Role of organic acids (formic, acetic, pyruvic and oxalic) in the formation of cloud condensation nuclei (CCN): a review   总被引：2，自引：0，他引：2  

Shaocai Yu   《Atmospheric Research》2000,53(4):4289

Although it is believed that organic aerosols play a key role in cloud nucleation and make an important contribution to the cloud condensation nuclei (CCN) population, their specific species remain poorly characterized. This paper reviews the current knowledge of organic acids (mainly formic, acetic, pyruvic and oxalic acids). Without specification, organic acids in this paper refer to these four organic acids in the gas and aerosol phases. This paper analyzes the extent to which organic acids act as CCN and compares the physical and chemical properties of organic acids with those of CCN. The results show that aerosol formate and acetate concentrations range from 0.02 to 5.3 nmol m⁻³ and from 0.03 to 12.4 nmol m⁻³, respectively, and that between 34 to 77% of formate and between 21 to 66% of acetate are present in the fine fraction of aerosols. It was found that although most (98–99%) of these volatile organic acids are present in the gas phase, their concentrations in the aerosol particles are sufficient to make them a good candidate for CCN. The results also show that organic acids may make an important contribution to the formation of CCN in some special sources such as vegetation emissions and biomass-burning. Organic acids are expected to contribute significantly to the estimates of indirect (cloud-mediated) forcing due to aerosols.  相似文献   

Thermal waters of the Hornonitrianska kotlina depression and their utilization     

O. Franko  J. Franko 《Environmental Geology》2000,39(5):501-515

 Slovakia has many areas rich in thermal waters one of which is the Hornonitrianska kotlina depression. At four localities three types of waters are found. The first belongs to the Ca–Mg–HCO₃ type with T.D.S. 0.7 g/l, the second to the Ca–Mg–SO₄ type with T.D.S. 1.37–2.01 g/l and the third to the Ca–Mg–SO₄–HCO₃ type with T.D.S. 0.97 g/l. Discharge at individual localities varies up to 30 l/s and temperatures of water reach 32.5–66.6  °C. The waters are predominantly used for healing, rehabilitation purposes, recreation and heating. Received: 8 March 1999 · Accepted: 7 June 1999  相似文献   

昆明市东川拖布卡金矿矿石岩石学研究   总被引：2，自引：0，他引：2  

张学诚  高俊彩 《云南地质》2006,25(3):276-285

中-低温热液型拖布卡金矿，与碱性（钠质）岩浆作用密切相关，尤以与纳长斑岩、二长斑岩最为明显。三类矿源岩石组合提供金质。自然金、显微裂隙金及包裹金组成金的主要赋存状态。提出拖布卡-播卡金矿成矿模式。  相似文献   

Application of multivariate spatial analysis in scale-based distribution and source study of PAHs in the topsoil: an example from Tianjin,China     

X. J. Wang  R. M. Liu  K. Y. Wang  J. D. Hu  Y. B. Ye  S. C. Zhang  F. L. Xu  S. Tao 《Environmental Geology》2006,49(8):1208-1216

Polycyclic aromatic hydrocarbons (PAHs) in soil originate from various sources under different spatial scales. Coregionalization analysis is more revealing than univariate geostatistical analysis. Scale-dependent spatial features of variables reflect different sources of spatial variability. In this study, 188 topsoil samples in the Tianjin area were collected. The contents of 16 PAHs and soil background properties were determined for all samples. A multivariate geostatistical approach was used for multi-scale spatial analysis for PAH compounds. Results show that coal combustion was the major source for the spatial distribution patterns of PAHs in the topsoil of the studied area. It worked mainly at the short-range scale (5–10 km). Significant spatial variation patterns were identified. In contrast, no significant spatial distribution trends at the nugget (0–5 km) or long-range scales (10–50 km) were seen. Long-range transport and site contamination of PAHs might not be key contributors in forming the distribution pattern of PAHs in the topsoil of Tianjin area.  相似文献   

南京市气溶胶PM2.5一次来源解析   总被引：14，自引：4，他引：10  

樊曙先  徐建强  郑有飞  谢学俭 《气象科学》2005,25(6):587-593

在南京大学鼓楼校区（市区）和南京信息工程大学（郊区）校园,分季采集PM2.5及其主要排放源的颗粒样品,在南京大学现代分析测试中心用X-荧光分析法分析样品中的化学元素,应用化学元素平衡法（CMB）计算了各主要源对PM2.5的贡献。结果表明对市区扬尘和建筑尘是PM2．5最主要的贡献源,贡献率合计约70％;燃煤尘和冶炼尘仅为约15％。对郊区扬尘和煤烟尘是PM2．5的最主要贡献源,平均贡献率分别为50％和22．4％,建筑尘的平均贡献率为8．3％,冶炼尘的贡献小于8％。这些结果可为治理气溶胶细颗粒源提供决策依据。  相似文献   

Large microplastic particles in sediments of tributaries of the River Thames,UK – Abundance,sources and methods for effective quantification     

Alice A. Horton  Claus Svendsen  Richard J. Williams  David J. Spurgeon  Elma Lahive 《Marine pollution bulletin》2017,114(1):218-226

Sewage effluent input and population were chosen as predictors of microplastic presence in sediments at four sites in the River Thames basin (UK). Large microplastic particles (1 mm–4 mm) were extracted using a stepwise approach to include visual extraction, flotation and identification using Raman spectroscopy. Microplastics were found at all four sites. One site had significantly higher numbers of microplastics than other sites, average 66 particles 100 g^? 1, 91% of which were fragments. This site was downstream of a storm drain outfall receiving urban runoff; many of the fragments at this site were determined to be derived of thermoplastic road-surface marking paints. At the remaining three sites, fibres were the dominant particle type. The most common polymers identified included polypropylene, polyester and polyarylsulphone. This study describes two major new findings: presence of microplastic particles in a UK freshwater system and identification of road marking paints as a source of microplastics.

Capsule

This study is the first to quantify microplastics of any size in river sediments in the UK and links their presence to terrestrial sources including sewage and road marking paints.  相似文献