕层土壤物理性质和土壤水分动态.结果表明:与休闲地相比,农田土壤容重增加7.47％,而孔隙度、饱和含水量和田间持水量均呈降低趋势,分别下降2.59、6.04和1.90百分点;肥料的施入尤其是施用有机肥和秸秆还田能够改善土壤物理性质;裸地土壤物理性质最差.由于植被耗水量较大,农田和休闲地土壤剖面年平均体积含水量显著低于裸地,施用化肥和秸秆还田可显著降低农田土壤剖面年平均体积含水量.各处理土壤剖面水分变异系数均随土壤深度的增加(0～70 cm深处)而呈先减小后增加趋势.由于植被生长的耗水作用,休闲地和农田土壤水分变化比裸地强烈,秸秆还田加剧了农田土壤水分的变异.土壤储水量的动态变化与降水量之间存在明显相关性,不同土地利用方式和施肥管理对浅层土壤储水量的影响较大,但随着土壤深度的增加,各处理对土壤储水量的影响越来越不明显.     

微生物法处理海上钻井废钻井液

微生物法适用于海上钻井含油废弃物的处理。通过多次对菌株采集、分离、纯化和培养驯化,选育得到了3株对石油烃类有很好降解效果的石油类降解菌;确定了石油类降解菌适宜的生化处理条件:最佳生长及原油降解温度为50℃、最佳生长及原油降解酸碱性环境为pH=6.0、最佳菌株接种量2%、最佳原油初始浓度为500mg/L。处理后的含油废弃钻井液含油量基本稳定在2mg/L以下,降解率达98%以上。     

Two-Compartment Sorption of Phenanthrene on Eight Soils with Various Organic Carbon Contents

Sorption characteristics of phenanthrene (PHE) were studied on eight soils with organic carbon contents spanning over an order of magnitude using phase distribution relationships (PDRs) at 1 h, 48 h, and 720 h contact times. A new algebraic method was employed to describe the sorption characteristics at different time intervals (between 1 h and 48 h, and 1 h and 720 h). It was found that nonlinearity increased with increasing contact time and sorption that occurred in the subsequent time interval following the initial 1 h exhibited stronger isotherm nonlinearity. Sorption coefficients were positively correlated with the organic carbon contents of the soils. Detailed sorption dynamics were also examined on these soils. A two-compartment, first-order model was used to describe the sorption dynamics. The rate constants of the two compartments differed 18–170 times, suggesting the dissimilar sorption behaviors of the mathematically separated compartments. These two compartments were labeled fast and slow sorption compartment according to the rate constants. Calculation showed that the fast compartment accounted for over 80% of the overall sorption at the initial 1 h, while the slow compartment predominated the total sorption in the following 47 h. By combining the discussion of PDRs and sorption dynamics, the contributions of the two compartments to linear and nonlinear sorption were differentiated. The slow sorption compartment made a major contribution to nonlinear sorption and possibly to sequestration of organic pollutants by these soils.     

Effect of land management on soil microbial N supply to crop N uptake in a dry tropical cropland in Tanzania

In Sub-Saharan Africa, conservation of available soil N during early crop growth, when N loss by leaching generally occurs, is important to improve crop productivity. In a dry tropical cropland in Tanzania, we assessed the potential role of soil microbes as a temporal N sink-source to conserve the available soil N until later crop growth, which generally requires substantial crop N uptake. We evaluated the effect of land management [i.e., no input, plant residue application before planting (P plot) with or without fertilizer application, fertilizer application alone, and non-cultivated plots] on the relationship between soil N pool [microbial biomass N (MBN) and inorganic N] and crop N uptake throughout the ∼120-d crop growth period in two consecutive years. In the P plot, MBN clearly increased (∼14.6-29.6 kg N ha⁻¹) early in the crop growth period in both years because of immobilization of potentially leachable N, and it conserved a larger soil N pool (∼10.5-21.2 kg N ha⁻¹) than in the control plot. Especially in one year in which N leaching was critical, increased MBN maintained a larger soil N pool in the P plot throughout the experimental period, and a delay of increased MB C:N ratio and a substantial decrease in MBN was observed, indicating better soil microbial N supply for crop N uptake during later crop growth. Therefore, plant residue application before planting should enhance the role of soil microbes as a temporal N sink-source, leading to the conservation of potentially leachable N until later phase of crop growth, especially in years in which N leaching is relatively severe. Although further studies are necessary, our results suggest that plant residue application before planting is a promising option to achieve better N synchronization.     

北湖流域水质改善系统动力学研究

利用系统动力学擅长研究动态、非线性复杂系统的特点,将其应用于北湖水质改善分析,构建了系统动力学-水质耦合模型,可实现长时间序列的连续模拟和水环境管理的情景分析。文章定量分析了三产比例调整、城镇化率提高与污水集中处理等因素对流域纳污控制及水质改善的影响,推演出可协调经济发展-水环境保护-污水治理资金三方矛盾的合理方案,为类似小城镇的发展提供可借鉴的思路和方法。     

广东南水水库富营养化与浮游植物群落动态

南水水库是广东省第三大水库,属饮用水源一级保护区。于2011年1~12月对该水库的水文、水质和浮游植物进行了每月一次、为期一年的调查,采用营养状态指数(TSI)进行了水质综合评价,分析了浮游植物群落的动态变化规律,选择冗余分析(RDA)研究了影响浮游植物群落结构的环境因素。结果表明:南水水库现为贫营养型,全年浮游植物的种类变化不大,共鉴定出浮游植物6门50属(种),优势种以适应贫营养的种类为主,且浮游植物的丰度、生物量及叶绿素a浓度都较低,其均值分别为8.72×104～2.51×105cells/L、0.031～0.423 mg/L和0.83～2.80 mg/L。浮游植物群落主要以硅藻、甲藻和绿藻种群为主,硅藻种群全年占优势,甲藻和绿藻在不同季节优势度有变化,体现出从硅藻型到硅藻-甲藻型,到硅藻-绿藻型,再到硅藻-甲藻型的变化过程。温度、氮磷比和水体稳定性的季节变化是影响上述浮游植物群落动态的主要因子。     

一株Acinetobacter johnsonii的部分反硝化特性及动力学研究

从实验室A²/O小试设备中分离纯化出一株具有高亚硝酸盐氮（NO₂^--N）积累率的反硝化菌株ZY04,经过16SrDNA鉴定和基因比对后,初步鉴定为Acinetobacter johnsonii.使用Logistic模型可以很理想地拟合菌株ZY04的生长特性曲线,得到生长方程常数a=0.6588,b=24.08,k=0.2413.在维持初始基质中硝酸盐氮（NO₃^--N）浓度为100mg/L的条件下,改变碳源乙酸钠的浓度,使碳氮比（TOC/TN）为3.5,4.5,5.5,6.5,研究菌株ZY04部分反硝化性能,发现该菌株在不同碳氮比条件下均能够保持95%以上的NO₃^--N降解率,在碳氮比为3.5和4.5时,17h后NO₂^--N积累率达到70%以上;在碳氮比为5.5和6.5时,NO₂^--N积累率在更快的11h后达到85%以上,碳氮比为5.5时达到最高NO₂^--N积累率91%.使用Aiba,Edwards和Andrews模型对菌株的基质抑制动力学进行拟合,结果表明,3种模型均可以很好的拟合NO₃^--N和乙酸钠对菌株的单基质抑制动力学,在双基质抑制的9种组合中,有6种模型成功拟合了NO₃^--N和乙酸钠对菌株的双基质抑制动力学,得到了相关半饱和参数和基质抑制参数,相关系数（R²）可以达到98%.     

波尔多液对土壤过氧化氢酶活性与构象的影响

为初步探讨波尔多液对土壤过氧化氢酶的作用机理及变化规律,采用人工模拟和荧光光谱法研究了波尔多液对土壤过氧化氢酶活性特征及构象的影响.结果表明:1)不同浓度波尔多液对土壤过氧化氢酶活性总体呈现低浓度激活、高浓度抑制作用.不同配制方式波尔多液对土壤过氧化氢酶活性抑制效应顺序为多倍量式>倍量式>半量式>等量式.浓度为200mg·kg-1左右的等量式波尔多液处理对土壤过氧化氢酶活性的影响最小.2)24h培养时间下,随波尔多液浓度的增加,酶促反应米氏常数Km和最大反应速率Vmax均呈先减小后增大趋势.统计分析表明,Km和Vmax均与波尔多液浓度呈显著正相关(p<0.01),土壤过氧化氢酶Km值可表征波尔多液对土壤过氧化氢酶活性的影响程度,其作用机理为反竞争性抑制类型.3)波尔多液对离体过氧化氢酶的内源荧光有较强的猝灭作用,Cu(Ⅱ)和离体过氧化氢酶的结合常数K及结合位点数n分别为69.1831mol·L-1和0.6878.     

Role of glycine on sulfuric acid-ammonia clusters formation: Transporter or participator

Glycine(Gly) is ubiquitous in the atmosphere and plays a vital role in new particle formation(NPF).However,the potential mechanism of its on sulfuric acid(SA)-ammonia(A)clusters formation under various atmospheric conditions is still ambiguous.Herein,a(Gly)_x·(SA)_y·(A)_z(z≤x+y≤3) multicomponent system was investigated by using density functional theory(DFT) combined with Atmospheric Cluster Dynamics Code(ACDC) at different temperatures and precursor concentrations....