天津市道路车流量特征分析

车流量是移动源和道路扬尘排放清单计算的一个重要参数,直接影响排放清单的不确定性.为了解天津市道路车流量特征,通过人工摄录法获取天津市一年四季5种不同类型共9条道路的车流量及车型分布信息,并对其特征进行分析.结果表明:天津市不同类型道路之间车流量总体上呈快速路（8 790辆/h）>主干道（4 077辆/h）>外环线（3 335辆/h）>次干道（2 461辆/h）>支路（1 507辆/h）的特征;冬季车流量最大,而春、夏两季相对较小.各类型道路车流量占比最大的车型均为轻型车（76.88%~90.71%）,中型车（5.31%~11.80%）次之,重型车（3.20%~11.31%）最少;快速路和外环线工作日的车流量大于非工作日,并且差异具有统计学意义,呈"周末效应".研究显示:次干道和支路车流量与主干道车流量呈线性相关,在后续进行道路扬尘和移动源清单编制时,可以考虑通过将主干道车流量与次干道、支路拟合的方式减小工作量;此外,主干道、次干道和支路的早高峰,上、下午平峰,中午和晚高峰的车流量差异不大,可将一天划分为白天、夜晚和凌晨3个时段进行统计,从而节约时间和成本.      

Cesium accumulation by fish following acute input to lakes: a comparison of experimental and Chernobyl-impacted systems

An uptake parameter u (L kg⁻¹ d⁻¹) and a loss rate parameter k (d⁻¹) were estimated for the patterns of accumulation and loss of ¹³³Cs by three fish species following an experimental ¹³³Cs addition into a pond in South Carolina, USA. These u and k parameters were compared to similar estimates for fish from other experimental ponds and from lakes that received ¹³⁷Cs deposition from Chernobyl. Estimates of u from ponds and lakes declined with increasing potassium concentrations in the water column. Although loss rates were greater in the experimental ponds, the times required to reach maximum Cs concentrations in fish were similar between ponds and lakes, because ponds and lakes had similar retentions of Cs in the water column. The maximum Cs concentrations in fish were largely determined by initial Cs concentrations in the water column. These maximum concentrations in fish and the times required to reach these maxima are potentially useful indicators for assessments of risks to humans from fish consumption.     

上海市大气中HO2自由基的测定与特征

为研究上海市大气中ＨＯ２自由基的分布特征,建立了化学放大法测定ＨＯ２自由基系统,对上海市大气中ＨＯ２自由基浓度进行了没定邦等结果表明,ＨＯ２自由基的典型日变化基本上为双峰型,峰值出现在阳光辐射较强的中午时分,实验测得ＨＯ２自由基最大浓度达２．２４×１０＾８分子·ｃｍ＾－３,ＨＯ２自然基民ＮＭＨＣ,Ｃ烽Ｏ２等具有一定的相关性,ＨＯ２自由基的研究对于大气光化学烟雾的研究具有重要意义     

基于去耦合直接法的兰江流域地表水水质预测方法研究

针对影响因素众多、耦合机制复杂情况下的地表水污染物浓度预测问题,将河道污染物浓度的变化量表示为各种影响因子一阶偏导项和二阶偏导项的线性叠加。其中,一阶偏导项可描述影响因子变化与污染物浓度变化的直接关系,二阶偏导项可描述影响因子之间交互作用对污染物浓度变化的影响。在此基础上,提出了用以模拟地表水污染物浓度的去耦合直接法。采用2014—2016年兰江流域将军岩、低田、半潭、沈村、焦岩5个断面的水文和氨氮、高锰酸盐指数、总氮、总磷4项污染指标逐日实测数据,通过差分法求解了一阶和二阶偏导项,并采用2017—2019年实测数据对模型进行了验证和评价。结果表明：去耦合直接法能够有效预测地表水主要污染物浓度的变化方向和变化量,且模拟结果和实测结果的符合情况较好,4项污染指标模拟值的Nash-Sutcliffe系数为0.479～0.654,模拟值与实测值的偏差为0.070～0.352;汇流区面积增加后,影响因子不确性对污染物浓度的扰动减小,污染物浓度变化的规律性增强,去耦合直接法的模拟精度升高。与SWAT模型的对比分析结果显示,在污染成因不发生显著变化的情况下,去耦合直接法的模拟精度优于SWAT模型。     

生物膜填料塔处理高流量负荷下低浓度甲苯废气的初探

采用净化甲苯专用菌种对生物膜填料塔净化处理高流量负荷下低浓度甲苯废气的技术进行了初步实验研究。实验结果表明 ,当气体流量在 0 8m3 /h、进口浓度为 10 5mg/m3 、停留时间 18 3s时 ,甲苯的去除率可达到 6 1 90 % ,出口甲苯浓度低于国家对现有企业的排放标准 (≤ 6 0mg/m3 )。适宜的操作温度应控制在 19～ 2 5℃之间 ,氮磷营养添加量的配比应控制为C∶N∶P =2 0 0∶5∶1,操作压降与气体流量呈线性关系。结合实验数据 ,对相关的基础理论进行了初步探讨。     

Natural radionuclide concentrations in two phosphate ores of east Algeria

Ore is considered as an important source of many elements such as the iron, phosphorus, and uranium. Concerning the natural radionuclides, their concentrations vary from an ore to other depending on the chemical composition of each site.In this work, two phosphate ores found in East of Algeria have been chosen to assess the activity concentration of natural radionuclides represented mainly by three natural radioactive series ²³⁸U, ²³⁵U and ²³²Th, and the primordial radionuclide ⁴⁰K where they were determined using ultra-low background, high-resolution gamma-ray spectroscopy.The measured activity concentrations of radioactive series ranged from 6.2 ± 0.4 to 733 ± 33 Bq.kg⁻¹ for the ²³²Th series, from 249 ± 16 to 547 ± 39 Bq.kg⁻¹ for the ²³⁸U series, around 24.2 ± 2.5 Bq.kg⁻¹ for the ²³⁵U series, and from 1.4 ± 0.2 to 6.7 ± 0.7 Bq.kg⁻¹ for ⁴⁰K.To assess exposure to gamma radiation in the two ores, from specific activities of ²³²Th, ⁴⁰K and ²²⁶Ra, three indexes were determined: Radium equivalent (Ra_eq), external and internal hazard indexes (H_ex and H_in), their values ranged from 831 ± 8 to 1298 ± 14 Bq.kg⁻¹ for Ra_eq, from 2.2 ± 0.4 to 3.5 ± 0.7 Bq.kg⁻¹ for H_ex, and from 4.2 ± 0.7 to 4.5 ± 0.7 Bq.kg⁻¹ for H_in.     

大气汞的来源及其浓度分布特征研究进展

大气汞是全球性的污染物,其来源有自然源和人为源,亚洲地区是最大的人为大气汞排放源,占全球人为排汞量的67％(质量分数),其中又以中国为最.燃煤和有色金属冶炼对中国大气汞排放的贡献最大.环境界面的释汞通量是全球大气汞预算的重要组成部分,也是目前的研究热点之一.综述了不同环境界面的释汞通量及其影响因素,并比较了不同地区大气...     

The sea–air exchange of mercury (Hg) in the marine boundary layer of the Augusta basin (southern Italy): Concentrations and evasion flux

The first attempt to systematically investigate the atmospheric mercury (Hg) in the MBL of the Augusta basin (SE Sicily, Italy) has been undertaken. In the past the basin was the receptor for Hg from an intense industrial activity which contaminated the bottom sediments of the Bay, making this area a potential source of pollution for the surrounding Mediterranean. Three oceanographic cruises have been thus performed in the basin during the winter and summer 2011/2012, where we estimated averaged Hg_atm concentrations of about 1.5 ± 0.4 (range 0.9–3.1) and 2.1 ± 0.98 (range 1.1–3.1) ng m⁻³ for the two seasons, respectively. These data are somewhat higher than the background Hg_atm value measured over the land (range 1.1 ± 0.3 ng m⁻³) at downtown Augusta, while are similar to those detected in other polluted regions elsewhere. Hg evasion fluxes estimated at the sea/air interface over the Bay range from 3.6 ± 0.3 (unpolluted site) to 72 ± 0.1 (polluted site of the basin) ng m⁻² h⁻¹. By extending these measurements to the entire area of the Augusta basin (∼23.5 km²), we calculated a total sea–air Hg evasion flux of about 9.7 ± 0.1 g d⁻¹ (∼0.004 t yr⁻¹), accounting for ∼0.0002% of the global Hg oceanic evasion (2000 t yr⁻¹). The new proposed data set offers a unique and original study on the potential outflow of Hg from the sea–air interface at the basin, and it represents an important step for a better comprehension of the processes occurring in the marine biogeochemical cycle of this element.     

低浓度SO2和NOx自动监测系统性能评价方法

通过对7种废气自动监测系统的比较研究和现场测试,提出了非分散红外法、紫外差分法、紫外荧光法、化学发光法等多种SO2和NO x自动监测技术在低浓度范围实现准确定量监测的性能评价方法,定义了CEMS的系统检出限及其主要影响因素。建议采用系统检出限、线性误差等关键参数作为低浓度CEMS的性能评价方法,提出将全系统多点标准气体校准或加标回收率作为验收和质控监督的基本方法。     

北京市PM2.5质量浓度特征及组分化学质量闭合研究

2013年7—9月分2次在北京市朝阳区的4个采样点(来广营、垡头、奥体和建外)进行PM_2.5手工采样,共获得164个有效滤膜样品。以石英滤膜为例,这4个采样点的均值分别为85、94、81、86 μg/m³。数据显示PM_2.5质量浓度呈"南高北低"的特点。化学质量闭合研究表明:碳质组分(OM+EC)和二次无机离子是PM_2.5的主要组成;碳质组分对夏季PM_2.5的质量浓度贡献比较稳定,2次采样对PM_2.5的贡献均在1/3左右,与采样时间和地点无关;二次无机离子的贡献则与采样时间有关,对PM_2.5的贡献在第一和第二次采样时间分别约为30%和20%。4个采样点中,最南端的垡头PM_2.5质量浓度最高,有机颗粒物、SO₄^2-、NO₃^-和NH₄⁺的质量浓度平均值最高,分别为26、18.2、10.5、5.9 μg/m³。