Methane emissions during storage of di erent treatments from cattle manure in Tianjin

Many studies on methane emissions from animal manure have revealed that animal manure is a major source of methane emissions to the atmosphere that can have negative consequences for people, animals and environment. In general, the release of methane can be influenced by the type of feed taken by animals, temperature, manure characteristics and so on. This study aimed at quantifying and comparing methane release from dairy manure with di erent piling treatments. Four treatments were designed including manure piling height 30, 45, 60 cm and adding 6 cm manure every day until the piling height was 60 cm. Static chamber method and gas chromatography were adopted to measure the methane emissions from April to June in 2009. Methane emission rates of all four manure treatments were low in the first week and then increased sharply until reaching the peak values. Subsequently, all the methane emission rates decreased and fluctuated within the steady range till the end of the experiment. Wilcoxon nonparametric tests analysis indicated that methane emission rate was greatly influenced by manure piling height and manner. There were no significant relationships between methane emission rates and the temperatures of ambience and heap. However, regression analysis showed that the quadratic equations were found between emission rates of all treatments and the gas temperature in the barrels.     

Characteristics of typical dissolved black carbons and their influence on the formation of disinfection by-products in chlor(am)ination

● The physicochemical and structural properties of DBC were characterized. ● The effects of DBC on DBPs and DBPFP generation during disinfection were evaluated. ● The DBPs and DBPFP generation during chlor(am)ination were compared. Dissolved black carbon (DBC) released from biochar can be one of the potential disinfection by-products (DBPs) precursors in the dissolved organic matter pool. However, the physiochemical and structural properties of DBC and the effects on the development of DBPs and DBP formation potential (DBPFP) during the disinfection process remain unclear. In this study, the characteristics of two kinds of DBC, namely, animal-derived DBC (poultry litter DBC, PL-DBC) and plant-derived DBC (wheat straw DBC, WS-DBC), were investigated. The effects of different kinds of DBC on the evolution of DBPs and DBPFP in chlorine and chloramine disinfection processes were compared with natural organic matter (NOM). The results showed that the total DBPs concentrations derived from PL-DBC, WS-DBC and NOM were similar during chlorination (i.e., 61.23 μg/L, 64.59 μg/L and 64.66 μg/L, respectively) and chloramination (i.e., 44.63 μg/L, 44.42 μg/L and 45.58 μg/L, respectively). The lower total DBPs and DBPFP concentrations in chloramination could be attributed to the fact that the introduction of ammonia in chloramine inhibited the breaking of the bond between the disinfectant and the active group of the precursor. Additionally, DBC presented much lower total DBPFP concentrations than NOM in both chlorination and chloramination. However, both kinds of DBC tended to form more monochloroacetic acids and haloacetamides than NOM, which could result from the higher organic strength, higher protein matter, and nitrogen-rich soluble microbial products of DBC.     

Evaluation of historical CMIP6 model simulations and future projections of temperature over the Pan-Third Pole region

Environmental Science and Pollution Research - The Pan-Third Pole (PTP) region, which encompasses the Eurasian highlands and their surroundings, has experienced unprecedented, accelerated warming...     

Microalgae cultivation and culture medium recycling by a two-stage cultivation system

Nutrients and water play an important role in microalgae cultivation. Using wastewater as a culture medium is a promising alternative to recycle nutrients and water, and for further developing microalgae-based products. In the present study, two species of microalgae, Chlorella sp. (high ammonia nitrogen tolerance) and Spirulina platensis (S. platensis, high growth rate), were cultured by using poultry wastewater through a two-stage cultivation system for algal biomass production. Ultrafiltration (UF) or centrifuge was used to harvest Chlorella sp. from the first cultivation stage and to recycle culture medium for S. platensis growth in the second cultivation stage. Results showed the two-stage cultivation system produced high microalgae biomass including 0.39 g·L^–1Chlorella sp. and 3.45 g·L^–1S. platensis in the first-stage and second-stage, respectively. In addition, the removal efficiencies of NH₄⁺ reached 19% and almost 100% in the first and the second stage, respectively. Total phosphorus (TP) removal reached 17% and 83%, and total organic carbon (TOC) removal reached 55% and 72% in the first and the second stage, respectively. UF and centrifuge can recycle 96.8% and 100% water, respectively. This study provides a new method for the combined of pure microalgae cultivation and wastewater treatment with culture medium recycling.

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中国地表水酸沉降临界负荷的区划

为了解中国地表水体对酸沉降的响应情况,应用基于酸度平衡的稳态法研究中国地表水酸沉降临界负荷区划.结果表明,中国地表水硫沉降临界负荷呈较明显的地带分布.其中,大兴安岭北端水体的硫沉降临界负荷最低,大部分小于2 keq·(hm²·a)^-1,东北北部部分水体和秦岭-淮河以南大部分地区水体的硫沉降临界负荷介于2～10 keq·(hm²·a)^-1之间,其余地区水体硫沉降临界负荷普遍大于10 keq·(hm²·a)^-1.地表水酸度临界负荷的地区分布和数值大小类似于硫沉降临界负荷由于中国地表水酸度临界负荷普遍大于2 keq·(hm²·a)^-1,因此大部分地表水对酸化并不敏感,近期内不易酸化.     

清洁发展机制中的额外性问题探讨

清洁发展机制(CDM)是国际社会应对全球气候变化所作努力的一个重要部分。就清洁发展机制实施中的关键问题之一——额外性问题（additionality)进行了细致的探讨。分析了额外性的基本含义，各个不同国家在这个问题上的观点，各种不同判断准则的合理性和可操作性等。提出了额外性的层次等重要概念。     

Groundwater arsenic removal by coagulation using ferric(III) sulfate and polyferric sulfate: A comparative and mechanistic study

Elevated arsenic (As) in groundwater poses a great threat to human health. Coagulation using mono- and poly-Fe salts is becoming one of the most cost-effective processes for groundwater As removal. However, a limitation comes from insufficient understanding of the As removal mechanism from groundwater matrices in the coagulation process, which is critical for groundwater treatment and residual solid disposal. Here, we overcame this hurdle by utilizing microscopic techniques to explore molecular As surface complexes on the freshly formed Fe flocs and compared ferric(III) sulfate (FS) and polyferric sulfate (PFS) performance, and finally provided a practical solution in As-geogenic areas. FS and PFS exhibited a similar As removal efficiency in coagulation and coagulation/filtration in a two-bucket system using 5 mg/L Ca(ClO)₂. By using the two-bucket system combining coagulation and sand filtration, 500 L of As-safe water (< 10 μg/L) was achieved during five treatment cycles by washing the sand layer after each cycle. Fe k-edge X-ray absorption near-edge structure (XANES) and As k-edge extended X-ray absorption fine structure (EXAFS) analysis of the solid residue indicated that As formed a bidentate binuclear complex on ferrihydrite, with no observation of scorodite or poorly-crystalline ferric arsenate. Such a stable surface complex is beneficial for As immobilization in the solid residue, as confirmed by the achievement of much lower leachate As (0.9 μg/L–0.487 mg/L) than the US EPA regulatory limit (5 mg/L). Finally, PFS is superior to FS because of its lower dose, much lower solid residue, and lower cost for As-safe drinking water.     

双极性脉冲高压介质阻挡放电降解氯苯和甲苯

将双极性脉冲高压引入介质阻挡反应器(螺旋棒式不锈钢电极、石英玻璃介质),分别对氯苯和甲苯的分解特性进行了实验研究.结果发现,这种放电形式可以高效注入能量,兼有脉冲电晕放电和介质阻挡放电的特点.脉冲高压使电场强度急剧增强,瞬间产生大功率放电和高能粒子,可以实现对VOCs化学键的高效裂解.与工频交流高压、单极性脉冲高压的试验结果比较表明,双极性脉冲高压取得了最高的降解效果;氯苯比甲苯难以分解.     

气力管道输送在垃圾收运领域的应用研究

气力管道输送应用于垃圾收运在国内尚处于起步阶段,开发该项技术目前还存在一定的技术困难,但若该技术能在环境领域成功应用,它将完全改变传统的垃圾收运模式,大大提高垃圾收集的效率,减小垃圾收运过程中对环境造成的影响。本文主要对该技术的优势及在国内应用的技术困难进行探讨,并在此基础上提出了解决方法。     

2000—2015年江汉平原农田生态系统NPP时空变化特征

基于MODIS数据和VPM（Vegetation Photosynthesis Model）模型估算2000—2015年江汉平原农田NPP,利用空间自相关和Sen趋势分析方法,分析16年间江汉平原农田NPP的时空变化特征及其影响因素。结果表明：（1）江汉平原农田年均NPP在2000—2005年呈上升趋势,2005—2009年呈波动性下降趋势,2009—2015年呈上升趋势;农田年NPP总量在2000—2015年整体上趋于平稳。（2）高中低产田面积占比分别为66.03%、27.04%和6.93%。2000—2015年NPP具有很强的空间聚集性且呈逐年增强趋势,并随空间距离增加聚集性减弱;江汉平原NPP主要呈高—高聚集和低—低聚集特征。（3）江汉平原农田NPP显著上升、无显著变化和显著下降区域面积分别占1.30%、69.50%和29.20%。