典型岩溶地下河流域水体中硝酸盐源解析

地下河是岩溶地区地下水赋存运动的主要场所和重要水源,近年来,硝酸盐污染严重.为解析典型岩溶地下河流域水体中硝酸盐的来源,利用δ~(15)N-NO~-_3、δ~(18)O-NO~-_3和δ~(18)O-H_2O稳定同位素示踪技术开展研究,并通过SIAR稳定同位素模型,对不同污染源的贡献率进行了定量识别,同时阐明了土地利用类型对流域水体硝酸盐分布及来源的影响.结果表明:①降雨/化肥中的氨盐、土壤有机氮和粪肥污水是流域内水体硝酸盐的主要来源;②流域内水体硝酸盐的转化过程主要以硝化作用为主导,水体硝酸盐氮氧同位素初始值未受分馏影响;③基于SIAR模型,不同端元对流域内水体硝酸盐的贡献比例呈季节性差异,化肥、土壤有机氮和粪便污水对丰水期流域内水体硝酸盐的贡献比例分别为57.07%、 34.06%和8.87%;对流域内枯水期水体硝酸盐的贡献比例分别为34.14%、 33.02%和32.84%.     

Biogeochemical cycling of metals impacting by microbial mobilization and immobilization

Microbial mobilization and immobilization processes can affect the bioavailability and mobility of metals thereby influencing their toxicity and can therefore be utilized to treat solid and liquid wastes contaminated by metals. However, the microbial mobilization and immobilization of metals depends on the microbial metabolism, the environment conditions. In this review, mobilization and immobilization of metals are discussed with regard to the presence and function of involved microorganisms and in relation to applications such as bioleaching. Furthermore, the biosorption process is evaluated as a possible approach for microbial immobilization of metal on the basis of four mechanisms:(1) physical adsorption,(2) ion exchange,(3) complexation, and(4) microprecipitation. In addition, sulfide precipitation by sulfate reducing bacteria was included as an example of an application of microbial immobilization. Based on the evaluation and recommendations in this paper, bioremediation strategies for metals can be improved thus increasing the opportunity for field applications.     

Buses retrofitting with diesel particle filters: Real-world fuel economy and roadworthiness test considerations

Retrofitting older vehicles with diesel particulate filter(DPF) is a cost-effective measure to quickly and efficiently reduce particulate matter emissions. This study experimentally analyzes real-world performance of buses retrofitted with CRT DPFs. 18 in-use Euro III technology urban and intercity buses were investigated for a period of 12 months. The influence of the DPF and of the vehicle natural aging on buses fuel economy are analyzed and discussed. While the effect of natural deterioration is about 1.2%–1.3%, DPF contribution to fuel economy penalty is found to be 0.6% to 1.8%, depending on the bus type. DPF filtration efficiency is analyzed throughout the study and found to be in average 96% in the size range of 23–560 nm. Four different load and non-load engine operating modes are investigated on their appropriateness for roadworthiness tests. High idle is found to be the most suitable regime for PN diagnostics considering particle number filtration efficiency.     

美国食品安全形势及其污染环境法律保障研究

食品的安全对人类的身体健康和生存条件有较大影响。为了对食品安全、生态环境和人类的身体健康进行保障,需要对食品的安全形式及其污染环境法律进行研究。食品安全事件的发生会造成消费者死亡、急性发病或慢性发病,对人类的健康造成严重的或长期的危害。食品安全事件也会给国家的经济造成巨大损失,并对土壤、空气、河流等自然环境造成了严重的污染。阐述食品安全法律保护的必要性,依据美国政府系统、全面、科学的食品安全管理体系,在指导原则的基础上,通过政府的司法、立法和执法三个部分对食品安全进行监督,提高食品安全问题的重视程度。     

Field studies on 32P movement and P leaching from flooded paddy soils in the region of Taihu Lake, China

Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2 32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0-5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25-30 cm layer was only about 1-2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0-30 cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5-5.8% and 1.6-2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist.     

循环流化床锅炉处理褐煤加压气化炉炉渣的技术评价

褐煤加压气化炉对环境有重大影响.在生产过程中,由于褐煤煤质差,灰份含量高,炉渣的产生量大,炉渣可用循环流化床锅炉进行处理.结合国内的实际情况,对循环流化床锅炉处理褐煤加压气化炉炉渣进行了技术评价.     

三维Pd/OMC粒子电极体系电催化泛影酸盐还原脱碘研究

以泛影酸盐(DTZ)的高效还原脱碘为目标,通过硼氢化钠还原法制备钯负载有序介孔碳(Pd/OMC)作为粒子电极,以碳纤维(CFP)电极作为主阴极,建立了三维电极电催化还原体系.该体系在低阴极电位下(-0.6～-0.8 V)可实现电化学/感应电化学的耦合还原,其脱碘速率是单独阴极体系的2.38～3.65倍;在阴极电位高于析氢电位(-1.5 V)时,可实现电化学/感应电化学/化学催化加氢多还原过程协同去除碘代有机物,其反应速率为单独阴极体系的1.27～4.69倍.进一步研究了DTZ初始浓度、Pd/OMC投加量及Pd的负载量对DTZ还原去除的影响.电化学测试结果表明三维电化学体系具有良好的电子传递能力与电还原性能.利用自由基淬灭实验与ESR自由基捕获对活性还原物种分析,表明原子H~*在三维电化学还原脱碘过程中起重要作用.     

Role of extractable and residual organic matter fractions on sorption of phenanthrene in sediments

Two sediments were demineralized and sequentially fractionated into extracted fractions [free lipid (FL), bound lipid (BL) and lignin (LG)] and residual fractions [free lipid free (FLF), bound lipid free (BLF) and lignin free (LGF)]. The sorption isotherms of phenanthrene (Phen) were examined to evaluate the importance of various fractions on sorption. A lignin extraction procedure was for the first time applied to separate the lignin or degraded lignin fraction from sediment organic matter (SOM). The extracted LG was similar to model lignin in terms of elemental ratios and sorption behavior. FL and LG fractions were quite important, as their contents were much higher than reported values. Phen sorption for the extracted fractions was almost linear, whereas that for the residual fractions was nonlinear, especially for LGF with n 0.56–0.63. As the different organic fractions were removed sequentially, sorption energy distribution on the residual sediment organic matter (SOM) became more heterogeneous. In addition, increasing sorption capacity for the residual fractions, except for BLF with its high polarity, suggested that more sorption sites on the SOM matrix became accessible to Phen. The sorption capacity for LGF was comparable to that of condensed SOM. The residual fraction LGF generally controlled the overall sorption at low Phen concentration, but the extractable fraction FL surpassed the former fraction at high Phen concentration, demonstrating the importance of condensed SOM in the sorption of hydrophobic organic compounds (HOCs) in sediments.     

Improving the accuracy of emission inventories with a machine-learning approach and investigating transferability across cities

ABSTRACT

This study presents a novel method for integrating the output of a microscopic emission modeling approach with a regional traffic assignment model in order to achieve an accurate greenhouse gas (GHG, in CO_2-eq) emission estimate for transportation in large metropolitan regions. The CLustEr-based Validated Emission Recalculation (CLEVER) method makes use of instantaneous speed data and link-based traffic characteristics in order to refine on-road GHG inventories. The CLEVER approach first clusters road links based on aggregate traffic characteristics, then assigns representative emission factors (EFs), calibrated using the output of microscopic emission modeling. In this paper, cluster parameters including number and feature vector were calibrated with different sets of roads within the Greater Toronto Area (GTA), while assessing the spatial transferability of the algorithm. Using calibrated cluster sets, morning peak GHG emissions in the GTA were estimated to be 2,692 tons, which is lower than the estimate generated by a traditional, average speed approach (3,254 tons). Link-level comparison between CLEVER and the average speed approach demonstrates that GHG emissions for uncongested links were overestimated by the average speed model. In contrast, at intersections and ramps with more congested links and interrupted traffic flow, the average speed model underestimated GHG emissions. This proposed approach is able to capture variations in traffic conditions compared to the traditional average speed approach, without the need to conduct traffic simulation.

Implications: A reliable traffic emissions estimate is necessary to evaluate transportation policies. Currently, accuracy and transferability are major limitations in modeling regional emissions. This paper develops a hybrid modeling approach (CLEVER) to bridge between computational efficiency and estimation accuracy. Using a k-means clustering algorithm with street-level traffic data, CLEVER generates representative emission factors for each cluster. The approach was validated against the baseline (output of a microscopic emission model), demonstrating transferability across different cities .     

Copper-promoted heterogeneous Fenton-like oxidation of Rhodamine B over Fe3O4 magnetic nanocatalysts at mild conditions

Environmental Science and Pollution Research - Rhodamine B (RhB) is used in various industries and its effluent must be effectively treated because of its harmful and carcinogenic nature. In this...