基于TMVOC的地下水位波动带苯系物迁移转化模拟

为探究水位波动情况下苯系物的迁移转化规律,提高石油污染场地地下水污染治理精度,以西北某傍河石化场地为研究对象,基于TMVOC模型对特征污染物苯系物开展泄漏模拟,通过情景模拟比较水位波动对苯系物迁移转化的影响,并从污染分布、相间转化等方面,解析地下水位稳定和波动状态下苯系物迁移转化过程差异.结果表明:①TMVOC模型较好地模拟了水位波动状态下苯系物迁移转化过程.②相较于水位稳定状态下,水位波动作用下苯系物污染深度增加0.5 m,污染面积增加25%,总质量增加12 kg.③水位稳定和波动状态下苯系物"气-液-NAPL（Non-Aqueous Phase Liquids）相"占比分别为0.17%、2.03%、97.8%和0.04%、3.69%、96.27%.④NAPL相苯系物饱和度分布与苯系物质量分布呈正相关,水位波动造成NAPL相初始饱和度降低,且初始水位面以下NAPL相饱和度升高.⑤对于苯而言,水位波动状态下非饱和带中苯在液相中的质量是水位稳定状态下的1.11倍,饱和带为10.15倍.研究显示,水位波动显著地影响了苯系物的迁移转化过程,促进了苯系物的溶解,并使更多的苯系物残留在地下介质中.      

特殊区域地表水环境背景值表征技术方法研究与应用

选取黑龙江省源头水保护区作为研究对象,根据DEM数据对保护区内随机布设的水质监测点控制单元进行划分并提取单元内的相关指标建立监测点背景特性量化模型,基于量化结果提出地表水环境背景值监测方案,建立背景值数据库.选取研究区自然属性指标与空间属性指标,以空间叠置技术与聚类分析方法对研究区地表水进行背景值分区,最终将黑龙江省分为六大地表水水质背景值地理分区,并计算了各分区地表水环境背景值表征范围.表征范围显示：依据现行标准进行水质评价,保护区内水质背景值已超出Ⅱ类水质标准限值.因此,基于水质背景值研究成果提出了考虑背景值影响下的水环境质量评价方法,并将方法应用于研究区,结果表明方法切实可行且优于单因子评价法.研究成果可为区域制定背景值影响下的水环境评价方法提供科学的数据支撑与理论依据.     

腐植酸中不同分子量组分与As(Ⅲ)的络合性能

采用超滤方法将腐植酸（HA）分成5个不同分子量组分,利用平衡透析法研究HA中不同分子量组分与As（III）的络合特征和作用机理,计算络合过程的条件分配系数、表观稳定常数.结果表明,腐植酸组分的分子量对HA与As（III）的络合过程有显著的影响,当分子量小于10kDa时,HA与As（III）络合能力明显强于其他条件.其中羧基和酚羟基在HA与砷络合中起重要作用,为主要络合位点.采用Scatchard分析和双位点配体模型对络合结果进行拟合,发现HA中不同分子量组分和As（III）的络合过程中均存在强和弱2种络合位点.     

滦河秋季大型底栖动物群落结构空间格局与关键环境影响因子识别

掌握水生生物的空间分布特征及其关键影响因子是科学制定生物多样性保护策略的基础.于2016年秋季对滦河53个样点开展了大型底栖动物和环境因子的现场调查,分析了大型底栖动物群落结构与空间分布特征,并识别出影响大型底栖动物物种空间分布的关键环境因子.结果表明:①滦河（河北省）共采集并鉴定出大型底栖动物206种,隶属于8纲22目70科144属,以纹石蚕（Hydropsyche sp.）和东方蜉蝣（Ephemera orientalis）为优势种.②根据滦河大型底栖动物群落结构相似性,53个样点在空间上被分为3组.第1组分布在滦河干流的中下游及支流下游,无指示物种;第2组分布在支流上游,指示种为纹石蚕、朝大蚊（Antocha sp.）和中华小长臂虾（Palaemonetes sinensis）;第3组分布在滦河干流中上游,指示种为东方蜉蝣和中华齿米虾（Neocaridina denticulate sinensis）.③第3组的分类单元数显著高于第1组和第2组;第1组的多样性指数显著高于第2组;第1组的均匀度指数显著高于其他2组.单因素方差分析（one-way ANOVA）发现,pH、TN、底质、河道变化、水质状况和河岸土地利用类型等环境因子在第2组与第3组之间差异显著,第2组明显高于第3组.典范对应分析（CCA）表明,栖境复杂性、河水水量状况和河岸土地利用类型是影响滦河大型底栖动物空间分布的关键环境因子.研究显示,降低河岸带干扰强度、恢复河道生境多样性是未来滦河大型底栖动物多样性保护恢复的重要管理措施.      

Simulation of a 100-MW solar-powered thermo-chemical air separation system combined with an oxy-fuel power plant for bio-energy with carbon capture and storage (BECCS)

The combination of concentrated solar power–chemical looping air separation (CSP-CLAS) with an oxy-fuel combustion process for carbon dioxide (CO₂) capture is a novel system to generate electricity from solar power and biomass while being able to store solar power efficiently. In this study, the computer program Advanced System for Process Engineering Plus (ASPEN Plus) was used to develop models to assess the process performance of such a process with manganese (Mn)-based oxygen carriers on alumina (Al₂O₃) support for a location in the region of Seville in Spain, using real solar beam irradiance and electricity demand data. It was shown that the utilisation of olive tree prunings (Olea europaea) as the fuel—an agricultural residue produced locally—results in negative CO₂ emissions (a net removal of CO₂ from the atmosphere). Furthermore, it was found that the process with an annual average electricity output of 18 MW would utilise 2.43% of Andalusia’s olive tree prunings, thereby capturing 260.5 k-tonnes of CO₂, annually. Drawbacks of the system are its relatively high complexity, a significant energy penalty in the CLAS process associated with the steam requirements for the loop-seal fluidisation, and the gas storage requirements. Nevertheless, the utilisation of agricultural residues is highly promising, and given the large quantities produced globally (~?4 billion tonnes/year), it is suggested that other novel processes tailored to these fuels should be investigated, under consideration of a future price on CO₂ emissions, integration potential with a likely electricity grid system, and based on the local conditions and real data.

     

牛粪-化肥配施对水稻田氮磷迁移转化的影响

在控制外源N输入量相同的前提下,通过田间小区实验,探讨有机肥与化肥不同施用量（牛粪施用量：5,10,20t/hm²）对稻田田间土-水界面氮磷迁移转化特征的影响.结果表明：控制稻田水中NH₄⁺-N、NO₃^--N、TN和TP输出的最佳时期分别为施肥后的第5,30,7,20d,且TN和TP浓度随时间变化符合单指数衰减方程（0.7444≤R²≤0.9724;1.1×10^-6≤F≤0.0055）.采用牛粪部分代替化肥的施肥方式,在一定范围内能降低稻田退水中TN、TP输出负荷（41.8%、36.0%、64.3%;20.3%、39.1%、48.9%）,还可以降低稻田水中N/P,降低水体富营养化风险.同时,牛粪的施用可提高土壤中脲酶和磷酸酶的含量,促进氮磷向植物可吸收形态转化.综合经济成本和生态效益核算,采用10t有机肥代替无机肥的处理是相对经济环保的施肥方法,该施肥方式下,氮磷年输出负荷分别为17.70,1.26kg/hm².     

Potential of secondary aerosol formation from Chinese gasoline engine exhaust

Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds(VOCs). However,little information on secondary aerosol formation from exhaust for Chinese vehicles and fuel conditions is available. In this study, chamber experiments were conducted to quantify the potential of secondary aerosol formation from the exhaust of a port fuel injection gasoline engine. The engine and fuel used are common in the Chinese market, and the fuel satisfies the China V gasoline fuel standard. Substantial secondary aerosol formation was observed during a 4–5 hr simulation, which was estimated to represent more than 10 days of equivalent atmospheric photo-oxidation in Beijing. As a consequence, the extreme case secondary organic aerosol(SOA) production was 426 ± 85 mg/kg-fuel, with high levels of precursors and OH exposure. The low hygroscopicity of the aerosols formed inside the chamber suggests that SOA was the dominant chemical composition. Fourteen percent of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatile organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reductions of emissions of aerosol precursor gases from vehicles are essential to mediate pollution in China.     

Mercury flows in large-scale gold production and implications for Hg pollution control

Large-scale gold production(LSGP) is one of the five convention-related atmospheric mercury(Hg) emission sources in the Minamata Convention on Mercury. However, field experiments on Hg flows of the whole process of LSGP are limited. To identify the atmospheric Hg emission points and understand Hg emission characteristics of LSGP, Hg flows in two gold smelters were studied. Overall atmospheric Hg emissions accounted for 10%–17% of total Hg outputs and the Hg emission factors for all processes were 7.6–9.6 kg/ton. There were three dominant atmospheric Hg emission points in the studied gold smelters, including the exhaust gas of the roasting process, exhaust gas from the environmental fog collection stack and exhaust gas from the converter of the refining process. Atmospheric Hg emissions from the roasting process only accounted for 16%–29% of total emissions and the rest were emitted from the refining process. The overall Hg speciation profile(gaseous elemental Hg/gaseous oxidized Hg/particulate-bound Hg) for LSGP was 34.1/57.1/8.8. The dominant Hg output byproducts included waste acid, sulfuric acid and cyanide leaching residue. Total Hg outputs from these three byproducts were 80% in smelter A and 84% in smelter B. Our study indicated that previous atmospheric Hg emissions from large-scale gold production might have been overestimated.Hg emission control in LSGP is not especially urgent in China compared to other significant emission sources(e.g., cement plants). Instead, LSGP is a potential Hg release source due to the high Hg output proportions to acid and sludge.