初始扰动对CO2抑制瓦斯爆炸特性研究*

为了预防实际生产过程中发生的瓦斯爆炸事故,利用20 L球形爆炸装置,通过改变粉尘仓充压压力产生不同的扰动,研究9.5%CH4浓度下不同扰动条件对CO2抑爆特性的影响。通过对所得参数进行分析,得到CO2抑爆特性与初始扰动的关系。研究结果表明:相较于均匀静置状态,初始扰动的存在均能提高CH4的爆炸强度,当引发初始扰动的粉尘仓压力为1.5 MPa时,最大爆炸压力达到0.78 MPa;随CO2浓度增大,爆炸强度整体下降,呈二次下降趋势、最大爆炸压力时间呈上升趋势,且各初始扰动压力间爆炸强度均大于均匀静置状态、最大爆炸压力时间小于均匀静置状态;同时利用CHEMKIN软件得到绝热平衡压力,计算热损失参数发现,同一气体混合比例工况下,初始扰动状态的热损失及热损失分数明显低于均匀静置状态的,且当CO2浓度为15%时,差距最大,不同初始扰动间热损失及热损失分数最小值分别为0.013 19 kJ/m2,17.9%,远小于静置状态下0.036 29 kJ/m2,46.4%,说明初始扰动对于CO2抑爆效果存在削弱作用。     

阳离子聚电解质聚二甲基二烯丙基氯化铵的絮凝机理初探

以聚二甲基二烯丙基氯化铵PDADMAC(特性粘度分别为2.7,1.4,0.7)为絮凝剂,对比PAC和PFC,通过残余浊度、Zeta电位、FI絮凝指数的测定,研究了PDADMAC对高岭土悬浊体系(浊度分别为6000,1000,200和10 NTU)的絮凝特性,并对其絮凝作用机理进行了探讨.结果表明,PDADMAC的吸附构型决定其絮凝机理在较低初始悬浊物浓度下(200 NTU)为单个颗粒物表面吸附覆盖及其"吸附电中和"絮凝模型;在高浊条件下(＞1000 NTU)为单颗粒表面(Monomer)部分吸附覆盖及其"吸附架桥"絮凝模型.     

旅游活动对九寨沟地表径流氮磷流失的影响研究

2005年4—9月,选择九寨沟旅游热点景点五花海与珍珠滩,设置了4组对比样地(干扰与未干扰对照),采用径流实验方法定位监测了25个降雨事件下的地表径流、湖边水体与地表降水中的全氮、全磷含量,分析了旅游活动对九寨沟核心景区林下地表径流与湖边水质中氮/磷含量的影响,探讨了旅游活动对湖泊水质变化的影响。研究发现:(1)地表径流中的全氮/全磷含量均显著高于近地表层降水中的全氮与全磷,也显著高于天然降水中的含量;(2)旅游活动后,径流全氮和全磷含量都增大;(3)径流全氮和全磷含量与土壤物理因子呈显著相关关系,地被覆盖因子中的凋落物因子影响径流全磷含量较显著;(4)地表径流全氮、全磷含量大于湖边水全氮、全磷含量,两者之间为正相关关系,表明旅游活动引起了氮/磷向湖泊的输入加大。研究结果提示,控制游客的游径扩大,湖岸边地被层植被恢复等措施是削减湖泊富营养化的有效措施。     

硅藻指数在嫩江支流甘河的适用性评估

为了筛选出适用于甘河水生态评价的硅藻指数,合理评价甘河水生态健康状况,2018年8月在嫩江支流甘河调查了19个点位的着生硅藻群落结构和水环境特征.应用21种硅藻指数对甘河水生态健康状况进行评价,采用箱体图法分析了所选硅藻指数的适用性,使用Spearman相关分析研究了硅藻指数与环境因子的相关性,最后应用多元线性回归方法分析了不同因素对硅藻指数在甘河评价正确率的影响.结果表明:①所选硅藻指数中,IBD（biological diatom index,硅藻生物指数）、EPI-D（diatom eutrophication pollution index,富营养污染硅藻指数）和IPS（specific pollution sensitivity index,特定污染敏感指数）的评价结果区分度最好,最适用于甘河水生态健康状况评价.②甘河丰水期水生态健康状况总体较好,约70%的点位水生态健康状况为健康、较好和一般,约30%的点位水生态健康状况为较差和极差,极差的点位全部位于甘河下游区域.③硅藻指数与COD_Cr的相关性对硅藻指数评价正确率有显著影响（P < 0.01）,硅藻指数与COD_Cr相关性越强,评价的正确率越高;物种覆盖度对硅藻指数评价的正确率也有影响,但不显著,各点位最小物种覆盖度高于65%时,物种覆盖度对藻指数评价的正确率影响较为明显.研究表明,硅藻指数可以有效地评价水生态健康状况,但硅藻指数与环境因子之间的相关性等因素会影响评价的正确率,因此选择合适的硅藻指数进行研究区域的水生态健康状况评价尤为重要.      

粤北大宝山AMD水-表层沉积物的重金属分布特征及其影响因素

粤北大宝山铁铜多金属矿床的尾矿富含硫化物矿物,在化学和生物氧化作用下,产生pH5的酸性矿山废水(AMD).本文对大宝山槽对坑、铁龙AMD的10个采样点的表层沉积物进行物相和微观形貌分析,测定水样和表层沉积物中Pb、Cu、Mn、Cr等重金属离子的含量,讨论pH与次生矿物对重金属元素在水-表层沉积物分布差异的影响.结果表明:AMD的表层沉积物的次生矿物主要由铁、锰的氢氧化物、铁矾类矿物、羟氧硫铅矿和偏砷酸氢铁矿组成,其中含铁次生矿物具有一定的空间演化特征.水-表层沉积物的重金属浓度空间分布差异主要受pH和次生矿物组合控制.水的重金属含量总体是随着pH的降低而增大,且Pb、Cu、Mn具有显著相关性.羟氧硫铅矿是Pb的主要沉淀方式;水钠锰矿的析出沉淀影响Mn、Pb、Cu的沉降率;水铁矿、针铁矿、施威特曼石控制低pH环境中Cu的沉降行为;针铁矿、黄钾铁矾、施威特曼石是水溶液中Cr的强力清除剂.     

The effects of Herba Andrographitis hedgerows on soil erodibility and fractal features on sloping cropland in the Three Gorges Reservoir Area

To evaluate if hedgerows could improve the soil physicochemical properties and enhance the soil anti-scouring and anti-shearing capabilities, the effects of Herba Andrographitis hedgerows on soil erodibility and fractal features on sloping cropland in the Three Gorges Reservoir Area were investigated. Results showed that: (1) the clay particle accumulation around the hedgerows was significantly affected by the hedgerows; (2) the fractal dimension of soil particles was positively correlated with both silt and clay contents and had a negative linear correlation with sand content; (3) fine-grained content significantly influenced fractal dimension of the soil particles; (4) soil erodibility K was significantly and positively correlated with the sand content (correlation coefficient r?=?0.870), but significantly and negatively correlated with the silt content (r?=??0.538), clay content (r?=??0.739), organic carbon content (r?=??0.603), the aggregation degree (r?=??0.486), and soil fractal dimension (r?=??0.538); and (5) the contents of organic matter and clay particles in the soil were found to be the effective indicators for soil erodibility at the Three Gorges Reservoir Area. The hedgerows may improve soil fractal features and decrease soil erodibility. The effective distance between hedgerows on a slope of 10° was less than 6 m.     

高盐废水盐度对中度嗜盐菌生长动力学的影响

高盐废水盐度变化是影响微生物生长的重要因素之一。研究以中度嗜盐菌Halomonassp．STSY．3为例，测定其在不同盐度下生长对数期末OD600,并以葡萄糖为限制性基质，利用Monod方程，对菌株进行生长动力学拟合。结果表明，Halomonassp．STSY-3的最适生长盐度为7％（以NaCl计），此盐度下其OD600 为2．56，而0%和34％盐度下OD600分别为0．47和0．06；Halomonassp．STSY-3的生长动力学模型与实验数据能较好地拟合，在最适生长盐度下动力学模型参数μmax 为2．257h-1，Ks为0．0082g／L。比较不同盐度下STSY-3生长动力学参数，得出中度嗜盐菌STSY-3的生长存在3个明显分区：最适盐度区（盐度2％～9％）、嗜盐过渡区（盐度9％～20％和0．68％～1．76％）及生长抑制区（盐度≤2％或≥20％）。其中嗜盐过渡区0．68％～1．76％由于范围较小，实际意义小，忽略不计。     

双氯芬酸的吸附去除过程与机制

研究了非甾体抗炎药双氯芬酸的吸附去除过程与机制。对吸附处理效果较好的活性炭与纳米羟基氧化铁（α-FeOOH）进行了比表面积、Zeta电位等表面特性的表征，研究比较了双氯芬酸在活性炭与α—FeOOH2种材料上的吸附去除效果与吸附机制。结果表明，在相同的实验条件下，活性炭与α-FeOOH对双氯芬酸吸附去除率可分别达到97．9％和84．3％；双氯芬酸在活性炭上的吸附主要是由于活性炭较大的比表面积与疏水分配作用，在α-FeOOH上的吸附主要是由于静电引力作用；活性炭与α-FeOOH对双氯芬酸的吸附去除效果均随pH的升高而降低；在pH=6时，活性炭与α-FeOOH对双氯芬酸钠的吸附等温线均符合Langmuir方程，单位饱和吸附量分别为109．98mg／g和58．96mg／g；活性炭对双氯芬酸具有更强的吸附能力。     

Effects of hydrodynamics on the distribution of trace persistent organic pollutants and macrobenthic communities in Bohai Bay

In recent years, the rapid economic development along Bohai Bay, has brought out continuous increasing of the pollution loads in the Bohai Sea, especially by the large coastal reclamation project, Tianjin Binhai New Area. In the period of 2007-2009, we collected the sediments of the main rivers, estuaries, intertidal zone, and near-shore area of Bohai Bay, and Macrobenthos associated with the marine sediments to assess the influence of hydrodynamics in the coastal environment on the pattern of trace contaminants and the macrobenthic community. Based on data derived from these samples, the levels of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) in sediments followed the order PAHs > OCPs > PCBs > PBDEs. The higher concentrations of PCBs, OCPs, PAHs and PBDEs were found in the estuarine and near-shore environment of the Dagu Drainage River. The spatial distribution of OCPs was different to that of PCBs due to the direction of the velocity field of Bohai Bay in its old and new topography, and the higher water-solubility of OCPs than that of PCBs. The results of the Pearson correlation and the PCA indicate that the medium diameter (MD) of sediments was the predominant factor influencing the distribution of PCBs and OCPs, most sampling sites were characterized mainly by TOC of sediments and biomass of macrobenthos. The results indicate that the distribution of trace contaminants and macrobenthic community in Bohai Bay are mainly affected by the hydrodynamic conditions.     

活性炭纤维载体生物膜法处理洗车废水研究

为了实现洗车废水的循环使用,进行了以聚丙烯腈基活性炭纤维(PAN-ACF)为生物膜载体处理洗车废水的实验研究。以LAS、COD和NH3-N等指标考察了活性炭纤维生物膜反应器对洗车废水的处理效果。结果表明:在常温下、pH=6.5~7,当进水流量在30 mL/min时,反应器达到最佳运行参数,活性炭纤维载体生物膜法对LAS、COD和NH3-N等的去除率分别达到了97%、80%和60%。出水水质完全达到《生活杂用水水质标准》(CJ/T48-99)中洗车用水主要水质指标的规定。此外,实验表明PAN-ACF作为生物膜载体具有很好的生物亲和性和再生性。