Effects of controlled drainage on N and P losses and N dynamics in a loamy sand with spring crops

The effects of controlled drainage on N and P losses from soil were examined in a 4-year field drainage experiment on a loamy sand in Southern Sweden. Of the three plots (0.2 ha each), one was drained by conventional subsurface drainage (CD), and two by controlled drainage (CWT1 and CWT2). The groundwater level in the CWT plots was naturally drained to at least 70 cm below the soil surface during the vegetation period between early spring and harvest but allowed to rise to 20 cm below the soil surface during the rest of the year. Measurements of precipitation, drain outflow, weir depths and air and soil temperatures were carried out hourly. Groundwater levels were measured and samples of drain outflow for analyses were collected twice a month. Mineral N contents in soil were measured three times a year and grain yields and N uptake in crops after harvest.     

Remediation of polycyclic aromatic hydrocarbon-contaminated soils using microbes and nanoparticles: A review

Polycyclic aromatic hydrocarbon(PAH) pollution is a global concern because of their toxicity to environment and ecosystem, which induces adverse effects on plants, animals, and humans. Hydrocarbons are mainly released from natural and anthropogenic activities, such as incomplete fuel combustion, leakages in oil pipelines, and the extensive use of pesticides; PAH contaminants include petroleum hydrocarbons(PHCs), halogenated hydrocarbons, chlorophenols, and pesticides. Bioremediation using microo...     

三峡库区消落带典型草被对氮磷污染物迁移的影响

为明确三峡库区消落带草被对农业面源污染防治的作用,采用野外放水冲刷试验,分析草带对地表径流中氮磷的拦截率和冲刷前后氮磷含量在土壤内的空间变化,研究消落带典型草被对氮磷污染物迁移的影响。结果表明:(1)草带拦截污染物的效率总体较好,对NO_3~--N的拦截率最高,达93.5%～99.3%。拦截率与草带宽度成正比,与冲刷强度成反比。(2)冲刷前后TN、TP、NO_3~--N和NH_4~+-N污染物含量的变化率最大值分别为2.30,1.96,5.01,4.75,均出现在小区下坡。随着草带宽度增加以及冲刷强度的减弱,污染物含量的变化率增大。(3)各氮磷污染物在0—10 cm土层的变化率较大,变化范围为0.91～5.01。TN、TP和NH_4~+-N在10—30 cm土层的变化率普遍接近1,而NO_3~--N在该土层依然存在较大的变化率。(4)RDA结果显示,影响冲刷前后污染物变化最大的因子是土层深度,其次是坡位、草带宽度、冲刷强度。综上,消落带草被能够有效拦截污染物并促进其向土壤内部迁移,在消落带草本植物恢复及面源污染防治过程中应注意增加消落带草被覆盖宽度,减小高强度降雨径流的影响,促进污染物在上坡位被拦截并进一步向土壤内部迁移,降低污染物向上覆水释放的风险,为三峡库区消落带草本植被恢复及农业面源污染防治提供理论依据。     

海洋污染物对菲律宾蛤仔的免疫毒性

环境污染能够影响养殖贝类的免疫能力,是导致贝类大规模死亡的重要原因之一。探讨了大连周边4个海区污染物对采集的菲律宾蛤仔(Ruditapes philippinarum)免疫毒性影响。结果发现:污染物浓度和种类对蛤仔的免疫和生理指标具有重要影响,在重金属和石油污染物浓度较低的皮口海区,血细胞总数、亮氨酸氨基肽酶活性和血淋巴溶菌酶活性均显著高于其它3个海区(P<0.05),而蛤仔的脂质氧化水平则较低;在重金属和石油污染物浓度较高的黑石礁海区,蛤仔血淋巴谷胱甘肽含量显著高于其它3个海区(P<0.05);在重金属浓度较高的庄河海区,蛤仔表现出较高的超氧化物歧化酶活性(P<0.05)。     

原位生物技术对城市重污染河道底泥的治理效果

以扬州市典型城市内河河道为例研究了人工曝气、生态砖覆盖、生物填料覆盖、低位植物浮床(简称低位浮床)等原位生态处理技术对河道底泥污染释放及其对上覆水污染负荷贡献的治理效果.研究结果表明:经不同原位生态处理后,1)底泥中氨氮的释放速率下降50.3％-89.64％,平均为59.27％;底泥污染释放对上覆水氨氮负荷贡献量的去除率为36.59％-82.67％,平均为53.33％;2)底泥中总氮的释放速率下降20.96％-88.94％,平均为42.32％;底泥总氮释放对上覆水污染负荷贡献量的污染去除率为38.00％-67.06％,平均为54.96％;3)底泥中总磷的释放速率下降27.49％-91.00％,平均为55.31％;底泥总磷释放对上覆水总磷污染负荷贡献量的去除率为67.14％-98.46％,平均为84.33％;4)底泥中CODMn的释放速率下降11.84％-79.32％,平均为41.16％;底泥上覆水中CODMn的释放速率下降-1.25％--70.74％,平均为29.83％.研究还发现,原位生态处理技术在运行中对底泥污染治理的效果受该技术对底泥的扰动程度的影响,在进行集成应用的时候,对底泥扰动较大的技术应与对底泥扰动较小的技术相间应用,以减少工程技术运行中对底泥扰动造成的污染爆发式释放,达到更好的整体处理效果.     

玉米秸秆压缩加载条件对其裂纹和机器功耗的影响

针对中国北方刚收获的玉米秸秆含水率高需进行调质处理的情况,为设计玉米秸秆调质装置,该文通过单因素试验,研究了压缩调质时加载方式(单点直压和三点弯曲)、加载位置(节间和节部)和加载方向(长轴和短轴)对相同含水率玉米秸秆压缩裂纹、载荷和功耗的影响。结果表明:施压过程中,2种加载方式的秸秆表皮均沿轴向产生4条主裂纹,且其呈上、下、左、右对称分布。加载位置和加载方向相同时,三点弯曲和单点直压开始产生各主裂纹的压下位移相近,但前者的载荷和功耗均低于后者。当达到最佳调质压下位移(18 mm)时,三点弯曲载荷和功耗的均值较单点直压分别显著降低约55.5%和25.5%(α=0.05)。研究结果为玉米秸秆收获调质装备关键部件的设计提供依据。     

塑料大棚设计中基本风压取值方法

目前塑料大棚设计中基本风压基本按照《建筑结构荷载规范》取值,但塑料大棚结构轻,覆盖大棚的塑料薄膜在强度上远不如工业与民用建筑所用的砖石结构、钢筋混凝土结构及轻钢结构。此外,往往瞬时风速就有可能将整个大棚结构摧毁,因此按工业与民用建筑标准的荷载取值方法不尽适合塑料大棚的结构设计。该文针对塑料大棚特点,提出采用3 s瞬时风速作为计算基本风压的依据,并搜集整理了中国各台站近30 a的气象数据,形成了塑料大棚结构设计的专用资料库,并绘制出中国基本风压等值线图,可供塑料大棚结构设计应用。     

我国杀虫剂类持久性有机污染物管理状况研究

论述了我国杀虫剂类POPs生产历史和使用状况,分析了我国杀虫剂类POPs的管理现状,指出了我国管理上存在的一些问题。针对我国杀虫剂类POPs管理上的不足,提出了几点建议,希望能帮助解决相关的问题,加强我国的履约能力。     

Uncertainty analysis of critical loads for terrestrial ecosystems in Russia

The goal of this study is to give a comprehensive and quantitative estimation of the uncertainty of computed in different scale nitrogen (N) and sulphur (S) critical loads (CL) values for terrestrial ecosystems of the Northern Asia, European part and the North-Western regions of Russia. The CL values are used to set goals for future deposition rates of acidifying compounds so that the environment is protected. In this research CL values for terrestrial ecosystems are determined using the expert-modelling geoinformation system (EM GIS) approach. UNCSAM software package is used as the tool for uncertainty analysis. The analysis presented here focuses on the estimation and effect of the input source uncertainties and sensitivities on the CL values in various regions under study. In spite of the region, nitrogen uptake by vegetation, nitrogen leaching from terrestrial ecosystems and the difference between deposition and uptake by plants of base cations (BC) are the most influential factors for all terrestrial ecosystems of Russia.     

Critical loads mapping in Poland: Lessons learned

Since 1990 the Institute for Ecology of Industrial Areas, acting as National Focal Center, is actively involved in an international research programme aimed at the calculation and mapping of critical loads of acidifying compounds. Following the methodological guidelines elaborated under the leadership of UN/ECE Task Force on Mapping and Coordination Center for Effects, national maps of critical loads and their exceedances for acidity, sulphur and nitrogen have been produced. These maps have already been utilized in derivation of European maps of critical loads of acidity and sulphur submitted to the UN/ECE LRTAP Convention as scientific input to the negotiations on the Second Sulphur Protocol. The lessons learned from the critical loads mapping exercise can be summarized as follow: