Modeling of SO2, Pb and Cd atmospheric deposition over a one-year period

Atmospheric deposition of SO₂, and fine particles of Pb and Cd are calculated over a one-year period in a 66 km² airshed with a segment-puff model. Emission variations, hourly mixing heights and meteorological values are considered to compute monthly averages of concentrations and deposition. Dry deposition is calculated by means of deposition velocities which are season- and land use-dependent. Wet deposition is determined using a washout coefficient. To assess the simulation performance, calculated SO₂ results from the combination between the deposition velocity, the windspeed and direction and the location and type of sources. As annual averages, results for dry plus wet deposition are computed to be 0.84 mg m⁻²d⁻¹ for sulfur, 4.15 μgm⁻²d⁻¹ for lead and 0.0013 μgm⁻²d⁻¹ for cadmium. A variation factor is derived from a sensitivity analysis. This factor amounts to 2.3−2.8 for the concentrations and 2.6−3.1 for the deposition, depending on the pollutant.     

A paired comparison of two precipitation chemistry sites in East-Central Mississipi

A paired comparison was performed on 2 years of precipitation chemistry data from Meridian and Newton, MS. The Meridian site is in violation of several National Atmospheric Deposition Program siting criteria, whereas the Newton site, 35 km west, is mostly in compliance. The two sites are compared through the use of volume-weighted means, deposition, logarithmic distributions, boxplots, paired t-tests, the nonparametric Wilcoxon test, and a form of linear regression analysis that accounts for cases in which both populations are subject to error. Results indicate Meridian has higher concentrations of all measured ions except NH₄⁺. Elevated NH₄⁺ concentrations at Newton are most likely due to the location of the site in a cattle pasture. Significant differences (95% confidence level) were found for Cl⁻, Na⁺, K⁺, Ca²⁺ and Mg²⁺. SO₄²⁻ was found to be borderline significant.     

The use of rice crop residues as a non-commercial energy source in the developing world: The energy and environmental implications

The potential biomass energy that can be derived from the harvest of rice crop residues is calculated for three methods of crop production. The potential energy available amounts to 3.70 × 10¹⁰ J ha^?1 year^?1 for traditional methods, 7.93 × 10¹⁰ J for the labor-intensive and 8.36 × 10¹⁰ J for the capital-intensive methods. The net energy benefits available for cooking, heating and biogasification are calculated on a per hectare basis taking into account the costs of collection, transportation and processing. The amounts of energy available for cooking and heating range from 3.70 × 10⁹ to 8.33 × 10⁹ J ha^?1, and the amounts of energy for methanol use range from 1.85 × 10⁹ to 4.17 × 10⁹ J ha^?1 year^?1.The ecological problems associated with soil erosion, nutrient loss and pesticide use are evaluated in terms of the compensatory energy costs involved, and the resultant net energy balance for each method of rice production is calculated. The net energy available per hectare for the traditional method is 3.43 × 10¹⁰ J, for the labor-intensive method, 7.25 × 10¹⁰ J and for the capital-intensive method, 7.02 × 10¹⁰ J. The harvest of rice crop residues in the developing world could provide up to 5.80 × 10¹⁸ J year^?1.The use of rice crop residues is investigated within the context of the rural village energy system. The prospects for the use of rice crop residues are evaluated in relation to alternative energy sources and it is concluded that regional residue harvest programs should be implemented cautiously, integrating soil management and environmental planning procedures where appropriate.     

Forestry Mitigation Options for Mexico: Finding Synergies between National Sustainable Development Priorities and Global Concerns

We examine carbon (C) reference and mitigation scenarios for the Mexicanforest sector between the year 2000 and 2030. Estimates are presentedseparately for the period 2008–2012.Future C emissions and capture are estimated using a simulation modelthat: a) allocates the country land use/land cover classes among differentfuture uses and categories using demand-based scenarios for forestryproducts; b) estimates the total C densities associated to each land usecategory, and c) determines the net carbon implications of the process ofland use/cover change according to the different scenarios.The options analyzed include both afforestation/reforestation, such ascommercial, bionenergy and restoration plantations, and agroforestrysystems, and forest conservation, through the sustainable management ofnative forests and forest protection.The total mitigation potential, estimated as the difference between the totallong-term carbon stock in the reference and the mitigation scenario reaches300 × 10⁶ Mg C in the year 2012 and increases to 1,382 × 10⁶ Mg C in 2030. The average net sequestration in the 30 year period is 46 × 10⁶ Mg C yr^-1, or 12.5 × 10⁶ Mg C yr^-1 within the period 2008 to 2012. The costs of selected mitigation options range from 0.7–3.5 Mg C^-1 to 35 Mg C^-1. Some options are cost effective.     

Interplanetary dust

The interplanetary dust cloud, total mass 10¹⁰–10²⁰ g in round figures, originates as fragments of comets and produces a mean flux at the earth-moon system in the range 10^?13–10^?12 g m^?2 s^?1. Over 2/3 of the mass consists of particles with individual weights 10^?3 to 10^?6 g. They are fragile, are continually broken up into smaller pieces by collisions, and have a chemical composition similar to that assumed as the average for the entire solar system. The cloud extends to roughly 3 a.u. from the sun in the ecliptic plane, with a particle space density falling off as r ^?v , where r is distance from the sun and v is in the range 1 to 1.5.     

岩溶山区表土中7Be、137Cs、226Ra和228Ra的地球化学相分配及其侵蚀示踪意义

利用ＧＣ－ＭＳ定性及ＧＣ－ＦＩＤ定量，测定了１９９３年１１月采自厦门西海域８个站位的表层沉积物样品。应用模糊聚类的方法，结合献资料，对甾醇的指标作用进行了探讨；利用聚类结果去除少量不合理数据，将甾醇划为３类，其在海域中的分布各有特点；Ａ类甾醇带有经处理过的污水的特征，表现出从厦门市最大生活污排污口向四周扩散的过程；     

北京东郊污灌区表层土壤微量元素的小尺度空间结构特征

岩溶山区表土中＾７Ｂｅ、＾１３７Ｃｓ、＾２２６Ｒａ和＾２２８Ｒａ地球化学相分配的实验研究表明，４种核素绝大部分存在于Ｆｅ－Ｍｎ氧化物，有机质及残渣相中。它们在表土的迁移过程中具微粒迁移性，能较好地随土粒般运，可作为土粒侵蚀或沉积的示踪剂。     

Scavenging ratios and deposition of sulphur,nitrogen and chlorine species in eastern England

Measurements of wet deposited NH₄⁺, SO₄²⁻, NO₃⁻ and Cl⁻, as well as airborne concentrations of these species and gaseous HNO₃, HCl and NH₃, have been made at a site in eastern England. Scavenging ratios based solely upon aerosol-associated species and upon aerosol plus gaseous airborne species are presented and compared with literature values. It appears that HCl and HNO₃ have only a rather minor influence upon wet deposition at our site. Gaseous NH₃ influences ground-level air chemistry appreciably, but scavenging ratios for NH₄⁺ are low, even when based upon aerosol NH₄⁺ concentrations alone, presumably due to altitudinal gradients in this species. The problems inherent in interpretation of scavenging ratios are discussed. Deposition of nitrogen in various chemical forms is estimated from rainwater and air composition. If a transport-limited deposition velocity is assumed for ammonia gas, dry deposition of this species accounts for around 40% of total nitrogen deposition to the ground.     

Measurements of the optical properties of the smoke emissions from plastics,hydrocarbons, and other urban fuels for nuclear winter studies

We have measured the optical and microphysical properties of smoke from burning plastic materials and other components of the urban fuel mix, including hydrocarbons, rubber, and wood, to provide information on the source term for possible aerosol clouds injected into the atmosphere following large scale urban fires. Our measurements included measurements of emission factors; in situ optical measurements of aerosol absorption, scattering, and attenuation; and collection of particles using both filters and cascade impactors for size and mass concentration determinations.These measurements were made under a variety of conditions to investigate the range of variation of these optical parameters and to relate observed differences in smoke properties to differences in fuel composition and fire conditions.The plastic data show average B_e values near 10 m² g⁻¹ at 488 nm and 8 m² g⁻¹ at 633 nm. Values of B_e measured during smoldering combustion are significantly less than in flaming combustion. Flaming combustion B_e values for the rubber appear to be somewhat higher, particularly for the tire rubber; petroleum product fuel values are comparable to the plastic fuel values; and oak smoke emissions values are slightly lower than the plastic values. Measured 633 nm B_a values were approximately 6 m² g⁻¹ for the petroleum products, 7 m² g⁻¹ for the rubber, 6 m² g⁻¹ for the wood, and 6 m² g⁻¹ for the plastic.     

Nutrient cycling within the developing oil palm-legume ecosystem

Oil palms (Elaeis guineensis Jacq.) are normally planted in fields stripped of all other vegetation. Leguminous cover crops are planted simultaneously to protect the soil surface and to provide other, less tangible benefits. Nutrient cycling, especially of nitrogen, was followed in a commercial oil palm plantation and showed that: (a) legumes contribute about 150 kg nitrogen ha^?1 year^?1 to the system through nitrogen fixation; (b) during the early stages of oil palm growth the legumes absorb 149 kg nitrogen ha^?1 year^?1 from the soil; (c) with a loss of nitrogen through litter fall of 123 kg nitrogen ha^?1 year^?1, legumes accumulate a net amount of 176 kg nitrogen ha^?1 year^?1 in their foliage; (d) in comparison with “natural” covers, leguminous covers reduce leaching losses by 63 kg nitrogen ha^?1 year ^?1 so that the total benefits of leguminous covers amount to 239 kg nitrogen ha^?1 year^?1; (e) the combined inputs from fertilization and oil palm debris in plots without legumes is 208 kg nitrogen ha^?1 year^?1; and (f) during the initial growth phase, oil palms need only 175 kg nitrogen ha^?1 year^?1. Since legumes fix nitrogen and thoroughly scavenge the soil for minerals they eventually provide more nitrogen to the oil palms than is needed for growth. This surplus nitrogen is “banked” in the legume foliage. Then, when the rooting system of the oil palms has grown under the inter-rows, competition for nutrients causes a gradual decline in the cover-crop. Nutrients “deposited” in the legumes are thus slowly re-released stimulating root-growth and general development of the oil palm.     

中国工业行业的生态效率

中国工业是资源消费和污染物排放的主要源头,解析工业各行业的生态效率可为中国产业结构调整和整体环境质量改善提供必要信息.在分析工业构成并构建工业系统与外部环境之间关系的基础上,选择能源消费和废水、固体废物、SO2、工业烟尘、粉尘等污染物的排放量作为研究的环境影响类别,界定了与这些环境影响相关的生态效率,估算了中国2007年的工业生态效率现状,结果为:能源效率615.5万元·ktce-1;废水和固废方面的生态效率分别为54.3万元·kt-1和1.9万元·t-1;工业SO2、烟尘和粉尘方面的生态效率分别为59.6、169.2和184.6万元·t-1.深入分析了39个工业部门的生态效率,结果表明,以上几种生态效率具有明显的行业不均衡性,表现为不同行业在不同类型生态效率中的工业排序明显不同;与此同时,对于同一种生态效率,不同工业行业的数值可相差几百倍到几万倍,表明通过优化工业结构将具有较大的提高工业生态效率的可能性.     

沙颍河流域典型癌病高发区水体硝态氮污染及健康风险

分别在雨季和旱季对癌病高发区地表水和地下水进行采样分析,探讨该区域地表水和地下水NO~-_3-N和NO~-_2-N污染状况、季节变化和空间分布特点,以及相应的健康风险.结果表明,雨季地表水和地下水NO~-_3-N含量明显高于旱季.受污染沙颍河水的影响,沿岸癌病高发村庄饮水井雨季NO~-_3-N污染严重,平均含量达到38.32 mg·L~(-1),超标近3倍,而旱季则存在NO~-_2-N污染,平均含量达到0.69 mg·L~(-1).研究区癌病高发村庄居民存在饮水NO~-_3-N暴露的健康风险,其年平均健康总风险达到1.02×10~(-8) a~(-1),为其他村庄居民的6倍以上,饮水NO~-_3-N污染是癌病高发村庄居民的健康危害因素.     

岩溶易旱区地下水水文地球化学特征及其控制因素——以兴仁县为例

地下水是岩溶易旱区极其重要的水资源,是当地生态环境和人类生存的基本保障。通过收集整理岩溶易旱区兴仁县地下水水化学数据,分析与研究,发现岩溶易旱区地下水的溶解组分主要来源于碳酸盐岩的溶蚀,水化学类型主要为HCO_3-Ca型和HCO_3-Ca·Mg型,部分地区由于受到岩层中石膏夹层溶解的影响,水化学类型为HCO_3·SO_4-Ca·Mg型。地下水中Ca~(2+)、Mg~(2+)、HCO_3~-等离子受流经区域地层岩性和水-岩相互作用的影响,表现出显著的区域性特征,属自然来源;K~+、Na~+、Cl~-、NO_3~-等指标与人类活动关系密切,SO_4~(2-)受水-岩相互作用和人类活动共同影响。岩溶易旱区地下水水文地球化学容易受到人为活动的干扰且日趋明显,降低人为活动对岩溶地下水的影响是确保岩溶易旱区地下水环境及饮水安全的关键。     

膨润土吸附－絮凝法处理污水中的重金属离子

研究了天然膨润土对Pb2、Cd2、Cr3的吸附和膨润土的絮凝沉降条件,将吸附与絮凝过程结合起来形成处理污水的新工艺,加入0．04％膨润土和0．006％的PAC可使低浓度污水中Pb2脱除93．1％。      

Sulphate in atmospheric particulate at five sites in Norwich (U.K.): Use of national survey archive filters

Air sample filters from a Local Authority archive have been analyzed for sulphate using XRF. This has allowed an assessment to be made of the spatial distribution of 24-h sulphate concentrations in the city of Norwich in eastern England, over a 9-month period. The overall mean sulphate concentration was 10.4 μg m⁻³, with a range of overall mean values between the sites of 7.7–12.2 μg m⁻³. This spatial variability within the city is similar to the spatial variability between cities found in another previous study. The mean SO²⁻₄/SO₂ and smoke/SO²⁻₄ ratios at the different sites are similar, but there are distinct variations in the overall mean ratios over the measurement period. There appear to be relationships between the SO²⁻₄/SO₂ ratio and temperature and humidity. The ratios are also related to wind direction, with some evidence that a proportion of the SO²⁻₄ in the urban atmosphere of Norwich originates via long-distance transport from the east.     

黑藻吸附Cu2+机制研究

生物吸附法是一种经济有效的去除废水中有害重金属离子的方法.以黑藻(Hydrilla verticillata)干样为生物吸附材料,研究了黑藻对水体中Cu<'2+>等温吸附的基本特征,并通过测定吸附前后溶液离子浓度变化以及pH值、基团屏蔽对Cu<'2+>吸附的影响,结合红外光谱技术,从静电吸附作用、离子交换作用、基团作用...     

Preliminary results from the analysis of stone tablets from the National Materials Exposure Programme (NMEP)

The NMEP programme consists of 29 sites at which samples of stone and metals are being exposed for a minimum of 4 years to determine rates of decay in the current pollution climate. The sites were chosen to cover a wide range of environmental conditions, climate and topography. Information on meteorological conditions and atmospheric pollutants is being collected from all the sites. Four of the sites also form part of an international programme that is operating concurrently for the United Nations Economic Commission for Europe (UNECE).The stone tablets are 50 × 50 × 8 mm and are exposed on freely rotating carousels in sheltered and unsheltered positions which represent the washed and unwashed areas of buildings. Tablets of Portland limestone and White Mansfield dolomitic sandstone are exposed at all sites and in addition Monks Park limestone is exposed at the nine sites. Prior to exposure the tablets were cleaned and weighed, and in some cases the surface roughness was measured using an oblique light source and image analysis system.Tablets have been retrieved after 1 and 2 years of exposure and re-weighed following drying. Samples of powder have been removed from the surface of pristine, sheltered and unsheltered tablets and analysed using ion-chromatography for soluble ionic species (Ca²⁺, Mg²⁺, Na⁺, NH₄⁺, SO₄⁻⁴, NO₃⁻, Cl⁻). The results showed the expected increases in acid species and soluble calcium in the sheltered tablets and increases in chlorides in tablets exposed near to the coast. Tablet surfaces have also been studied to obtain further diagnostic detail.The results from the analysis of the stone tablets and from the monitoring of pollutant concentrations and meteorological variables have been used to identify empirical relationships and as a basis for mathematical modelling. Preliminary findings from these studies are presented in this paper.     

Photolysis of Fe (III)-hydroxy complexes as sources of OH radicals in clouds,fog and rain

Photolysis of the monohydroxy complex of Fe(III), Fe(OH)²⁺, has been proposed as a major source of OH radicals in rain. It is also a significant source of OH radicals in clouds and fog, and probably in some acidic surface waters. Fe(OH)²⁺ is the dominant monomeric Fe(III)-hydroxy complex between pH 2.5 and 5, based on currently available equilibrium constants for Fe(III)-hydroxy complexes. Quantum efficiencies for the photolysis of Fe(OH)²⁺ are 0.04±0.04 at 313 nm and 0.017±0.003 at 360 nm (293 K, ionic strength = 0.03 M). The measured rate constant for midday June sunlight photolysis of Fe(OH)²⁺ is 6.3 × 10⁻⁴s⁻¹ (half life = 18 min). Model calculations based on measured quantum yields and absorption spectra are in satisfactory agreement with measured sunlight photolysis rates of monomeric Fe(III).     

危险废物填埋场复合衬层渗漏分析与污染物运移预测

以我国危险废物填埋场次防渗层采用1 mm高密度聚乙烯(HDPE)土工膜和0.5 m压实粘土衬垫(CCL)组成的复合衬层为研究对象,采用经验公式以及解析方法计算了不同缺陷条件下复合衬层的渗漏率.在此基础上,采用一维污染物对流扩散运移方程对重金属Cd~(2+)、Zn~(2+)、Cu~(2+)、Pb~(2+)击穿复合衬层的时间进行了计算和分析.结果表明:复合衬层渗漏率主要受到复合衬垫界面接触条件,渗滤液水位以及缺陷类型的影响;当复合衬层的漏洞密度为20个·hm~(-2)时,半径为5.64 mm的圆孔型缺陷其最大渗漏率为22.7 m~3·a~(-1)·hm~(-2);当单位面积裂缝长度为200m·hm~(-2)时,宽度为2 mm长度为1 m的裂缝型缺陷其最大渗漏率为42.5 m~3·a~(-1)·hm~(-2);Cd~(2+)可作为重金属污染物击穿复合衬层的指示性污染物,其击穿时间最长为2.74 a,最短为1.38 a;通过改变土工膜下伏土壤衬层的性能或增加土壤衬层厚度可延缓污染物击穿时间.     

赣江流域山丘荒地的形成、危害和开发途径

赣江流域的山丘荒地总面积约为 2902×10⁴亩,除 35×10⁴亩属于“十边草地”零星分布于路边、河边、田边、村边、沟边之外,比较成片的约有 2867×10⁴亩（见表 1）,略多于现有耕地,而且相当于现有林地的一半。这些荒地 3/4以上分布在红壤丘陵（低丘岗地 388×10⁴亩,占13.5％;中低丘1236×10⁴亩,占43.1％;高丘605×10⁴亩,占21.2％;山地638×10⁴亩,占22.3％）,而且主要分于于上、中游地区（上游地区占60.2％,中游地区占25.4％,下游地区占14.4％）。综合开发治理、合理利用这些山丘荒地,是赣江流域、特别是上、中游地区的农民摆脱贫穷落后困境、实现小康目标的重要环节之一。