石灰预处理和干发酵对稻草热解特性影响

深入研究生物质热解有助于热解机理的理解,利用热重分析来探讨石灰预处理和干发酵对稻草热解特性的影响。结果表明:预处理使木质素和半纤维素含量增加,而干发酵使VS、半纤维素和纤维素含量降低;预处理和干发酵改变稻草热解特性,但未改变稻草的热反应机理;热解一级动力学方程很好模拟稻草热解的主失重阶段,稻草热解活化能数值为42.3～47.8 kJ/mol,属于正常范围;预处理降低反应活化能,而干发酵增加反应活化能。这为秸秆及其干发酵残渣的气化提供了重要的设计依据。     

Selective recovery of Cu2+ and Ni2+ from wastewater using bioelectrochemical system

As the bioelectrochemical system, the microbial fuel cell (MFC) and the microbial electrolysis cell (MEC) were developed to selectively recover Cu²⁺ and Ni²⁺ ions from wastewater. The wastewater was treated in the cathode chambers of the system, in which Cu²⁺ and Ni²⁺ ions were removed by using the MFC and the MEC, respectively. At an initial Cu²⁺ concentration of 500 mg·L^-1, removal efficiencies of Cu²⁺ increased from 97.0%±1.8% to 99.0%±0.3% with the initial Ni²⁺ concentrations from 250 to 1000 mg·L^-1, and maximum power densities increased from 3.1±0.5 to 5.4±0.6 W·m^-3. The Ni²⁺ removal mass in the MEC increased from 6.8±0.2 to 20.5±1.5 mg with the increase of Ni²⁺ concentrations. At an initial Ni²⁺ concentration of 500 mg·L^-1, Cu²⁺ removal efficiencies decreased from 99.1%±0.3% to 74.2%±3.8% with the initial Cu²⁺ concentrations from 250 to 1000 mg·L^-1, and maximum power densities increased from 3.0±0.1 to 6.3±1.2 W·m^-3. Subsequently, the Ni²⁺ removal efficiencies decreased from 96.9%±3.1% to 73.3%±5.4%. The results clearly demonstrated the feasibility of selective recovery of Cu²⁺ and Ni²⁺ from the wastewater using the bioelectrochemical system.     

不同施肥处理对红壤晚稻田CH_4排放的影响

选取不同施肥处理的双季稻田为研究对象,采用静态箱-气相色谱法对晚稻田CH4排放通量进行观测。结果表明,与不施肥对照(T1)相比,各施肥处理CH4排放通量均有不同程度增加。其中秸秆还田+化肥处理(T5)CH4平均排放通量为9.96mg.m-2.h-1,比增氮磷施肥处理(T4)和对照分别增加26.1%和120.0%;平衡施肥处理(T2)和减氮磷施肥处理(T3)CH4平均排放通量比对照增加20%左右。说明施化肥可能提高水稻植株运输能力,进而增加CH4排放,但并未发现施化肥处理(T1、T2、T3和T4)之间CH4排放存在显著差异。同时对相关环境因素的分析表明,各处理CH4排放通量与土壤5cm深处温度间存在指数函数关系,并与田间水层厚度呈正相关关系(P<0.05)。综合考虑温室效应和稻谷产量,认为T2为推荐施肥方式,即N、P2O5和K2O施用量分别为180、90和135kg.hm-2,在插秧前1d施入占总N量70%的碳铵和全部磷肥、钾肥(过磷酸钙和氯化钾)作为基肥,并在分蘖期(2008年7月19日)追施占总N量30%的尿素。     

Preparation of spherical iron nanoclusters in ethanol-water solution for nitrate removal

In this study, a higher surface area spherical nanoscale zero valent iron (HNZVI) cluster (80 nm, 54.25 m(2)g(-1)) was synthesized in ethanol-water mixed solvent in the presence of dispersion agent of polyglycol (PEG). At the same time, a lower surface area nanoscale zero valent iron (LNZVI) particle (80 nm, 8.08 m(2)g(-1)) was also prepared with only de-ioned water as reaction media. Their structures, compositions and physical properties were characterized by transmission electron microscope (TEM), X-ray diffractometer (XRD), inductively coupled plasma atomic emission spectrophotometer (ICP-AES), and Brunauer-Emmett-Teller (BET) surface area analyzer and the results obtained for these two kinds of nanoscale iron were compared with each other and also with those reported in the literatures. The HNZVI clusters seemed to be accumulated by smaller iron particles (<10 nm). At the same time, whiskers were formed in the final produce. Reactivity of the HNZVI was affirmed via denitrification of nitrate. The factors controlling the reduction of nitrate, such as pH, dissolved oxygen (DO), iron content as well as the initial nitrate concentration were also discussed. Finally, kinetic analysis revealed that chemical reduction of nitrate by HNZVI could not be described by the first- or pseudo-first-order kinetic model.     

Leaching and degradation of ethametsulfuron-methyl in soil

Leaching and degradation of the herbicide ethametsulfuron-methyl[methyl 2-[(4-ethoxy-6-methylamino-1,3,5-triazine-2-yl)carbamoylsulfamoyl]benzoate] in three soils were investigated under laboratory conditions. Ethametsulfuron-methyl was mobile on soils when tested using non-aged and aged soil columns; this mobility agreed reasonably well with Freundlich soil isotherm constants. It was found that ethametsulfuron-methyl was more mobile in alkaline sandy Vertisol soil and neutral loamy Alfisol soil than in acidic clayey Red soil. Degradation of ethametsulfuron-methyl in soils was pH-dependent; calculated half-life (t(1/2)) values ranged from 13 to 67 days. Ethametsulfuron-methyl was more persistent in neutral or weakly basic than in acidic soil. Five soil metabolites were isolated and identified by LC/MS/MS analysis. The degradation pathways included the cleavage of the sulfonylurea bridge, N- and O-dealkylation, and triazine ring opening.     

我国北方风沙灾害加剧的成因及其发展趋势

综合分析了我国风沙灾害加剧的原因,并从我国北方沙漠、沙地形成演变的地理格局,探讨了我国沙化过程的中、长期发展趋势。本文认为,我国近年风沙灾害的加剧是在气候趋于干燥化背景下,人类大面积发展沙区生产的结果,但是,目前的流沙分布范围仍不及末次冰期极盛时期。未来我国风沙灾害的发展主要取决于气候增温背景下降水的时空分布、沙区的风化变化与地表土地的利用格局。     

遥感技术在农业灾害监测中的应用

农业灾害作为自然灾害系统中最大的部门灾害，其大面积的发生严重影响了我国农业的可持续发展。近年来，我国农业灾害表现为规模增大、程度加深的趋势。农业灾害的遥感监测克服了传统监测方法的不足，具有十分广阔的应用前景。分析了当前主要农业灾害遥感监测应用的原理和方法，就如何进一步加强遥感技术在农业灾害监测中的应用进行了讨论。要提高遥感技术在农业灾害监测中的应用范围和精度，必须进一步加强农业灾害遥感机理的研究，采用多传感器、多时相、多分辨率遥感数据相结合的监测方式。     

富氏凹头蚁在樟子松林内生活习性的观察

我们首次发现富氏凹头蚁(Formica frkali),是松阿扁叶蜂(Acantholyda posticalis Matsumura)的重要捕食者,该蚁建巢在沙草上,当人工移置蚁巢,该蚁的生活习性正常且巢是扩大的.     

会仙岩溶湿地丰平枯时期地下水金属元素污染与健康风险

以我国面积最大的亚热带低海拔岩溶湿地为研究区,对该区不同时期(丰水期、平水期和枯水期)地下水27 组样品中10种金属元素(Cd、Cr、As、Al、Cu、Pb、Zn、Mn、Hg和Fe)进行测试和分析,分别运用综合污染评价法、多元统计分析及健康风险评价模型揭示了丰平枯时期地下水中10 种金属元素的污染特征、分布状况和健康风...     

废水中有机污染指标监测方法的选择

综合考察了废水中各种有机污染物综合指标的测试对象、干扰、准确度、精确度及其分析测试技术等各种因素 ,对实现其自动化连续测量的影响。针对某些监测技术产生的严重二次污染问题 ,提出了绿色 (清洁 )监测技术的概念。文章认为在重点废水污染源安装在线监测系统实行总量控制的过程中 ,应避免使用造成严重二次污染的 CODCr在线监测仪 ,而应当采用臭氧氧化法在线监测仪 ,或其他综合指标 ,如 TOC