Filtering with a drill pump: an efficient method to collect suspended sediment

Water quality monitoring programs across multiple disciplines use total suspended solids (TSS), and volatile suspended solids (VSS), to assess potential impairments of surface water and groundwater. While previous methods for instream filtering have been developed, the need for rapid, cost‐effective, high volume sampling has increased with the need to verify and supplement data produced by sondes and instantaneous data loggers. We present an efficient method to filter water instream with a portable drill pump that results in reduced sample processing time, and potentially reduced error associated with sample transportation, preservation, contamination, and homogenization. This technical note outlines the advantages of filtering instream vs. in the laboratory. It also compares TSS and VSS concentrations filtered with a drill pump vs. standard filtration methods with a vacuum pump as outlined by USEPA methods 160.2 and 160.4. Samples were collected at 4 sites and filtered in the field, or transported to the laboratory and filtered within 12 or 24 h of collection. Overall TSS and VSS samples filtered instream with a drill pump vs. in the laboratory produced similar concentrations with a similar range in variability for each method. Sample filtering with a drill pump decreased processing time by five minutes per sample.     

不完全竞争行业中的环境工具有效性研究:一个理论框架

各级政府贯彻落实绿色发展的理念,实现经济增长与环境保护的共赢,才能真正实现"绿水青山就是金山银山"。在经济"新常态"背景下,防治环境污染是个复杂而系统性的工程,需要进行经济追因与综合治理,其中,制定实施有效的环境政策工具尤为关键。本文把微观经济学中的双寡头产量竞争模型作为基准模型拓展用于环境经济分析,并把环境税、环境规制、排污权交易这三类主要环境工具对企业生产决策的影响纳入基准模型,旨在对比研究不完全竞争行业中环境工具的有效性问题。结果表明:主要基于市场机制的环境经济政策比行政色彩浓厚的环境规制更有效率。提高环境税率或排污权价格均能显著削减行业污染物排放量,如果环境税率恰好等于排污权价格,则环境税与排污权交易这两类环境工具的效力相等。这对进一步建立和完善我国尚处于探索或初始实施阶段的环境工具,促进石化、电力、钢铁等不完全竞争行业的主要污染物减排,具有一定参考价值和借鉴意义。     

煤炭资源耗减价值及其“利益共享、风险共担”补偿机制研究

煤炭行业清费建税,资源税从价计征引起了社会各界对资源税费制度改革的热议,而资源耗减价值是资源税费制度改革的重要依据之一。将资源回采率纳入使用者成本模型,科学计量了我国2000-2011年间煤炭资源的耗减价值。分析表明:2000-2011年间,4%折现率下煤炭资源耗减价值增加了22倍之多,而资源税费却仅仅增长了7倍,煤炭资源耗减价值与资源税费实际征收额之间存在有巨大缺口得不到补偿;国家资源所有者权益的实现度与煤炭经济形势呈逆向分布,煤炭工业利润率的上升并没有带来国家资源所有者权益的增加,导致这种错位的原因与我国不合理的资源税收机制有很大关系;资源税税率的理论区间为1.11%-8.85%,与国家规定的2%-10%高度重合,从而说明国家决策的合理性。为使资源所有者权益的实现度与煤炭工业经济形势相"挂钩",以资源税收入等于资源耗减价值为切入点,对资源所有者权益的实现度进行数理分析,求得了资源税税率与当期资源价格的关系,发现固定税率的资源税难以适应市场波动,于是提出"资源税+利润税"的组合税收工具,确定了利润税的起征点,计算得出了资源税和利润税的税率组合。该组合税制在一定程度上能够平抑经济周期对煤炭工业造成的影响,同时又维护国家资源所有者权益,从而实现国家与煤炭工业"利益共享、风险共担"。     

三峡库区典型土壤酸碱缓冲性能及其影响因素研究

受酸沉降和化肥施用等外源性酸输入的影响,三峡库区土壤面临着严重的酸化威胁。通过选取三峡库区两种典型土壤(紫色土和黄壤)作为研究对象,采用酸碱滴定法对土壤酸碱缓冲性能及其影响因素进行了研究。结果表明:在一定的p H范围内,紫色土(p H 6.5~2.5、6.2~11.5)和黄壤(p H 5.6~2.8、5.5~10.7)的p H变化与外源性酸、碱加入量均呈线性相关关系。通过分段拟合获取的缓冲容量结果显示,紫色土酸、碱缓冲容量分别为101.3、34.6 mmol/kg;而黄壤酸、碱缓冲容量分别为105.3、38.0 mmol/kg。黄壤和紫色土主要受碳酸钙与阳离子交换的缓冲作用;缓冲体系及初始p H、机械组成等土壤理化性质的不同是导致库区典型土壤酸碱缓冲容量差异的主要原因,总体表现为黄壤酸、碱缓冲性能略优于紫色土。此外,由于近年来酸沉降和氮肥用量的增加,使得库区土壤面临的酸化威胁呈上升趋势。该结果对库区土壤环境容量和典型土壤酸化潜势等研究具有参考价值,还可为区域外源性酸临界值评估以及应对策略制定提供理论依据。     

基于效果-效率-适应性的养殖废弃物资源化利用管理模式评价框架构建及初步应用

由于产业发展正处于转型阶段,我国畜禽养殖污染治理中的管理问题比技术问题更加突出,选择适宜的组织管理模式尤其重要。融合了效果分析、效率评价和适应性分析,尝试构建一个养殖废弃物资源化利用管理模式综合评价框架,并选择太湖流域4个不同类型的典型案例进行方法例证。研究表明,传统的养殖企业主导型管理模式应用于小型、分散养殖废弃物资源化利用时面临着经济效率低、适应性差难题;农村废弃物处理中心、种植企业和有机肥企业的参与可以改善小型、分散养殖废弃物资源化利用的经济效率;综合考虑效果、效率与适应性,种植企业、有机肥企业主导型模式的适宜推广范围更广。应根据不同地区种植-养殖产业关系、污染治理需求、经济发展水平与政府投入能力等,灵活组合应用不同管理模式。     

On-line production of ferrate with an electrochemical method and its potential application for wastewater treatment – A review

A number of studies on the oxidation of various organic/inorganic contaminants by ferrate(VI) were reported in the 1980s and 1990s. The exploration of the use of ferrate(VI) for water and wastewater treatment has been well addressed recently. However, challenges have existed for the implementation of ferrate(VI) technology in practice due to the instability of a ferrate solution or high production cost of solid ferrate products. The research has been carried out aiming at the generation and application of ferrate(VI) in situ. This paper thus reviews ferrate chemistry and its overall performance as a water treatment chemical, discusses the factors affecting the ferrate yield efficiency using the electrochemical method, and finally, summarises the work on the production and use of ferrate in situ which is currently under study.     

Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions

The hydrolysis/precipitation behaviors of Al³⁺, Al₁₃ and Al₃₀ under conditions typical for flocculation in water treatment were investigated by studying the particulates' size development, charge characteristics, chemical species and speciation transformation of coagulant hydrolysis precipitates. The optimal pH conditions for hydrolysis precipitates formation for AlCl₃, PAC_Al13 and PAC_Al30 were 6.5–7.5, 8.5–9.5, and 7.5–9.5, respectively. The precipitates' formation rate increased with the increase in dosage, and the relative rates were AlCl₃ ? PAC_Al30 > PAC_Al13. The precipitates' size increased when the dosage increased from 50 μM to 200 μM, but it decreased when the dosage increased to 800 μM. The Zeta potential of coagulant hydrolysis precipitates decreased with the increase in pH for the three coagulants. The iso-electric points of the freshly formed precipitates for AlCl₃, PAC_Al13 and PAC_Al30 were 7.3, 9.6 and 9.2, respectively. The Zeta potentials of AlCl₃ hydrolysis precipitates were lower than those of PAC_Al13 and PAC_Al30 when pH > 5.0. The Zeta potential of PAC_Al30 hydrolysis precipitates was higher than that of PAC_Al13 at the acidic side, but lower at the alkaline side. The dosage had no obvious effect on the Zeta potential of hydrolysis precipitates under fixed pH conditions. The increase in Zeta potential with the increase in dosage under uncontrolled pH conditions was due to the pH depression caused by coagulant addition. Al–Ferron research indicated that the hydrolysis precipitates of AlCl₃ were composed of amorphous Al(OH)₃ precipitates, but those of PAC_Al13 and PAC_Al30 were composed of aggregates of Al₁₃ and Al₃₀, respectively. Al³⁺ was the most un-stable species in coagulants, and its hydrolysis was remarkably influenced by solution pH. Al₁₃ and Al₃₀ species were very stable, and solution pH and aging had little effect on the chemical species of their hydrolysis products. The research method involving coagulant hydrolysis precipitates based on Al–Ferron reaction kinetics was studied in detail. The Al species classification based on complex reaction kinetic of hydrolysis precipitates and Ferron reagent was different from that measured in a conventional coagulant assay using the Al–Ferron method. The chemical composition of Al_a, Al_b and Al_c depended on coagulant and solution pH. The Al_b measured in the current case was different from Keggin Al₁₃, and the high Al_b content in the AlCl₃ hydrolysis precipitates could not used as testimony that most of the Al³⁺ was converted to highly charged Al₁₃ species during AlCl₃ coagulation.     

A review and test of predictive models for the bioaccumulation of radiostrontium in fish

Empirical relations between the ⁹⁰Sr concentration factor (CF) and the calcium concentration in freshwater aquatic systems have previously been determined in studies based on data obtained prior to the Chernobyl accident. The purpose of the present research is to review and compare these models, and to test them against a database of post-Chernobyl measurements from rivers and lakes in Ukraine, Russia, Belarus and Finland. It was found that two independently developed models, based on pre-Chernobyl empirical data, are in close agreement with each other, and with empirical data. Testing of both models against new data obtained after the Chernobyl accident confirms the models’ predictive ability. An investigation of the influence of fish size on ⁹⁰Sr accumulation showed no significant relationship, though the data set was somewhat limited.     

环境库兹涅茨曲线假说在中国的经验研究

改革开放以来,中国年均98%的经济持续增长举世瞩目,然而对经济增长所付出的环境代价却存在着诸多争议。环境库兹涅茨曲线（EKC）假说是对环境 收入关系研究的经典表述,可以直观地展现环境与收入变化的关系。在前人研究EKC时运用单一或多个单一指标测量污染程度存在缺陷的基础上,基于 1982～2006年中国6类环境污染物,用改进的熵值法计算出代表我国整体环境污染状况的环境污染指数,利用协整检验来研究中国环境库兹涅茨曲线的存在性及其“本土化”特征,发现与一般发达国家和新兴发展中国家的“倒U”型环境库兹涅茨曲线不同,中国综合环境污染模型呈“正U”型,以21世纪初为分界点,之前环境污染水平不断下降,之后环境污染又开始有所恶化;利用脉冲响应函数来考察环境污染和经济增长的互动关系,发现经济增长在追溯期内对环境污染均为正向影响,而环境污染仅在短期对经济增长有促进作用。这一研究旨在为制定符合中国国情的环境、经济政策,实现经济与环境协调发展提供理论依据.     

Toxic masking and synergistic modulation of the estrogenic activity of chemical mixtures in a yeast estrogen screen (YES)

Background, aim and scope

Estrogenic and non-estrogenic chemicals typically co-occur in the environment. Interference by non-estrogenic chemicals may confound the assessment of the actual estrogenic activity of complex environmental samples. The aim of the present study was to investigate whether, in which way and how seriously the estrogenic activity of single estrogens and the observed and predicted joint action of estrogenic mixtures is influenced by toxic masking and synergistic modulation caused by non-estrogenic chemical confounders.

Materials and methods

The yeast estrogen screen (YES) was adapted so that toxicity and estrogenicity could be quantified simultaneously in one experimental run. Mercury, two organic solvents (dimethyl sulfoxide (DMSO) and 2,4-dinitroaniline), a surfactant (LAS-12) and the antibiotic cycloheximide were selected as toxic but non-estrogenic test chemicals. The confounding impact of selected concentrations of these toxicants on the estrogenic activity of the hormone 17ß-estradiol was determined by co-incubation experiments. In a second step, the impact of toxic masking and synergistic modulation on the predictability of the joint action of 17ß-estradiol, estrone and estriol mixtures by concentration addition was analysed.

Results

Each of the non-estrogenic chemicals reduced the apparent estrogenicity of both single estrogens and their mixtures if applied at high, toxic concentrations. Besides this common pattern, a highly substance- and concentration-dependent impact of the non-estrogenic toxicants was observable. The activity of 17ß-estradiol was still reduced in the presence of only low or non-toxic concentrations of 2,4-dinitroaniline and cycloheximide, which was not the case for mercury and DMSO. A clear synergistic modulation, i.e. an enhanced estrogenic activity, was induced by the presence of slightly toxic concentrations of LAS-12. The joint estrogenic activity of the mixture of estrogens was affected by toxic masking and synergistic modulation in direct proportion to the single estrogens, which allowed for an adequate adaptation of concentration addition and thus unaffected predictability of the joint estrogenicity in the presence of non-estrogenic confounders.

Discussion

The modified YES proved to be a reliable system for the simultaneous quantification of yeast toxicity and estrogen receptor activation. Experimental results substantiate the available evidence for toxic masking as a relevant phenomenon in estrogenicity assessment of complex environmental samples. Synergistic modulation of estrogenic activity by non-estrogenic confounders might be of lower importance. The concept of concentration addition is discussed as a valuable tool for estrogenicity assessment of complex mixtures, with deviations of the measured joint estrogenicity from predictions indicating the need for refined analyses.

Conclusions

Two major challenges are to be considered simultaneously for a reliable analysis of the estrogenic activity of complex mixtures: the identification of known and suspected estrogenic compounds in the sample as well as the substance- and effect-level-dependent confounding impact of non-estrogenic toxicants.

Recommendations and perspectives

The application of screening assays such as the YES to complex mixtures should be accompanied by measures that safeguard against false negative results which may be caused by non-estrogenic but toxic confounders. Simultaneous assessments of estrogenicity and toxicity are generally advisable.