Mobility of free surface in different liquids and its influence on water striders locomotion

Dynamics of the surface layer in different liquids is examined by means of infrared thermography of the surface and simultaneous velocity fields measurements using surface and infrared Particle Image Velocimetry. This technique allows measurements and comparison of two velocity fields—at the surface and at small depth about 50–200 μm. In distilled water the velocity fields at the surface and at small depth exhibit significant dissimilarity. The flow field below the surface is essentially 3D, whereas the surface flow is characterized by vanishing 2D divergence of velocity, indicating predominantly planar motion. In contrast, in ethanol–butanol mixture two velocity fields are well correlated, both corresponding to 3D flow with continuous surface renewal. Thermal patterns, observed at the surface, and the flow field structure in different liquids are associated with different boundary conditions for velocity at the surface. Water surface is seldom renewed, which inhibits heat and mass exchange between the liquid and atmosphere. However, absence of vertical advection also enables organisms to live within the surface layer, to stand and walk on the free surface. This is illustrated by the difficulties a water strider faces on the surface of ultrapure water, which exhibits Marangoni convection.     

Research on Methods for Building Volcano Disaster Information System--taking Changbai Mountain as an example

1IntroductionAs a many-volcano-distributed country,China is covered with many volcanoes and lava rocks.A-mong the one-thousand-or-so volcanoes,Changbai Mountain Volcano,Wudalianchi Volcano,Tengchong Volcano and Ashikule Volcano of West Kunlun are the mostlatentcatastrophic erup-tive active volcanoes.In recent years,the activity of the earth' s crust in some volcanic areas isobviously becoming increasing violent.Butfew scholars have monitored and evaluated volcano inChina.So building VDI…     

308 nm光作用下α-Fe2O3表面HNO3的光解

采用紫外可见光谱(UV-Vis)、傅立叶变换红外光谱(FTIR)及离子色谱(IC)技术对HNO3在α-Fe2O3表面暗反应和308nm下光解反应进行了研究.考察了时间、HNO3浓度、相对湿度(RH)等条件对反应的影响.结果表明,随着HNO3浓度、光照时间的增加,HNO3在气相与α-Fe2O3表面光解产物浓度均呈指数增加;HNO3在α-Fe2O3表面光解产生的NO2、NO分别为气相产生的3.27及3.87倍,而无论气相还是表面光解的NO2浓度均约为NO的2倍.随着RH的增加,HNO3光解产生的HONO的浓度随之呈指数增大,其产率从RH 20%时的0.023增加到90%时的0.087.α-Fe2O3的表面效应在HNO3的表面光解反应中起主导作用.     

夏、冬季降雨中溶解性有机质(DOM)光谱特征及来源辨析

利用紫外-可见光谱与三维荧光光谱,结合拉格朗日混合单粒子轨道模型及火点图,研究了重庆2013年夏、冬两季雨水DOM光谱特征,并对其来源进行解析.结果表明,雨水DOM与水体、土壤DOM具有类似性质光谱特征,证明降雨DOM也是陆地及水环境中DOM地化特征的重要贡献者.雨水DOM中DOC含量为0.88~12.80 mg·L-1,CDOM含量在3.17~21.11m-1之间,夏、冬两季降雨DOM差异明显(P0.05).与夏季相比,冬季降雨DOM分子量较小,芳香性程度较低,腐殖化程度也更低,输入主要以本地和短距离输送为主;而夏季DOM来源较分散.尽管吸收和荧光光谱可用于解析雨水DOM组成和来源,但在光谱特征的解析和来源识别上与其他来源DOM有所区别,传统"内、外源区分"并不适用于雨水DOM.     

长期施肥下浙江稻田不同颗粒组分有机碳的稳定特征

依托浙江水网地区稻田长期定位施肥试验(1996~2013年),利用固态13C核磁共振波谱技术,研究长期不同施肥措施下土壤各颗粒组分有机碳含量及其化学结构特征.结果表明,与不施肥对照(CK)相比,秸秆与化肥配施(NPKRS)、栏肥与化肥配施(NPKOM)、单施化肥(NPK)和单施栏肥(OM)处理均显著(P0.05)增加了砂粒(2~0.02 mm)、粉粒(0.02~0.002mm)和黏粒(0.002 mm)组分中有机碳含量;而单施秸秆(RS)处理仅显著增加砂粒组分有机碳含量.此外,与单施化肥处理相比,有机肥和化肥配施促进了新增有机碳在粉粒和黏粒组分的分配,更有利于新增有机碳的稳定.应用13C-NMR波谱技术进行结构表征,结果表明粉粒和黏粒组分有机碳的化学结构存在明显差异,粉粒组分烷氧碳、芳香碳的相对含量高于黏粒,而烷基碳、羰基碳的相对含量低于黏粒.长期有机肥与化肥配施下粉粒和黏粒烷基碳相对含量较单施有机肥处理分别降低9.1%~11.9%和13.7%~19.9%,烷氧碳的相对含量则分别增加2.9%~6.3%和13.4%~22.1%,表明有机肥与化肥配施处理降低了粉粒和黏粒组分有机碳的分解程度.长期单施化肥处理下粉粒和黏粒组分有机质的芳化度和疏水性低于单施有机肥处理和不施肥处理,有机质的矿化稳定性较低.长期有机肥与化肥配施,尤其是NPKOM处理,通过增加化学抗性化合物和碳水化合物的积累,并且减缓活性组分的分解提高粉粒和黏粒组分有机碳含量,是促进稻田土壤有机碳可持续积累的有效措施.     

Can we take the pulse of environmental governance the way we take the pulse of nature? Applying the Freshwater Health Index in Latin America

Quantitative assessments have long been used to evaluate the condition of the natural environment, providing information for standard setting, adaptive management, and monitoring. Similar approaches have been developed to measure environmental governance, however, the end result (e.g., numeric indicators) belies the subjective and normative judgments that are involved in evaluating governance. We demonstrate a framework that makes this information transparent, through an application of the Freshwater Health Index in three different river basins in Latin America. Water Governance is measured on a 0–100 scale, using data derived from perception-based surveys administered to stakeholders. Results suggest that water governance is a primary area of concern in all three places, with low overall scores (Guandu-26, Alto Mayo-38, Bogotá-43). We conclude that this approach to measuring governance at the river basin scale provides valuable information to support monitoring and decision making, and we offer suggestions on how it can be improved.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01407-8) contains supplementary material, which is available to authorized users.     

Dynamic characteristics of chlorine dispersion process and quantitative risk assessment of pollution hazard

Environmental Science and Pollution Research - The aim of this study was to analyze dispersion behavior characteristics and pollution hazard risk after a release of liquid chlorine. A full-scale...     

Long-term study of heavy metal pollution in the northern Hangzhou Bay of China: temporal and spatial distribution,contamination evaluation,and potential ecological risk

Environmental Science and Pollution Research - Coastal ecosystem is vulnerable to heavy metal contamination. The northern Hangzhou Bay is under intensifying impact of anthropogenic activities. To...     

Polycyclic aromatic hydrocarbon and n-alkane pollution characteristics and structural and functional perturbations to the microbial community: a case-study of historically petroleum-contaminated soil

Characterization of the typical petroleum pollutants, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, and indigenous microbial community structure and function in historically contaminated soil at petrol stations is critical. Five soil samples were collected from a petrol station in Beijing, China. The concentrations of 16 PAHs and 31 n-alkanes were measured by gas chromatography-mass spectrometry. The total concentrations of PAHs and n-alkanes ranged from 973 ± 55 to 2667 ± 183 μg/kg and 6.40 ± 0.38 to 8.65 ± 0.59 mg/kg (dry weight), respectively, which increased with depth. According to the observed molecular indices, PAHs and n-alkanes originated mostly from petroleum-related sources. The levels of ΣPAHs and the total toxic benzo[a]pyrene equivalent (ranging from 6.41 to 72.54 μg/kg) might exert adverse biological effects. Shotgun metagenomic sequencing was employed to investigate the indigenous microbial community structure and function. The results revealed that Proteobacteria and Actinobacteria were the most abundant phyla, and Nocardioides and Microbacterium were the important genera. Based on COG and KEGG annotations, the highly abundant functional classes were identified, and these functions were involved in allowing microorganisms to adapt to the pressure from contaminants. Five petroleum hydrocarbon degradation-related genes were annotated, revealing the distribution of degrading microorganisms. This work facilitates the understanding of the composition, source, and potential ecological impacts of residual PAHs and n-alkanes in historically contaminated soil.

     

Biodegradable microplastics (BMPs): a new cause for concern?

Environmental Science and Pollution Research - With the increasingly serious pollution of plastics, biodegradable plastics (BDPs) have attracted attention as a new material that can replace...