北京夏季高温高湿和降水过程对大气颗粒物谱分布的影响

2004-07-13～2004-08-23使用TDMPS-APS系统在线测量颗粒物的数浓度谱分布,并于07-16～07-18选取了高温闷热夜晚、日间高温高湿和雨后晴朗干洁3种天气条件,使用多级串联撞击式采样器(MOUDI)测量颗粒物的质量浓度谱分布,结果表明,高温高湿天气条件下颗粒物的污染、尤其细粒子污染严重,导致很低的能见度(2.5km);PM_1.8和PM₁₀的质量浓度分别为170.68μg/m³和249.35μg/m³,细粒子质量浓度占PM10的68%;粒径为50～100nm颗粒物的数浓度最高,为2×10⁴～3×10⁴个/cm³;降雨过程对粗粒子和细粒子均有去除作用,对细粒子的去除作用尤为明显;降雨后PM₁₀和PM_1.8浓度分别比降雨前降低3倍和6倍;降雨过后的晴朗干洁天气有利于新粒子(3～20nm)的生成,生成的新粒子快速长大到50～100nm;随着污染物的累积,以后几天内又变为污染天气.     

生物炭负载氮还田对水稻生长、根系形态及氮素利用的影响

建立连接富营养化水体养分与农田养分的枢纽是减少农田养分投入、缓解水体富营养化的难点.为探明生物炭材料负载氮还田的可行性,开展了基于溶液氮及生物炭负载氮两种氮源添加方式的水稻根箱试验.结果表明,生物炭负载氮添加方式分别较溶液氮添加方式降低了水稻地上部分生物量及氮累积16%及14%,提高了生物量根冠比25%～27%,降低了氮利用效率.不定根的根长及体积是两种氮源添加方式在水稻地下部分差异的体现,地下部分生物量及氮累积与土壤铵态氮含量呈正相关关系,而地上部分氮累积与根尖数呈负相关关系.生物炭负载氮完全替代化学肥料施用农田会影响水稻生物量及氮素利用.但生物炭负载氮与普通化学肥料共同施用,水稻并不会显现利用偏好.生物炭负载氮对水稻氮素利用无不良影响,且能有效提高土壤矿质态氮固持量.因此,生物炭可以作为载体实现水体到农田土壤的氮素迁移,鉴于化肥氮替代比例对作物生长的影响,适宜替代比例还需进一步研究确定.     

A Site-Related Suitability Analysis for the Production of Biomass as a Contribution to Sustainable Regional Land-Use

The use of renewable energy in Europe offers the possibility of reducing greenhouse gas emissions, and contributes to energy security and independence. With the reform of the Common Agricultural Policy (CAP) and a variety of recently introduced national directives supporting renewable energy sources in the European Union, the economic attractiveness of bioenergy production has distinctly increased. This article combines an economic evaluation of biomass production with site-related natural conditions of the Havelland region, situated in the north-east area of Germany. Two methods for evaluating site-specific potential biomass yields were compared. For three example biomass crops, evaluations of yield estimations at agricultural lots for site-optimized suitability (SOS) and conventional suitability (CS) were carried out. Both modelling approaches were compared. The results of the GIS modelling indicate that the financial support for increasing the use of renewable energy with the German feed-in system, called Erneuerbare-Energien-Gesetz (EEG), will possibly lead to an increased cultivation of crops with high biomass output. This monocultural orientation of farming practices and the negative effects on the ecosystem could act in opposition to other environmental initiatives of the EU. The outputs of the SOS analysis show that high biomass production could be integrated into environmental policy proposals. Therefore, new EU policy should take modified subsidies into consideration in order to avoid developing conflicts between small-scale changes in landscape ecosystems caused by large-scale transformations in energy policy.     

Acidification of soil-water in low base-saturated sand soils of the superior uplands under acid and normal precipitation

Lakes and streams are acidified by direct precipitation and water channeled through nearby soils, but water in low base-saturation soils can produce highly acidic percolate after prolonged contact and subsequent degassing in surface waters. Theories advanced by Reuss (1983), Reuss and Johnson (1985), and Seip and Rustad (1984) suggest that soils with less than 15% base saturation are susceptible to soil-water pH depression of up to 0.4 unit, which is sufficient to cause negative alkalinity in soil solutions. High concentrations of mobile anions (notably sulfate) are responsible for the negative alkalinity and these solutions on CO₂ degassing in surface waters can retain acidities equivalent to a pH value of 5.0 or less. This mechanism purports to explain why some lakes acidify when they are surrounded by acid soils and cation leaching is not required.Ambient precipitation set to pH 5.4 and pH 4.2 was applied to columns of low base-saturated, sand, soils, starting in 1985. The columns (15 cm diameter and 150 cm long) were collected from soils with base saturations falling into one of three groups (0–10, 10–20, and 20–40%) from national forests in the Superior Uplands area (includes Boundary Waters Canoe Area, Rainbow Lakes, Sylvania, Moquah Barrens, and other Wilderness and Natural areas). The soils were Haplorthods and Udipsamments mainly from outwash plains.The soil columns were instrumented and reburied around a subterranean structure used to collect leachate water and to maintain natural temperature, air, and light conditions. Three humus treatments were applied to soil column (none, northern hardwood, and jack pine) to measure the effect of natural acidification compared to acidification by acid precipitation. The cores were treated with precipitation buffered to pH 5.4 to simulate natural rain and pH 4.2 to simulate acid rain.Columns were treated in 1985 and 1986 with approximately 200 cm of buffered precipitation each year over the frost-free season. Data is now being analyzed for the 1986 treatment year. In leachate collected from the upper horizons of the soil colums, there was a significant difference in pH, alkalinity, nitrate, and sulfate concentrations between the pH 5.4 and pH 4.2 precipitation treatments. This difference, however, disappears at the bottom of the columns. This could be partly due to exchange reactions in the B horizon. The pH and alkalinities are higher in bottom leachate. Chloride and nitrate also increased significantly due mainly to concentrating effects. Even with a pickup of sulfate in the B horizon, sulfate adsorption decreased bottom leachate concentrations well below surface values.Alkalinity, pH, and sulfate concentration in the leachate decreased over the treatment season. Nitrate concentration increased by 4- to 5-fold over the season. Leachate from the bottom of the soil columns is becoming more acidic with time with negative alkalinities appearing more frequently in columns with soils of lower base saturation. There were some significant alkalinity differences due to humus treatments; however, these were not consistent between pH treatments, and need further study. This research will eventually answer whether soil processes can be important to the acidification of lakes in poor, sandy, outwash plains of the Superior Uplands, and whether a reduction in acid sulfate deposition will reverse the percolate alkalinity from negative to positive.Contribution from Fourth World Wilderness Congress-Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987.     

Unusual polar metabolites in the groundwater of a contaminated waste site indicate a new pathway of mononitrotoluene transformation

At a mononitrotoluene-contaminated waste disposal site, the groundwater was screened for polar transformation products of mononitrotoluenes, by means of HPLC-MS, HPLC-NMR and further off-line NMR and MS techniques. Besides expected metabolites such as aminotoluenes (ATs) and nitrobenzoic acids (NBAs), three unknowns (di- and tetrahydro-derivatives of (2-oxo-quinolin-3-yl) acetic acid) could be identified which, in the context of explosives and related compounds, are new metabolites. Evidence could be provided by microcosm experiments with 2-nitrotoluene (2-NT) that these metabolites are microbial transformation products of 2-NT under anaerobic conditions. The NMR and MS data are presented and the possible pathway for the formation of these metabolites after addition of 2-NT to fumarate is discussed.     

Symposium Objectives

The Control Systems Laboratory (CSL) of the Environmental Protection Agency has been developing improved technology for the control of participate emissions from stationary sources for nearly ten years. Starting about three years ago, emphasis has been gradually shifted to the study of fine particulate which we define as solid or liquid particles less than about 3µ in diameter. Rationale for this shift in emphasis is covered in Mr. Harrington’s Keynote Paper.     

Using the Sediment Quality Triad to characterize baseline conditions in the Anacostia River, Washington, DC, USA

The Sediment Quality Triad (SQT) consists of complementary measures of sediment chemistry, benthic community structure, and sediment toxicity. We applied the SQT at 20 stations in the tidal portion of the Anacostia River from Bladensburg, MD to Washington, DC to establish a baseline of conditions to evaluate the effects of management actions. Sediment toxicity was assessed using 10-day survival and growth tests with the freshwater amphipod, Hyalella azteca and the midge, Chironomus dilutus. Triplicate grabs were taken at each station for benthic community analysis and the Benthic Index of Biotic Integrity (B-IBI) was used to interpret the data. Only one station, #92, exhibited toxicity related to sediment contamination. Sediments from this station significantly inhibited growth of both test species, had the highest concentrations of contaminants, and had a degraded benthic community, indicated by a B-IBI of less than 3. Additional sediment from this station was tested and sediment toxicity identification evaluation (TIE) procedures tentatively characterized organic compounds as the cause of toxicity. Overall, forty percent of the stations were classified as degraded by the B-IBI. However, qualitative and quantitative comparisons with sediment quality benchmarks indicated no clear relationship between benthic community health and contaminant concentrations. This study provides a baseline for assessing the effectiveness of management actions in the Anacostia River.     

Incentives to diffuse advanced abatement technology under environmental liability law

Polluting firms with advanced abatement technology at their disposal have incentives or disincentives to share this technology with other polluting firms. The ‘direction’ and extent of those incentives depends on the liability rule applicable and the way technical change impacts marginal abatement costs. We establish that incentives for diffusion are socially optimal under strict liability and socially suboptimal under negligence if technical change lowers marginal abatement costs for all levels of abatement. Negligence may, however, induce better diffusion incentives than strict liability if technical change decreases (increases) marginal abatement costs for low (high) levels of abatement.     

Groundwater contamination by polycyclic aromatic hydrocarbon due to diesel spill from a telecom base station in a Nigerian City: assessment of human health risk exposure

Diesel pollution of groundwater poses great threat to public health, mainly as a result of the constituent polycyclic aromatic hydrocarbons (PAHs). In this study, the human health risk exposure to polycyclic aromatic hydrocarbons (PAHs) in diesel contaminated groundwater used by several families at Ring Road, Jos, Nigeria (as caused by diesel spill from a telecom base station) was assessed. Prior to the groundwater being treated, the residents were using the water after scooping off the visible diesel sheen for purposes of cooking, washing, and bathing. Until this study, it is not clear whether the groundwater contamination had resulted in sub-chronic exposure of the residents using the water to polycyclic aromatic hydrocarbons (PAHs) to the extent of the PAHs posing a health risk. The diesel contaminated groundwater and uncontaminated nearby groundwater (control) were collected and analyzed for PAHs using gas chromatography-mass spectrometry (GC-MS). The dosage of the dermal and oral ingestion entry routes of PAHs was determined. The estimation of the non-carcinogenic health risk was via hazard quotients (HQ) and the associated hazard index (HI), while the estimation of the carcinogenic health risk was via lifetime cancer risks (LCR) and the associated risk index (RI). Obtained results indicate that the exposure of the residents to the PAHs may have made them susceptible to the risk of non-carcinogenic health effects of benzo(a)pyrene and the carcinogenic health effects of benzo(a)anthracene and benzo(a)pyrene.