An analysis of wet deposition of sulfate using a trajectory model for East Asia

A long-range transport model for East Asia was developed to estimate the wet deposition of sulfate. The model is a trajectory type which is appropriate for long-term analysis. Trajectories of air masses are calculated by tracing the wind field which changes spatially and temporally. The processes of reactions, rainout removal, intake of sulfate in cloud water into rain water, and dry and wet depositions are considered. It is possible to calculate the concentration of sulfate in precipitation at a receptor by performing material balance in a grid box containing the receptor.The results obtained by the long-range transport model were evaluated through comparison with observation data of acidic deposition. The observation was conducted at 21 stations throughout Japan for one year. The calculated amount of wet deposition of sulfate in Japan was 0.22Tg/y in S equivalent, while the observed amount was 0.29Tg/y. The long-range transport model can predict almost 80% of observed wet deposition. The contributions of domestic anthropogenic sources and volcanic eruption to wet deposition of sulfate in Japan were estimated using the longrange transport model. The ratio of the deposition of sulfate due to Japanese anthropogenic sources to that due to the Asian continental sources was about 1 to 2. Since air stream from the direction of the Asian continent dominates during winter, the contribution of Japan to wet deposition in the region which faces the Sea of Japan amounted to less than 15%. The contribution of the sulfur oxides from volcanoes was about 20%.     

Carbon dynamics determined by natural C abundance in microcosm experiments with soils from long-term maize and rye monocultures

Understanding carbon dynamics in soil is the key to managing soil organic matter. Our objective was to quantify the carbon dynamics in microcosm experiments with soils from long-term rye and maize monocultures using natural ¹³C abundance. Microcosms with undisturbed soil columns from the surface soil (0-25 cm) and subsoil (25-50 cm) of plots cultivated with rye (C₃-plant) since 1878 and maize (C₄-plant) since 1961 with and without NPK fertilization from the long-term experiment ‘Ewiger Roggen’ in Halle, Germany, were incubated for 230 days at 8 °C and irrigated with 2 mm 10⁻² M CaCl₂ per day. Younger, C₄-derived and older, C₃-derived percentages of soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass (C_mic) and CO₂ from heterothropic respiration were determined by natural ¹³C abundance. The percentage of maize-derived carbon was highest in CO₂ (42-79%), followed by C_mic (23-46%), DOC (5-30%) and SOC (5-14%) in the surface soils and subsoils of the maize plots. The percentage of maize-derived C was higher for the NPK plot than for the unfertilized plot and higher for the surface soils than for the subsoils. Specific production rates of DOC, CO₂-C and C_mic from the maize-derived SOC were 0.06-0.08% for DOC, 1.6-2.6% for CO₂-C and 1.9-2.7% for C_mic, respectively, and specific production rates from rye-derived SOC of the continuous maize plot were 0.03-0.05% for DOC, 0.1-0.2% for CO₂-C and 0.3-0.5% for C_mic. NPK fertilization did not affect the specific production rates. Strong correlations were found between C₄-derived C_mic and C₄-derived SOC, DOC and CO₂-C (r≥0.90), whereas the relationship between C₃-derived C_mic and C₃-derived SOC, DOC and CO₂-C was not as pronounced (r≤0.67). The results stress the different importance of former (older than 40 years) and recent (younger than 40 years) litter C inputs for the formation of different C pools in the soil.     

Laboratory study of SO2 dry deposition on limestone and marble: Effects of humidity and surface variables

The dry deposition of gaseous air pollutants on stone and other materials is influenced by atmospheric processes and the chemical characteristics of the deposited gas species and of the specific receptor material. Previous studies have shown that relative humidity, surface moisture, and acid buffering capability of the receptor surface are very important factors. To better quantify this behavior, a special recirculating wind tunnel/environmental chamber was constructed, in which wind speed, turbulence, air temperature, relative humidity, and concentrations of several pollutants (SO₂, O₃, nitrogen oxides) can be held constant. An airfoil sample holder holds up to eight stone samples (3.8 cm in diameter and 1 cm thick) in nearly identical exposure conditions. SO₂ deposition on limestone was found to increase exponentially with increasing relative humidity (RH). Marble behaves similarly, but with a much lower deposition rate. Trends indicate there is little deposition below 20% RH on clean limestone and below 60% RH on clean marble. This large difference is due to the limestone's greater porosity, surface roughness, and effective surface area. These results indicate surface variables generally limit SO₂ deposition below about 70% RH on limestone and below at least 95% RH on marble. Aerodynamic variables generally limit deposition at higher relative humidity or when the surface is wet.     

高密度二氧化碳对蛋清液中沙门氏菌和大肠杆菌杀菌效果和杀菌动力学的研究

研究了不同温度、压力和时间条件下,高密度二氧化碳(DPCD)处理对蛋清液中沙门氏菌和大肠杆菌的杀菌效果,并对DPCD处理蛋清液中大肠杆菌的杀菌动力学进行了分析。结果表明,在15 MPa,45℃下DPCD处理60 min,沙门氏菌和大肠杆菌分别降低了4.46和5.57个对数值,其中大肠杆菌对DPCD处理较沙门氏菌敏感。30 MPa,45℃,DPCD处理30 min,可以完全杀灭蛋清液中的大肠杆菌。线性模型能较好地拟合DPCD对大肠杆菌的杀菌效果,其中30 MPa,45℃下D值最小为5.830。     

湿米粉中吊白块含量的测定

利用甲醛与乙酰丙酮及铵离子反应,将生成的黄色物质与标准系列比较,定量测定甲醛含量,并用碘标准溶液滴定二氧化硫含量,从而对湿米粉中吊白块含量进行检测,效果良好。     

表面活性剂与纳米SiO2作用下聚合铝的絮凝特性

在6NTU高岭土原水中,溶入低浓度溶解性有机物-阴离子表面活性剂(十二烷基硫酸钠,SDS),投加聚合铝PAC与新型水处理剂-纳米SiO2稳定分散液进行动态混凝实验与静止沉降实验.借助图像分析技术与分形理论,对SDS与纳米SiO2作用下PAC的絮凝特性与絮体分形结构的形态学特征进行研究.结果表明:存在SDS时,高岭土颗粒表面ζ电位增加.SDS在颗粒表面的吸附等温曲线符合Langmiur方程;PAC对无机颗粒的去除效果明显,但对SDS的表观去除率较低.SDS阻碍絮凝初絮体的形成.纳米SiO2使颗粒表面ζ电位增加,对无机颗粒处理效果较差,但对去除有机物有利.絮凝机理主要是吸附架桥;助凝剂纳米SiO2能促进PAC对无机颗粒与SDS絮凝,处理效果显著.悬浊液中絮体粒径大,有效质量密度增加,沉速加快,分维值下降.     

SO2对采后葡萄的急性伤害研究

以 7个葡萄品种为试材 ,研究了常温下 SO2 对不同品种葡萄的急性伤害。结果表明 ,SO2 对不同品种葡萄的急性伤害阈值大小依次为红宝石 <红地球 <马奶 <秋黑 <巨峰 <玫瑰香 <龙眼 ;SO2 的熏蒸浓度、熏蒸时间与漂白指数呈极显著复相关 ,SO2 熏蒸浓度是影响急性伤害的最主要因素 ;果梗和果皮可能是 SO2进入果实内部的两大主要通道     

混合表面活性剂分散纳米CeO2颗粒的协同效应

选用CTAB阳离子型和SDBS阴离子型分别与Tween80非离子型表面活性剂进行复配，通过Zeta电位、吸附等温线以及沉降性能测定，研究了混合表面活性剂对水相介质中纳米CeO2颗粒分散稳定性能影响的协同效应。结果表明：不同混合表面活性剂体系中纳米CeO2颗粒表现出不同的表面电性，从而影响其分散稳定行为；纳米CeO2颗粒对两种混合表面活性剂均有良好的吸附性能，但其吸附等温线形式有所不同；碱性条件下，混合表面活性剂能显著改善纳米CeO2颗粒的分散稳定性，其中SDBS与Tween 80的协同作用更为明显。     

木质纤维素稀酸糖化研究初探

木质纤维素的分解利用对于解决未来的能源危机与环境问题具有重大意义。以脱脂棉、滤纸模拟生物质的主要组分之一纤维素，在不同稀硫酸浓度、时间和温度反应参数下，进行纤维素水解糖化试验研究，以还原糖量为指标，考察纤维素糖化最佳反应条件。研究结果表明，在加热时间为60min时，还原糖得率随硫酸浓度的增加而增加；在加热时间为80min时，还原糖得率在硫酸浓度4％处出现最大值。综合硫酸及废液处理成本考虑，得到实验最佳条件为4％硫酸加热80min。     

纳米二氧化硅对脲醛树脂胶性能的影响

研究了纳米SiO2对低摩尔比脲醛树脂游离甲醛含量、粘度、固化时间、羟甲基含量及胶合强度的影响,结果表明:纳米SiO2的加入可降低脲醛树脂胶的游离醛含量,增大粘度,提高胶合板的胶合强度,使羟甲基含量略有降低,但对固化速度影响不大