石笋有机质碳同位素组成研究的进展与挑战

洞穴石笋因其精准的定年和蕴含的多种代用指标,已成为古气候和古环境变化研究的重要载体之一。在石笋研究的多种代用指标中,碳酸盐碳同位素由于受到多重因素的影响,应用其重建过去环境变化历史一直局限在少数几个研究地点。洞穴上覆土壤有机质是洞穴石笋中有机质的重要来源,除此之外,洞穴原位产生的微生物及基岩中的有机质也有贡献。由于主要继承了地表植被和土壤有机质的同位素组成,石笋有机质碳同位素组成的时间序列能够很好地指示地表植被的演变及土壤过程的变化。本文对石笋有机质碳同位素组成的研究现状进行了综述,介绍了最新建立的石笋有机质碳同位素组成分析方法,并指出应用这一指标研究环境变化需要解决的关键问题和未来面临的挑战。     

海洋自然环境下舰载武器失效模式分析

目的分析舰载武器在海洋自然环境下的失效模式。方法对舰载武器装备全寿命周期环境剖面进行分析,经过梳理确认与海洋自然环境有关的任务剖面。以提高产品海洋自然环境适应性和可靠性为目标,设计海洋自然环境试验,根据产品实际使用所处的海洋自然环境,确定参试产品投放的位置为远海库内和平台库内。根据产品的组成,确定失效模式分析的对象,给出了失效模式分析的流程。结果基于试验结果,给出了舰载武器在海洋自然环境下的4种失效模式。结论舰载武器在海洋自然环境下的典型失效模式,包括单机壳体表面金属材料生锈、单机产品表面涂漆气泡、活动部件迟钝及接插件表面锈蚀等。     

An improved and simple method for removal of arsenic from drinking water

<正>Arsenic (As) is a naturally occurring element. The toxicity of arsenic is dependent on the specific arsenic species, and the concentration and duration of exposure to the arsenic species(Moe et al., 2016). Chronic human exposure to high concentrations of inorganic arsenic species has been associated with     

Overqualification and counterproductive work behaviors: Examining a moderated mediation model

The current study examined the effect of employees' perceived overqualification on counterproductive work behaviors (CWBs). Building on person–job fit theory and prior research on such organizational phenomena, we conceptualized overqualification as a type of poor person–job fit. Drawing on the dual‐process model, we further suggested that in processing their person–job misfit, overqualified employees might cognitively appraise themselves as less worthy organizational members and experientially feel angry toward the employment situation. We also suggested that to the extent that overqualified people are sensitive to justice, they may react more or less strongly to being overqualified. We tested our predictions using time‐lagged data from a sample of 224 workers and their supervisors employed in a large manufacturing company in China. Consistent with our theoretical framework, we found that organization‐based self‐esteem (OBSE) and anger toward employment situation mediated the positive relationships between perceived overqualification and both self‐rated and supervisor‐rated CWBs. In addition, justice sensitivity moderated the relationship between perceived overqualification and the mediators (i.e., OBSE and anger) and the indirect relationship between perceived overqualification and CWB. The theoretical and practical implications of these findings as well as future research directions are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Cyanobacterial bloom dynamics in Lake Taihu

<正>Lake Taihu is the third largest freshwater lake in China and serves as an important drinking water source for the local populace;however,decades of excessive nutrient loading fueled by anthropogenic activities have resulted in hypertrophic conditions,promoting the annual formation of nuisance phytoplankton blooms(Chen et al.,2003;Duan et al.,2009)     

Removal of nanoparticles by coagulation

<正>Nanoparticles(NPs)from anthropogenic sources have applications in several commercial products,including cosmetics,pharmaceuticals,and materials.There is evidence that during their usage and disposal,engineered nanoparticles can and will be released into wastewater(Gottschalk et al.,2013;Pasricha et al.,2012;Westerhoff et al.,2013;Zheng et al.,2015).If water and wastewater treatment plants are inefficient or incapable of removing NPs from water,NPs will be released with the treated effluent,entering drinking water sources and natural aquatic environments,increasing exposure for plants,microorganisms,     

河西走廊中段荒漠绿洲土壤生态化学计量特征

为探究荒漠绿洲土壤C、 N、 P和K的含量变化及生态化学计量特征,阐明其对环境因子的生态学响应,选择河西走廊中段张掖临泽荒漠绿洲10块样地,采集表层土壤样品,测定土壤C、 N、 P和K含量,揭示不同生境中土壤养分含量变化和化学计量比的分布特征以及与其他环境因子间的相关关系.结果表明：(1)土壤C在各样点分布不均匀且具有明显的异质性(R=0.761,P=0.06).其中,ω(C)在绿洲平均值最高,为12.85 g·kg^-1,过渡带次之,为8.65 g·kg^-1,荒漠最低,为4.1 g·kg^-1;(2)土壤K含量除在盐碱地含量较低外,在荒漠、过渡带和绿洲之间均无显著变化且含量较高;(3)土壤C∶N平均值为12.92,C∶P平均值为11.69,N∶P平均值为0.9,均低于全球土壤平均水平(13.33、 72.0、 5.9)和中国土壤平均水平(12、 52.7、 3.9);(4)土壤含水量为影响荒漠绿洲土壤C、 N、 P、 K和生态化学计量特征的最大影响因子,贡献率为86.9%,其次为土壤酸碱度和土壤孔隙度,贡献率分别为9.2%...     

How application of agricultural waste can enhance soil health in soils acidified by tea cultivation: a review

Environmental Chemistry Letters - Tea is one of the world’s most consumed beverages and an important crop of many developing countries. Intensive tea cultivation has negative impacts on soil...     

In Situ Compatibilization of Isotactic Polypropylene and High-Density Polyethylene by a Melt Cobranching Reaction

Incompatible polypropylene (PP) and polyethylene (PE) are difficult to separate in mixed recycling streams such as waste plastic packaging, which makes polyolefin mixtures unsuitable for high-quality products. In this work, based on the free radical branching reaction, a co-branching reaction of isotactic polypropylene (iPP) and high-density polyethylene (HDPE) blends was carried out in the presence of the peroxide, free radical regulator and multifunctional acrylate monomer, and a star-like long-chain branching (LCB) copolymer was obtained. The effect of in situ compatibilization on the structures and mechanical properties of iPP/HDPE was investigated, and the compatibilization mechanism was discussed. Results showed that the mechanical properties of the modified blends were largely improved, and efficient in-situ compatibilization of iPP and HDPE could be taken place in a wide process window. Moreover, the sizes of the dispersed phase in the modified blends were clearly decreased, and the interfacial thickness increased. Compared with the pure iPP/HDPE blend, the initial crystallization temperature of iPP in the modified iPP/HDPE blend was increased, and long branched chains of the LCB copolymers were physically entangled with the chemical identical homopolymers or even participated in the crystallization of iPP and HDPE. Thanks to the in situ compatibilization strategy, the compatibility of iPP/HDPE was significantly improved.