饮用水中异嗅物质-土臭素及二甲基异冰片的测定方法

导致饮用水土霉味的常见物质为土臭素(GSM)和二甲基异冰片(2-MIB),此两种物质通常在原水及饮用水中痕量存在,浓度低于几百ng/L.总结了用感官分析法和仪器分析法测定痕量GSM和2-MIB.对液液萃取、固相萃取、固相微萃取及各种衍生水样预处理方法进行了对比,评价了各种方法的优劣,并对异嗅物质分析方法的发展提出了展望.     

Uranium series radionuclides in surface waters from the Shu river (Kazakhstan)

The concentrations of (238)U, (234)U, (226)Ra, (210)Po and (210)Pb have been determined in surface waters collected along the course of the Shu River, lying on the border between Kazakhstan and Kyrgyzstan. In the study area, the river runs through some of the largest uranium deposits worldwide, which were actively exploited during the nuclear weapons and nuclear energy programmes of the former Soviet Union. The data show an increasing trend in uranium concentrations downstream the river from the city of Tokmak to the city of Shu, with good correlation between total uranium concentrations and total dissolved solids. Data on uranium isotopes disequilibrium show the presence of technogenic uranium inputs into the Shu River downstream from the city of Karasu, evidenced by a decrease in the measured (234)U/(238)U isotopic ratio from 1.63 in uncontaminated sites to 1.29 in sites affected by past mining activities.     

Mathematical Modeling and Numerical Algorithms for Simulation of Oil Pollution

This paper deals with the mathematical modeling and algorithms for the problem of oil pollution. For solving this task, we derive the adjoint problem for the advection–diffusion equation describing the propagation of oil slick after an accident, which we call the main problem. We prove a fundamental equality between the solutions of the main and the adjoint problems. Based on this equality, we propose a novel method for the identification of the pollution source location and the accident time of oil emission. This approach is illustrated on an example for an accident in the offshore of the central part of the Vietnamese coast. Numerical simulations demonstrate the effectiveness of the proposed method. Besides, the method is verified for 1D model of substance propagation.     

微生物对冰封期湖泊沉积物中有机磷降解释放的影响

以寒旱区湖泊乌梁素海为研究对象,以有机磷降解过程中的形态转化为主线,探讨了冰封期内底物添加与灭菌处理对有机磷释放特征的影响.结果表明,180 d冰封期内,灭菌处理(T_N)上覆水中可溶性总磷酸盐(DTP)和可溶性正磷酸盐(DIP)及可溶性有机磷(DOP)的质量浓度均高于底物添加处理(T_M),揭示T_M体系中厌氧微生物的同化利用降低了上覆水中磷的质量浓度;同时微生物驱动下铁的异化还原作用也是影响水-沉积物界面有机磷释放的重要机制.释放周期内,沉积物中活性有机磷(LOP)、总活性磷(TLP)的含量均减少;T_M体系的中等活性有机磷(MLOP)含量先减少后增加,非活性有机磷(NLOP)的含量先增加后减少;T_N的MLOP含量波动性增加,NLOP的含量波动性减少.释放初期(0~60 d),T_M的MLOP含量高于T_N,而NLOP的含量低于T_N;释放中末期(60~180 d),T_M的MLOP含量低于T_N,而NLOP的含量高于T_N.揭示释放中沉积物MLOP与NLOP之间存在相互转化的可能性.释放过程中,T_M沉积物有机磷的相对含量降低,无机磷的相对含量增高,呈现有机磷向无机磷转化的趋势,沉积物有机磷约有6.1%转化为无机磷,揭示了冰封期内,微生物可加速沉积物有机磷向无机磷的转化,提高了磷的生物可利用率,增加了沉积物磷向上覆水释放的风险.     

Irrigation water quality and the benefits of implementing good agricultural practices during tomato (Lycopersicum esculentum) production

The implementation of good agricultural practices (GAP) from irrigation water to the tomato packaging process enhances the safety of fresh produce and its value throughout the food chain. The aim of the present study was to show that fresh produce farms that apply and enforce GAP could reduce the presence of Salmonella in finished produce. Samples were collected biweekly from six packing houses from the central region of Sinaloa, México, for the isolation of Salmonella spp by the ISO 6579:2002 method, and the isolated strains were serotyped and genotyped by the Kauffmman-White scheme and pulsed field gel electrophoresis (PFGE), respectively. Salmonella strains were detected in 13 (36.1 %) irrigation water samples, while only two tomato samples were positive (5.5 %). Eight different serotypes were identified in irrigation water, and Salmonella Oranienburg (34 %) was the most prevalent; however, only Salmonella Agona and Salmonella Weltevreden were present on tomatoes. Salmonella Oranienburg was the most widely dispersed and variable serotype, with 10 different PFGE profiles. Salmonella Weltevreden was isolated from both types of samples, albeit with distinct genetic profiles, implying that the sources of contamination differ. These results confirm the utility of implementing good agricultural practices to reduce Salmonella contamination in irrigation water and the packaging process.     

Calculating of river water quality sampling frequency by the analytic hierarchy process (AHP)

River water quality sampling frequency is an important aspect of the river water quality monitoring network. A suitable sampling frequency for each station as well as for the whole network will provide a measure of the real water quality status for the water quality managers as well as the decision makers. The analytic hierarchy process (AHP) is an effective method for decision analysis and calculation of weighting factors based on multiple criteria to solve complicated problems. This study introduces a new procedure to design river water quality sampling frequency by applying the AHP. We introduce and combine weighting factors of variables with the relative weights of stations to select the sampling frequency for each station, monthly and yearly. The new procedure was applied for Jingmei and Xindian rivers, Taipei, Taiwan. The results showed that sampling frequency should be increased at high weighted stations while decreased at low weighted stations. In addition, a detailed monitoring plan for each station and each month could be scheduled from the output results. Finally, the study showed that the AHP is a suitable method to design a system for sampling frequency as it could combine multiple weights and multiple levels for stations and variables to calculate a final weight for stations, variables, and months.     

Water Conservation Versus Soil Salinity Control

This paper tackles the increasingly significant problem of irrigation-induced soil salinity within a groundwater management model. Irrigation can result not only in heavier salt concentrations but also in the removal of salt from the soil through return flows. Given these contradictory observations, we are interested in the effects on soil salt concentration if irrigation efficiency is improved. We develop a model of salt concentration patterns in both soil and groundwater. We introduce a negative externality to the production process by assuming that soil degradation due to higher soil salinity affects total factor productivity. Within this framework, we show that in the presence of this externality, increasing irrigation efficiency can lead to higher or lower soil salt concentration, depending on the social cost of transferring salt from one reservoir to another.