低温条件下生态槽深度处理农村生活污水的日变化特性

针对农村生活污水处理设施出水水质偏高污染环境的现状,构建了以水生植物为主体的生态槽深度处理农村生活污水,研究了低温条件下生态槽深度处理生活污水过程中DO、pH、COD、NH4+-N、TP等指标的日变化特性。结果表明,生活污水COD为37.67～60.23 mg/L、NH4+-N为13.66～16.76 mg/L、TP为1.32～1.78 mg/L、水温为9～11℃,HRT为5 d时,生态槽出水COD、NH4+-N和TP平均为21.07 mg/L、0.99 mg/L和0.19 mg/L,均可达《地表水环境质量标准》(GB3838-2002)之Ⅳ类水标准。各级生态槽内DO浓度夜间低于昼间。夜间植物对NH4+-N和TP具有较强的吸收作用,平均去除率分别达94.83%和89.87%;而TN去除效果稍差,平均去除率为59.9%。     

北京大气CH4、CO2、TOC日变化规律及垂直分布的自动连续观测

提出了一种能自动连续监测CH4、CO2、TOC日变化及垂直分布的系统,利用该系统监测了2002年冬季CH4、CO2、TOC垂直分布的日变化的变化趋势.结果发现,距地面高度增加,受湍流扩散的影响,CH4、CO2、TOC浓度降低.冬季CH4浓度的日变化呈现明显的单峰周期变化,CO2日变化呈双峰形分布,TOC日变化没有明显的特征,其日变化受机动车尾气排放的影响很大.根据2002年冬季CO2浓度与2000年以前的对比结果发现,北京市冬季燃煤排放的污染物已处于一个相对稳定期,而随着北京市机动车保有量迅速增加,尾气排放成为影响某些大气微量气体日变化的主要因素.     

天津市夏季PM2.5中碳组分时空变化特征及来源解析

为研究天津市夏季PM_2.5中碳组分的时空变化特征及来源,于2019年7—8月设立2个点位分昼夜采集天津市PM_2.5样品,并测定了其中有机碳(OC)和元素碳(EC)的含量。结果表明,城区PM_2.5、OC和EC浓度日均值分别为(53.4±20.8)μg·m^-3、(8.72±2.56)μg·m^-3和(1.67±0.90)μg·m^-3,郊区PM_2.5、OC和EC浓度日均值分别为(54.2±24.5)μg·m^-3、(7.54±2.50)μg·m^-3和(1.82±1.06)μg·m^-3;白天PM_2.5、OC、EC的平均浓度分别为(47.3±16.1)μg·m^-3、(8.7±2.1)μg·m^-3和(1.5±0.6)μg·m^-3,夜间PM_2.5、OC、EC的平均浓度分别为(60.2±26.2)μg·m^-3、(7.5±2.9)μg·m^-3和(2.0±1.2)μg·m^-3。OC浓度表现为城区高于郊区,白天高于夜间;EC及PM_2.5浓度表现为郊区高于城区,夜间高于白天。OC/EC比值分析得,城区(6.04)高于郊区(5.08);白天(6.58)高于夜间(4.54)。城区OC与EC相关性弱于郊区,白天OC与EC相关性弱于夜间。采用EC示踪法与MRS模型对SOC含量进行估算,得到白天与夜间SOC浓度分别为(5.71±1.35)μg·m^-3和(3.81±1.20)μg·m^-3,白天SOC污染比夜间严重。丰度分析与主成分分析的结果表明,天津市夏季城郊区PM_2.5中碳组分均主要来源于燃煤和机动车尾气排放。     

Source characterization of fine and coarse particles at the East Mediterranean coast

Fine and coarse atmospheric particles were collected in Ashdod—a midsize industrial city on the southeastern Mediterranean coast, and in Gedera—a rural site, to characterize ambient particles and to determine their long-range transport during two major seasons—winter and summer. Manual PM2.5 and PM10 samplers, dichotomous samplers, continuous automated PM10 samplers, and denuders were used to sample particulate and gaseous pollutants.Fine and coarse concentrations in Ashdod were 21.2 and 39.6 μg m⁻³, and 23.9 and 30.5 μg m⁻³ in the fall–winter and summer campaigns, respectively. Crustal material, as calcites or dolomites mixed with silicates, dominated the coarse fraction and also the fine fraction on dusty days. In the fall–winter, S, P, and Ni were coupled with minerals. Coarse Ni was associated with crustal material during dust storms, while P originated from shipping and deposition of phosphates in the urban area around.Sulfates dominated the fine fractions in the summer season averaging 12 μg m⁻³. Multivariate analysis indicated that S was associated with As and Se, V and Ni, both associated with heavy fuel combustion, and Zn and Pb. In winter, those mixed sources were local, but in summer they were part of long-range transport. In the fall–winter, Zn and Pb were strongly associated with Mn, Ga, and Cu—elements emitted from either traffic or metal processing plants.Although the influence of crustal material on both size fractions was significant, most heavy metals were associated with PM2.5. Higher concentrations were linked to a larger number of particles in this fraction, to a larger surface area available for biochemical reaction [Harrison, R., Shi, J., Xi, S., Khan, A., Mark, D., Kinnersley, R., Yin, J., Philos, T., 2000. Measurement of number, mass and size distribution of particles in the atmosphere. Philosophical Transactions of the Royal Society 358, 2567–2579], and finally to a larger concern in regards to health effects.     

Malondialdehyde and heavy metal concentrations in tissues of wild boar (Sus scrofa L.) from central Croatia

The aim of this research was to assess the degree of heavy metal (cadmium, lead and mercury) contamination of wild boars from central Croatia and thereby conduct further tests to connect the contamination to oxidative stress occurrence. The highest cadmium concentration was noticed in the kidneys of older boars, the lead concentration was approximately the same in the liver and kidneys, but it was much higher than the concentration in the muscles, while the highest mercury concentration was measured in the kidneys of all wild boars. The correlation between the malondialdehyde (MDA) and the heavy metal concentrations was higher in tissue samples taken from younger animals (1 to 3 years of age) than in the tissue samples taken from older animals (5 to 6 years of age). In the kidneys of all wild boars there was a statistically significant connection between the MDA and cadmium concentration; in the kidneys of younger wild boars there was a statistically significant connection between the MDA and lead concentration. Further research on this topic should focus on MDA potential to find its use, not only as a contamination biomarker in the area of ecotoxicology, but also in the evaluation of the hygienic acceptability of animal products.     

Atmospheric mercury pollution at an urban site in central Taiwan: mercury emission sources at ground level

Total gaseous mercury (Hg) (TGM), gaseous oxidized Hg (GOM), and particulate-bound Hg (PBM) concentrations and dry depositions were measured at an urban site in central Taiwan. The concentrations were 6.14 ± 3.91 ng m⁻³, 332 ± 153, and 71.1 ± 46.1 pg m⁻³, respectively. These results demonstrate high Hg pollution at the ground level in Taiwan. A back trajectory plot shows the sources of the high TGM concentration were in the low atmosphere (<500 m) and approximately 50% of the air masses coming from upper troposphere (>500 m) were associated with low TGM concentrations. This finding implies that Hg is trapped in the low atmosphere and comes from local Hg emission sources. The conditional probability function (CPF) reveals that the plumes of high TGM concentrations come from the south and northwest of the site. The plume from the south comes from two municipal solid waste incinerators (MSWIs). However, no significant Hg point source is located to the northwest of the site; therefore, the plumes from the northwest are hypothesized to be related to the combustion of agricultural waste. Dry deposition fluxes of Hg measured at this site considerably exceeded those measured in North America. Overall, this area is regarded as a highly Hg contaminated area because of local Hg emission sources.     

Testing the Hydrological Landscape Unit Classification System and Other Terrain Analysis Measures for Predicting Low-Flow Nitrate and Chloride in Watersheds

Elevated nitrate concentrations in streamwater are a major environmental management problem. While land use exerts a large control on stream nitrate, hydrology often plays an equally important role. To date, predictions of low-flow nitrate in ungauged watersheds have been poor because of the difficulty in describing the uniqueness of watershed hydrology over large areas. Clearly, hydrologic response varies depending on the states and stocks of water, flow pathways, and residence times. How to capture the dominant hydrological controls that combine with land use to define streamwater nitrate concentration is a major research challenge. This paper tests the new Hydrologic Landscape Regions (HLRs) watershed classification scheme of Wolock and others (Environmental Management 34:S71-S88, 2004) to address the question: Can HLRs be used as a way to predict low-flow nitrate? We also test a number of other indexes including inverse-distance weighting of land use and the well-known topographic index (TI) to address the question: How do other terrain and land use measures compare to HLR in terms of their ability to predict low-flow nitrate concentration? We test this for 76 watersheds in western Oregon using the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program and Regional Environmental Monitoring and Assessment Program data. We found that HLRs did not significantly improve nitrate predictions beyond the standard TI and land-use metrics. Using TI and inverse-distance weighting did not improve nitrate predictions; the best models were the percentage land use—elevation models. We did, however, see an improvement of chloride predictions using HLRs, TI, and inverse-distance weighting; adding HLRs and TI significantly improved model predictions and the best models used inverse-distance weighting and elevation. One interesting result of this study is elevation consistently predicted nitrate better than TI or the hydrologic classification scheme.     

浅水型湖泊水温日成层现象的初步探讨——以太湖为例

水温是湖泊环境研究中的重要物理参数之一。本文以典型浅水型湖泊———太湖为研究对象,根据连续定点监测资料,分析了太湖的水温结构及其影响因素,证明了日成层现象的存在,并从物理、化学和生物学角度论述了水温分层现象对湖泊水质的影响。     

基于自动站资料的深圳灰霾特征对比分析

利用深圳自动气象站的气象要素和深圳大气成分监测系统采集的大气成分数据,分析了深圳城区和郊区灰霾季节变化、日变化差异和不同风向下污染物浓度差异,结果表明,城区由于人类活动频繁导致灰霾日比郊区多,以轻微灰霾偏多为主。秋、冬季城区冷空气活动频繁、能源消耗大,灰霾出现频率是郊区的1~2倍;春季冷空气和海上暖湿气流容易形成对峙,沿海颗粒物更容易吸湿增长,郊区灰霾频率反而比城区高25%;夏季对流强、降水频密,城郊差异最小。城区灰霾频率受早晚交通高峰期影响,日变化呈双峰型。而郊区受太阳辐射和光化学反应影响大,呈单峰型。偏北风条件下污染物浓度明显升高,偏南风带来的清洁空气使得颗粒物浓度降幅明显。     

基于Matlab小波分析的南京北郊大气O3浓度变化特征研究

以2008年南京北郊大气中O₃ 质量浓度观测资料和常规观测资料为基础,利用Matlab小波分析工具,对O₃浓度的年时间序列进行分析,得出该地区的O₃ 日均浓度的变化特征：春、夏季节O3浓度大于秋、冬季节,最高浓度出现在春末夏初,最低浓度出现在冬季;并且全年共有5个突变点;弱高压的天气系统、较高的温度、较低的湿度和晴朗少云的天气是造成南京北郊O₃浓度突变的主要气象因素。结合HYSPLIT气流后向轨迹模拟,对污染源来源进行追踪,结果表明：南京北郊O₃高浓度污染来源主要分为本地局地污染和外来污染物输送两类;垂直方向上,O₃的区域尺度或中尺度的输送主要稳定在混合层的底层。