中国湖泊水环境基准的研究进展

中国湖泊污染形势严峻、生态健康效应复杂,亟需适合中国区域特点的水环境基准作为加强污染控制、治理和管理的理论依据,但目前我国湖泊水环境基准的系统研究尚未开展,本文从水环境基准的意义、概念、研究历史、现状和发展趋势等几个方面对中国湖泊水环境基准研究进行了剖析回顾和展望:首先阐述了开展区域性水环境基准研究的迫切性和科学意义,揭示了"科学确定基准"的内涵;然后详细回顾了国内外湖泊水环境基准的研究历史、现状及存在的关键问题,提出了湖泊水环境基准的"三性"原则(科学性、基础性和区域性),指出环境暴露、效应识别和风险评估是基准研究的三个关键环节;最后提出中国湖泊水环境基准的研究方向和发展趋势,本文强调:阐明中国水环境的演变规律和特征,需要开展水环境污染过程和生态毒理效应研究;建立具有我国区域特点的湖泊水环境基准理论、技术和方法体系是面向国际科学前沿和解决中国环境管理重大科技需求的重要任务,它既可推动中国毒理学、生物学、生态学及环境与生物地球化学等学科的发展,又可为湖泊流域的环境管理和污染防治提供技术支撑,整体提升我国环境保护科学研究的水平和国际地位.     

Characteristics of size distributions and sources of water-soluble ions in Lhasa during monsoon and non-monsoon seasons

To understand the physical and chemical characteristics, particle size distribution and sources of size-separated aerosols in Lhasa, which is located on the Tibetan Plateau (TP), six sizes of aerosol samples were collected in Lhasa in 2014. Ca²⁺, NH₄⁺, NO₃^?, SO₄^2?and Cl^? were the dominant ions. The ratio of cation equivalents (CE) to anion equivalents (AE) for each particle size segment indicated that the atmospheric aerosols in Lhasa were alkaline. SO₄^2? and NO3^? could be neutralized by Ca²⁺, but could not be neutralized by NH₄⁺, according to the [NH₄⁺]/[NO₃^??+?SO₄^2?] and [Ca²⁺]/[NO₃^??+?SO₄^2?] ratios. Mobile sources were dominant in PM_0.95–1.5, PM_1.5–3 and PM_3–7.2, while stationary sources were dominant in the other three size fractions according to the [NO₃^?]/[SO₄^2?] ratios. The particle size distribution of all water-soluble ions during monsoon and non-monsoon periods was characterized by a bimodal distribution due to the different sources and formation mechanisms, and it was revealed that different ions had different sources in different seasons and different particle size segments by combining particle size distribution with correlation analysis. Source analysis of aerosols in Lhasa was performed using the Principal component analysis (PCA) for the first time, which revealed that combustion sources, motor vehicle exhaust, photochemical reaction sources and various types of dust were the main sources of Lhasa aerosols. Furthermore, Lhasa''s air quality was also affected by long-distance transmission, expressed as pollutants from South Asiaand West Asia, which were transmitted to Lhasa according to backward trajectory analysis.     

An inventory of N(2)O emissions from agriculture in China using precipitation-rectified emission factor and background emission

Fertilized agricultural soils are a major anthropogenic source of atmospheric N₂O. A credible national inventory of agricultural N₂O emission would benefit its global strength estimate. We compiled a worldwide database of N₂O emissions from fertilized fields that were consecutively measured for more than or close to one year. Both nitrogen input (N) and precipitation (P) were found to be largely responsible for temporal and spatial variabilities in annual N₂O fluxes (N₂O–N). Thus, we established an empirical model (N₂O–N = 1.49 P + 0.0186 P · N), in which both emission factor and background emission for N₂O were rectified by precipitation. In this model, annual N₂O emission consists of a background emission of 1.49 P and a fertilizer-induced emission of 0.0186 P · N. We used this model to develop a spatial inventory at the 10 × 10 km scale of direct N₂O emissions from agriculture in China. N₂O emissions from rice paddies were separately quantified using a cropping-specific emission factor. Annual fertilizer-induced N₂O emissions amounted to 198.89 Gg N₂O–N in 1997, consisting of 18.50 Gg N₂O–N from rice paddies and 180.39 Gg N₂O–N from fertilized uplands. Annual background emissions and total emissions of N₂O from agriculture were estimated to be 92.78 Gg N₂O–N and 291.67 Gg N₂O–N, respectively. The annual direct N₂O emission accounted for 0.92% of the applied N with an uncertainty of 29%. The highest N₂O fluxes occurred in East China as compared with the least fluxes in West China.     

Kinetic and mechanism studies of the ozonolysis of three unsaturated ketones

Reaction rate constants and products of 1-octen-3-one,3-octen-2-one and 4-hexen-3-one with ozone were studied in a 100-L fluorinated ethylene propylene(FEP) Teflon film bag using absolute rate method at 298 ± 1 K and atmospheric pressure.The rate constants were(1.09 ± 0.12) × 10^-17,(3.48 ± 0.36) × 10^-17 and(5.70±0.60) × 10^-17 cm³/(molecule·sec),respectively.According to the obtained rate constants,the effects of carbonyl were discussed.The carbonyl gro...     

A review of atmospheric benzene homologues in China: Characterization, health risk assessment, source identification and countermeasures

Benzene homologues are important chemical precursors to the formation of ground-level ozone and secondary organic aerosol(SOA) in the atmosphere,in addition,some toxic species are harmful to human health.Strict countermeasures have been taken to fight air pollution since 2013,and total amount control of volatile organic compounds is being promoted in China at present.Therefore,it is important to understand the pollution situation and the control status of ambient benzene homologues in China.This...     

漫湾电站库区降雨侵蚀力时空变化

漫湾水电站是澜沧江水能梯级开发的第一个干流大型水电站,加强库区水土流失治理与监督监测尤为必要,而降雨侵蚀力的时空分布规律研究则是实现区域土壤侵蚀定量监测预报的重要基础。根据有关降雨侵蚀力的计算方法,利用漫湾电站库区4个测站1980～2000年的逐月平均降雨资料,估算了其降雨侵蚀力R值的时空分布规律及其变化特征。结果表明：漫湾电站库区多年平均降雨侵蚀力在1 9336～3 9727 MJ·mm/hm2·h;R值的年内变化显著,且较大值集中分布在雨季的5月～10月,平均R值占全年的867%,尤其6～8月连续3个月的降雨侵蚀力平均占全年侵蚀力的一半以上;R值的年际变化显示20世纪90年代漫湾电站库区降雨侵蚀力比80年代平均增加2835 MJ·mm/hm2·h;R值的空间分布上以凤庆站点的年降雨侵蚀力最大;南涧站点的年降雨侵蚀力最小,但是其年际波动幅度较大。全面地分析了漫湾电站库区降雨侵蚀力R值的时空变化特征,为该地区有效防止与监测水土流失情况、更好地安置水电站工程移民提供参考。     

A modified steady-state model for evaluation of ammonia concentrations behind a water curtain

Water curtain system has been proved an effective mitigation measurement for ammonia spill dispersion. Calculating of ammonia cloud concentration with water curtain was less studied. This paper presents a steady-state calculation model to calculate open and forced ammonia spill dispersion. The formula of ammonia absorption was built and integrated into the calculation model. The calculated downwind ammonia concentrations for open and forced spill dispersion were reproduced and compared with literature using a statistical method. In addition, the relationship between ammonia concentration in water droplet and the droplet diameter was studied. The results display that the formula of ammonia absorption is suitable for calculating mass transfer process between the ammonia cloud and the water curtain. The calculation model presents good performances for open and forced ammonia spill dispersion. This study indicates that the calculation model can be satisfactory in determining the impact of open and forced ammonia spill dispersion and the design of water curtain mitigation system.     

Particulates pollution management and economic analysis of small rural enterprises in mountain areas: A case study of Wenquan town in China

At present, many rural enterprises in China's mountainous areas are developing rapidly, and due to poor planning and improper management, in an uncontrolled manner. These small enterprises are making atmospheric pollution far more serious and more difficult to control than before. Thus, as is the case with most developing countries, China is facing the challenge of managing the increased environmental pollution that is accompanying its economic development. This paper examines the case of cement dust pollution in the town of Wenquan in Sichuan province in order to determine how to adjust the relationship between development of rural enterprises and atmospheric environmental pollution in mountainous areas. Using the single objective linear programming method, and based on the principle of overall optimization, an optimal control plan for different pollution sources was worked out and an economic assessment on reclamation of cement dust was completed. According to our analysis, after implementation of this plan for four years, two months, the concentrations of suspended particles in Wenquan will achieve the requirement of the national third-order ambient air quality standard; the current serious dust pollution will be completely controlled; and the reclamation of cement dust will totally compensate for the cost of dust control and will result in 92,000 yuan of pure profit per year. At that time, the economy and environment will be in harmony.     

大气环流异常与地震关系初探

本文以海城、乌恰地震为例分析了我国强震前特大干旱的大气环流特征。表明强地震前的气象异常是显著的，且大气环流相对于多年平均环流具有明显的干旱特征，从而揭示了地震与大气环流异常之间的相互联系，这对提高强地震中长期预测的准确率有一定实际意义。