Coupled oxidation of aromatic hydrocarbons by horseradish peroxidase and hydrogen peroxide

The oxidation capability of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) coupled oxidation of aromatic hydrocarbons (o-xylene-d10 and naphthalene-d8) was investigated. Batch experiments were conducted using horseradish peroxidase prepared in potassium phosphate buffer in the presence of H2O2. The oxidation of aromatic hydrocarbon was tested as a function of HRP at a fixed concentration of H2O2, and as a function of the concentration of H2O2 at a constant HRP activity (4000 units/ml). The mass removal of o-xylene-d10 and naphthalene-ds increased with increasing HRP enzymatic activity, and up to 54% and 51% of mass removal were observed for o-xylene-d10 and naphthalene-d8, respectively. Increasing the concentration of H2O2 resulted in increased mass removal of aromatic hydrocarbons.     

Effect of Rainfall Regime and Slope on Runoff in a Gullied Loess Region on the Loess Plateau in China

Runoff was measured from seven plots with different slopes nested in Tuanshangou catchment on the Loess Plateau to study effect of slopes on runoff in relation to rainfall regimes. Based on nine years of field observation and K-mean clusters, 84 rainfall events were grouped into three rainfall regimes. Rainfall regime A is the group of events with strong rainfall intensity, high frequency, and short duration. Rainfall regime C consists of events with low intensity, long duration, and infrequent occurrence. Rainfall regime B is the aggregation of events of medium intensity and medium duration, and less frequent occurrence. The following results were found: (1) Different from traditional studies, runoff coefficient neither decreased nor increased, but presented peak value on the slope surfaces; (2) For individual plot, runoff coefficients induced by rainfall regime A were the highest, and those induced by rainfall regime C were the lowest; Downslope, the runoff coefficients induced by three rainfall regimes presented the same changing trend, although the peak value induced by regime A occurred on a shorter slope length compared to those by regime B and C; (3) Scale effect on runoff induced by rainfall regime A was the least, and that induced by rainfall regime C was the largest. These results can be explained by the interactions of crusting, soil moisture content, slope length and gradient, and erosion units, etc., in the context of different rainfall regimes.     

关于中国的水安全问题及其对策探讨

随着全球性资源生态危机的加剧及全球化进程的飞速发展 ,国家安全要素扩大到包括资源环境在内的一些非传统安全要素上 ,现今 ,水安全已成为国家安全问题的核心内容之一。为此 ,笔者探讨了我国水安全存在的一些主要问题 ;分析了产生这些问题的原因 ;提供了解决这些问题的对策。     

Estimating runoff phosphorus losses from calcareous soils in the Minnesota River basin

Bioavailable phosphorus (BAP) in stormwater runoff is a key issue for control of eutrophication in agriculturally impacted watersheds. Laboratory experiments were conducted in soil runoff boxes to determine BAP content in simulated storm runoff in 10 (mostly) calcareous soils from the Minnesota River basin in southern Minnesota. The soluble reactive phosphorus (SRP) portion of the runoff BAP was significantly correlated with soil Mehlich-III P, Olsen P, and water-extractable P (all r2 > 0.90 and p < 0.001). A linear relationship (r2 = 0.88, p < 0.001) also was obtained between SRP in runoff and the phosphorus saturation index based on sorptivity (PSIs) calculated with sorptivity as a measure of the inherent soil P sorption capacity. Runoff levels of BAP estimated with iron oxide-impregnated paper were predicted well by various soil test P methods and the PSI, of the soils, but correlation coefficients between these variables and runoff BAP were generally lower than those for runoff SRP. Using these relationships and critical BAP levels for stream eutrophication, we found corresponding critical levels of soil Mehlich-III P and Olsen P (which should not be exceeded) to be 65 to 85 and 40 to 55 mg kg(-1), respectively.     

Uncertainty analysis of predicted disturbance from off-road vehicular traffic in complex landscapes at fort hood

The US Army Engineering Research Development Center (ERDC) uses a modified form of the Revised Universal Soil Loss Equation (RUSLE) to estimate spatially explicit rates of soil erosion by water across military training facilities. One modification involves the RUSLE support practice factor (P factor), which is used to account for the effect of disturbance by human activities on erosion rates. Since disturbance from off-road military vehicular traffic moving through complex landscapes varies spatially, a spatially explicit nonlinear regression model (disturbance model) is used to predict the distribution of P factor values across a training facility. This research analyzes the uncertainty in this model's disturbance predictions for the Fort Hood training facility in order to determine both the spatial distribution of prediction uncertainty and the contribution of different error sources to that uncertainty. This analysis shows that a three-category vegetation map used by the disturbance model was the greatest source of prediction uncertainty, especially for the map categories shrub and tree. In areas mapped as grass, modeling error (uncertainty associated with the model parameter estimates) was the largest uncertainty source. These results indicate that the use of a high-quality vegetation map that is periodically updated to reflect current vegetation distributions, would produce the greatest reductions in disturbance prediction uncertainty.     

旋转式滗水器的数学模型分析与改进设计

旋转式滗水器是SBR工艺处理法中重要装置.针对其实际运行过程中出现的问题,通过建立旋转式滗水器的数学模型,并进行受力分析,找出了工作中受力的变化规律.在此基础上对其进行了改进设计,经过实际运用表明,理论分析是正确的.这对于SBR工艺处理法的实际运行具有良好的推进作用.     

天然水体底质中Mn元素含量采样和分析质量控制研究

利用采样和分析全程质量控制程序(SAX),对于吉林省内7个天然水体底质中Mn元素的采样和分析过程进行了质量控制(QC)实例研究.实验采用了平行采样平行分析的设计方案,并进行了空白实验、重复测定和加标回收率的测定.然后利用稳健方差分析(Robust ANOVA)计算了采样分析全过程中的地理方差、采样方差和分析方差,并对整个质控过程按照适目的性原则进行了评价.通过本文的研究以及其他工作成果,可知评价中采用的比例限值标准在一般意义下的SAX过程中是行之有效的.但是,也应注意到该限值标准不是绝对的,在具体的实验设计中需要考虑多方面因素.     

黄杆菌P3-2降解对硫磷的质粒

黄杆菌(Flavobacterium sp.)P3-2具有水解对硫磷农药的能力.该菌在L.B培养基或以乙酸、乙醇或甘油为碳源的合成培养基上能产生对硫磷水解酶.用碱裂解法从P3-2菌株中分离出一种质粒(PAR).P3-2菌株经丝裂霉素C处理后,消除质粒的原菌株丧失了产生对硫磷水解酶的性能.用蔗糖梯度离心纯化的质粒DNA经EcoRI和BamHI消化,分别产生16和2个DNA片段、以EcoRI消化λDNA产生的6个片段的分子量作标准,测得PAR质粒的分子量约为37.16×10~6 dalton.在电镜下观察呈环状的DNA分子.     

SBR法处理化粪池出水的工艺研究

采用经实验运行得到SBR工艺处理化粪池出水的合理的操作模式,能获得90%以上稳定的COD_(cr)去除率及更好的BOD_5去除效果,NH_3-N去除率大于75%,TN去除率大于45%.并考察了污泥浓度、泥龄、污泥负荷与处理效果的关系,以及闲置期对反应周期的影响.实验结果表明,SBR工艺对处理水质、水量负荷变化很大的化粪池出水,是一种理想的工艺选择.     

镁砂窑烟尘污染治理调查研究

根据对辽宁省重点镁砂窑烟尘治理技术的现场调查和分析，总结出经验，为从事镁砂窑烟尘污染治理的人员提供参考