Vertical distributions of soil carbon and nitrogen fractions as affected by land-uses in the Ili River Valley

In this study, soil samples were collected to a depth of 100?cm from different land-uses, including maize field (MZ), wheat field (WT), paddy field (PD), apple orchard (OC), grassland (GL) and wetland (WL) in the Ili River Valley in northwest China, to investigate the effects of land-use on vertical distributions of soil carbon (C) and nitrogen (N) fractions, and examine whether such effects were different between topsoil (0–40?cm) and subsoil (40–100?cm). The results showed that soil organic C, water-extractable organic C, microbial biomass C, total N and microbial biomass N of croplands (MZ, WT, PD and OC) were significantly lower than those of natural lands (GL and WL) in both topsoil and subsoil, indicating that contents of soil C and N fractions can be reduced by agricultural land-uses, and the reductions are not limited to topsoil. However, the contents of soil ammonium N and nitrate N showed complex trends under different land-uses, possibly due to that the plant species and agricultural practices (e.g. application rate of fertiliser and irrigation) are considerably different among land-uses. Therefore, we suggest that more nutrient inputs should be applied to croplands to improve soil fertility in the Ili River Valley.     

Occurrence of and risk posed by highly carcinogenic dibenzo[def,p]chrysene isomers in urban soil

Dibenzopyrene and its isomers are considered the most potent carcinogens of all polycyclic aromatic hydrocarbons tested to date. However, despite public concerns over their deleterious effects, they have not been extensively studied. The occurrence of four highly carcinogenic isomers of dibenzopyrene – dibenzo[def,p]chrysene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, and dibenzo[a,h]pyrene in urban soil samples from Shanghai, China, have been determined in this study, as well as that of benzo[a]pyrene and coronene. A total of 14 peaks with ions at m/z 302 were detected by gas chromatography-mass spectrometry. Although the concentrations of benzo[a]pyrene and the sum of the 16 priority polycyclic aromatic hydrocarbons were greater than that of dibenzopyrene and its isomers, the carcinogenic potency of the latter was higher than that of benzo[a]pyrene. The results also indicate that the relative carcinogenic potency of the four dibenzopyrene isomers in the samples is higher than that of the 16 priority polycyclic aromatic hydrocarbons.     

A/O/O工艺处理含油污水的模拟评估

利用Bio Win 5.0软件建立了某炼油厂A/O/O工艺处理含油污水的数学模型,对其工艺参数进行了评估,并提出了改进建议。经调整部分动力学参数后,模拟结果与实测值吻合度较好,相关系数在0.75~0.81之间,建立的模型可较好反映工艺的运行工况。模拟优化主要针对一级处理装置,在仅考虑NH_3-N和COD去除的情况下,目前装置的工艺参数较合理,若考虑TN,无法实现TN和NH_3-N同时达标。对一级处理装置的模型进行改进后,出水模拟值中COD轻微上升2%,但ρ(NH_3-N)和TN分别下降83%和66%,可有效减轻后续处理装置负荷。     

Accounting for the Impact of Management Scenarios on Typha Domingensis (Cattail) in an Everglades Wetland

Environmental Management - The coupled regional simulation model, and the transport and reaction simulation engine were recently adapted to simulate ecology, specifically Typha domingensis...     

高氨废水短程硝化特性简

采用SBR装置,针对高氨废水的特点,在高氨条件下,以高氨低氧为转化手段,实现高氨废水短程硝化过程中亚硝化菌的驯化与积累。控制温度为28~31℃,曝气量为15~60 L/h,pH控制在7.8~8.2的条件下连续运行78 d。实验结果表明,运行11 d后实现了短程硝化,从11 d至78 d属于系统氨氮负荷提高期。在运行过程中,氨氮污泥负荷从开始的0.023 kg/（kg·d）逐步上升为0.3 kg/（kg·d）,最高时达到0.34 kg/（kg·d）,此时氨氮去除率仍维持90%以上。为观察驯化后短程硝化菌的形态,取驯化好的污泥进行电镜扫描,结果表明,污泥中的细菌形态主要以球状菌为主。     

印染废水生化出水中各类有机物在小型活性炭床吸附过程中的去除效果

采用连续流活性炭炭床处理印染废水生化出水,通过XAD-8/XAD-4吸附树脂将印染废水生化出水中的溶解性有机物分为4类:疏水酸、非酸疏水物质、弱疏水物质和亲水物质,采用超滤膜法测定水样的分子量分布,对印染废水生化出水中不同种类以及不同分子量大小的有机物在煤质炭、椰壳炭2种活性炭动态实验处理过程中的去除特性进行研究。实验结果表明,2种活性炭对该水样中的有机物均有明显的去除效果,其中以煤质炭的处理效果较优。煤质炭吸附疏水性和亲水性有机物均有明显的处理效果,对非酸疏水物质和弱疏水有机物的吸附效果较差。煤质炭对分子量<10 k的小分子有机物的吸附效果对实验结果的贡献较大。     

铁碳微电解-Fenton法预处理苯胺基乙腈生产废水的动力学研究

通过采用铁碳微电解-Fenton法预处理苯胺基乙腈生产废水的实验研究,分析了处理过程的COD降解动力学;同时研究了单纯活性炭吸附和微电解过程中COD去除率的变化。结果表明,铁碳微电解的初期COD降解过程近似符合一级反应动力学,并且得到微电解与活性炭吸附对铁碳微电解降解COD的关系式;Fenton反应中通过研究有机物浓度和过氧化氢初始浓度与反应进程的关系,建立了反应动力学模型;单纯吸附实验COD去除率在24 h内快速下降,而微电解在相应时间内COD去除率波动较小,为实际应用提供了数据经验和理论依据。     

红枫湖水体中叶绿素a的遥感监测

以地处贵州中部的红枫湖水库为研究区,2010年的ALOS影像为基础,利用B3、B4(三波段和四波段)的乘积影像研究红枫湖水库库区表面的叶绿素a分布情况。结果表明,库区水体叶绿素a浓度在空间分布上呈现自三岔河入水口到北湖逐渐降低,沿岸边向湖中心逐渐降低的态势。探讨了适宜该库区的水体叶绿素a的提取方法,并引入基于费歇尔准则的最优分割算法,利用计算机编程实现了该库区叶绿素a分布水平的最优分划。这一系列针对该库区水体叶绿素a提取、分析和监测的优化方法,对该水源地的污染监测和库区的生态治理有一定的参考价值。     

Sorption and photodegradation of chlorpyrifos on riparian and aquatic macrophytes

Surface water bodies may become contaminated via spray drift following pesticide application. In this investigation, the photodegradation and sorption of chlorpyrifos was studied in four riparian macrophytes representative of Mediterranean flora (Phragmites australis, Iris pseudacorus, Equisetum pratense and Typha latifolia). The results of experiments with both the active ingredient and the formulation DURSBAN 48® EC confirm the ability of these species to interact with chemicals such as chlorpyrifos. The maximum sorption of chlorpyrifos at equilibrium was observed in Phragmites australis (22%). And, the maximum instantaneous sorption of chlorpyrifos was observed in the dried biomass of Phragmites australis (49%). The epicuticular waxes present on leaves influence photodegradation processes, resulting in a decrease in chlorpyrifos persistence depending on the nature of the extract. The half-life of chlorpyrifos residues in leaf waxes decreased from 34 to 99 minutes when irradiated.