基于有效性改进的流域生态系统恢复条件价值评估——以长江流域生态系统恢复为例

综合利用有效性改进的方法对流域生态系统恢复的价值进行评估,具体方法包括:①采用二分式选择法作为引导技术以模拟真实市场并解决调查中"没有回应的问题;②设计恰当的核心估值问题并通过图片展示克服CVM的"假想特性";③通过大样本发放、多次调查和调查员培训缩小CVM"假设偏差"以及"调查者偏差";④使用开放式和支付卡式问卷进行预调查以获得二分式选择问卷调查的投标值;⑤分析WTP支付水平影响因素的边际效用以减少"范围问题"的干扰;⑥利用中值法估计WTP分布函数以避免函数"右偏"并减少"厚尾"问题的困扰;⑦根据样本中两次均回答"否"的比例数选择对数logit模型以降低估计结果的偏差;⑧由于WTP的标准误以及95%置信区间都要比单界模式下的估计结果更为精确,故选择双界二分法测算WTP值.通过上述方法测算的南京市民对于长江流域生态系统恢复的支付意愿为270.7元/户·年,而大幅提高居民家庭收入水平是提高居民支付意愿最为有效的途径.     

Mitigation effects of silicon rich amendments on heavy metal accumulation in rice (Oryza sativa L.) planted on multi-metal contaminated acidic soil

The mechanisms of stabilization by silicon-rich amendments of cadmium, zinc, copper and lead in a multi-metal contaminated acidic soil and the mitigation of metal accumulation in rice were investigated in this study. The results from a pot experiment indicated that the application of fly ash (20 and 40 g kg⁻¹) and steel slag (3 and 6 g kg⁻¹) increased soil pH from 4.0 to 5.0-6.4, decreased the phytoavailability of heavy metals by at least 60%, and further suppressed metal uptake by rice. Diffusion gradient in thin-film measurement showed the heavy metal diffusion fluxes from soil to solution decreased by greater than 84% after remediation. X-ray diffraction analysis indicated the mobile metals were mainly deposited as their silicates, phosphates and hydroxides in amended treatments. Moreover, it was found metal translocation from stem to leaf was dramatically restrained by adding amendments, which might be due to the increase of silicon concentration and co-precipitation with heavy metals in stem. Finally, a field experiment showed the trace element concentrations in polished rice treated with amendments complied with the food safety standards of China. These results demonstrated fly ash and steel slag could be effective in mitigating heavy metal accumulation in rice grown on multi-metal contaminated acidic soils.     

An analytical solution to contaminant diffusion in semi-infinite clayey soils with piecewise linear adsorption

The adsorption of contaminants onto soil particles typically is nonlinear if the contaminant concentration is sufficiently high. A simplified piecewise linear adsorption isotherm consistent with experimental results is proposed as an approximation for nonlinear adsorption behavior. This approximation allows for the use of analytical solution to model solute diffusion of contaminants that exhibit nonlinear adsorption. A moving boundary is introduced to represent significant changes in the retardation factor of clay with an increase in solute concentration. The proposed analytical solutions were validated using experimental data presented in the literature. There is negligible difference between the results obtained by the proposed analytical solution and those obtained by the linear model when C_m/C₀ reached 0.5. The results also show that the model based on linear adsorption using the initial secant of the Freundlich isotherm leads to significantly lower estimated breakthrough time for the contaminant of interest than that obtained using the proposed model. The earlier breakthrough is due to an under-estimation of the amount of adsorption. The proposed method is relatively simple to apply and can be used for evaluating experimental results and verifying more complex numerical models.     

Assessing the impact of ambient ozone on growth and yield of a rice (Oryza sativa L.) and a wheat (Triticum aestivum L.) cultivar grown in the Yangtze Delta, China, using three rates of application of ethylenediurea (EDU)

Foliar applications of ethylenediurea (abbreviated as EDU) were made at 0, 150, 300 or 450 ppm to field-grown rice and wheat in the Yangtze Delta in China. Rice and wheat responded differently to ambient ozone and EDU applications. For wheat, some growth characteristics, such as yield, seed number per plant, seed set rate and harvest index, increased significantly at 300 ppm EDU treatment, while for rice no parameters measured were statistically different regarding EDU application. The reason may be that the wheat cultivar used may be more sensitive to ozone than the rice cultivar. EDU was effective in demonstrating ozone effects on the wheat cultivar, but not on the rice cultivar. Cultivar sensitivity might be an important consideration when assessing the effects of ambient ozone on plants.     

土壤镉污染防治对策的研究

本文概述了国内外土壤镉污染治理技术成果,比较了各种不同技术的使用条件及特点,并简要说明了其原理。针对天津市镉污染现状,对一些镉污染防治对策进行了研究,并提出可行性建议和措施。     

CODCr测定方法探讨

对经典测定水样ＣＯＤＣｒ的方法进行了改进,以硫酸银－硫酸铜作催化剂代替单独作用硫酸银,用适量硝酸银、硝酸铋代替硫酸汞消除氯离子的干扰,适当提高了消解用硫酸浓度,缩短回流时间。     

海岸带污染负荷预测模型及其在渤海湾的应用

针对海岸带及其近岸海域污染的特点,建立旨在为污染负荷总量的控制与削减以及在不同部门的重新分配提供技术手段和科学依据的海岸带水污染负荷预测模型．该模型涵盖了海岸带区域的主要污水排放部门,综合采用统计回归、灰色预测等方法,解决了由于数据缺乏或相互关系不明确而带来的环境系统的不确定性问题,并依据天津市污染负荷历年统计数据对模型加以验证．通过对天津市近岸海域近10年氮、磷、石油类和耗氧有机物排放量估算结果可以看出,万元产值工业废水排放量逐年下降,耗氧有机物排放量逐年缓慢增长．在污水排放总量中,有2／3的耗氧有机物和75％以上的氮来自于生活污水,因此天津市应重点控制生活污水排放．     

废旧电路板中溴的回收工艺研究

在废旧电路板热解处理过程中,溴化阻燃剂分解产生大量溴化氢,为了减少溴化氢对热解设备和环境的危害,提出了碳酸钙吸附分离溴化氢的处理工艺,生成的溴化钙通过水的浸取、过滤、蒸发、浓缩等过程,获得了质量分数为52%,密度为1.7 g/mL的溴化钙水溶液.研究了热解温度、碳酸钙用量对溴化钙产率的影响规律及溴化钙的浸取工艺条件.热解吸附试验表明,碳酸钙与电路板的质量比为1.2～1.4,热解温度约为600 ℃时,溴化钙的产率最高可达86%;浸取试验表明,溴化钙的单次浸取率随浸取剂的浓度增大而降低,随温度升高而提高.溴的回收率主要取决于溴化钙的产率,通过选择合适的热解吸附条件,废旧电路板中溴的总回收率高于80%,所回收的溴化钙液体产品主要技术指标接近同类市售产品.     

生物膜法A/O系统处理腈纶废水工业试验

本工业试验规模为１４００—１６００ｔ／ｄ,装置Ａ／Ｏ容积比１：３,当平均停留时间２２．６ｈ,回流比３．２,水温约３５℃左右时,平均去除率ＣＯＤｃｒ达８８．３６％、ＢＯＤ５９７．４９％、ＴＮ７７．６７％、ＡＮ９９．４１％。出水各项指标平均值为ＣＯＤＣｒ５３．５７ｍｇ／Ｌ、ＢＯＤ５５．６ｍｇ／Ｌ、ＴＮ１４．９４ｍｇ／Ｌ、ＮＨ３－Ｎ６．９２ｍｇ／Ｌ、ＡＮ１．０２ｍｇ／Ｌ、ＮａＳＣＮ２．６７ｍｇ／Ｌ,ＳＳ仅２０ｍｇ／Ｌ,因此不设二沉池。     

动床条件下泥石流运动参数变化特征实验研究∗

泥石流运动参数变化特征与泥石流流量、沟床纵坡和沟床物源物质组成等紧密相关,准确确定泥石流运动参数变化特征对于进行流域风险评估和防治工程规划设计具有重要意义。通过室内水槽实验探索了不同来流流量、 沟床纵坡和物源细粒含量条件下,沟槽观测点处泥石流流深、流速和容重的变化情况。结果表明：来流流量和沟床纵坡越大,物源细粒含量越小时,泥石流冲刷能力越强;相同实验条件下,流体流深与来流流量间呈正相关关系,与细粒含量间呈负相关关系,且流深受来流流量的影响大于细粒含量;流体流速与来流流量和沟床纵坡间呈正相关关系,与细粒含量间呈负相关关系,且流速受沟床纵坡的影响最大,受细粒含量的影响最小;流体容重与来流流量和细粒含量间呈负相关关系,与沟床纵坡间呈正相关关系,且容重受沟床纵坡和细粒含量的影响大于来流流量。 通过水槽实验数据对泥石流流量进行拟合,采用流量拟合式对锅圈岩沟 2013 年“7·26”泥石流峰值流量进行计算, 与野外实测值对比精度高于 80%。