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901.
Xiang Yang Sun Cheng Da Gao Lin Zhang Su Yan Li Yong Qiao 《Environmental monitoring and assessment》2011,175(1-4):193-200
CO2 release from forest soil is a key driver of carbon cycling between the soil and atmosphere ecosystem. The rate of CO2 released from soil was measured in three forest stands (in the mountainous region near Beijing, China) by the alkaline absorption method from 2004 to 2006. The rate of CO2 released did not differ among the three stands. The CO2 release rate ranged from ??341 to 1,193 mg m???2 h???1, and the mean value over all three forests and sampling times was 286 mg m???2 h???1. CO2 release was positively correlated with soil water content and the soil temperature. Diurnally, CO2 release was higher in the day than at night. Seasonally, CO2 release was highest in early autumn and lowest in winter; in winter, negative values of CO2 release suggested that CO2 was absorbed by soil. 相似文献
902.
Tsung-Hung Hsu Jen-Yang Lin Tsu-Chuan Lee Harry X. Zhang Shaw L. Yu 《Environmental monitoring and assessment》2010,163(1-4):81-94
It is vitally important to define the critical condition for a receiving water body in the total maximum daily load (TMDL) development process. One of the major disadvantages of using a continuous simulation approach is that there is no guarantee that the most critical condition will be covered within the subjectively selected representative hydrologic period, which is usually several years depending on the availability of data. Another limitation of the continuous simulation approach, compared to a design storm approach, is the lack of an estimate of the risk involved. Because of the above limitations, a storm event-based critical flow-storm (CFS) approach was previously developed to explicitly address the critical condition as a combination of a prescribed stream flow and a storm event of certain magnitude, both having a certain frequency of occurrence and when combined, would create a critical condition. The CFS approach was tested successfully in a TMDL study for Muddy Creek in Virginia. The present paper reports results of a comparative study on the applicability of the CFS approach in Taiwan. The Dy-yu creek watershed in northern Taiwan differs significantly from Muddy Creek in terms of climate, hydrology, terrain, and other characteristics. Results show that the critical condition for different watersheds might be also different, and that the CFS approach could clearly define that critical condition and should be considered as an alternative method for TMDL development to a continuous simulation approach. 相似文献
903.
904.
采用全二维气相色谱-飞行时间质谱法(GC×GC TOF-MS)分析了混标样品Aroclor 1260、Aroclor 1254、Aroclor 1242中的多氯联苯(PCBs)单体,考察了在复杂体系下对7种PCBs指示剂的分离能力。结果表明,与优化柱系统的分离效果相比,136种单体的混标样品中共分离出121种单体,7种指示剂经一维和二维的保留时间及质谱定性,在121种单体的2D斑点图中清晰可辨。全二维对于复杂体系的PCBs和指示剂的分离表明其强大的分离能力和对于检测复杂体系中指示剂的分辨能力,对该类物质的定性和定量检测具有重要意义。 相似文献
905.
固相微萃取-气相色谱法测定废水中三乙胺和苯胺 总被引:4,自引:0,他引:4
采用固相微萃取-气相色谱法建立了测定废水中三乙胺和苯胺的方法,对萃取条件和气相色谱条件进行了优化。方法的相对标准偏差为0.5%~0.8%,加标回收率为96.3%~107.0%。总分析时间小于1h,适用于快速分析废水中胺类化合物。 相似文献
906.
907.
生态系统功能与生态系统服务的概念辨析 总被引:4,自引:0,他引:4
"生态系统功能(Ecosystem functions)"和"生态系统服务(Ecosystem services)"已成为生态学中的重要研究领域.针对国内部分研究人员对"生态系统功能"与"生态系统服务(功能)"概念和术语混淆使用的问题,在归纳总结国内外有关的重要研究的基础上,通过分别论述"生态系统功能"与"生态系统服务"的定义和内涵,辨析和阐明了生态系统"功能"与"服务"的区别与关系.生态系统功能是构建系统内生物有机体生理功能的过程,侧重于反映生态系统的自然属性,是维持生态系统服务的基础;生态系统服务是由生态系统功能产生的,是基于人类的需要、利用和偏好,反映了人类对生态系统功能的利用,是生态系统功能满足人类福利的一种表现.因此"生态系统服务功能"这一术语不准确,容易产生误解. 相似文献
908.
介绍了江苏省重污染天气监测预报预警系统以及大气重污染预警会商流程,将2015年13个地级市的模式预报、人工预报结果分别与实际观测值进行比较。结果表明:人工预报更准确,PM_(2.5)日均值、臭氧日最大8 h平均值、AQI 3个指标人工预报和实况的相关性分别比模式预报高出12.8%、0.3%、11.4%,平均标准误差(MNE)分别低20.7%、3.1%、23.1%。依据国家空气质量预报技术指南评分办法,对各市2015年全年空气质量级别为"良"时进行评分。通过开展07∶00预报更新,使2015年上半年空气质量预报级别得分平均提高了0.9分,全年级别得分平均提高了2.6分;通过改进模式预报参数,使PM_(2.5)日均预报值、臭氧日最大8 h平均预报值、AQI预报值和实际观测值的相关性比上年同期分别提高26.0%、5.0%、33.9%,MNE分别降低3.6%、31.3%、7.6%。 相似文献
909.
Yunpeng Yu Fanghong Nie Anthony Hay Hongying Lin Yi Ma Xianghong Ju Dongliang Gong Jinjun Chen Ravi Gooneratne 《Environmental monitoring and assessment》2017,189(6):289
Dioxin-like polychlorinated biphenyls (DLPCBs) are ubiquitous persistent pollutants that cause adverse effects in many environmental organisms. DLPCBs in marine sediments can be absorbed by benthic organisms, bioaccumulate, and biomagnify through the food chain and threaten animal and human health. There are no reports of DLPCBs concentrations in the Zhanjiang Gulf seabed. This study was designed to investigate the concentration of DLPCBs in the Zhanjiang coastal sediment and histopathological changes in zebrafish (Diano rerio) embryos exposed to environmentally relevant concentrations of DLPCBs. Of the five sites selected, two sites TS and JSW contained DLPCBs at concentrations of 0.08 and 22.54 ng/g dry sediment, respectively. Two groups of zebrafish embryos were used. One group was exposed to 3.75, 7.5, 15, 30, and 60 mg/ml of DLPCBs extracted from the sediments sampled from the TS site and the second group to 4.375, 8.75, 17.5, 35, and 70 mg/ml of DLPCBs from JSW site from 0.75 h post-fertilization (hpf) to 96 hpf. The zebrafish exposed to 60 and 70 mg/ml of DLPCBs at 96 hpf displayed gross histopathological changes with cardiac lesions including pericardial edema being the most deleterious. Other changes observed were hydropic degeneration of gill filaments and hepatocytes, loss of intestinal folds, and uninflated swim bladder. It appears that only a few sites of the Zhanjiang gulf are contaminated with DLPCBs. This is the first report of histopathological changes in the gills, hepatocytes, intestines, heart, and the swim bladder in zebrafish embryos exposed to DLPCBs from a coastal sediment. Further studies with sampling at different stages of development are required to identify which organ/tissue is most sensitive to DLPCBs. 相似文献
910.
高灵敏XRF测定废水中痕量砷 总被引:2,自引:0,他引:2
本文提出了在硫酸介质中,以锌粒还原产生氢化物,溴化铜溶液吸收,微孔滤膜过滤制成薄样,X射线荧光测定水中痕量砷的分析方法。 相似文献