降雨过程中气溶胶湿沉降的数值模拟

为了参数化降雨湿去除气溶胶的过程,首先定量计算了雨滴和气溶胶的碰撞效率与它们尺度之间的依存关系,以及雨滴尺度谱满足对数正态分布时气溶胶的清除系数与其尺度的依存关系;然后利用多重Monte Carlo算法模拟了降雨过程中气溶胶尺度谱的时间演变过程,考察了气溶胶湿沉降过程与降雨类型和雨强的相关性.当雨滴尺度谱和气溶胶尺度谱均满足对数正态分布时,数值模拟的结果表明,典型的小雨、中雨和大雨过程对中等尺度气溶胶的湿去除效果均不理想,但都可以有效地湿去除大尺度气溶胶和小尺度气溶胶;3种降雨类型对大尺度气溶胶的湿去除效果均依次好于小尺度气溶胶和中等尺度气溶胶;对于任何尺度的气溶胶,雨强的增加将有利于其湿沉降.     

湿沉降离子平衡参数取值范围的计算

为保证湿沉降监测数据的可靠性及国际间数据的可比性,对不同类型湿沉降监测的离子平衡参数(R₁)的参考值X_R1的范围进行了计算和分析.结果表明,X_R1的取值主要受降水中离子组成、离子浓度以及监测准确性的影响.不同类型降水的X_R1的取值范围有所差别,同一类型降水的X_R1也会因降水中总离子浓度的差别而不同.降水中总离子浓度(C+A)>100μeq/L时,海陆相间型降水的X_R1的取值范围为5%～7%;内陆型降水的X_R1的取值范围为5%～9%;海洋型降水X_R1的取值范围为5%～11%.当(C+A)<50μeq/L时,总离子浓度越小,实验的精密度越差,离子浓度的精密度(ai)值越大.当ai取100%时,X_R1的取值范围为33%~71%.国际间同类降水监测规范比较,(C+A)≥50μeq/L时,_R1的取值基本在X_R1的计算范围内;而(C+A)<50μeq/L时,各个标准之间的差别较大.     

Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests, USA

Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America’s maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry, and total N deposition from the Communities Multi-Scale Air Quality model, and 3) ambient particulate N from Interagency Monitoring of Protected Visual Environments (IMPROVE). Sensitive species declines of 20-40% were associated with CLs of 1-4 and 3-9 kg N ha⁻¹ y⁻¹ in wet and total deposition. CLs increased with precipitation across the landscape, presumably from dilution or leaching of depositional N. Tight linear correlation between lichen and IMPROVE data suggests a simple screening tool for CL exceedance in US Class I areas. The total N model replicated several US and European lichen CLs and may therefore be helpful in estimating other temperate-forest lichen CLs.     

基于灰色支持向量机的湿天然气集输管道腐蚀研究

湿天然气集输管道系统运行时间长,管道腐蚀严重,失效泄漏事故频发,其系统风险评价面临诸多问题,因而研究其腐蚀率预测有重要意义。基于灰色支持向量机(GSVM)方法,综合考虑管道材质及其各种影响因素,对其进行灰色相关分析,并根据结果选取有较高相关度的影响因子作为输入变量,将腐蚀率作为目标输出函数,建立湿天然气集输管道腐蚀预测模型。并通过实证分析比较,发现用该模型计算出的管道腐蚀率平均相对误差较小,其预测结果与实际值吻合程度较高,使预测精度得到提高。     

Deposition and Resuspension of Selected Aerosols Particles on Electrically Charged Filter Materials for Respiratory Protective Devices

The primary aim of the study was to analyse the non-steady state of filtration for selected electrostatic filter materials designed for use in respiratory protective devices. The obtained results showed that the filtration process in electrostatic filters was dependent in the main on the following factors: type of the filter material, electrostatic field strength of the material, and the charge of the aerosol.

To a lesser degree the filtration process depended on the sign of the charge and the relative humidity of the air. A significant correlation was found between the increase in the penetration and the decrease in breathing resistance while the filter was being loaded.

The effect of resuspension (tearing off and re-deposition of dust agglomerates inside the filter) on the filtration process very significant. It was also observed that under certain conditions electrostatic filter materials lost their protection properties.     

Effects of soil warming and nitrogen deposition on leaf and soil stoichiometric characteristics of Cunninghamia lanceolata saplings北大核心CSCD

Warming and nitrogen deposition directly or indirectly affect the plant-soil element cycle under global change. To examine the effects of warming and nitrogen deposition on leaf and soil carbon (C), nitrogen (N), phosphorus (P) contents, and their stoichiometric ratios in Cunninghamia lanceolata saplings, four types of treatments were assigned: control (CT), warming (W, + 4 ºC), nitrogen deposition (N, 40 kg ha-1 a-1), and warming + nitrogen deposition (WN) treatments. The results showed that: (1) compared with CT, W treatment significantly decreased leaf P content by 54.54% and increased leaf C/P and N/P by 85.26% and 83.39%, respectively; WN treatment significantly decreased leaf C content and P content by 1.99% and 51.03%, respectively, but increased the leaf C/P by 68.01% with no significant differences in leaf N content among treatments. The leaf N/P ratio of each treatment was less than 10, but that of the W and WN treatments were closer to 10 than that of the CT treatment. Meanwhile, W and WN treatments significantly increased tree height. (2) No significant differences were observed in soil total carbon (TC), total nitrogen (TN), and total phosphorus (TP) contents among treatments. Compared with CT, W treatment significantly decreased soil C/N by 4.09%, while neither W nor WN treatment affected soil C/P and N/P. W treatment increased the available soil content compared to CT treatment. (3) The correlation analysis showed that leaf N content was significantly negatively correlated with soil C/N in the CT treatment; in the W treatment leaf N content and N/P were significantly positively correlated with soil TN and TP content, respectively. Leaf N content was significantly negatively correlated with soil TC and TN in the N treatment, and leaf contents had no significant correlation with soil C, N, and P contents or their stoichiometric characteristics in the WN treatment. This study showed that N limitation still exists in C. lanceolata saplings. Warming and the interaction between warming and nitrogen deposition could alleviate N limitation and promote the growth of C. lanceolata. © 2022 Authors. All rights reserved.     

2000~2018年我国大气重金属沉降通量时空变化特征

大气沉降物中的重金属对土壤环境的影响不容忽视.为研究我国大气重金属（As、Cd、Cr、Cu、Hg、Ni、Pb和Zn）沉降通量现状及时空变化特征,基于中国知网和Web of Science数据库收集了2001~2021年公开发表的大气重金属沉降通量文献99篇,各重金属元素监测点718~1672个.采用Meta-analysis方法计算中国大气重金属沉降通量加权均值,运用亚组分析法研究了2000~2018年不同时期大气沉降通量时空变化,对比分析了农业农村区、城市区和工业区等不同类型区的组间差异.结果表明,我国大气重金属年沉降通量［mg·（m²·a）^-1］为：Zn （96.75）>Pb （23.37）>Cu （12.77）>Cr （11.04）>Ni （6.61）>As （2.97）>Cd （0.48）>Hg （0.05）,2000~2018年沉降通量总体估计值高于1995~1998年英国乡村地区;工业区和城市区的沉降通量显著高于农业农村区,工业区大气重金属污染较为严重;长株潭地区As和Cd的沉降通量较高,东北地区、珠三角和华北平原大气重金属沉降通量较其它区域严重;近20年来Cd的年沉降通量均值在总体均值附近波动,无明显下降趋势;其中,城市区和农业农村区的Cd沉降通量呈增加趋势.本文建议结合区域产业结构特征建立分级分类分区的大气排放精准治理和风险管控措施,针对当前大气Cd沉降通量较大的问题实行更加严格的限制性措施.     

Development of environmental performance indicators for textile process and product

The increasing demand for environmental performance evaluation of industry requires development of sector-specific environmental performance indicators (EPIs). For the consumer product manufacturing industry, in this case the textile industry, the need to evaluate environmental performance both from process and product life cycle perspectives leads to development of EPIs of process and product dimensions. Such types of EPIs have been developed, with best achievable values being identified, by this study for cotton woven products and wet processing. An in-depth discussion has been presented concerning problems in developing and applying EPIs, while areas for further research are also recommended.     

碱性高锰酸钾溶液湿法脱硝氮氧化物废气的实践

为解决某研究所排放废气中NOx超标的问题,试验比较了碱液、氨水和碱性高锰酸钾溶液3种吸收液对氮氧化物的去除效果,选用碱性高锰酸钾溶液湿法脱硝法进行废气处理.设计了一套脱氮装置系统,脱氮装置系统的运转实践表明,废气中NOx去除率达到80%以上.本文研究可为其他相关企业的废气处理提供借鉴.     

Modelling the dynamic air-water-sediment coupled fluxes and occurrence of polychlorinated biphenyls in a high altitude lake

The BIODEP model in terms of atmosphere-lake interactions was developed. The model was applied to an oligotrophic, dimictic high altitude lake (Lake Redo, Pyrenees) for a range of polychlorinated biphenyl (PCB) congeners. High altitude lakes, which receive their contaminant inputs uniquely from the atmosphere through long-range atmospheric transport, provide ideal controlled environments for the study of the interactions between atmospheric depositional and water column biogeochemical processes. The BIODEP model was able to predict dissolved water concentrations and PCB accumulation in the lake sediment within a factor of 2. This shows that the BIODEP model captures the essential processes driving the sink of POPs in high altitude lakes and that POP occurrence in the lake is driven by direct atmospheric inputs with limited influence from the watershed. An important seasonal variability in water column concentrations is predicted which should have important implications in sampling strategies. Furthermore, it is shown that diffusive air-water exchange dominated the PCB dynamics in the lake, especially for the less chlorinated biphenyls.