宁波市大气可吸入颗粒物PM1o和PM2.5的源解析研究

在宁波市布设4个代表性点位,于2010年春季、夏季和冬季进行大气PM10和PM2.s的采样,同时采集了多种颗粒物源样品,建立了PM10、PM2.5和源样品的化学成分谱.采用化学质量平衡模型(CMB)对宁波市PM10、PM2.5进行源解析.结果表明,城市扬尘、煤烟尘、机动车尾气尘是宁波市PM10、PM2.5的3大污染源,...     

Parameterization of Albedo over Heterogeneous Surfaces in Coupled Land-Atmosphere Schemes for Environmental Modeling. Part I: Theoretical Background

In grid-based environmental models, the underlying surface consists of patches of solid and liquid parts and different plant communities, creating a very heterogeneous picture in the grid cell. In these cases, numerical modelers usually use a simple arithmetic average to determine the grid-cell albedo, a key variable in the parameterization of the land-surface radiative transfer over the grid cell. The object of this paper is to consider the assumptions for aggregating the albedo over a very heterogeneous surface where various surfaces occur at different heights, and, then propose a method for deriving a general expression for it. The suggested expression for the albedo is compared with the conventional approach, for the two-patches grid-cell with a simple geometrical distribution and different heights of its components. A numerical test is performed to compare the two approaches by numerical simulation of the evolution of the surface temperature over the particular grid-cell. Specifically, a one-dimensional land-surface model was applied to an isolated rocky grid-cell with a hole in the center; the model was forced with meteorological observations taken on July 17, 1999 in Philadelphia, PA.     

Radioactivity in the Baltic Sea

The Baltic Sea is, like the Mediterranean, a marginal sea, which with the Black Sea, were marine environments contaminated from the Chernobyl accident.

Radiocaesium and plutonium isotopes were studied in water, sediment and macroalgae in the Baltic Sea since 1982. the inventory of ¹³⁷Cs in the Baltic increased from 0.65 PBq to 5.85 PBq following the Chernobyl accident. the corresponding increase for ^{239 + 240}Pu was less significant and yielded 1.5 TBq to a total value of 16.5 TBq.

For plutonium, 98% is trapped in the sediment and the net-exchange of this element through the Baltic straits is very small (1 GBq/year), while for radiocaesium, 45% is in the water phase and there is a net-loss of 60 000 GBq annually into the adjacent water (Kattegatt).     

Fate of Co at a sludge land application site

Vertical distributions of ⁶⁰Co are determined in soil cores obtained from a 10-ha grassland, where anaerobically digested sludge was applied by surface spraying from 1986 to 1995 on the U.S. Department of Energy's Oak Ridge Reservation. These results, along with historical application records, are used to estimate vertical-migration rates and perform a mass balance. The presence of ⁶⁰Co results solely from the sludge-application process. Soil, vegetation, and surface-water samples were collected. Eleven soil cores were sectioned into 3-cm increments and analyzed by gamma-ray spectrometry. No ⁶⁰Co was detected in the vegetation or water samples. The downward migration rate of ⁶⁰Co in the upper 15 cm of soil ranged from 0.50 to 0.73 cm/yr. About 98%, 0.020 ± 0.011 Bq/cm², of ⁶⁰Co remained in the upper 15 cm of soil, which compared favorably with the expected ⁶⁰Co activity based on historical records of 0.019 ± 0.010 Bq/cm².     

Microbial biomass yield and turnover in soil biodegradation tests: carbon substrate effects

Most of the standardized biodegradation tests used to assess the ultimate biodegradation of environmentally degradable polymers are based solely on the determination of net evolved carbon dioxide. However, under aerobic conditions, it has to be considered that heterotrophic microbial consortia metabolize carbon substrates both to carbon dioxide and in the production of new cell biomass. It is generally accepted that in the relatively short term, 50% of the carbon content of most organic substrates is converted to CO₂, with the remaining carbon being assimilated as biomass or incorporated into humus. The latter is particularly important when the metabolism of the organic matter occurs in a soil environment. A straightforward relationship between the free-energy content of a carbon substrate (expressed as the standard free-energy of combustion) and its propensity for conversion to new microbial biomass rather than mineralization to CO₂ has been established. This can potentially lead to underestimation of biodegradation levels of test compounds, especially when they consist of carbon in a fairly low formal oxidation state and relatively high free-energy content. In the present work, the metabolism of different kind of carbon substrates, especially in soil, is reviewed and compared with our own experimental results from respirometric tests. The results show that conversion of highly oxidized materials, such as the commonly used reference materials, cellulose or starch, to CO₂ may be significantly overestimated. The addition of glucosidic material to soil leads to greatly increased respiration and is accompanied by a very low conversion to biomass or humic substances. In contrast, relatively less oxidized substrates metabolize more slowly to give both CO₂ and biomass to an extent which may be significantly underestimated if glucosidic materials are used as the reference. The need for an overall carbon balance taking into account both the carbon immobilized as biomass and that volatized as CO₂ must be considered in standard respirometric procedures for assessing the biodegradability of slowly degrading macromolecules.     

厌氧序批式反应器预处理垃圾渗滤液的碳平衡研究

为初步了解垃圾渗滤液中有机物降解过程的物质和能量转化,对渗滤液实际处理工程提供借鉴,在最优工艺参数条件下,分别用处于中温(35±1)℃和常温状态的厌氧序批式反应器(ASBR)对垃圾渗滤液进行预处理。通过对反应器内的液相、气相和固相碳素进行全面的分析测定,结果表明:中温(常温)条件下,整个反应周期内约有86.4%(77.6%)的碳进入气相,约有1.7%(1.4%)的碳进入固相,其余约11.7%(22.3%)的碳仍存于液相中;其中,进入气相部分的碳有77.6%(71.3%)以甲烷形式存在,8.8%(4.7%)以二氧化碳形式存在,这说明ASBR预处理垃圾渗滤液过程中产生的甲烷资源化利用潜力较大。另外,反应器在中温状态下较常温状态处理效果更佳。     

烟台市环境受体PM2.5四季污染特征与来源解析

于2016～2017年四季在烟台市3个点位采集了PM_(2.5)样品,分析了其质量浓度和化学组分特征.利用CMB模型对受体进行解析,并利用后向轨迹和PSCF对传输气流和潜在源区进行了分析.结果表明,烟台市监测点位冬季、春季、夏季和秋季的PM_(2.5)平均质量浓度分别为(89. 45±56. 80)、(76. 78±28. 44)、(32. 65±17. 92)和(57. 32±24. 60)μg·m~(-3). PM_(2.5)浓度表现出明显的季节变化特征(P 0. 01).全年PM_(2.5)各源类分担率大小依次为:二次硝酸盐源(20. 3%)城市扬尘源(15. 7%)机动车排放源(14. 9%)燃煤源(13. 8%)二次硫酸盐源(12. 8%) SOC(6. 1%)建筑水泥尘源(5. 5%)海盐源(2. 9%),可以看到烟台市以二次源、扬尘、机动车排放源和燃煤源为主要污染源.春季硝酸盐源和城市扬尘源是重要贡献源类,夏季硫酸盐源贡献突出,燃煤源在秋冬季占比突出.烟台市气流输送和潜在源区也呈现出明显的季节变化:冬季主要受烟台市短距离输送的影响;夏季主要受烟台东部沿海和本地的影响;春秋季主要受山东东北部和东部沿海地区的区域传输和烟台市本地源的影响.     

自上而下的城市能源消耗碳排放估算方法

快速的城镇化进程带来城市碳排放的快速增长,准确的城市水平碳排放数据对于制定科学合理的碳减排政策极为关键,明确碳排放源的关键类别可以做到有的放矢和精准管控.但是目前中国碳排放数据的研究主要集中在国家、地区和省级层面,城市水平由于所需基础数据的不透明和不准确,长久以来缺乏完整的碳排放清单.为解决该问题,在以前相关研究的基础上,通过省级能源平衡表,尝试利用合理的分配指标从省级碳排放数据估算出下属城市的碳排放,构建了一套自上而下的城市能源消耗碳排放估算方法.通过与现有可获得的城市水平数据进行对比,发现估算差距均在10%以内,证明了该方法的可行性和准确性,并尝试在时间尺度进行了扩展.为获取在时间和空间上均连续的中国城市能源消耗碳排放数据提供了科学的方法和合理的思路,也能为各城市分配减排任务和城市间进行减排协商提供可靠的数据支撑.     

溶解性微生物产物在GO/PVDF杂化膜面的污染行为

为了解析溶解性微生物产物（SMP）在GO/PVDF杂化膜面的污染特性,对膜片进行了宏观污染实验,并采用耗散石英微晶天平（QCM-D）从微观角度分析了SMP在自制镀膜芯片上的吸附规律和污染层结构变化.结果表明,GO含量为0.5wt%的膜污染恢复率最高（79.95%）,抗污染能力最强.QCM-D实验发现,GO含量为0wt%镀膜芯片表面SMP吸附量最大,污染较为严重.膜片亲水性越强,吸附频率变化越小,抗污染能力越强.此外,GO含量为0.5wt%镀膜芯片表面的污染物结构比较疏松和柔软,其他膜表面的污染物结构较为坚硬和致密.     

Application of interface material and effects of oxygen gradient on the performance of single-chamber sediment microbial fuel cells (SSMFCs)

Single-chamber sediment microbial fuel cells(SSMFCs) have received considerable attention nowadays because of their unique dual-functionality of power generation and enhancement of wastewater treatment performance. Thus, scaling up or upgrading SSMFCs for enhanced and efficient performance is a highly crucial task. Therefore, in order to achieve this goal, an innovative physical technique of using interface layers with four different pore sizes embedded in the middle of SSMFCs was utilized in this study.Experimental results showed that the performance of SSMFCs employing an interface layer was improved regardless of the pore size of the interface material, compared to those without such layers. The use of an interface layer resulted in a positive and significant effect on the performance of SSMFCs because of the effective prevention of oxygen diffusion from the cathode to the anode. Nevertheless, when a smaller pore size interface was utilized, better power performance and COD degradation were observed. A maximum power density of 0.032 mW/m~2 and COD degradation of 47.3% were obtained in the case of an interface pore size of 0.28 μm. The findings in this study are of significance to promote the future practical application of SSMFCs in wastewater treatment plants.