沉积物再悬浮-重金属释放机制研究进展

水-沉积物界面重金属迁移和转化行为已成为水环境质量研究的热点。因自然、生物、人为活动等驱动的沉积物再悬浮使得沉积物颗粒吸附和结合的重金属可能通过吸附-解吸平衡和氧化还原反应而释放进入上覆水体。随着外在污染源输入逐步得到控制,沉积物再悬浮释放重金属将成为水体重要的内在污染源而对水环境质量和水生生物产生影响。本文综述了最近几年的相关研究文献,对沉积物再悬浮的动力来源及发生机制、再悬浮-重金属释放机制及主要影响因素进行了阐述,探讨了该领域未来可能的研究方向。相关研究发现,当干扰切应力大于沉积物的临界切应力值时,沉积物再悬浮发生,且再悬浮颗粒量随干扰切应力的增强而增大;再悬浮使还原态沉积物暴露于有氧环境,有机质和硫化物的氧化是沉积物结合态重金属释放的主要机理,而沉积物颗粒电性吸附的重金属则通过解吸进入水体;切应力大小、再悬浮水体理化性质、沉积物理化性质以及微生物活性等因素调控着沉积物吸附态或结合态重金属的释放。本文指出再悬浮沉积物释放重金属的去向（再分配机理）以及再悬浮-重金属释放的动力学过程、沉积物悬浮-重金属释放复合预测模型的建立、沉积物悬浮-释放重金属的生物可利用性及生物毒害评价将是本领域需要进一步研究的重点。     

大气中硫化氢测定方法研究

对用亚甲基蓝分光光度法测定大气中硫化氢的标准溶液、样品的稳定性、温度对试剂空白的影响等问题进行了一些研究。得出：硫化氢标准使用液用磁性锌氨络盐吸收液配制，冰箱保存至少可稳定２个月；温度对试剂空白值有影响，应根据不同显色温度，确定不同显色时间；绘制标准曲线和样品测定应用同一量器迅速加入显色剂，以提高其灵敏度。     

北京市密云县潮河周边土壤中类二恶英PCBs分析评价

为了探讨密云水库上游流域可能给水库带来的非点源污染,本研究测定了入库河流潮河下游周边土壤中12种类二恶英多氯联苯(DL-PCBs)的含量水平。结果表明,ΣDL-PCBs的总含量水平为0.0039~0.0365 ng·g-1,其中PCB-118,115,77为12种DL-PCBs的主要成分,PCB-81,114,157均低于检出限。草地、林地和果园中ΣDL-PCBs的含量高于玉米地,表明研究区的DL-PCBs主要受大气沉降和河流沉积物的影响,受当地人类活动影响不大。与其他研究相比,采样区域的PCBs含量总体处于偏低水平,毒性当量处于中等水平。而毒性当量因子(TEF)较高的PCB-126与PCB-169,可能会对人类和生物产生危害,应给予足够的重视。     

天然水中Cr(Ⅵ)与硫化物的氧化还原反应环境动力学的研究

本文模拟研究了地表水及土壤水介质中Cr(Ⅵ)在硫系统作用下的氧化还原反应动力学.在通常的pH及夏、秋温度和厌氧还原条件下进行动力学实验,采用了流动注射技术分析测定.初步确定了在一定的温度及pH条件下,当Cr(Ⅵ)与硫化物浓度相近时,二者之间的氧化还原反应为二级反应,其反应速率与Cr(Ⅵ)及总硫化物浓度的一次方乘积成正比.其速率常数随温度升高而增大,随pH升高却产生较为复杂的变化,总的说来,在pH5.5—7.0范围内速率常数较大.而在pH>7时反应很慢,近于停止了.当硫化物浓度远大于Cr(Ⅵ)时,二者之间的反应为准一级反应,Cr(Ⅵ)的还原速率与Cr(Ⅵ)浓度的一次方成正比,其反应速率常数随温度升高而增大,在pH5.0—7.8范围内速率常数随pH升高而逐渐减小.     

粉煤灰的改性及其对高盐苯胺废水的处理

以盐酸和硫酸作为改性剂,对粉煤灰进行改性。通过正交实验得到最佳改性粉煤灰制备条件为：V（盐酸）∶V（硫酸）=1∶5,浸泡时间6h,活化时间6h,活化温度250℃。在初始苯胺质量浓度为200mg/L、氯化钠质量分数为15%、吸附时间为60min的条件下,采用在最佳条件下制备得到的改性粉煤灰对苯胺进行吸附,吸附量可达4.16mg/g。采用Freundlich方程可更好地对改性粉煤灰吸附苯胺的过程进行拟合。     

Effects of water management on arsenic and cadmiumspeciation and accumulation in an upland rice cultivar

Pot and field experiments were conducted to investigate the effects of water regimes on the speciation and accumulation of arsenic (As) and cadmium (Cd) in Brazilian upland rice growing in soils polluted with both As and Cd. In the pot experiment constant and intermittent flooding treatments gave 3-16 times higher As concentrations in soil solution than did aerobic conditions but Cd showed the opposite trend. Compared to arsenate, there were more marked changes in the arsenite concentrations in the soil solution as water management shifted, and therefore arsenite concentrations dominated the As speciation and bioavailability in the soil. In the field experiment As concentrations in the rice grains increased from0.14 to 0.21 mg/kg while Cd concentrations decreased from 0.21 to 0.02 mg/kg with increasing irrigation ranging from aerobic to constantly flooding conditions. Among the various water regimes the conventional irrigation treatment produced the highest rice grain yield of 6.29 tons/ha. The As speciation analysis reveals that the accumulation of dimethylarsinic acid (from 11.3% to 61.7%) made a greater contribution to the increase in total As in brown rice in the intermittent and constant flooding treatments compared to the intermittent-aerobic treatment. Thus, water management exerted opposite effects on Cd and As speciation and bioavailability in the soil and consequently on their accumulation in the upland rice. Special care is required when irrigation regime methods are employed to mitigate the accumulation of metal(loid)s in the grain of rice grown in soils polluted with both As and Cd.     

季节性缺氧水库铁、锰垂直分布规律及优化分层取水研究

经多年对阿哈水库Ｆｅ，Ｍｎ污染的研究表明，Ｆｅ，Ｍｎ分布随着季节为化、水库水温分层而变化，呈现明显的垂直分布规律，高浓度Ｆｅ、Ｍｎ主要出现在水温分层期水库中、下层、与库底缺氧、ＰＨ下降，沉积物中的Ｆｅ、Ｍｎ向上覆水释放造成的二次污染等密切相关，为自来水厂优化分层取水提供了依据。     

Influence of fuel mass load, oxygen supply and burning rate on emission factor and size distribution of carbonaceous particulate matter from indoor corn straw burning

The uncertainty in emission estimation is strongly associated with the variation in emission factor (EF),which could be influenced by a variety of factors such as fuel properties,stove type,fire management and even methods used in measurements.The impacts of these factors are complicated and often interact with each other.Controlled burning experiments were conducted to investigate the influences of fuel mass load,air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter (PM) from indoor corn straw burning in a cooking stove.The results showed that the EFs of PM (EFPM),organic carbon (EFOC) and elemental carbon (EFEC) were independent of the fuel mass load.The differences among them under different burning rates or air supply amounts were also found to be insignificant (p > 0.05) in the tested circumstances.PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 μm,contributing 86.4%±3.9% of the total.The size distribution of PM was influenced by the burning rate and air supply conditions.On average,EF PM,EF OC and EF EC for corn straw burned in a residential cooking stove were (3.84±1.02),(0.846±0.895) and (0.391±0.350) g/kg,respectively.EF PM,EF OC and EF EC were found to be positively correlated with each other (p < 0.05),but they were not significantly correlated with the EF of co-emitted CO,suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.     

Adsorption behavior of phosphate on Lanthanum（III） doped mesoporous silicates material

A series of lanthanum doped meosoporous MCM-41 (LaxM41, x is Si/La molar ratio) was prepared by sol-gel method. The surface structure of the materials was investigated with X-ray diffraction and N2 adsorption/desorption technique. The content of La in the materials was determined by ICP. It was found that the La content of La25M41, La50M41 and La100M41 was 7.53%, 3.89% and 2.32%, respectively. The phosphate adsorption capacities increased with increasing amount of La incorporation. With 0.40 g La25M41 99.7% phosphate could be removed. The effects of Si/La molar ratio, LaxM41 dose, pH, initial concentration of phosphate solution, co-ions on phosphate adsorption were also evaluated. The phosphate adsorption kinetics of LaxM41 could be well-described by the pseudo second-order model, and Langmuir isotherm fit equilibrium data much better than the Freundlich isotherm.     

石油化工区光化学烟雾模拟模式研究

本工作以上海金山石油化工区为对象,探讨和建立了描述该地区光化学烟雾污染的大气质量模拟模式(简称SJMM),并与1980年10月29日实测数据进行了比较和分析。所用化学模式与国外烟雾箱数据及模式数据进行了对比。结果表明SJMM模式基本上能描述该地区的O_3、NO、NO_2的浓度分布和日变化情况。并利用模式预断了该地区出现光化学烟雾污染的可能性。