Extracellular polymeric substance induces biogenesis of vivianite under inorganic phosphate-free conditions

Vivianite is often found in reducing environments rich in iron and phosphorus from organic debris degradation or phosphorus mineral dissolution. The formation of vivianite is essential to the geochemical cycling of phosphorus and iron elements in natural environments. In this study, extracellular polymeric substances (EPS) were selected as the source of phosphorus. Microcosm experiments were conducted to test the evolution of mineralogy during the reduction of polyferric sulfate flocs (PFS) by Shewanella oneidensis MR-1 (S. oneidensis MR-1) at EPS concentrations of 0, 0.03, and 0.3 g/L. Vivianite was found to be the secondary mineral in EPS treatment when there was no phosphate in the media. The EPS DNA served as the phosphorus source and DNA-supplied phosphate could induce the formation of vivianite. EPS impedes PFS aggregation, contains redox proteins and stores electron shuttle, and thus greatly promotes the formation of minerals and enhances the reduction of Fe(III). At EPS concentration of 0, 0.03, and 0.3 g/L, the produced HCl-extractable Fe(II) was 107.9, 111.0, and 115.2 mg/L, respectively. However, when the microcosms remained unstirred, vivianite can be formed without the addition of EPS. In unstirred systems, the EPS secreted by S. oneidensis MR-1 could agglomerate at some areas, resulting in the formation of vivianite in the proximity of microbial cells. It was found that vivianite can be generated biogenetically by S. oneidensis MR-1 strain and EPS may play a key role in iron reduction and concentrating phosphorus in the oligotrophic ecosystems where quiescent conditions prevail.     

A novel approach for VOC source apportionment combining characteristic factor and pattern recognition technology in a Chinese industrial area

Volatile organic compound (VOC) emission control and source apportionment in small-scale industrial areas have become key topics of air pollution control in China. This study proposed a novel characteristic factor and pattern recognition (CF-PR) model for VOC source apportionment based on the similarity of characteristic factors between sources and receptors. A simulation was carried out in a typical industrial area with the CF-PR model involving simulated receptor samples. Refined and accurate source profiles were constructed through in situ sampling and analysis, covering rubber, chemicals, coating, electronics, plastics, printing, incubation and medical treatment industries. Characteristic factors of n-undecane, styrene, o-xylene and propane were identified. The source apportionment simulation results indicated that the predicted contribution rate was basically consistent with the real contribution rate. Compared to traditional receptor models, this method achieves notable advantages in terms of refinement and timeliness at similar accuracy, which is more suitable for VOC source identification and apportionment in small-scale industrial areas.     

Phenol degradation in waters with high iodide level by layered double hydroxide-peroxodisulfate: Pathways and products

Recently, layered double hydroxide-peroxodisulfate (LDH-PDS) as an advanced oxidation system can effectively remove organics by the pathway of free radical. However, little has been known if there is a potential risk regarding the formation of high toxic iodine byproducts through another pathway when LDH-PDS is used in high iodide waters at coastal areas. Therefore, this study investigated phenol degradation pathways and transformation products to evaluate both removal mechanism and potential risk by LDH-PDS in high iodide waters. The results showed that in LDH-PDS system, with the degradation of PDS, phenol degraded till below detection limit in 1 hr in the presence of iodide, while PDS and phenol were hardly degraded in the absence of iodide, indicating iodide accelerated the transformation of PDS and the degradation of phenol. What is more, it reached the highest phenol removal efficiency under the condition of 100 mg/L LDH, 0.1 mmol/L PDS and 1.0 mmol/L iodide. In LDH-PDS system, iodide was rapidly oxidized by the highly active interlayer PDS, resulting in the formation of reactive iodine including hypoiodic acid, iodine and triiodide instead of free radicals, which contributed rapid degradation of phenol. However, unfortunately toxic iodophenols were detected. Specifically, 2-iodophenol and 4-iodophenol were formed firstly, afterwards 2,4-diiodophenol and 2,6-diiodophenol were produced, and finally iodophenols and diiodophenols gradually decreased and 2,4,6-Triiodophenol were produced. These results indicated that LDH-PDS should avoid to use in high iodide waters to prevent toxic iodine byproduct formation although iodide can accelerate phenol degradation.     

长三角区域人为源活性挥发性有机物高分辨率排放清单

基于长三角区域41个城市本地实测,结合美国EPA的SPECIATE 4.4数据库,建立了长三角区域人为源活性挥发性有机物(VOCs)高分辨率排放清单,分析了区域内VOCs的排放特征和组分构成;计算了VOCs的臭氧生成潜势(OFP)和二次有机气溶胶生成潜势(SOAP).结果表明,2017年,长三角区域人为源VOCs排放总量为4.9×10⁶ t,其中工艺过程源、工业溶剂使用源、移动源、生活源、储运源、农业源和废弃物处理源排放贡献分别为：34.3%、27.1%、19.5%、9.7%、6.1%、2.5%和0.4%.芳香烃和烷烃是VOCs的主要种类,均各占长三角VOCs排放总量的25%.工艺过程源、工业溶剂使用源、移动源和生活源OFP贡献率分别为38.3%、21.5%、16.4%和13.2%,SOAP贡献率分别为26.2%、34.1%、18.1%和17.9%,与VOCs排放量的主要贡献源基本一致.各城市VOCs重点排放行业存在较大差异,重点城市群以石化化工和装备制造为主,区域北部则以木材家具等涂装行业为主.计算表明,丙烯、间/对-二甲苯和乙烯是臭氧主要贡献源;甲苯、1,2,...     

浅谈秦皇岛外语语言软环境的优化策略

秦皇岛作为著名的沿海旅游城市,外语语言环境作为旅游软环境的一个重要因素直接影响着整个旅游产业的综合竞争力。鉴于此,对秦皇岛市外语语言软环境进行调查摸底。调查结果表明,旅游景区标示语及城市公示语的翻译存在不同程度的问题,旅游从业人员总体素质不高,市民的外语能力普遍偏低。以调查结果为依托,从政府导向、行业把关、全民参与三方面提出了优化秦皇岛市旅游业外语语言软环境的建议。     

A Recourse‐Based Interval Fuzzy Programming Model for Point‐Nonpoint Source Effluent Trading under Uncertainty

In this study, a recourse‐based interval fuzzy programming (RIFP) model is developed for tackling uncertainties expressed as fuzzy, interval, and/or probabilistic forms in an effluent trading program. It can incorporate preregulated water‐pollution control policies directly into its optimization process, such that an effective linkage between environmental regulations and economic implications (i.e., penalties) caused by improper policies due to uncertainty existence can be provided. The RIFP model is applied to point‐nonpoint source effluent trading of the Xiangxi River in China. The efficiency of trading efforts between water quality improvement and net system benefit under different degrees of satisfying discharge limits is analyzed. The results are able to help support (1) formulation of water‐pollution control strategies under various economic objectives and system‐reliability constraints, (2) selection of the desired effluent trading pattern for point and nonpoint sources, and (3) generation of tradeoffs among system benefit, satisfaction degree, and pollutant mitigation under multiple uncertainties. Compared with the traditional regulatory approaches, the results demonstrate that the water‐pollution control program can be performed more cost‐effectively through trading than nontrading.     

长输管道事故数据库的对比分析

从影响长输管道安全的外部因素、事故定义、事故分类以及事故数据分析和事故报告等几个方面,对国际上主要长输管道事故数据库进行了对比分析,提出了建立我国长输管道事故数据库的建议.