POLICY OBJECTWES AND ECONOMIC INCENTWES FOR CONTROLLING AGRICULTURAL SOURCES OF NONPOINT POLLUTION1

In this paper, we review the physical characteristics of agricultural non point pollution and discuss the implications for setting appropriate pollution control objectives and designing incentive-based pollution control policies. First, we discuss that policy objectives must be designed carefully to ensure positive economic net benefits can be expected from pollution control. Next, we review several classes of incentives and recommend the use of design-based incentives (i.e., incentives based on variable input use, management practices, and land use) for controlling non point pollution. Cost-effectiveness requires that incentives elicit three types of responses from farmers: (1) use variable inputs at appropriate levels, (2) adopt appropriate management practices, and (3) make appropriate land use decisions at the extensive margin of production. If a set of incentives fails to induce the correct responses, the resulting runoff levels and hence ambient pollution levels and damages will be too large relative to policy goals. A review of existing programs suggests that greater program coordination and improved targeting of incentives are needed for further water quality improvements. Alternatively, properly designed market-based systems may be effective alternatives. These systems would reduce overall pollution control costs by allowing markets to allocate point source and non point source control costs more efficiently.     

冀西北半干旱区等高植物篱面源污染控制机理

坡面养分流失是造成面源污染的主要形式.本研究利用冀西北黄土丘陵区的试验小区的长年观测资料,并结合野外全坡面大型人工模拟降雨试验及室外实验数据,分析了冀西北温带及半干旱地区等高植物篱对面源污染控制机理,得出在暴雨条件下细沟产生并导致侵蚀剧烈增加的临界坡长为10～15m;研究揭示出冀西北半干旱区面源污染形态以泥沙携带养分流失为主,等高植物篱控制面源污染的途径是控制土壤颗粒中的养分流失.     

浦东新区骨干河道非点源污染及防治对策

根据上海浦东新区骨干河道污染源调查及研究,指出新区骨干河道的主要非点污染源,提出具体的污染防治对策。     

电生成Fenton试剂处理染料废水

对电生成Fenton试剂处理酸性铬兰K染料废水进行了研究。采用石墨作阴、阳极,电解过程中向阴极表面通纯氧,并在废水中加入-定量的Fe2+,氧在阴极上还原生成H2O2,H2O2又产生强氧化剂·OH,进而对酸性铬兰K染料废水进行脱色降解。在槽电压为6 V、pH为2.5、电解液中FeSO4·7H2O的质量浓度为0.5 g／dm3、Na2SO4的质量浓度为20 g／dm3的条件下电解废水60 min,染料废水脱色率和COD去除率分别达74.1％和57.9％,电解废水120min后,染料废水脱色率和COD去除率分别达92.9％、71.3％。动力学研究表明,染料的降解符合一级动力学过程,速率常数k为0.02224 min-1。     

非爆破施工震动安全判据引用探讨

通过几个非爆破施工振动影响相邻建筑的鉴定检测实例,结合国内外爆破振动安全判据标准,提出爆破施工振动和非爆破施工振动2个概念,根据这2种施工振动的各自特点,初步探讨非爆破施工中的振动如何引用爆破振动安全判据,并提出非爆破施工振动安全判据质点振动速度范围值以供探讨.     

无纺布填料处理污水试验及机理

采用无纺布作为一种新型悬浮填料,探索无纺布填料处理污水的适用条件、运行参数及降解机理.研究认为不同容积负荷应采取不同的填料投配率:当CODCr容积负荷低于1.2kg/(m³·d)时,取填料投配率为20%;当CODCr容积负荷在1.2～2.0kg/(m³·d)之间时,取填料投配率为38%;当CODCr容积负荷达2.0 kg/(m³·d)以上时,取填料投配率为29%模型结果表明,附着微生物降解有机物的规律可用Monod方程的形式描述.     

抑制薇甘菊生长的日本菟丝子化感物质研究

采用制备型高效液相色谱、重结晶等方法从有害植物日本菟丝子（Cuscuta japonica Choisy）的水浸液有机萃取物中分离出能显著抑制薇甘菊（Mikania micrantha H.B.K.）种子萌发的化感物质,并采用核磁共振（1HNMR、13CNMR）法、质谱（MS）法等对其结构进行分析和鉴定。结果表明：能显著抑制薇甘菊种子萌发的日本菟丝子化感物质为桂皮酸（cinnamicacid）和3-苯基丙酸（3-phenylpropanoic acid）。这2种化合物在菟丝子属的植物中属首次分离鉴定。这2种化感物质具有开发为生物源农药（如除草剂）的潜力。研究结果为入侵植物薇甘菊的防治提供了参考依据,也为日本菟丝子的开发利用开辟了一条新途径。     

腐殖酸作用下沉积物中纳米氧化铜对铜锈环棱螺生态毒性的影响

为了探讨不同水平腐殖酸作用下沉积物中纳米氧化铜(CuO-NPs)对底栖生物生态毒理学效应的影响,以铜锈环棱螺(Bellamya aeruginosa)为受试生物,通过腐殖酸和CuO-NPs加标沉积物的慢性(28 d)生物测试,研究了肝胰脏中Cu的生物积累、Na+K+-ATP酶(ATPase)、超氧化物歧化酶(SOD)以及过氧化氢酶(CAT)活性的变化规律.结果表明,在低浓度CuO-NPs处理组(60 μg·g1),沉积物中腐殖酸水平对Cu的生物积累以及ATPase、SOD和CAT活性均没有显著影响.在中、高浓度CuO-NPs处理组(≥180 μg·g-1),Cu的生物积累均随腐殖酸水平的增加而显著升高;肝胰脏ATPase活性随腐殖酸水平的增加而显著下降;当腐殖酸水平为0.05 g·g-1时,SOD活性显著高于未添加腐殖酸组,表现为显著诱导,当腐殖酸水平≥0.1g·g-1时,SOD活性开始下降,并具有浓度依赖性;随腐殖酸水平的增加,肝胰脏CAT活性总体上表现为浓度依赖性显著下降.由于沉积物中腐殖酸的存在,显著增加CuO-NPs在沉积物中的分散稳定性,更容易被铜锈环棱螺摄取,从而通过增加CuO-NPs的生物积累而增强对铜锈环棱螺的生态毒性.     

Septic tank and agricultural non‐point source pollution within a rural watershed

This investigation addresses the problem of Non‐Point Source (NPS) pollution in the rural Lake Weatherford watershed in Parker County, Texas. This reservoir is the primary municipal water supply for the City of Weatherford, Texas. The principal method of wastewater disposal is the on‐site system or septic tanks for the small residential areas surrounding the reservoir.

Sources of NPS pollution of interest in this watershed include agricultural operations as well as the residential areas. These sites were identified with the aid of aerial photography and field investigation. Suspected NPS problems were substantiated through a sampling program involving chemical and biological testing of the reservoir. Results indicate that there is significant NPS pollution contamination of Lake Weatherford from agricultural sources and seepage from on‐site wastewater disposal systems. Excessive fecal coliform and fecal streptococcus counts (>500 bacteria/100 ml) were generally associated with rainfall events and several samples showed values > 100000 bacteria/100 ml. The fecal coliform/fecal streptococcus ratios indicated contamination from human sources, animal sources, and a combination of both. Nutrient concentrations fluctuated from quite low to high with ammonia as the most consistent problem. High ammonia values were also associated with rainfall events.     

Clam‐sediment accumulation factors for polychlorinated biphenyl congeners at a contaminated estuarine marsh

Clam‐sediment accumulation factors for hexa‐, hepta‐ and octa‐chlorobiphenyls were estimated at an intertidal marsh that has been contaminated with Aroclor 1268. Accumulation factors for PCB congeners with K _ow > 6.5 were in the range of 0.07–0.88, indicating that their uptake was hindered by steric factors, contamination levels, non‐equilibrium conditions and stronger affinity to sediment organic carbon. Biota‐sediment accumulation factors (BSAFs) were negatively correlated with log K _ow of superhydrophobic PCB congeners. BSAFs estimated based on 2,3,7,8‐TCDD equivalents of PCBs were 2‐fold greater than those derived from total PCB concentrations.