改性稻草吸附铜离子的热力学研究

研究表明稻草改性后吸附铜离子的能力得到很大提高。在4种温度下（15、27、37、50℃）,改性稻草吸附铜离子的最大吸附量分别为1．10、1．24、1．34、1．50mmol／g。不同温度下,吸附自由能△G大大小于零,吸附过程具有强烈的自发趋势。吸附焙△H和吸附熵△S都大于零,吸附过程是熵增加推动的。     

Source profiles of particulate organic matters emitted from cereal straw burnings

Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain producing areas in China. Fine particulate matters （PMzs） from the cereal straws subjected to control burnings, both under smoldering and flaming status, were sampled by using a custom made dilution chamber and sampling system in the laboratory. Element carbon （EC） and organic carbon （OC） was analyzed. 141 compounds of organic matters were measured by gas chromatography-mass spectrum （GC-MS）. Source profiles of particulate organic matters emitted from cereal straw burnings were obtained. The results indicated that organic matters contribute a large fraction in fine particulate matters. Levoglucosan had the highest contributions with averagely 4.5% in mass of fine particulates and can be considered as the tracer of biomass burnings. Methyloxylated phenols from lignin degradation also had high concentrations in PM2.5, and contained approximately equal amounts of guaiacyl and syringyl compounds. 13-Sitostrol also made up relatively a large fraction of PMz5 compared with the other sterols （0.18%-0.63% of the total fine particle mass）. Normal alkanes, PAHs, fatty acids, as well as normal alkanols had relatively lower concentrations compared with the compounds mentioned above. Carbon preference index （CPI） of normal alkanes and alkanoic acids showed characteristics of biogenic fuel burnings. Burning status significantly influenced the formations of EC and PAHs. The differences between the emission profiles of straw and wood combustions were displayed by the fingerprint compounds, which may be used to identify the contributions between wood and straw burnings in source apportionment researches.     

Preparation1 and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution

In order to reduce the impact of eutrophication caused by agricultural residues (i.e. excess nitrate) in aqueous solution, economic and effective anionic sorbents are required. In this article, we prepared anionic sorbent using wheat straw. Its structural characteristics and adsorption properties for nitrate removal from aqueous solution were investigated. The results indicate that the yield of the prepared anionic sorbent, the total exchange capacity, and the maximum adsorption capacity were 350%, 2.57 mEq/g, and 2.08 mmol/g, respectively. The Freundlich isotherm mode is more suitable than the Langmuir mode and the adsorption process accords with the first order reaction kinetic rate equation. When multiple anions (SO42-, H2PO4-, NO3-, and NO2-) were present, the isotherm mode of prepared anionic sorbent for nitrate was consistent with Freundlich mode; however, the capacity of nitrate adsorption was reduced by 50%. In alkaline solutions, about 90% of adsorbed nitrate ions could be desorbed from prepared anionic sorbent. The results of this study confirmed that the wheat straw anionic sorbent can be used as an excellent nitrate sorbent that removes nitrate from aqueous solutions.     

秸秆还田对稻田温室气体排放的影响:Meta分析——以长江中下游地区为例

全球气候变暖是人类面临的严峻挑战,稻田生态系统在全球气候变暖中起到重要的作用。目前已有许多学者通过大田试验的方法研究了不同秸秆还田方式下温室气体排放的特征,但由于试验地点等因素的不同导致最终的结果差异很大。通过整合这些结果来研究区域内不同秸秆还田方式(翻耕秸秆还田(CTS)、免耕秸秆还田(NTS)和旋耕秸秆还田(RTS))下稻田温室气体排放的特征,能够准确地反映一定区域内稻田生态系统的净减排潜力。本文基于长江中下游地区32篇关于秸秆还田对稻田温室气体排放的文献收集173组数据,利用Meta分析方法研究了3种秸秆还田方式下稻田CH_4和N_2O排放的特征,并估算出不同秸秆还田方式下稻田的全球增温潜势和净增温潜势。结果表明,CTS、NTS和RTS处理下稻田CH_4周年排放的效应值分别为0.76、0.37和0.68,稻田N_2O周年排放的效应值分别为0.44、0.36和0.52;在两熟制下,不同秸秆还田方式下稻田CH_4周年排放的效应值的大小为RTSCTSNTS,但N_2O周年排放的效应值的大小为RTSNTSCTS。在三熟制下,三种秸秆还田方式下稻田CH_4的周年排放的效应值的高低为CTSRTSNTS,而N_2O周年排放的效应值的高低为RTSNTSCTS。在相同的秸秆还田方式下,三熟制稻田温室气体周年排放的效应值都高于两熟制。此外,不同的还田秸秆种类影响稻田温室气体的排放;结合前期研究,估算出CTS、NTS和RTS处理下稻田的净增温潜势分别为12 375.55、11 232.36和15 982.87 kg CO_2-equivalent·hm~(-2)。因此,免耕秸秆还田是长江中下流地区稻田净减排条件下适宜的秸秆还田方式。     

Some basic principles of grassland fire management

Fire management of grasslands is best executed based on an understanding of the fundamental properties of grassland components, structures, and environments, and the nature of fire behavior in grassland fuels. The art of controlled burning combines experience, practicality, empirical knowledge, and sensitivity, with the effects of fire, the role of fire (particularly under natural conditions), inherent climatic conditions, and sound ecological management objectives. Some of the properties, effects, roles, conditions, experiences, and objectives of grassland burning are presented.     

Adsorption of Cu（Ⅱ） on rice straw char from acidic aqueous solutions

研究了稻草炭对Cu（Ⅱ）的吸附特征,探讨了Cu（Ⅱ）的吸附机制.结果表明,稻草炭对Cu（Ⅱ）有很高的吸附容量,Langmuir方程能很好地拟合Cu（Ⅱ）吸附等温线,因此可以描述稻草炭对Cu（Ⅱ）的吸附,其预测的Cu（Ⅱ）在pH 4.5和pH 5.0时的最大吸附量分别为0.628 mol.kg-1和0.763 mol.kg-1.稻草炭对Cu（Ⅱ）的吸附量随体系pH升高而增加,但吸附Cu（Ⅱ）的解吸率呈相反的变化趋势.当吸附体系pH≤4.5时,Cu（Ⅱ）解吸率大于55%,说明此时以静电吸附为主;在较高pH条件下Cu（Ⅱ）以非静电吸附机制为主.红外光谱的分析结果表明,稻草炭表面有丰富的—COOH和—OH等含氧官能团,Cu2＋与含氧官能团形成有机络合物导致—COOH吸附峰位移.Cu（Ⅱ）吸附使稻草炭颗粒的Zeta电位向正值方向位移.结果说明Cu（Ⅱ）在稻草炭表面发生了专性吸附.     

Forest-user attitudes toward alternative fire management policies

The formulation and implementation of new fire policies in the national forests depend upon public acceptance. A national survey of organized groups of forest users indicates that, contrary to the concern of many forest managers, considerable support exists for flexible fire suppression policies. Forest users are also willing to accept the risk associated with the manager's use of prescribed fire. However, important intergroup differences do exist. Such variation is discussed in relation to a number of socioeconomic variables, general fire knowledge, specific knowledge about the effects of low-intensity fires, and risk preference levels.     

GC-MS分析碱法草浆造纸废水中的有机污染物组成

碱法草浆造纸废水在酸性条件下经乙醚萃取--K-D浓缩器浓缩,采用气相色谱-质谱(GC-MS)联用仪对其有机污染物进行了分析研究.结果表明,该废水中共含有29种有机物,其中主要为有机酸类,占有机物总量的50.84%.其次为难降解的呋喃类和毒性较大的苯环类有机物,它们分别占有机物总量的25.12%和13.53%.     

上海市燃煤的现状分析及其污染管理措施

上海市以燃煤作为主要能源的工,商业大城市,大气污染以煤烟污染为主,燃煤排放的烟尘达到１９．８万ｔ／ａ,ＳＯ２为３９．６万ｔ／ａ;市区的燃煤密度相当高,在市区１３５个街道地区的燃煤密度＞２．０万ｔ／ｋｍ＾２·ａ,占２６％。为此,本文提出在实施近,远期环境保护规划时,应进一步加强监督管理措施,制定燃煤污染防治和定量管理目标考核方法,修订烟尘污染管理方法,并建议制定《上海市大气污染防治管理条例》。     

中国作物秸秆资源利用潜力的多适宜性综合评价

由于作物秸秆类型不同,其营养成分和利用价值也不同,因此仅根据草谷比系数法以质量形态衡量其利用价值,难以全面直接地反映秸秆资源的多种利用价值.为综合定量评价不同利用方式下我国作物秸秆资源的各种利用价值,依据能量流动定律,构建作物秸秆多适宜性综合统一评价体系.结果表明:①以质量、能量和谷物当量3种形态综合核算我国秸秆资源量,其计量结果年际变化趋势较为一致,并且能量和谷物当量形态更能直接体现秸秆资源能源化和饲料化的实际利用价值;②1991-2015年我国作物秸秆资源利用价值总量整体上升,至2015年我国作物秸秆肥料化、基料化和原料化形态质量为6.88×1011 kg,能源化利用价值为8.89×1018 J,适宜饲料化的作物秸秆资源利用量为6.26×1011 kg谷物当量,折合当年全国粮食总产量的100.66%,因此秸秆饲料化具有较高的利用价值,并且符合当前我国"粮改饲"农业改革发展方向;③我国各地秸秆资源量在空间上呈现出显著的地域边缘属性,秸秆资源丰富地区主要集聚在华北、东北和长江中下游地区.研究显示,就作物秸秆主要利用方式而言,饲料化具有相对较高的适宜性和利用价值,但是由于经济收益、经营规模和市场供需不对称等原因,当前农户秸秆饲料化的意愿不高,可利用经济和政策等措施引导该产业有序开展.