How do inundation provoke the release of phosphorus in soil-originated sediment due to nitrogen reduction after reclaiming lake from polder

Different N and P fractions in microcosm incubation experiment was measured using high-resolution in-situ Peeper and DGT techniques combining with sequential extraction procedure. The results showed the synchronous desorption and release of PO₄^3-, S^2- and Fe²⁺ from the solid soil-originated sediment. This trend indicated that the significant reduction of Fe-P and SO₄^2- occurred in the pore water during the inundation. The concentrations of PO₄^3- in the overlying water and pore water increased to more than 0.1 and 0.2 mg/L at the beginning of the incubation experiment. Decreased NO₃^-concentrations from more than 1.5 mg/L to less than 0.5 mg/L combining with increasing NH₄⁺ concentrations from less than 1 mg/L to more than 5 mg/L suggested the remarkable NO₃^- reduction via dissimilatory nitrate reduction to ammonia (DNRA) pathway over time. High NH₄⁺ concentrations in the pore water aggravated the release of Fe²⁺ through reduction of Fe(III)-P as electric acceptors under anaerobic conditions. This process further stimulated the remarkable releasing of labile PO₄^3- from the solid phase to the solution and potential diffusion into overlying water. Additionally, high S^2- concentration at deeper layer indicated the reduction and releasing of S^2- from oxidation states, which can stimulated the NO₃^- reduction and the accumulation of NH₄⁺ in the pore water. This process can also provoke the reduction of Fe-P as electric acceptors following the release of labile PO₄^3- into pore water. Generally, inundation potentially facilitate the desorption of labile P and attention should be paid during the reclaiming lake from polder.     

Mercury transformation processes in nature: Critical knowledge gaps and perspectives for moving forward

The transformation of mercury (Hg) in the environment plays a vital role in the cycling of Hg and its risk to the ecosystem and human health. Of particular importance are Hg oxidation/reduction and methylation/demethylation processes driven or mediated by the dynamics of light, microorganisms, and organic carbon, among others. Advances in understanding those Hg transformation processes determine our capacity of projecting and mitigating Hg risk. Here, we provide a critical analysis of major knowledge gaps in our understanding of Hg transformation in nature, with perspectives on approaches moving forward. Our analysis focuses on Hg transformation processes in the environment, as well as emerging methodology in exploring these processes. Future avenues for improving the understanding of Hg transformation processes to protect ecosystem and human health are also explored.     

加油站油气回收现状与展望

通过理论计算和案例分析,对目前在用加油站油气回收系统的有效运行率进行了分析,阐述加油站三次油气回收装置的配备条件,介绍了加油站油气回收新技术(ORVR),提出了我国应使用新的加油站油气回收技术的结论。     

气相色谱法测定饮用水中三氯乙烯含量的不确定度评定研究

分析和评定气相色谱法测定饮用水中三氯乙烯含量过程中引入的不确定度,分析了标准物质、分析操作、重复性测定等方面对不确定度的影响,实验表明在置信水平95%,包含因子k=2时,水中三氯乙烯测量结果的相对扩展不确定度为8.31%,三氯乙烯含量为3.17μg/L,扩展不确定度为0.263μg/L,测试过程的随机效应引入的不确定度对合成不确定度的贡献最大.     

镉、铬复合污染水源水的处理技术研究

重金属引起的给水污染是威胁人体健康的元凶首恶之一,也为传统给水处理工艺提出更大的挑战.本文以强化混凝沉淀的方法处理铬、镉复合污染的水源水,旨在通过优化原工艺应对突发污染.研究表明,针对铬和镉的初始污染浓度分别为0.170 0 mg/L和0.030 0 mg/L的复合污染水源水,采用分段工艺,只需在原水的pH值的条件下,投加混凝剂(FeCl3)20.0 mg/L,混凝剂(PAFC)的投加量为2mg/L,出水即可以达到国家出水标准.处理过程模拟水厂现有工艺,无需新增设备,易于操作.     

Reliability analysis of subsea blowout preventer control systems subjected to multiple error shocks

Two configurations of subsea blowout preventer (BOP) distributed control systems, which are triple modular redundancy (TMR) control system and double dual modular redundancy (DDMR) control system, are presented. With respect to common-cause failures, the performances of the two systems are evaluated by using Markov method with multiple error shock model. Due to the complexity, each system is split into three independent modules, and the corresponding Markov models are proposed subsequently. The probability of failure on demand, availability and reliability of the systems are evaluated by merging the independent Markov modules by Kronecker product approach. The results indicate that a same safety integrity level of SIL3 can be attained for the two configurations, which satisfies the requirement of subsea BOP control system, even though both of them have some advantages and shortcomings. In addition, for TMR control system, the effects of multiplicity distribution of multiple error shock and mean time to repair on reliability performances are studied.     

地表水环境非点源污染研究

地表水环境的非点源污染已越来越受到人们的重视。在阐述非点源污染的概念、危害性的基础上,对国内外地表水环境非点源污染研究现状进行综述。分析了国内外研究存在的不足。讨论了地表水环境非点源污染研究的未来发展趋势     

环嗪酮对生态环境影响评价研究

在实验室测定了环嗪酮有不同ｐＨ条件下的水解、不同土壤中的降解及其在直径为２ｃｍ长为３０ｃｍ的玻璃管中的淋溶移动情况,试验结果表明,环嗪酮在ｐＨ为５、７、９三种不同缓冲溶液中的水解半衰期分别为５１７９．３、２４１３．９、８６６．４天;在东北黑土、江苏黄棕壤、浙江黄壤与江西红壤四种不同土壤中的降解半衰期分别为４０．３、９．６、７７．１和１２０．３天;在上述四种土壤中的移动速率次序为东北黑土＜江苏黄棕＜浙江黄壤＜江西红壤。田间试验结果表明,环嗪酮在试验区土壤中的淋溶性能极高,施药后半月内即可淋溶到６０～１２０ｃｍ深的土层中,淋溶到６０ｃｍ以下土层中的量占环嗪酮总使用量的１４．７％,在试验区内外的观测井中也检测到它的残留。但其在土壤的消失速率也很快,施药２个月后,在试验区各土层与观测井中均已无残留检出,在试验区环境条件下,它的使用将不会导致对地下水的污染。     

次级河流水污染事件应急处置程序及环境损害评估技术路线

近年来,随着我国经济的发展,次级河流突发性水污染事件频繁发生,对生态环境及居民生活造成了严重的影响。次级河流突发性水污染事件发生后,为减少污染造成的损失和影响,保证受损的环境资源得到恢复和补偿,不仅要立即采取行之有效的应急处置措施,而且应当积极开展环境损害鉴定评估工作,全面追究污染者的环境责任。根据次级河流本身的特点,结合各省市在环境应急处置过程中的具体做法,建立了一套应对突发性次级河流水污染事件的应急处置工作程序;阐述了环境损害鉴定评估的必要性、工作方法和技术路线,同时从受损环境资源的确认、污染源和污染物的识别以及暴露途径的建立3个方面构建了开展次级河流突发性水污染事件环境损害鉴定评估工作的因果关系链条,对实际开展相关工作具有重要意义。     

Isolation and characterization of a newly isolated pyrene-degrading Acinetobacter strain USTB-X

The pryene-degradation bacterium strain USTB-X was newly isolated from the polycyclic aromatic hydrocarbon (PAH)-contaminated soil in Beijing Coking Plant, China. The strain was identified as Acinetobacter with respect to its 16S rDNA and morphological and physiological characteristics. The strain was Gram-negative, non-mobile, non-acid-fast, and non-spore-forming, short rods in young culture and 0.8–1.6 μm in diameter and 1.2–2.5 μm long in the stationary phase of growth. Strain USTB-X could utilize pyrene, naphthalene, fluorene, phenanthrene, benzene, toluene, ethylbenzene, ethanol, methanol, and Tween 80 as sole source of carbon and energy. The strain could produce biosurfactants which enhanced the removal of pyrene and could remove 63 % of pyrene with an initial concentration of 100 mg·L^?1 in 16 days without other substrates. Based on the intermediates analyzed by gas chromatography-mass spectrometry, we also deduced the possible metabolic pathway of strain USTB-X for pyrene biodegradation. Results indicated that the strain USTB-X had high potential to enhance the removal of PAHs in contaminated sites.