基于余震序列分布信息的地震极灾区快速判断方法研究

利用震级加权标准差椭圆法研究了基于震后短期内(24 h)余震序列判定地震极灾区的方法,研究结果表明:1利用该方法判断宏观震中是一种比较可行的方法,不同震源破裂方式的震例利用该方法判断宏观震中的精度不同,倾滑-近倾滑型破裂方式的震例利用余震序列判定宏观震中的精度最高;2整体上看,利用该方法判断极灾区长轴方向的准确性低于利用距震中最近活动断裂判断的准确性,但对于倾滑-近倾滑型破裂方式的震例,利用该方法的准确性高于利用断层数据判定的准确性。     

Phosphorus recovery from biogas fermentation liquid by Ca–Mg loaded biochar

Shortage in phosphorus (P) resources and P wastewater pollution is considered as a serious problem worldwide. The application of modified biochar for P recovery from wastewater and reuse of recovered P as agricultural fertilizer is a preferred process. This work aims to develop a calcium and magnesium loaded biochar (Ca–Mg/biochar) application for P recovery from biogas fermentation liquid. The physico-chemical characterization, adsorption efficiency, adsorption selectivity, and postsorption availability of Ca-Mg/biochar were investigated. The synthesized Ca–Mg/biochar was rich in organic functional groups and in CaO and MgO nanoparticles. With the increase in synthesis temperature, the yield decreased, C content increased, H content decreased, N content remained the same basically, and BET surface area increased. The P adsorption of Ca–Mg/biochar could be accelerated by nano-CaO and nano-MgO particles and reached equilibrium after 360 min. The process was endothermic, spontaneous, and showed an increase in the disorder of the solid–liquid interface. Moreover, it could be fitted by the Freundlich model. The maximum P adsorption amounts were 294.22, 315.33, and 326.63 mg/g. The P adsorption selectivity of Ca–Mg/biochar could not be significantly influenced by the typical pH level of biogas fermentation liquid. The nano-CaO and nano-MgO particles of Ca–Mg/biochar could reduce the negative interaction effects of coexisting ions. The P releasing amounts of postsorption Ca–Mg/biochar were in the order of Ca–Mg/B600 > Ca–Mg/B450 > Ca–Mg/B300. Results revealed that postsorption Ca–Mg/biochar can continually release P and is more suitable for an acid environment.     

Adsorption of three pharmaceuticals on two magnetic ion-exchange resins

The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen (IBU), diclofenac (DC), and sulfadiazine (SDZ), by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactionswere dependent on the specific surface area and functional groups of the resin. The adsorption isothermfittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl^- and SO₄^2- suppressed the adsorption amount, butwith different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior andmechanismof pharmaceuticals onmagnetic ion-exchange resins. The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters.     

Can arbuscular mycorrhiza and fertilizer management reduce phosphorus runoff from paddy fields?

Our study sought to assess how much phosphorus (P) runoff from paddy fields could be cut down by fertilizer management and inoculation with arbuscular mycorrhizal fungi. A field experiment was conducted in Lalin River basin, in the northeast China: six nitrogen–phosphorus–potassium fertilizer levels were provided (0, 20%, 40%, 60%, 80%, and 100% of the recommended fertilizer supply), with or without inoculation with Glomus mosseae. The volume and concentrations of particle P (PP) and dissolved P (DP) were measured for each runoff during the rice growing season. It was found that the seasonal P runoff, including DP and PP, under the local fertilization was 3.7 kg/ha, with PP, rather than DP, being the main form of P in runoff water. Additionally, the seasonal P runoff dropped only by 8.9% when fertilization decreased by 20%; rice yields decreased with declining fertilization. We also found that inoculation increased rice yields and decreased P runoff at each fertilizer level and these effects were lower under higher fertilization. Conclusively, while rice yields were guaranteed arbuscular mycorrhizal inoculation and fertilizer management would play a key role in reducing P runoff from paddy fields.     

Water chemistry controlled aggregation and photo-transformation of silver nanoparticles in environmental waters

The inevitable release of engineered silver nanoparticles (AgNPs) into aquatic environments has drawn great concerns about its environmental toxicity and safety. Although aggregation and transformation play crucial roles in the transport and toxicity of AgNPs, how the water chemistry of environmental waters influences the aggregation and transformation of engineered AgNPs is still not well understood. In this study, the aggregation of polyvinylpyrrolidone (PVP) coated AgNPs was investigated in eight typical environmental water samples (with different ionic strengths, hardness, and dissolved organic matter (DOM) concentrations) by using UV–visible spectroscopy and dynamic light scattering. Raman spectroscopy was applied to probe the interaction of DOM with the surface of AgNPs. Further, the photo-transformation and morphology changes of AgNPs in environmental waters were studied by UV–visible spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The results suggested that both electrolytes (especially Ca^2 + and Mg^2 +) and DOM in the surface waters are key parameters for AgNP aggregation, and sunlight could accelerate the morphology change, aggregation, and further sedimentation of AgNPs. This water chemistry controlled aggregation and photo-transformation should have significant environmental impacts on the transport and toxicity of AgNPs in the aquatic environments.     

应用人工湿地技术处理屠宰废水:设计与运行探讨

污水分散式处理有独特的优点,人工湿地是其中主要的方法,特别适合在农村地区因地制宜地处理生活污水,具有运行费用低、处理效果好的特点,在新农村环境建设中发挥了很大作用。但人工湿地用于污染程度高的行业废水处理国内比较少见。该文依据一项中德环保合作项目——人工湿地技术处理蕲春某屠宰厂废水的示范工程,对人工湿地建造有关的设计及运行管理问题进行总结与探讨。     

活性炭负载MnO_x结合等离子体降解甲苯

通过对比Mn Ox/AC、AC、无催化剂对甲苯的去除率和副产物的浓度,得知Mn Ox能大大提高甲苯去除率和降低副产物浓度。实验同时研究了负载量、煅烧温度和载体活性炭的活化对甲苯去除率的影响,实验表明:20%Mn Ox负载经过850℃活化的活性炭在350℃下煅烧得到的催化剂的活性最高。试验用BET、XRD和红外对催化剂进行了表征,研究发现,经过活化的催化剂比表面积高于没有活化的催化剂,随着负载量的增加比表面积降低,温度为250℃时硝酸锰主要分解为Mn2O3,温度为350℃时主要分解产物为Mn3O4,温度为450℃时主要为Mn O。红外表明反应后的催化剂表面氧化基团增加。     

不同晶型纳米TiO_2在斑马鱼体内的富集与清除

为探讨纳米材料的慢性生物效应以及材料结构对生物富集的影响,开展了A-TiO2(锐钛型纳米TiO2)和R-TiO2(金红石型纳米TiO2)在斑马鱼(Danio rerio)体内的长期富集和清除试验.采用半静态暴露试验,试验周期为46 d(暴露阶段28 d,清除阶段18 d),每种晶型设置2个处理组(ρ分别为4.0和10.0 mg/L),测定各时间点斑马鱼体内不同晶型纳米TiO2含量(以w计);以暴露阶段的BAF(生物富集系数)以及清除阶段的排出速率常数、总量清除率为终点,比较斑马鱼对2种晶型纳米TiO2的富集、清除的异同.结果表明:在暴露阶段,A-TiO2在斑马鱼体内的富集量显著高于R-TiO2,10.0 mg/L处理组斑马鱼体内富集量均显著高于4.0 mg/L处理组;4.0和10.0 mg/L的A-TiO2处理组的BAF分别为76.7和105.4 L/kg,略高于R-TiO2(41.6和36.1 L/kg),二者在斑马鱼体内均不具有生物蓄积性.在清除阶段,斑马鱼体内的2种晶型的纳米TiO2均可被排出,清除阶段的清除率为88.0%~100%;斑马鱼体内2种晶型纳米TiO2富集量的下降均符合一阶指数衰减方程,排出速率常数在0.26~1.01 d-1之间.     

毛皮染色废水工艺的处理效率及微生物群落的影响

毛皮染色废水是一种高盐度、难降解、高污染的工业废水,整个处理环节都对环境生态有潜在的危害。文章采用4种不同废水处理工艺在相似操作运行参数下对毛皮染色废水进行处理,并利用T-RFLP技术观察不同处理工艺下活性污泥中细菌群落的多样性及群落结构的变化。结果表明,在4种处理工艺中,效果最好的是HA-SBR法,其COD、BOD5及NH4+-N的去除率分别可以达到93.75%、94%和93.59%。T-RFLP分析表明处理工艺的不同对细菌群落结构的变化有着较大的决定作用,变形杆菌门(Proteobacteria)、厚壁菌门(Firmicutes)及拟杆菌门(Bacteroidetes)是活性污泥中的优势种群,不同处理工艺下微生物群落多样性同NH4+-N浓度关系最为密切。研究还表明,通过添加特定微生物菌剂或调节生化工艺可以增加微生物群落多样性,从而增强污泥体系抗污染物冲击性能,提高处理效果。     

上海市郊不同耕地类型土壤微生物活性研究

该文利用土壤酶学法和土壤呼吸监测方法,分析了上海市郊不同耕地类型土壤的微生物活性,并对其相关影响因子进行了探讨。结果表明,除水稻田外,其他3种旱地作物的土壤FDA(荧光素双乙酸酯)水解酶活性和土壤呼吸速率均呈由高到低的趋势,即西瓜地设施菜地花菜地;土壤FDA水解酶活性与土壤有机质含量呈极显著正相关(P0.01),与全盐量呈显著负相关(P0.05);土壤呼吸速率与温度呈极显著正相关(P0.01),与含水率呈显著正相关(P0.05);3种旱地作物土壤FDA水解酶活性与土壤呼吸速率显著正相关(P0.05),两者均可反映土壤微生物活性,但土壤呼吸速率不适合用于监测水稻土壤的微生物活性变化,表明FDA水解酶活性在土壤微生物活性监测方面的适用性更为广泛。