Modeling of air quality with a modified two-dimensional Eulerian model： A case study in the Pearl River Delta （PRD） region of China

A modified two-dimensional Eulerian air quality model was used to simulate both the gaseous and particulate pollutant concentrations during October 21-24, 2004 in the Pearl River Delta （PRD） region, China. The most significant improvement to the model is the added capability to predict the secondary organic aerosols （SOA） concentrations because of the inclusion of the SOA formation chemistry. The meteorological input data were prepared using the CALMET meteorological model. The concentrations of aerosol-bound species such as NO3^-, NH4^＋, SO4^2-, and SOA were calculated in the fine particle size range （〈2.5 μm）. The results of the two-dimensional model were compared to the measurements at the ground level during the PRD Intensive Monitoring Campaign （IMC）. Overall, there were good agreements between the measured and modeled concentrations of inorganic aerosol components and O3. Both the measured and the modeled results indicated that the maximum hourly O3 concentrations exceeded the China National Air Quality Standard. The predicted 24-h average SOA concentrations were in reasonable agreement with those predicted by the method of minimum OC/EC ratio.     

Effect of sulfate on the methanogenic activity of a bacterial culture from a brewery wastewater during glucose degradation

The maximum specific methanogenic activity （SMA） of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/（g VSS.d） when biomass was in contact with sulfate at a ratio of 1：0.114 by weight.     

Topsoil organic carbon mineralization and CO2 evolution of three paddy soils from South China and the temperature dependence

Carbon mineralization and its response to climatic warming have been receiving global attention for the last decade. Although the virtual influence of temperature effect is still in great debate, little is known on the mineralization of organic carbon （SOC） of paddy soils of China under warming. SOC mineralization of three major types of China＇s paddy soils is studied through laboratory incubation for 114 d under soil moisture regime of 70% water holding capacity at 20℃ and 25℃ respectively. The carbon that mineralized as CO2 evolved was measured every day in the first 32 d and every two days in the following days. Carbon mineralized during the 114 d incubation ranged from 3.51 to 9.22 mg CO2-C/gC at 20℃ and from 4.24 to 11.35 mg CO2-C/gC at 25℃ respectively; and a mineralizable C pool in the range of 0.24 to 0.59 gC/kg, varying with different soils. The whole course of C mineralization in the 114 d incubation could be divided into three stages of varying rates, representing the three subpools of the total mineralizable C： very actively mineralized C at 1-23 d, actively tnineralized C at 24--74 d and a slowly mineralized pool with low and more or less stabilized C mineralization rate at 75-114 d. The calculated Q10 values ranged from 1.0 to 2.4, varying with the soil types and N status. Neither the total SOC pool nor the labile C pool could account for the total mineralization potential of the soils studied, despite a well correlation of labile C with the shortly and actively mineralized C, which were shown in sensitive response to soil warming. However, the portion of microbial C pool and the soil C/N ratio controlled the C mineralization and the temperature dependence. Therefore, C sequestration may not result in an increase of C mineralization proportionally. The relative control of C bioavailability and microbial metabolic activity on C mineralization with respect to stabilization of sequestered C in the paddy soils of China is to be further studied.     

强化厌氧污泥体系同步脱硫反硝化特性研究

以硫化物为电子给体的自养反硝化厌氧体系是代替传统异养反硝化工艺处理低C/N比含氮废水的有效工艺,可以同时去除硫化物和硝酸盐.将脱氮硫杆菌菌悬液接种到厌氧污泥体系中,脱氮硫杆菌快速富集,采用5组进水比N/S比不同的反应瓶进行试验,运行15d后,测定不同时段的出水硫化物、硝酸盐、亚硝酸盐、硫酸盐浓度等指标,考察强化厌氧污泥体系去除硫化物和硝酸盐的特性,并对生化反应机制进行初步研究.结果表明,强化厌氧污泥体系运行3h后,进水中90%的硫化物被去除,硫化物的去除与进水N/S比无关,硫化物(以S计)去除速率高达20～24g·(m3·h)-1,是相关文献报道的10倍左右;运行6h后,进水中65%的硝氮被去除,硝氮的去除负荷随着进水N/S比的提高而增大,最高达到940g·(m3·h)-1,约为硫自养反硝化体系硝氮去除负荷的2倍,此时体系中亚硝氮积累,最高浓度达到93mg·L-1,进水N/S比低的条件下,6h后亚硝氮消失,进水N/S比较高时,21h后出水中未检测到亚硝氮.表明强化厌氧污泥体系停留6h后可以实现同时去除硫化物和硝酸盐,但硝酸盐首先转化为亚硝氮.与以往不同的是研究发现硫化物与生物硫粒产生多硫化合物的链式反应,是硫化物迅速转化的主要途径,此外,还原硝氮的电子给体并不来源于硫化物,可能主要来源于体系中产生的单质硫.     

光腔衰荡光谱(CRDS)法观测我国4个本底站大气CO2

利用基于光腔衰荡光谱(CRDS)技术自组装的大气CO2在线观测系统,于2009年在青海瓦里关、浙江临安、北京上甸子和黑龙江龙风山4个世界气象组织全球大气观测网(WMO/GAW)大气本底站对大气CO2进行了在线观测.初步分析结果表明,4站全年大气CO2体积分数最低值出现在7～8月,夏季临安、龙风山和上甸子站CO2平均体积...     

谱系聚类法在小区域粮食安全预测中的应用——以昆山市为例

粮食安全对国民经济的可持续发展起着不可替代的基础性作用,小区域由于受政策因素的影响较大,粮食安全相关指标的变化呈一定阶段性,长时间序列的数学规律并不突出,不利于规划工作的展开。论文基于昆山市的研究,提出谱系聚类与数学模型相结合的基本思路,在此基础上推出了聚类结果有效性的量化判定标准并对聚类法运用准则做了深入的探讨。实际数据分析结果表明:昆山的粮食安全相关的社会经济指标变化确实呈明显阶段性;与利用全部时间序列数据建立的模型相比,运用谱系聚类的模型拟合和预测效果都有明显优势;至2015年,昆山市粮食自给率将下降至6%,最小人均耕地面积降低至0.022 hm²。通过进一步的分析、对比及讨论,文章认为,谱系聚类法运用于小区域粮食安全预测,方法可操作性强,结论科学性显著。     

粗粒子气溶胶远距离输送造成华南严重空气污染的分析

2009年4月末,发生了一次罕见的粗粒子气溶胶远距离输送造成华南地区出现严重的空气污染事件,其特征主要是气溶胶质量浓度超标,而能见度没有明显恶化,对这次空气污染事件进行分析的结果表明.在过程中,粗细粒子质量比(PM2.5/PM10)有明显的3次下降,最低达到0.3,即PM2.5仅占PM10的30%,这与珠江三角洲地区通常以细粒子为主的污染特征有很大不同,反映了外来粗粒子的侵入特征.长江流域浮尘天气的沙尘粒子变性后,长距离输送污染物叠加本地污染物,造成这次严重空气污染事件.     

聚硅酸对不同形态铝沉积行为的影响

针对给水管网中残余铝沉积和再溶解现象可能引起的水质问题,研究了聚硅酸对不同水解聚合形态铝沉积、再溶解的影响,并以石英微晶天平为表征手段,初步探讨了聚硅酸对不同形态铝沉积、再溶解过程影响的机理.结果表明,聚硅酸能显著改变不同水解聚合形态铝的沉积、再溶解行为.聚硅酸可与3种水解聚合形态的铝迅速结合而生成可沉积产物,但产物性质不同.以单体形态为主的Al_0与聚硅酸的反应产物性质较稳定,部分以溶解态存在,部分以非溶解态(可沉积态)存在;尽管铝的两种聚合形态Al_(13)和Al_(30)与聚硅酸反应也生成了部分可沉积产物,但随着时间的推移,这些产物又逐渐向溶解态转化.铝硅比对Al_0体系中铝的沉积溶解行为影响较小,而对Al_(13)和Al_(30)影响较大,且在0.2∶20(以Al和SiO_2计的质量比)时,沉积态铝的溶解速率最快.     

模拟水体硝态氮对黄菖蒲生长及其氮吸收的影响

为了对挺水植物在水环境与水生态修复中的应用提供参考依据,选取黄菖蒲(Iris pseudacorus L.)为对象,通过模拟水培实验,对比研究了6种水体硝态氮质量浓度(10.68、23.88、42.22、63.33、82.92、97.13 mg·L~(-1))下,黄菖蒲地上和地下生物量、根冠比、叶绿素含量、氮累计吸收量以及对硝态氮去除效果的差异,以期明确模拟水体硝态氮质量浓度对黄菖蒲生长及其氮吸收能力的影响.结果显示,首先,不同硝态氮质量浓度对黄菖蒲地上部分(茎叶)生长的影响大于地下部分(根);当硝态氮质量浓度为10.68 mg·L~(-1)时,黄菖蒲的根冠比增加;当硝态氮质量浓度为42.22~97.13 mg·L~(-1)时,黄菖蒲的根冠比减少.其次,黄菖蒲适宜生长的硝态氮质量浓度为23.88~63.33 mg·L~(-1);硝态氮质量浓度低于10.68 mg·L-1或高于82.92mg·L-1时,均会对黄菖蒲的叶绿素合成产生抑制作用.再次,黄菖蒲对氮的累积量随硝态氮质量浓度增加而增加,且地下部分对氮的累积能力优于地上部分;6种浓度下,单株黄菖蒲的氮累计吸收量为10.56~75.43 mg,其地下部分依次为地上部分的7.2、2.3、2.5、2.1、1.6以及1.5倍.此外,黄菖蒲对氮的利用效率与硝态氮质量浓度之间成显著的幂函数关系,且地上部分的氮利用效率高于地下部分.最后,黄菖蒲对硝态氮的去除率随硝态氮质量浓度增加而增加,6种浓度下黄菖蒲对硝态氮的去除率介于94.9%和99.3%之间,且水体中硝态氮质量浓度随时间延续呈指数函数降低.结果表明,黄菖蒲对硝态氮有很好的去除效果,但黄菖蒲的生长及其对氮的吸收与去除效率受水体硝态氮质量浓度影响显著,且地上部分较地下部分更为敏感.     

Fenton试剂氧化法处理印染废水实验研究

通过将Fenton法应用于印染废水的处理,研究pH值、温度、反应时间、Fe2+投加量以及H2O2投加量对Fenton试剂处理印染废水的影响,同时确定Fenton法处理印染废水的最适反应条件。实验结果表明:(1)最适反应条件,即pH值、温度、反应时间、Fe2+投加量、H2O2投加量分别为3,50℃,45 min,70 mg/L,2.5 mL/L,此时COD的去除率最高,为66.60%。(2)pH值为3时,下列因素对COD的去除率影响程度大小依次为H2O2投加量Fe2+投加量反应时间反应温度。