九龙江北溪pH值异常变化与生化因子相关性的研究

监测结果表明,九龙江北溪部分断面CODMn浓度介于中富营养～富营养之间,总氮、总磷和叶绿素a浓度均达到极富营养水平。经统计分析,pH值与甲藻显著相关(r=0.327,P=0.025),与溶解氧(r=0.762,P=0.000)、高锰酸盐指数(r=0.456,P=0.001)、总氮(r=0.482,P=0.001)、总磷(r=0.507,P=0.000)和叶绿素a(r=0.649,P=0.000)等非常显著相关。研究表明,虽然各项化学因子与pH值密切相关,但不是pH值变化的直接原因,而是由于水体富营养程度严重且已形成了藻类生境,甲藻的异常增殖才导致pH值异常升高。     

碳氮比对悬浮填料生物反应器氮去除效果的影响

文章研究了C/N对悬浮填料生物反应器脱氮效果的影响。出水中NH4+-N、NO2--N和NO3--N浓度以及pH值变化均受C/N的影响,实验得到的最佳C/N质量比为12∶1,TN去除率平均在85%。     

Loss of carbofuran from rice paddy water: Chemical and physical factors

Abstract

The loss of carbofuran was studied from rice paddy water treated with a granular formulation of the insecticide, and from ponds filled with drainage from the paddy. The average half‐life (t_1/2) for carbofuran loss was 57 hr. Controlled experiments indicated that pH was the predominating factor governing carbofuran loss from water in the environment studied. The loss due to hydrolysis was over 700 times more rapid at pH 10 (t_1/2 = 1.2 hr.) than at pH 7 (t_1/2 = 864 hr.) in buffered deionized water. The average pH of the rice paddy was 8, but diurnal fluctuations of 7 to 9.5 are common in similar environments. Impurities in the water, sunlight, and temperature influence the rate of carbofuran loss but not nearly so much as pH. There was no evidence for significant loss due to evaporation or oxidation. The results have important implications for the duration of the insecticide's activity and the effect on fish within or downstream from treated paddies.     

Development of controlled release formulations of carbofuran and imidacloprid and their bioefficacy evaluation against aphid,Aphis gossypii and leafhopper,Amrasca biguttula biguttula Ishida on potato crop

Controlled release (CR) formulations of carbofuran and imidacloprid were prepared employing polyvinyl chloride and carboxymethyl cellulose (CMC) and their bioefficacy was evaluated against the aphid, Aphis gossypii and leafhopper, Amrasca biguttula biguttula Ishida on potato crop. The CR formulations of carbofuran and imidacloprid provided better or equal control of the pests than commercial formulations. CMC-based formulation provided a superior control of both the pests. The Imida-CMC, which showed the lowest population of leaf hopper (10.50 leafhopper/100 cl), provided significantly superior control among all treatments after 35 days after germination (DAG). The residue of carbofuran and imidacloprid in potato tuber and soils were not detectable at the time of harvesting in any one of the formulations.     

Bioefficacy evaluation of controlled release formulations based on amphiphilic nano-polymer of carbofuran against Meloidogyne incognita infecting tomato

In the present investigation, the bioefficacy of developed carbofuran formulations, with PEG-600 (7a, CP1) & PEG-900 (7b, CP2) @ 5, 10 and 20 ppm, along with commercial formulation of carbofuran 3G (CP0) were evaluated against the root-knot nematode, Meloidogyne incognita infecting tomato (cv. Pusa Ruby) in pot and field conditions. The bioefficacy data indicated that the formulations developed by utilizing polymers having PEG – 900 (7b) as hydrophilic segment were effective even at 14 days post inoculation (dpi) as evident from shoot and root length. Also, the reduction in penetration was found to be maximum with CP2 (3.6 – 4.6 J2s) at all concentrations compared to CP1 (6.6 – 16.4 J2s) and CP0 (29.3 – 32.6 J2s). Overall, CP2 was more effective in reducing the number of nematodes up to 14 days, compared to CP1 and CP0. Both the CR formulations (CP1 and CP2) in general significantly reduced the number of galls, when compared to CP0. However, under field conditions, lower concentrations (5, and 10 ppm) of CP2, were less effective in controlling the gall formation whereas, CP2 at 20 ppm, was most effective than other treatments. The study revealed that the developed CR formulations of carbofuran have the potential for effective management of M. incognita in tomato under field conditions.     

Differential sorption of herbicides as related to soil topography and organic matter 1

Abstract

The sorption of bromacil and simazine by the surface soil (0–15 cm) sampled at various positions along an 8% slope citrus grove (Candler fine sand; Typic Quartzipsamment) and at various depths (0–200 cm) at upper, middle, and lower positions along the slope were investigated. The sorption of both herbicides by the top 15 cm soil decreased considerably from the upper to mid position along the slope and increased at the lower position. The organic matter content and concentrations of Ca, Mg, K, P, and Cu in the soil showed evidence of transport of organic matter and mineral nutrients from the mid position on the slope and accumulation in the lower position. The differential sorption of herbicides by the soil samples taken at various positions along the slope was closely related to changes in organic matter content. Although sorption of bromacil and simazine varied considerably at various positions along the slope, the sorption of bromacil was very similar at depths below 30 cm regardless of positions along the slope. In the case of simazine, however, the sorption was much greater at all depths in the lower than in the upper and mid position of the slope. The sorption of both herbicides decreased considerably at depths below 30 cm at all positions along the slope, thus, indicating the potential for rapid leaching of the herbicides down the soil profile.     

完全自营养脱氮过程中的影响因素

基于正交实验考察了溶解氧（DO）、初始NH4＋-N浓度、pH对SBR自营养脱氮性能的影响。结果表明,DO和NH4＋-N浓度对好氧氨氧化速率影响大,pH对好氧氨氧化速率的影响小;DO、NH4＋-N浓度对亚硝酸氧化速率的影响较大,pH对亚硝酸氧化速率的影响较小;DO、NH4＋-N浓度和pH对厌氧氨氧化菌（ANAOB）的活性影响较小。好氧氨氧化菌（AOB）直接影响到CANON系统的总氮去除能力,是CANON系统的控制反应,DO是关键控制因子。实验确定的CANON系统优化运行条件为,DO（0．3±0．05）mg／L、初始NH4＋-N浓度150mg／L和pH7．4。     

不同pH下水葫芦与紫根水葫芦生长特性与净化效能对比研究

为了探讨不同pH条件下水葫芦与紫根水葫芦生长特性与净化效能的差异,以滇池草海原水为实验用水,利用HCl和NaOH稀溶液调节水体pH,设置3个pH处理,分别是8．00、9．50和11．00,开展了为期30d（重复3个周期）的静态模拟实验,结果表明,在实验条件下,pH过高会对水葫芦和紫根水葫芦的生长发育产生抑制作用,紫根水葫芦受到的抑制效果更为明显;水葫芦和紫根水葫芦的生长也会使水体pH降低至接近中性,水葫芦调节水体pH的能力更强;pH为8．00、9．50时,水葫芦和紫根水葫芦对水体氮磷污染物具有净化作用,水葫芦的净化能力更强;pH为11．00时,水葫芦和紫根水葫芦处理的水体氮磷浓度均表现起伏,表示在高碱度条件下,两者的净化能力减弱。     

pH对污水污泥中污染物浸出的影响

研究pH对污泥中污染物浸出的影响可以为投海过程中海洋水体酸碱性变化对污泥中污染物浸出的影响及其变化规律提供理论依据。为了得出不同pH值对污泥中污染物浸出的影响,采用CEN/TS 14429：2005浸出实验对上海5个污水处理厂脱水污泥中重金属、溶解性有机碳、溶解性硫化物和主要离子的浸出情况进行了研究,同时分别以超纯水和海水为浸提剂研究在相应pH范围内盐度对上述指标浸出的影响。结果表明,Zn、Cd、Pb和As在酸性和碱性条件下浸出量较高,在中性或接近中性条件下浸出量则最低,且海水中Zn和Cd的浸出量比超纯水中高;Cu在碱性条件下的浸出量明显比酸性条件高;在所研究的pH范围内,5个污泥样品中溶解性有机碳的浸出量均随pH的升高而增高;仅酸挥发性硫含量最高的S5在海水中有较明显的溶解性硫化物浸出;部分污泥样品中的氮在酸性纯水中有较高的浸出量,海水中浸出量较少;而无论海水或纯水中,磷在强酸和强碱条件下均有明显浸出。     

智能预测算法在污水处理pH值控制中的应用

在处理污水时pH值的变化过程具有高度非线性和时滞性,常规PID控制器的控制效果不够理想。介绍了污水处理过程的反应原理以及pH值控制方面存在的问题,阐述了非线性预测控制算法的一般步骤,确定了污水pH值智能预测控制的研究思路。确定了输入输出变量并搭建其数学模型,然后根据数学模型构建了神经网络预测模型。将粒子群与BP神经网络相结合,利用粒子群算法优化神经网络的初始权值阈值,既能克服BP算法局部最优的问题,又能提升收敛速度及预测精度。最后将智能预测控制算法的输出作用于PID控制回路的设定值。仿真结果表明,智能预测控制算法控制性能优于单纯PID控制,能更快跟踪设定值,具有更强的适应性。