Could biochar amendment be a tool to improve soil availability and plant uptake of phosphorus? A meta-analysis of published experiments

Environmental Science and Pollution Research - As one of the most important nutrients for plant growth, phosphorus was often poorly available in soil. While biochar addition induced improvement of...     

Synthesis of branched allylic sulfones by regioselective boron-catalysed hydrosulfonylation

Environmental Chemistry Letters - Branched allylic sulfones are scaffolds widely distributed in bioactive molecules and organic functional materials. The synthesis of allylic sulfones has been...     

水中总氮测定方法存在问题的研究及改进

碱性过硫酸钾消解紫外分光光度法测定水中总氮采用的消解器皿是玻璃比色管,易造成空白偏高、结果偏低等问题。采用双圆柱状的消解杯对水样进行消解。结果表明,消解杯消解水中总氮,线性相关系数均大于0.999,检出限为0.05 mg/L,相对标准偏差小于5%,相对误差为0.88%~1.00%;改进后的消解器皿具有较好的精密度和准确度,能够更加准确测定水中总氮的含量。     

不同培养条件下锰过氧化物酶(MnP)的合成及其对甲基橙的降解

高效、大规模、低成本合成木质素降解酶是直接采用其降解难降解有机污染物所必须解决的问题.对锰过氧化物酶(MnP)降解甲基橙和在非灭菌的反应器中连续合成MnP的可行性进行考察.结果表明,在采用2 mmol H2O2和1.5 mmol MnSO4的降解体系中,获最大脱色效果,且100、200和300 U/L的MnP可在8h内将甲基橙分别脱色18％、23％和35％;在非灭菌的反应器水平上实现了固定化培养的P.chrysosporium连续23 d合成MnP,但MnP酶活仅为2～ 23 U/L,难以酶解甲基橙;然而,在摇瓶培养条件下固定化的P.chrysosporium合成的MnP却能达1 152 U/L.因此,直接采用MnP对污染物进行降解以及在非灭菌的反应器中持续合成MnP是可行的,但就在非灭菌条件下如何提高MnP的合成量还有待开展深入的研究.     

藻渣添加对玉米秸秆厌氧发酵特征的影响

厌氧发酵是农业废弃物资源化的有效途径之一.将农业废弃物同其他富含氮元素的有机废物混合发酵能够有效地提高产气效率.以玉米秸秆为例,尝试利用藻渣作为添加剂,提高农业废弃物厌氧发酵的性能.实验主要研究了混合发酵比例对沼气产量、甲烷产量、沼渣沼液特征的影响.当玉米秸秆、藻渣和接种污泥的挥发性固体质量分数为10∶ 2∶2时,沼气产率最高可达421.0 mL/g,甲烷产率为218.7 mL/g.沼渣组分分析表明,纤维素和半纤维素降解效率分别为83.7％和68.4％,和对照相比纤维素的降解效率显著提高.结果表明,藻渣的添加能够有效地促进玉米秸秆厌氧发酵产甲烷过程.     

气质联用法测固定污染源中三氟甲烷、四氟甲烷、六氟乙烷和六氟化硫

建立了固定污染源排气中三氟甲烷、四氟甲烷、六氟乙烷和六氟化硫的采样和气质联用分析方法,检出限分别为0.06、0.15、0.21、0.71 mg/m3,精密度在3.2%以下,相关系数大于0.999 6,并对浙江省内2家典型企业排放的温室气体进行了监测,实际样品监测结果表明,该方法能够满足废气中4种温室气体的监测要求。     

城市大气中挥发性有机化合物监测技术进展

挥发性有机物(VOCs)是臭氧及二次有机颗粒物(SOA)的主要前体物。近年来,我国逐步将VOCs纳入大气污染物控制体系。准确可靠的监测技术是大气VOCs研究及控制的重要前提保障。按照采样方法、分析方法 2个方面介绍并讨论了城市大气中VOCs的现有监测方法,较为详细地介绍了几类广泛采用的离线及在线监测技术,简要讨论了目前VOCs监测中存在的一些问题,展望了今后的发展趋势。     

Preparation and Characterization of Xylan Derivatives and Their Blends

Although hemicellulose is found widely in nature, it is currently under-utilized as a raw material for commercial applications. It would be desirable to find new uses for hemicellulose in order to add value to this agro-based material. A common type of hemicellulose is xylan, which is found in a number of wood species and in cotton. In this work we prepared cationic and anionic xylan derivatives and characterized them by ¹³C NMR, FT-IR, size exclusion chromatography (SEC), thermal analysis, and rheology. In particular, the ¹³C NMR spectra of carboxymethyl xylan (CMX) and quaternary ammonium-adducted xylan (QAX) were fully assigned with the help of samples with different degrees of substitution. SEC indicated that the beechwood xylan showed a bimodal molecular weight distribution, but with derivatization the distribution tended to become unimodal. Thermal analysis and rheology studies did not uncover any surprises; the solution of xylan and its derivatives exhibited mostly Newtonian behavior. The blends of CMX and QAX produced a precipitate at almost all ratios, indicating the formation of a polyelectrolyte complex. When cationic and anionic xylan samples were added together to paper, the paper dry strength increased. Thus, the combination of cationic/anionic xylan may be of interest in selected applications.     

Adsorption of Ammonium by Graphene Oxide-Based Composites Prepared by UV Irradiation and Using as Slow-Release Fertilizer

A novel sodium alginate-grafted poly(acrylic acid)/graphene oxide (NaAlg-g-PAA/GO) composite hydrogel was prepared via ultraviolet irradiation, and characterized by infrared spectroscopy spectrometer. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. It was employed to adsorb NH₄⁺ from aqueous solution and used as slow-release nitrogen fertilizers (SNFs). Result indicated that the adsorption process for NH₄⁺ reached equilibrium within 50 min, with the adsorption capacity of 6.6 mmol g^?1 even if 30 wt% GO was incorporated. The results of adsorption kinetic and isotherm were well described by the pseudo-second-order and Freundlich model. The thermodynamics analysis showed the adsorption process was spontaneous. The study indicated excellent water-holding ratio of soil with 2 wt% SNFs was 81.2%, and nitrogen release was up to 55.1% within 40 days in soil. Overall, NaAlg-g-PAA/GO could be considered as an efficient adsorbent for the recovery of nitrogen with the agronomic reuse as a fertilizer.     

基于微型无人机遥感数据的城市水环境信息提取初探

近年来,黑臭水体整治已经成为各级政府的重要工作内容。为更好地开展黑臭水体筛查和监管工作,提出基于多旋翼无人机搭载多光谱相机的遥感监测方案,尝试采用影像特征变换结合面向对象分类方法提取黑臭水体的遥感信息。结果表明:(1)无人机影像上地物具有更加丰富的色彩和纹理;(2)与主成分变换和纹理分析方法相比,光谱指数对典型地物具有较好的判别能力;(3)采用标准最邻近分类法提取城市水环境信息,能够获得较高分类精度。