Influence of metal ions on sulfonamide antibiotics biochemical behavior in fiber coexisting system

Metal ions and fiber are common compounds in the livestock and poultry manure,which will affect the fate of organic compounds in aqueous environment. However,limited research has addressed the effect of coexisting metal ions and fiber on the biodegradation of sulfonamide antibiotics. Accordingly, a compositing study was performed to assess the effect of metal ions(Fe3+and Cu2+) on the biodegradation of sulfadimethoxine sodium salt(SDM) in the presence of fiber. The enhanced adsorption of SDM onto fiber in the presence of metal ions can be attributed to the π+–π electron donor acceptor(EDA) interaction. The microbial(Phanerochaete chrysosprium) could easily attach onto fiber forming attached microbial, and the degradation rates of SDM of immobilized bacteria in the presence of Fe3 +were 100%, which were significantly higher than those of free bacteria(45%). This study indicates that Fe3 +and fiber could enhance the biodegradation of SDM. Fiber acts as adsorbent, carrier, and substrate which enhanced the removal of SDM.     

Chemical characterization and source apportionment of atmospheric submicron particles on the western coast of Taiwan Strait, China

Taiwan Strait is a special channel for subtropical East Asian Monsoon and its western coast is an important economic zone in China. In this study, a suburban site in the city of Xiamen on the western coast of Taiwan Strait was selected for fine aerosol study to improve the understanding of air pollution sources in this region. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer(HR-To F-AMS) and an Aethalometer were deployed to measure fine aerosol composition with a time resolution of 5 min from May 1to 18, 2015. The average mass concentration of PM1 was 46.2 ± 26.3 μg/m~3 for the entire campaign. Organics(28.3%), sulfate(24.9%), and nitrate(20.6%) were the major components in the fine particles, followed by ammonium, black carbon(BC), and chloride. Evolution of nitrate concentration and size distribution indicated that local NOx emissions played a key role in high fine particle pollution in Xiamen. In addition, organic nitrate was found to account for 9.0%–13.8% of the total measured nitrate. Positive Matrix Factorization(PMF)conducted with high-resolution organic mass spectra dataset differentiated the organic aerosol into three components, including a hydrocarbon-like organic aerosol(HOA) and two oxygenated organic aerosols(SV-OOA and LV-OOA), which on average accounted for 27.6%,28.8%, and 43.6% of the total organic mass, respectively. The relationship between the mass concentration of submicron particle species and wind further confirmed that all major fine particle species were influenced by both strong local emissions in the southeastern area of Xiamen and regional transport through the Taiwan Strait.     

珠三角空气质量数值预报系统的检验与订正研究

通过对珠三角空气质量预报模式的模拟结果进行检验,发现模式预报值整体偏小,特别是峰值,但变化趋势与实测一致,峰值都能较好模拟出.模式对PM10的预报准确率要高于PM2.5,从等级预报来看PM10和PM2.5的二级预报准确率要高于一级,利用MOS方法对模式预报结果进行订正,订正后颗粒物平均偏差都有一定程度的下降,颗粒物等级预报准确率PM10由64.7%提高到77.6%,PM2.5由59.9%提高至74.5%,准确率的提高明显.     

Bayesian approach to estimating margin of safety for total maximum daily load development

A Bayesian-updating approach is presented to the estimation of total uncertainty-based Margin of Safety (MOS) for Total Maximum Daily Load (TMDL) calculations. Probability distributions are presented to construct the likelihood function, the prior probability distribution, and the posterior (total uncertainty) probability distribution. The Bayesian-updating approach is demonstrated through a case study for the Lower Amite River, Louisiana. The posterior probability distribution-based on the Bayesian approach updates the standard deviation of summer dissolved oxygen in the Amite River from 1.88 mg/L to 2.10 mg/L when the total uncertainty is considered. Results from the Bayesian-updating approach are compared with two conventional methods. The dissolved oxygen reserve based on a conventional margin of safety of 20% is estimated to be 45,682.26 kg/Day. The second conventional method, where we consider the standard deviation of 1.88 mg/L, produces a dissolved oxygen reserve of 40,516.09 kg/Day. The Bayesian approach yields the dissolved oxygen reserve of 38,614.43 kg/Day with the first level (μ-σ) of MOS, producing a deficit of 5606.65 kg/Day in dissolved oxygen. The dissolved oxygen reserve deficit increases to 23,895.13 kg/Day when the second level (μ-2σ) of MOS is used, which escalated to 42,383.52 kg/Day when the highest level (μ-3σ) of MOS is used. While the total uncertainty-based Bayesian approach is demonstrated for a TMDL development on the Amite River, the overall approach could be applied in any river system with similar available data.     

Responses of Soil CO<Subscript>2</Subscript> Efflux to Precipitation Pulses in Two Subtropical Forests in Southern China

This study was designed to examine the responses of soil CO₂ efflux to precipitation pulses of varying intensities using precipitation simulations in two subtropical forests [i.e., mixed and broadleaf forests (MF and BF)] in southern China. The artificial precipitation event was achieved by spraying a known amount of water evenly in a plot (50 × 50 cm²) over a 30 min period, with intensities ranging from 10, 20, 50 and 100 mm within the 30 min. The various intensities were simulated in both dry season (in December 2007) and wet (in May 2008) season. We characterized the dynamic patterns of soil CO₂ efflux rate and environmental factors over the 5 h experimental period. Results showed that both soil moisture and soil CO₂ efflux rate increased to peak values for most of the simulated precipitation treatments, and gradually returned to the pre-irrigation levels after irrigation in two forests. The maximum peak of soil CO₂ efflux rate occurred at the 10 mm precipitation event in the dry season in BF and was about 3.5 times that of the pre-irrigation value. The change in cumulative soil CO₂ efflux following precipitation pulses ranged from −0.68 to 1.72 g CO₂ m⁻² over 5 h compared to the pre-irrigation levels and was generally larger in the dry season than in the wet season. The positive responses of soil CO₂ efflux to precipitation pulses declined with the increases in precipitation intensity, and surprisingly turned to negative when precipitation intensity reached 50 and 100 mm in the wet season. These findings indicated that soil CO₂ efflux could be changed via pulse-like fluxes in subtropical forests in southern China as fewer but extreme precipitation events occur in the future.     

Analysis of the trade-off between economic growth and the reduction of nitrogen and phosphorus emissions in the Poyang Lake Watershed, China

Lake eutrophication leading to water pollution is a major global concern. In recent years, rapid economic growth and the increase in the intensity of resource exploitation in China have caused the influx of nitrogen and phosphorus into lakes. This in turn has led to more severe lake eutrophication, more frequent outbreaks of algal blooms, and the degradation of lake ecosystems. An effective plan balancing economic growth with the reduction of nitrogen and phosphorus emissions is greatly needed. The design and implementation of such a plan requires the collection and analysis of pertinent data. In this paper, we use the environmental computable general equilibrium (ECGE) model to identify the most effective way to balance economic growth with the reduction of nitrogen and phosphorus emissions. For the multiregional analysis, we use social accounting matrices (SAMs) and a provincial trade matrix based on the assumptions of the gravity model. We consider the Poyang Lake Watershed as a case study to illustrate the utility of the model. Based on present conditions in the Poyang Lake Watershed, restricting nitrogen and phosphorus emissions from sectors with the highest emissions is more effective for balancing economic growth and the reduction of nitrogen and phosphorus emissions than restricting nitrogen and phosphorus emissions from all sectors.     

Microbiological characteristics of multi-media PRB reactor in the bioremediation of groundwater contaminated by petroleum hydrocarbons

A multi-media bio-PRB reactor was designed to treat groundwater contaminated with petroleum hydrocarbons. After a 208-day bioremediation, combined with the total petroleum hydrocarbons content in the groundwater flowed through the reactor, microbiological characteristics of the PRB reactor including microbes immobilized and its dehydrogenase activity were investigated. TPH was significantly reduced by as much as 65% in the back of the second media layer, whereas in the third layer, the TPH content reached lower than 1 mg l?1. For microbes immobilized on the media, the variations with depth in different media were significantly the same and the regularity was obvious in the forepart of the media, which increased with depth at first and then reduced gradually, while in the back-end, the microbes almost did not have any variations with depth but decreased with the distance. The dehydrogenase activity varied from 2.98 to 16.16 mg TF L?1 h?1 and its distribution illustrated a similar trend with numbers of microbial cell, therefore, the noticeable correlation was found between them.     

三种吸附剂对饮用水中铝离子去除率的对比试验

传统的净水过程一般包括混凝—沉淀—过滤消毒工艺流程,主要去除水中的浊度和细菌,大部分有机物、有害的重金属仍残留在水体中。对活化沸石、聚苯乙烯树脂、活性炭3种材料的净水能力进行了研究。由于3种材料对饮用水中有害物质的去除主要以吸附作用为主,所以在水处理方法中主要阐述了吸附法,包括吸附的机理、吸附的类型、吸附的影响因素。在实验部分,以自来水出水中的铝离子为参照物,利用《生活饮用水卫生标准》国家标准检测方法分别测算出3种材料对铝离子的去除率,借此来比较3种吸附材料的吸附特性。     

Sequential impacts of Polynesian and European settlement on vegetation and environmental processes recorded in sediments at Whangapoua Estuary, Great Barrier Island, New Zealand

Whangapoua Estuary, Great Barrier Island, New Zealand, is central to a proposed Marine Reserve, and is currently managed for conservation by the Department of Conservation. This paper describes the sequential impacts of Maori and European people on the process of estuarine vegetation succession in time and space, and the rate of estuarine sedimentation. Multiple cores from one estuary gave confidence in assessing the temporal sequence of vegetation change, but bioturbation and other disturbance factors made it difficult to interpret ¹⁴C dates from the estuarine environment. The modern vegetation zonation pattern on the estuary is an active succession, which has been generated by rapid estuary in-filling, probably initiated as a consequence of erosion following Maori burning of the adjacent forest. European forest clearance for agriculture resulted in a further increase in estuarine sedimentation, and may have re-activated earlier sediments trapped in adjacent swamps. The combined effects of two phases of human exploitation have resulted in large-scale loss of nutrients and top-soil from catchments throughout Great Barrier Island. Conservation management of the estuary should take account of the anthropogenic impacts that have driven the plant succession and created the current vegetation zonation pattern. This pattern is neither static nor ‘natural’, but rather an on-going response to the changing human activities in the surrounding catchment.