超声协同Fenton法与类Fenton法预处理莠去津农药废水研究

针对莠去津农药废水有机物浓度高、含盐量高、有机物难降解等问题,提出了辅以超声协同的Fenton和类Fenton技术进行废水的预处理研究。分别研究了中性条件和酸性条件下,超声协同的Fenton以及类Fenton技术对废水有机物的去除率,并对比单独超声、Fenton以及类Fenton技术。结果表明:辅以超声作用后,TOC去除效果优于单独Fenton和类Fenton技术;针对超声Fenton和超声类Fenton协同技术,相比于中性条件下,酸性条件下能得到更高的TOC去除率,并且超声Fenton技术优于超声类Fenton技术,最高TOC去除率达到48.5%。因此,酸性条件下的超声辅助的芬顿法可作为莠去津农药废水的预处理方法。     

室内滴灌施药条件下阿特拉津在土壤中运移规律的研究II.数值仿真

本文以实验室内所开展的滴灌施用除草剂——阿特拉津在土壤中运移的物理模拟实验为基础，运用所求得的供试土壤的水力学参数和溶质运移参数及阿特拉津在该土壤中的吸附特性参数和降解速率常数，应用数值模拟软件HYDRUS-2D，对物理模拟的实验结果进行了仿真，并就不同初始含水量、不同滴头流量对土壤水分和阿特拉津动态分布的影响进行了数值分析，结果表明：随着初始含水量的增加，土壤水分的湿润范围增大，而阿特拉津的分布范围基本不变；当滴灌施药历时相同、滴头流量不同时，随着滴头流量的增加，土壤水分和阿特拉津的运动范围均增大。     

室内滴灌施药条件下阿特拉津在土壤中运移规律的研究Ⅰ.物理模拟与参数确定

利用滴灌系统施用农药可以将农药直接作用到植物根区，这是节水农业和生态农业中一种先进的灌溉施药方法。本文详细地描述了在实验室内开展的滴灌施用除草剂一阿特拉津在土壤中运移的物理模拟实验，介绍了采用批量平衡技术和批培养方法获得阿特拉津在供试土壤中吸附特性参数和降解速率常数的实验步骤，给出了根据Freundlich吸附等温线和一级动力学方程对实验数据的拟合结果。此外，由土壤干容重及吸管法求得的土壤质地，利用土壤传递函数间接求取了van Genuchten型水力学参数，并由易混合置换实验得到了溶质运移的弥散度。本文的研究成果为进一步开展滴灌施用阿特拉律在土壤中运移规律的数值分析奠定了基础。     

室内滴灌施药条件下阿特拉津在土壤中运移规律的研究Ⅰ：物理模拟与参数确定

利用滴灌系统施用农药可以将农药直接作用到植物根区，这是节水农业和生态农业中一种先进的灌溉施药方法。本文详细地描述了在实验室内开展的滴灌施用除草剂-阿特拉津在土壤中运移的物理模拟实验，介绍了采用批量平衡技术和批培养方法获得阿特拉津在供试土壤中吸附特性参数和降解速率常数的实验步骤，给出了根据Freundlich吸附等温线和一级动力学方程对实验数据的拟合结果。此外，由土壤干容重及吸管法求得的土壤质地，利用土壤传递函数间接求取了van Genuchten型水力学参数，并由易混合置换实验得到了溶质运移的弥散度。本文的研究成果为进一步开展滴灌施用阿特拉律在土壤中运移规律的数值分析奠定了基础。     

Pesticide-loss Simulation and Health Risk Assessment during the Flood Season in Watershed Systems

Abstract

There have been growing concerns over the negative effects of pesticide usage on human health and environmental sustainability. Pesticide residues, if they enter water bodies, will impair water quality and pose risks to human health. During flood season, floodwater could wash off large amount of pesticide residues to rivers and lakes. A pesticide-loss simulation and health-risk assessment (PSHA) system was developed to predict pesticide losses and evaluate associated health risks during flood season. A case study was conducted in the Auglaize-Blanchard Watershed in Ohio to calibrate and verify the proposed system. The results showed a reasonable prediction accuracy and model performance. The PSHA system was then applied to estimate pesticide losses and assess health risks during May 1997 to April 1998, especially during the flood season from May to August. The results show that water discharge during the flood season contributed 90 percent of the total pesticide losses. The chronic and acute health risks were then quantified and the results showed that the health risks caused by atrazine losses were markedly high during flood season. Therefore, pesticides applied during flood season would cause more serious pollution problems and higher health risks than that in other times. Flood season was shown to be a critical period for not only controlling flooding hazards but also mitigating pesticide pollution.     

Modeling atrazine transport in soil columns with HYDRUS-1D

Both physical and chemical processes affect the fate and transport of herbicides. It is useful to simulate these processes with computer programs to predict solute movement. Simulations were run with HYDRUS-1D to identify the sorption and degradation parameters of atrazine through calibration from the breakthrough curves (BTCs). Data from undisturbed and disturbed soil column experiments were compared and analyzed using the dual-porosity model. The study results show that the values of dispersivity are slightly lower in disturbed columns, suggesting that the more heterogeneous the structure is, the higher the dispersivity. Sorption parameters also show slight variability, which is attributed to the differences in soil properties, experimental conditions and methods, or other ecological factors. For both of the columns, the degradation rates were similar. Potassium bromide was used as a conservative non-reactive tracer to characterize the water movement in columns. Atrazine BTCs exhibited significant tailing and asymmetry, indicating non-equilibrium sorption during solute transport. The dual-porosity model was verified to best fit the BTCs of the column experiments. Greater or lesser concentration of atrazine spreading to the bottom of the columns indicated risk of groundwater contamination. Overall, HYDRUS-1D successfully simulated the atrazine transport in soil columns.     

镉-铜-阿特拉津三元复合体系中沉积物吸附阿特拉津过程的模型研究

建立了镉-铜-阿特拉津三元复合体系中沉积物吸附阿特拉津的BP神经网络模型,模型训练集、验证集、预测集的均方差分别为0.070,0.094和0.110,模型输入数据与其模拟值相关系数为0.974,验证实验表明该三元复合体系中阿特拉津吸附模型预测值与实验值的平均偏差为7.05%(7组数据)。所建模型的预测结果显示,镉-铜-阿特拉津三元复合体系中阿特拉津的主要吸附位是铁氧化物,其次是有机质,锰氧化物对阿特拉津的吸附具有抑制作用。与Cu2+相比,Cd2+的添加对复合体系中阿特拉津的吸附作用影响更显著,且复合污染效应主要发生在锰氧化物和有机质上,并随锰氧化物和有机质含量的不同表现出抑制作用或促进作用。