垂向水动力扰动机的蓝藻控制效应数值实验研究

在蓝藻水华的控制研究中,目前的发展趋势是采用快速、生态安全且经济有效的技术,其中使用垂向水动力扰动机抑制蓝藻备受关注,但缺乏深入和定量的工程设计与效果评估研究.针对垂向水动力扰动机的蓝藻抑制效应开展数值实验研究,以三维数值营养盐-藻类动力学模型(EFDC)为框架,定量探讨了扰动机数量及其位置分布对叶绿素、总氮和总磷的影响.模拟结果表明,扰动机的存在对蓝藻抑制具有比较明显的作用,随着扰动机数量由0逐渐增加到20个时,Chl-a峰值浓度共减少了37.695 2μg.L-1,并且扰动机对水质改善的程度与其数量存在很强的非线性关系,即当扰动机数量由无到有并逐渐增加时,藻类抑制的效果明显增强;但当扰动机的数量增加到一定量时,进一步增加数量将不会相应增强蓝藻抑制效果.这表明扰动机存在一个最佳数量问题.此外,本研究发现除了数量之外,扰动机的位置对蓝藻控制的效果也有很大影响.数值实验结果显示如果扰动机放置位置得当,少量的扰动机就可达到甚至超过更多扰动机所能达到的蓝藻控制效果.尤其是优化12个扰动机的位置后,Chl-a峰值浓度比扰动机为20个时减少了7.172 6μg.L-1.这些研究结果验证了国内外相关研究对水动力扰动机蓝藻控制效果的肯定性结果,并进一步表明了在实际应用该项技术时必须因地制宜,结合使用智能工程技术(如:高分辨率数值模型)确定最佳扰动机数量与位置,从而确保以最低成本获取最大的蓝藻控制效果.除蓝藻控制之外,数值实验结果也表明扰动机对营养盐浓度也有一定的降低效果.     

负载有度:论环境法的生态承载力控制原则

可持续发展要求社会经济适度发展的同时,环境质量不退化.为达到这一目标,在环境管理中就必须以生态承载力为标准判断经济发展的规模和速度是否具有正当性和合理性,这是化解经济发展与环境保护矛盾的关键所在.环境法应当把生态承载力控制作为一项基本原则,要求人们对环境问题的预防应当以生态承载力为依据,确保向环境排放污染物的总量不得超过环境容量,并保证开发、利用自然资源不能超过生态环境在一定时期内的供给能力.这是对执法者在处理经济发展与环境保护的矛盾中所享有的过大的自由裁量权的必要制约.然而,生态承载力控制原则的实施难度较大,除了需要立法的明文规定外,还应当注重研究、建立生态承载力的核算方法体系;此外,还应当对现行环境执法体制进行改革,促使地方环保部门在环境执法中摆脱地方保护主义的不当干涉,并积极加强公众参与,通过公众监督杜绝突破生态承载力的决策的制定和实施.     

Impact of Growing Income Inequality on Sustainable Development in China: A Provincial-level Analysis

Abstract

A growing body of literature has documented the rapidly increasing income disparities that accompanied China's economic growth in the 1980s and 1990s, and the driving factors behind this. Growing income inequality in its turn may have important implications for the accumulation of physical capital, human capital, and natural capital and as a consequence for sustainable economic development. The purpose of this paper is to investigate the potential impact of income inequality on savings, human resources and the environment in China. It starts with an overview of the different causal mechanisms through which income inequality may affect the accumulation of physical capital, human capital, and natural capital, and discusses to what extent these causal relationships may be relevant in the case of China. Next, provincial data for the year 2002 are used to explore the relationship between income inequality and different elements of sustainable development in China. It is found that income inequality does not affect aggregate savings levels. Rising inequality, however, contributes to lower health and possibly also to higher fertility levels. It also lowers the use of chemical fertilizers in agriculture and therefore is likely to reduce water pollution. Other types of environmental degradation are not affected.     

Uncertainty,Irreversibility and the Timing Problems of Environmental Policy

Abstract

Most environmental issues and policy designing are uncertain and irreversible; therefore, the timing of environmental policy implementation becomes especially important. This paper establishes a random dynamic programming model and analyzes the optimal timing problems in environmental policy under uncertain variables. This model results indicate that two variables have a significant impact on the timing of environmental policy implementation and they work in opposite directions: on one hand, the more uncertain the economy is, the higher the cost of policies implementation will be, and consequently the incentive to immediately adopt the policy will be stronger. On the other hand, the higher the uncertainty of the environment is, the stronger the irreversibility of ecological harm caused by pollutants per unit will be. Therefore, the government should implement new environmental policies as early as possible in order to gain more ecological benefits.     

The underground industry of wastewater adulteration: how to trick legal testing with COD removers

Environmental Chemistry Letters - Adulteration is an illegal practice often committed in food and cosmetic industries, yet rarely in environmental regulation compliance. The Chinese Ministry of...     

Sulfur mediated heavy metal biogeochemical cycles in coastal wetlands: From sediments,rhizosphere to vegetation

• In sediments, the transformation of sulfides may lead to the release of heavy metals. • In the rhizosphere, sulfur regulates the uptake of heavy metals by plants. • In plants, sulfur mediates a series of heavy metal tolerance mechanisms. • Explore interactions between sulfur and heavy metals on different scales is needed. The interactions and mechanisms between sulfur and heavy metals are a growing focus of biogeochemical studies in coastal wetlands. These issues underline the fate of heavy metals bound in sediments or released into the system through sediments. Despite the fact that numerous published studies have suggested sulfur has a significant impact on the bioavailability of heavy metals accumulated in coastal wetlands, to date, no review article has systematically summarized those studies, particularly from the perspective of the three major components of wetland ecosystems (sediments, rhizosphere, and vegetation). The present review summarizes the studies published in the past four decades and highlights the major achievements in this field. Research and studies available thus far indicate that under anaerobic conditions, most of the potentially bioavailable heavy metals in coastal wetland sediments are fixed as precipitates, such as metal sulfides. However, fluctuations in physicochemical conditions may affect sulfur cycling, and hence, directly or indirectly lead to the conversion and migration of heavy metals. In the rhizosphere, root activities and microbes together affect the speciation and transformation of sulfur which in turn mediate the migration of heavy metals. As for plant tissues, tolerance to heavy metals is enhanced by sulfur-containing compounds via promoting a series of chelation and detoxification processes. Finally, to further understand the interactions between sulfur and heavy metals in coastal wetlands, some major future research directions are proposed.     

Removal of Cr(VI) from aqueous solution by a novel ZnO-sludge biochar composite

Environmental Science and Pollution Research - The incorporation of ZnO into biochar has become a promising way to obtain adsorbents with enhanced adsorption capacity. In this study, a low-cost...     

Injectable Methylcellulose and Hyaluronic Acid Hydrogel Containing Silver Nanoparticles for Their Effective Anti-microbial and Wound Healing Activity After Fracture Surgery

Journal of Polymers and the Environment - Currently, the synthesis of silver nanoparticles (AgNPs) was utilized for various life-saving biomedical applications. Herein, we report the synthesis and...     

哈尔滨市沙尘暴发生规律与成因分析

通过对哈尔滨市1954-2003年沙尘暴、大风及降水等气象观测资料的分析认为,哈尔滨市沙尘暴发生次数的年代变化明显,沙尘暴的发生与大风风速、风向与降水均有显著的相关关系,同时与大气稳定度有关,也受下垫面性质的影响.通过对沙粒尺度的分析,认为哈尔滨市沙尘暴的远距离沙源为内蒙古境内沙地、科尔沁沙地,近距离沙源在松嫩平原和哈尔滨周边地区.     

UV/H2O2降解水中硝基酚及影响因素

UV H2 O2 氧化对硝基酚实验表明 ,H2 O2 光解产生·OH自由基是对硝基酚降解的直接原因 ,12min内 2 5mg L的对硝基酚去除率达到98%以上。溶液中TOC变化与对硝基酚的去除并不同步 ,说明对硝基酚的降解中生成了一系列的中间产物 ,然后再达到完全矿化的。体系中H2 O2 浓度变化显示产生的中间产物对H2 O2 光解没有明显影响。研究中还对对硝基酚起始质量浓度、H2 O2 浓度及pH影响进行了考察。研究认为UV H2 O2 是对硝基酚脱毒的一种有效方法