疏水性有机物和有机酸碱溶解度的估算

本文从理论上建立了疏水性有机物和任意pH条件下有机酸碱溶解度的估算方法,并估算了不同类型有机物的溶解度,和实测值比较,结构和辛醇相近的有机物吻合较好;结构不同,则有一定的偏差,这是由于假设有机物在辛醇中的活度系物等于1所致。经校正后得到了较好的结果。     

Simultaneous Measurements of Atmospheric Pollutants and Visibility with a Long-Path DOAS System in Urban Areas

In this paper, the applicability of a Long-Path Differential Optical Absorption Spectroscopy (LP-DOAS) system was checked for the feasibility of the simultaneous measurement of trace gases (such as O₃, NO₂, SO₂, and HCHO) and atmospheric visibility (light extinction by aerosols) in Asian urban areas. Field studies show that an LP-DOAS system can simultaneously measure the key pollutants (such as O₃, NO₂, SO₂, and HCHO) at detection limits in the ppb/sub-ppb range as well as the Mie extinction coefficient with an uncertainty of 0.1 km^–1 at time resolution of a few minutes. It is thus concluded that the use of LP-DOAS system is feasible for simultaneous measurement of gaseous pollutants as well as an atmospheric extinction coefficient which is tightly bound to fine particulate concentration.     

Comparability between PM2.5 and particle light scattering measurements

Particle light scattering and PM_2.5 (particles with aerodynamic diameters less than 2.5 m) concentration data from air quality studies conducted over the past ten years wereexamined. Fine particle scattering efficiencies were determinedfrom statistical relationships among measured light scattering and fine and coarse mass concentrations. The resulting fine particle scattering efficiencies ranged from 1.7 m² g^-1at Meadview in the Grand Canyon to over 5 m² g^-1 in Mexico City. Most of the derived fine scattering efficiencieswere centered around 2 m² g^-1, which is considerablylower than most values reported from previous studies.     

Patchy Distribution Fields: An Interleaved Survey Design and Reconstruction Adequacy

A mathematical model was used to compare the effects of a regular (one-pass) or interleaved (two-pass) acoustic survey on the adequacy of reconstructing patchy distribution fields. The model simulates fish or plankton patches of different shapes and spatial orientations, and a set of parallel or zigzag transects forming a regular or interleaved acoustic survey. The efficiency of a survey is determined by the adequacy of a reconstructed field to that originally generated, which is evaluated by calculating their correlations. Regarding the immovable fields, the efficiency of a regular or interleaved acoustic survey was tested with the following two alternative assumptions: (1) the entire survey was completed; (2) the survey was interrupted for some reason at the moment when one transect remained non-accomplished. In the former case, the efficiencies of both acoustic surveys were nearly the same; in the latter case, the efficiency of an interleaved survey was superior to that of a regular one. With respect to movable fields, the efficiency of the completed interleaved surveys was even higher than that of the regular ones. Thus, the results obtained allow us to conclude that an interleaved survey is expedient in cases where there is no preference regarding the position of a vessel for further work.     

Changes in visibility with PM2.5 composition and relative humidity at a background site in the Pearl River Delta region

In fall–winter, 2007–2013, visibility and light scattering coefficients(b sp) were measured along with PM_(2.5)mass concentrations and chemical compositions at a background site in the Pearl River Delta(PRD) region. The daily average visibility increased significantly(p 0.01) at a rate of 1.1 km/year, yet its median stabilized at ~13 km. No haze days occurred when the 24-hr mean PM_(2.5)mass concentration was below 75 μg/m~3. By multiple linear regression on the chemical budget of particle scattering coefficient(b sp), we obtained site-specific mass scattering efficiency(MSE) values of 6.5 ± 0.2, 2.6 ± 0.3, 2.4 ± 0.7 and 7.3 ± 1.2 m2/g,respectively, for organic matter(OM), ammonium sulfate(AS), ammonium nitrate(AN) and sea salt(SS). The reconstructed light extinction coefficient(b ext) based on the Interagency Monitoring of Protected Visual Environments(IMPROVE) algorithm with our site-specific MSE revealed that OM, AS, AN, SS and light-absorbing carbon(LAC) on average contributed 45.9% ± 1.6%,25.6% ± 1.2%, 12.0% ± 0.7%, 11.2% ± 0.9% and 5.4% ± 0.3% to light extinction, respectively.Averaged b ext displayed a significant reduction rate of 14.1/Mm·year(p 0.05); this rate would be 82% higher if it were not counteracted by increasing relative humidity(RH) and hygroscopic growth factor(f(RH)) at rates of 2.5% and 0.16/year-1(p 0.01), respectively, during the fall–winter, 2007–2013. This growth of RH and f(RH) partly offsets the positive effects of lowered AS in improving visibility, and aggravated the negative effects of increasing AN to impair visibility.     

水稻田非点源污染原位试验研究

为了研究野外水稻田的非点源污染,本试验采取一种新的原位观测方法:即在不改变水稻田原有出流特征前提下,在水稻生长季采集田面水水位和降雨信息,通过水位变化曲线计算水稻田每日的蒸散发和渗漏损失量,再根据水量平衡关系计算径流量.观测期间定期采集田面水测定总氮(TN)、总磷(TP)浓度,根据径流量和浓度估算非点源污染流出负荷量.试验选取北京市海淀区上庄镇某村水稻田试验田块,通过1年的试验观测得到在生长季内的37场降雨中共有9场降雨产生了出流.另外,还有2次人工排水和1次农田回归流形成了非点源污染.经计算试验区水稻田每个生长季TN输出系数为8.8 kg·hm-2,TP输出系数为0.47 kg·hm-2.该观测方法针对具有多出水口且最低田埂高度动态变化的野外水稻田的非点源污染观测具有较强的可操作性.     

填料在净化污水过程中渗透性能变化趋势的研究

选取腐殖垃圾和砂以及两者质量比分别为4:1、3:2、2:3的混合物共5种填料,在1.0 m/d的水力负荷下,进行人工快速渗滤系统净化生活污水的试验,研究填料在进水过程中渗透性能的变化趋势.结果表明,腐殖垃圾的初始饱和水力渗透系数(K)最大,为3.32×10-2cm/s,而砂的初始K只有5.14×10-3cm/s,腐殖垃圾含量越大的混合物其仞始K也越大.在净化污水的过程中,5种填料的K逐渐减小,腐殖垃圾含量越大的混合物其K降幅也越大.随着进水时间的延长,各个填料柱填料层50～250 mm处的水头损失占总水头损失(填料层50～450mm处)的比例均逐渐增加,最终各个填料柱均发生堵塞,堵塞均发生在填料层50mm以上范围内.     

Kinetics of endosulfan sorption on to wood charcoal

Abstract

A part of the research work conducted to evaluate the efficiency of a locally available low cost wood charcoal in removing endosulfan, an organochlorine insecticide, has been presented here in this paper. In the batch experiments conducted at 1 mg/I initial concentration of endosulfan, it was found that wood charcoal could remove endosulfan from water up to 95%. Kinetic profiles were developed for various conditions and they followed second order kinetic reactions. Adsorption equilibrium time was determined by two different approaches namely rough estimate and 2% slope criteria. The equilibrium time was found to be 5 hrs. Forward, reverse, and overall reaction rate constants were determined by approximating the kinetic data to the first order reversible kinetic model. Rate constants increased with increasing initial concentration of endosulfan. Rate limiting process was determined by using kinetics data and further confirmed by the multiple interruption test. Pore and film diffusion coefficients were determined from the half time equations. Film diffusion appeared to be the rate limiting which was further supported by the multiple interruption test.     

热水解-厌氧消化工艺中污泥的触变性分析

采用触变动力学系数作为评价指标,通过流变试验研究了热水解-厌氧消化联合工艺中污泥标准化黏度和触变性的变化规律,并探讨了屈服应力和触变性二者间的联系,从触变性角度为热水解-厌氧消化污泥的处理处置提供参考依据。结果表明:与滞后环相比,用触变动力学系数K更适合表征污泥的触变性;调配污泥、热水解污泥和厌氧消化污泥的标准化黏度均随时间增大逐渐减小;3种污泥的触变性随TSS质量分数增大而减小,经热水解-厌氧消化后污泥的触变性增大,流动性增强;污泥屈服应力越大,触变性越小,稳定性越强。     

轴装式转碟曝气机的研制

针对转碟曝气机在使用过程中出现的问题,进行重新设计,改善受力状况和工作条件,提高设备运行的可靠性,减少维护工作量,降低维护的难度和费用。