Assessment of private economic benefits and positive environmental externalities of tea plantation in China

Tea plantations are rapidly expanding in China and other countries in the tropical and subtropical zones, driven by relatively high private economic benefit. However, the impact of tea plantations on the regional environment, including ecosystem services and disservices are unclear. In this study, we developed an assessment framework for determining the private economic benefits and environmental externalities (the algebraic sum of the regulating services and disservices) of tea plantations in China. Our results showed that tea plantations provided private economic benefits of 5,652 yuan ha^?1 year^?1 (7.6 yuan?=?1 USD in 2007) for tea farmers, plus positive environmental externalities of 6,054 yuan ha^?1 year^?1 for the society. The environmental externalities were calculated as the sum of the value of four regulating services, including carbon sequestration (392 yuan ha^?1 year^?1); soil retention (72 yuan ha^?1 year^?1); soil fertility protection (3,189 yuan ha^?1 year^?1) and water conservation (2,685 yuan ha^?1 year^?1), and three disservices, including CO₂ emission (?39 yuan ha^?1 year^?1), N₂O emission (?137 yuan ha^?1 year^?1) and nonpoint source pollution (?108 yuan ha^?1 year^?1). Before the private optimal level, the positive environmental externalities can be maintained by private economic benefits; if a social optimal level is required, subsidies from government are necessary.     

净化SO2的生物膜填料塔中微生物类群分析

对净化废气中SO2的生物膜填料塔内的微生物进行了分离纯化并做鉴定,得到一株嗜酸性氧化硫硫杆菌(Acidithiobacillus thiooxdans IEL001)和一株分类地位非常接近链二孢属(Bispora sp.)的极端嗜酸真IEL002,生物膜填料塔内的极端酸性环境和有机营养的缺乏导致生物膜上的微生物种类较为...     

临江河回水区营养盐及富营养化特征分析

以2008年3～9月对库区次级河流临江河回水区水质的调查为依据，分析了临江河回水区氮、磷营养盐的污染分布及富营养化特征。结果表明，临江河回水区氨氮(NH₃-N)、总氮(TN)的浓度在7月中旬达到最小值，分别为1.963和5.128 mg/L, 之后在9月初出现峰值，而磷酸盐(PO^3-₄-P)和总磷(TP)的浓度却呈现出先增加后下降的变化规律；氮主要来自点源污染，而磷受面源污染影响较大；溶解性无机氮(DIN)和PO^3-₄-P是TN与TP的主要存在形态，平均分别占TN和TP的85.3%和77.8%,而DIN又以NH₃-N为主。营养盐浓度呈现出回水区中游最高，回水末端次之，河口处最低的空间分布特征。叶绿素a（Chl-a）的浓度在4月和9月出现峰值，其空间分布特征与营养盐的类似。研究表明，临江河回水区在重度污染的情况下，即便是河流型水体也可能发生富营养化；流速对Chl-a浓度的显著影响呈指数关系。     

进水碳氮比对SUFR系统脱氮除磷影响的特性分析

考察了进水碳氮比（C/N）对螺旋升流式反应器（spiral up-flow reactor，SUFR）系统生物脱氮除磷的影响，试验设计了进水C/N在7～13范围的数种工况，研究了SUFR系统中COD、总磷和氮的变化规律。结果表明，进水C/N对SUFR系统去除COD与TP效果的影响不明显，平均去除率分别为95.2%和93.9%；当进水C/N<9.4时，TN的去除率随C/N的增大而快速提高，而当进水C/N>9.4时，TN的去除率稳定在81.1%～85.6%；SUFR系统的硝化效果较稳定，氨氮的去除率保持在90.5%～98.8%；系统的反硝化作用随C/N的增大有所增强，出水硝酸盐氮浓度逐渐降低。     

辱虐管理对员工不安全行为的U型影响——一个双调节模型

为进一步探究辱虐管理与不安全行为之间的作用关系,更好地减少生产安全事故的发生,以242名高危行业企业员工为调查对象,应用层次回归方法实证检验辱虐管理与员工不安全行为之间的曲线关系以及正念、领导-成员交换在二者之间的调节作用.研究结果表明:辱虐管理对不安全行为有U型影响;正念调节辱虐管理与不安全行为之间的关系,二者之间的...     

电厂内冷水超净化处理出现的问题及处理方法

简要介绍了河北某电厂内冷水超净化处理工艺,并对运行中出现的问题及处理进行了详细讨论,实践证明,采用超净化处理技术能够保证该电厂内冷水水质符合标准要求。     

Toxicity evaluation in a paper recycling mill effluent by coupling bioindicator of aging with the toxicity identification evaluation method in nematode Caenorhabditis elegans

Toxicity identification evaluation (TIE) can be used to determine the specific toxicant(s) in industrial effluents.In the current study,the authors have attempted to combine the advantages of the model organism,Caenorhabditis elegans,with the virtues of the TIE technique,to evaluate and identify the toxicity on aging from a paper recycling mill effluent.The results indicate that only the toxicities from mixed cellulose (MC) filtration and EDTA treatment are similar to the baseline aging toxicity,suggesting ...     

Toxicity evaluation in a paper recycling mill e uent by coupling bioindicator of aging with the toxicity identification evaluation method in nematode Caenorhabditis elegans

Toxicity identification evaluation (TIE) can be used to determine the specific toxicant(s) in industrial e uents. In the current study, the authors have attempted to combine the advantages of the model organism, Caenorhabditis elegans, with the virtues of the TIE technique, to evaluate and identify the toxicity on aging from a paper recycling mill e uent. The results indicate that only the toxicities from mixed cellulose (MC) filtration and EDTA treatment are similar to the baseline aging toxicity, suggesting that the suspect toxicants inducing aging toxicity may largely be the heavy metal substances in this industrial e uent. Examination of the accumulation of intestinal autofluorescence in adult animals further confirms that the short lifespans are actually due to accelerated aging. In addition, exposure to fractions of EDTA manipulations cannot result in severe defects of reproduction and locomotion behaviors in C. elegans. Moreover, high levels of Ca, Al, and Fe in the e uent may account for the severe toxicity on aging of exposed nematodes, by TIE assay. The study here provides a new method for evaluating environmental risk and identifying toxicant(s) from the industrial e uent using C. elegans.     

活动导流墙同心圆工艺处理生活污水的试验研究

活动导流墙同心圆工艺为在OCO技术的基础上革新改进的一种新型污水处理技术.通过导流墙开角可以进行混合液回流量的调节,实现系统良好生物脱氮除磷效能的优化平衡.正交试验分析得出了该工艺处理中等浓度生活污水运行工况的最佳参数值,即主反应器总水力停留时间(HRT)为9.5 h,好氧曝气区中部溶解氧浓度为1.5 mg/L,污泥龄(SRT)为18 d,系统出水水质能够满足《城镇污水厂污染物排放标准》(GB18918-2002)的一级B标准的相关要求.试验结果表明,HRT和好氧曝气区DO水平是影响工艺污染物整体去除效能的关键因素,系统中存在着明显的同时硝化反硝化脱氮现象.