采用在线SPE技术的UPLC,用于分析饮用水中的农药和药物

水中的目标污染物通常为痕量水平(低于ppb级).为了使分析物的最终浓度在所选检测器(如UV,EISD,MS)的可检测范围内,必须进行预富集处理.富集因子通过原始样品体积和最终萃取体积进行计算.例如,将原始样品体积500 ml浓缩至最终体积1 ml,则为500:1的富集.通常的方法是将较大的初始体积(如1L)浓缩为尽可能低的最终体积(如500μl).这样的方法需要进行大量的手动操作,涉及加载、蒸发和重构等步骤,有时会花上好几个小时.采用在线SPE技术的UPLC用于此类分析时具有诸多优点:无需繁琐的蒸发和重构步骤;可管理多种方法,无需操作员干预;可以管理需要不同条件的方法;可以降低所需的样品体积;最大限度地降低了样品的转移和处理.     

Disparity of a Seat Cushion and Its Influence on Postural Control

Properties of supporting surfaces of a seat have an influence on postural control. Centre of pressure (COP) displacement parameters reflect both the balance controlling process and movements of the centre of a mass of entire body. The subjects of the study were 9 healthy men. A seat cushion was examined with a 2-force platform setup. Force exertion at a seat pan and feet and COP displacement at a seat pan were measured to analyse postural control. Analysis of variance determined the differences in postural control depending on a cushion type among the subjects. Significant differences in COP displacement parameters were in COP trajectory length, medio-lateral COP displacement and COP velocity. The results of the study showed that foam cushion ensures better postural control.     

The effect of nutrients shortage on plant’s efficiency to capture solar radiations under semi-arid environments

Radiation use efficiency (RUE) is considered critical for calculation of crop yield. The crop productivity can be improved by increasing the interception of solar radiation and maintaining higher RUE for plants. Irrigation water and nitrogen (N) supply are the main limiting factors for RUE in maize (Zea mays L.) across the semi-arid environments. Field experiments were conducted during two consecutive growing seasons (2009–2010) to optimize RUE in relation to N application timings and rates with varying irrigation water management practices. In experiment 1, three N application timings were made, while in experiment 2, three possible water management practices were used. In both experiments, five N rates (100, 150, 200, 250, and 300 kg N ha⁻¹) were applied to evaluate the effects of irrigation water and N on cumulative photosynthetic active radiation (PARi), dry matter RUE (RUE_DM), and grain yield RUE (RUE_GY). The results demonstrated that cumulative PARi and RUEs were not constant during the plant growth under varying the nutrients. The water and N significantly influenced cumulative PARi and RUEs during the both growing seasons. In experiment 1, the maximum cumulative PARi was observed by application of 250 kg N ha⁻¹ in three splits (1/3 N at V2, 1/3 N at V16, and 1/3 N at R1 stage), and the highest RUE_DM was achieved by the application of 300 kg N ha⁻¹. However, the highest RUE_GY was observed by application of 250 kg N ha⁻¹. In experiment 2, the maximum cumulative PARi was attained at normal irrigation regime with 250 kg N ha⁻¹, while the highest RUE_DM and RUE_GY were recorded at normal irrigation regime with the application of 300 kg N ha⁻¹. The regression analysis showed significant and positive correlation of RUE_GY with grain yield. Therefore, optimum water and N doses are important for attaining higher RUE, which may enhance maize grain yield semi-arid environment; this may be considered in formulating good agricultural practices for the environmental conditions resembling to those of this study.

     

Environment polluting conventional chemical control compared to an environmentally friendly IPM approach for control of diamondback moth, <Emphasis Type="Italic">Plutella xylostella</Emphasis> (L.), in China: a review

The diamondback moth, Plutella xylostella, is recognized as a widely distributed destructive insect pest of Brassica worldwide. The management of this pest is a serious issue, and an estimated annual cost of its management has reached approximately US$4 billion. Despite the fact that chemicals are a serious threat to the environment, lots of chemicals are applied for controlling various insect pests especially P. xylostella. An overreliance on chemical control has not only led to the evolution of resistance to insecticides and to a reduction of natural enemies but also has polluted various components of water, air, and soil ecosystem. In the present scenario, there is a need to implement an environmentally friendly integrated pest management (IPM) approach with new management tactics (microbial control, biological control, cultural control, mating disruption, insecticide rotation strategies, and plant resistance) for an alternative to chemical control. The IPM approach is not only economically beneficial but also reduces the environmental and health risks. The present review synthesizes published information on the insecticide resistance against P. xylostella and emphasizes on adopting an alternative environmentally friendly IPM approach for controlling P. xylostella in China.     

Nitrogen fertility and abiotic stresses management in cotton crop: a review

This review outlines nitrogen (N) responses in crop production and potential management decisions to ameliorate abiotic stresses for better crop production. N is a primary constituent of the nucleotides and proteins that are essential for life. Production and application of N fertilizers consume huge amounts of energy, and excess is detrimental to the environment. Therefore, increasing plant N use efficiency (NUE) is important for the development of sustainable agriculture. NUE has a key role in crop yield and can be enhanced by controlling loss of fertilizers by application of humic acid and natural polymers (hydrogels), having high water-holding capacity which can improve plant performance under field conditions. Abiotic stresses such as waterlogging, drought, heat, and salinity are the major limitations for successful crop production. Therefore, integrated management approaches such as addition of aminoethoxyvinylglycine (AVG), the film antitranspirant (di-1-p-menthene and pinolene) nutrients, hydrogels, and phytohormones may provide novel approaches to improve plant tolerance against abiotic stress-induced damage. Moreover, for plant breeders and molecular biologists, it is a challenge to develop cotton cultivars that can tolerate plant abiotic stresses while having high potential NUE for the future.     

Phyto-management of Cr-contaminated soils by sunflower hybrids: physiological and biochemical response and metal extractability under Cr stress

Environmental Science and Pollution Research - Chromium (Cr) is a biologically non-essential, carcinogenic and toxic heavy metal. The cultivation of Cr-tolerant genotypes seems the most favorable...     

Development and evaluation of a continuous coarse (PM10-PM2.5) particle monitor

In this paper, we describe the development and laboratory and field evaluation of a continuous coarse (2.5-10 microm) particle mass (PM) monitor that can provide reliable measurements of the coarse mass (CM) concentrations in time intervals as short as 5-10 min. The operating principle of the monitor is based on enriching CM concentrations by a factor of approximately 25 by means of a 2.5-microm cut point round nozzle virtual impactor while maintaining fine mass (FM)--that is, the mass of PM2.5 at ambient concentrations. The aerosol mixture is subsequently drawn through a standard tapered element oscillating microbalance (TEOM), the response of which is dominated by the contributions of the CM, due to concentration enrichment. Findings from the field study ascertain that a TEOM coupled with a PM10 inlet followed by a 2.5-microm cut point round nozzle virtual impactor can be used successfully for continuous CM concentration measurements. The average concentration-enriched CM concentrations measured by the TEOM were 26-27 times higher than those measured by the time-integrated PM10 samplers [the micro-orifice uniform deposit impactor (MOUDI) and the Partisol] and were highly correlated. CM concentrations measured by the concentration-enriched TEOM were independent of the ambient FM-to-CM concentration ratio, due to the decrease in ambient coarse particle mass median diameter with an increasing FM-to-CM concentration ratio. Finally, our results illustrate one of the main problems associated with the use of real impactors to sample particles at relative humidity (RH) values less than 40%. While PM10 concentrations obtained by means of the MOUDI and Partisol were in excellent agreement, CM concentrations measured by the MOUDI were low by 20%, and FM concentrations were high by a factor of 5, together suggesting particle bounce at low RH.     

Assessing the perceived impact of exploration and production of hydrocarbons on households perspective of environmental regulation in Ghana

This paper seeks to critically study the perceived impacts of the exploration of hydrocarbons in selected coastal communities in the Western region, the oil and gas industry benefits to local communities, and to determine whether hydrocarbon development is a means for sustainable development. The study uses both quantitative and qualitative approaches using a questionnaire survey, key informant interview, and focus group discussion tools to understand the impact of oil and gas exploration and production in selected affected communities along the coast of Ghana. The activities of oil production and exploration impact negatively on communities; it also leads to a sharp increase in food prices thereby increasing their costs of living. The activity has also caused a decline in fish catch levels which happens to be the main economic activity as a result of exclusion zones created by oil companies which limited the extent fishermen can go fishing. In terms of infrastructure, the three communities are lacking, 77% of respondents from Princess Town hold the view that there is no motorable road linking their community in the next town and 60% from Aketakyi also hold the same view. Infrastructure such as roads, schools, water provision, and clinics are woefully provided in these communities.

     

Determinants of CO2 emissions: exploring the unexplored in low-income countries

Environmental Science and Pollution Research - In thirst for economic growth, economies are engaged in anti-environmental activities that drive them towards climate change and CO2 emissions....     

Aerobic sludge digestion under low dissolved oxygen concentrations.

Low dissolved oxygen (DO) concentrations occur commonly in aerobic digesters treating thickened sludge, with benefits of smaller digester size, much reduced aeration cost, and higher digestion temperature (especially important for plants in colder areas). The effects of low DO concentrations on digestion kinetics were studied using the sludge from municipal wastewater treatment plants in Akron, Ohio, and Los Lunas, New Mexico. The experiments were conducted in both batch digestion and a mixed mode of continuous, fed-batch, and batch operations. The low DO condition was clearly advantageous in eliminating the need for pH control because of the simultaneous occurrence of nitrification and denitrification. However, when compared with fully aerobic (high DO) systems under constant pH control (rare in full-scale plants), low DO concentrations and a higher solids loading had a negative effect on the specific volatile solids (VS) digestion kinetics. Nonetheless, the overall (volumetric) digestion performance depends not only on the specific digestion kinetics, but also the solids concentration, pH, and digester temperature. All of the latter factors favor the low DO digestion of thickened sludge. The significant effect of temperature on low DO digestion was confirmed in the mixed-mode study with the Akron sludge. When compared with the well-known empirical correlation between VS reduction and the product (temperature x solids retention time), the experimental data followed the same trend, but were lower than the correlation predictions. The latter was attributed to the lower digestible VS in the Akron sludge, the slower digestion at low DO concentrations, or both. Through model simulation, the first-order decay constant (kd) was estimated as 0.004 h(-1) in the mixed-mode operations, much lower than those (0.011 to 0.029 h(-1)) obtained in batch digestion. The findings suggested that the interactions among sludges with different treatment ages may have a substantially negative effect on digestion kinetics. The use of multistage digesters, especially with small front-end reactors, may be advantageous in both "process" kinetics and "biological reaction" kinetics for sludge digestion.