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Ham PA Prommer H Olsson AH Schotting RJ Grathwohl P 《Journal of contaminant hydrology》2007,93(1-4):304-315
A model-based interpretation of laboratory-scale experimental data is presented. Hydrolysis experiments carried out using thin glass tanks filled with glass beads to construct a hypothetical and inert, homogeneous porous medium were analysed using a 2D numerical model. A new empirical formula, based upon results for non-reactive (tracer) experiments is used to calculate transversal dispersivity values for a range of grain sizes and any flow velocities. Combined with effective diffusion coefficients calculated from Stokes-Einstein type equations, plume lengths arising from mixing between two solutes can be predicted accurately using numerical modelling techniques. Moreover, pH and ion concentration profiles lateral to the direction of flow of the mixing species can be determined at any given point downstream, without the need for result fitting. In our case, this approach does not lead to overpredictions of lateral mixing, as previously reported when using parameters derived from non-reactive tracer experiments to describe reactive solute transport. The theory is based on the assumption of medium homogeneity. 相似文献
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Xiaoshan Zhou Wan Wei Xiaoran Duan Hui Zhang Xiaolei Feng Tuanwei Wang 《Journal of environmental science and health. Part. B》2020,55(6):525-529
AbstractTelomere length was found to be associated with omethoate exposure and polymorphisms in certain genes among occupational workers. However, whether the polymorphisms in telomere-binding protein genes influence telomere length remains unclear. To explore the correlation between telomere length and polymorphisms in telomere-binding protein genes, telomere length in peripheral blood leukocytes was determined by real-time quantitative polymerase chain reaction in 180 omethoate-exposed workers and 115 healthy controls. Polymorphisms in 10 pairs of alleles were detected using flight mass spectrometry or polymerase chain reaction–restriction fragment length polymorphism technique. The results showed that individuals with GG genotype in TRF1 rs3863242 had longer telomere lengths than those with AG?+?AA genotype in the control group (p?=?0.005). The multiple regression analysis suggested that both omethoate exposure (b?=?0.526, p?<?0.001) and TRF1 rs3863242 GG (b?=?0.220, p?=?0.002) were related to a longer telomere length. In conclusion, GG genotype in TRF1 rs3863242 is linked to prolongation of telomere length, and individuals with GG genotype are recommended to strengthen health protection in a Chinese occupational omethoate-exposed population. 相似文献
215.
Jessica R. Quinlan Shannon J. O'Leary Andrew T. Fields Martin Benavides Emily Stumpf Ramon Carcamo Joel Cruz Derrick Lewis Beverly Wade George Amato Sergios-Orestis Kolokotronis Gina M. Clementi Demian D. Chapman 《Conservation biology》2021,35(3):991-1001
Developing-world shark fisheries are typically not assessed or actively managed for sustainability; one fundamental obstacle is the lack of species and size-composition catch data. We tested and implemented a new and potentially widely applicable approach for collecting these data: mandatory submission of low-value secondary fins (anal fins) from landed sharks by fishers and use of the fins to reconstruct catch species and size. Visual and low-cost genetic identification were used to determine species composition, and linear regression was applied to total length and anal fin base length for catch-size reconstruction. We tested the feasibility of this approach in Belize, first in a local proof-of-concept study and then scaling it up to the national level for the 2017–2018 shark-fishing season (1,786 fins analyzed). Sixteen species occurred in this fishery. The most common were the Caribbean reef (Carcharhinus perezi), blacktip (C. limbatus), sharpnose (Atlantic [Rhizoprionodon terraenovae] and Caribbean [R. porosus] considered as a group), and bonnethead (Sphyrna cf. tiburo). Sharpnose and bonnethead sharks were landed primarily above size at maturity, whereas Caribbean reef and blacktip sharks were primarily landed below size at maturity. Our approach proved effective in obtaining critical data for managing the shark fishery, and we suggest the tools developed as part of this program could be exported to other nations in this region and applied almost immediately if there were means to communicate with fishers and incentivize them to provide anal fins. Outside the tropical Western Atlantic, we recommend further investigation of the feasibility of sampling of secondary fins, including considerations of time, effort, and cost of species identification from these fins, what secondary fin type to use, and the means with which to communicate with fishers and incentivize participation. This program could be a model for collecting urgently needed data for developing-world shark fisheries globally. Article impact statement: Shark fins collected from fishers yield data critical to shark fisheries management in developing nations. 相似文献
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长江中下游湖泊超微型真核藻类遗传多样性研究 总被引:3,自引:0,他引:3
用流式分选结合末端限制性片段长度多态性的方法对长江中下游30个湖泊中超微型真核藻类的遗传多样性进行了研究,以了解不同环境条件下超微型真核藻类多样性的分布规律及其影响的主要因子.长江中下游湖泊大都已富营养化,但超微藻的群落组成差异仍然很大,T-RFLP分析共发现197个T-RFs,有45%的T-RFs(89个)仅在不到3个湖泊中检测到,聚类分析中各湖相似度均低于80%.中营养水平湖泊中多样性指数较高,总氮浓度与超微型真核藻类群落结构显著相关(P=0.006),CCA分析中,第一轴与第二轴共解释了10.0%的超微型真核藻类群落组成的变化.本研究表明,湖泊中超微型真核藻类群落组成的环境异质性明显,其多样性与湖泊营养水平密切相关,此外其它非生物因素对其群落组成也可能存在重要影响. 相似文献
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基于二甘醇的扫描电迁移率粒径谱仪(DEG-SMPS)是常用的1~3 nm颗粒物粒径分布测量系统.目前对1~3 nm颗粒物在该系统中通过效率的量化不够准确,这给大气颗粒物粒径分布的测量带来了较大的不确定性.本文研究了1~3 nm颗粒物和离子在直管、弯管以及气溶胶中和器等系统组件中的通过效率,并使用等效管长法来量化颗粒物在这些组件单元中的通过效率.研究表明,1~3 nm颗粒物在直管内的通过效率不受颗粒物电性影响,且可以由Gormley-Kennedy (G-K)方程估算.当采样流量为2.5 L·min~(-1)时,DEG-SMPS系统中总等效管长约为433 cm,其中气溶胶中和器的等效管长为160 cm,弯头的等效管长为33 cm. 相似文献
220.
游离氨(FA)耦合曝气时间对硝化菌活性的抑制影响 总被引:11,自引:11,他引:0
本试验采用3个标记为R_(Ahead)、R_(Exact)和R_(Exceed)的序批式反应器(SBR),在实现短程硝化的基础上,深入研究了游离氨(FA)耦合曝气时间对氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)活性的抑制影响.本试验在3种FA浓度(0.5、5.1、10.1mg·L~(-1))耦合3种曝气时间(t_(Exact):氨被完全氧化时停曝气;t_(Ahead):氨被完全氧化前30 min停曝气;t_(Exceed):氨被完全氧化后30min停曝气)的条件下进行.结果表明,当FA浓度达到10.1 mg·L~(-1)时,3种系统均实现了短程硝化,但短程硝化实现的快慢关系为:R_(Ahead)最快、R_(Exact)次之、R_(Exceed)最慢,其所需运行周期分别为56、62和72.此外,3种系统中,相对于AOB,NOB活性受到的抑制作用更强,导致AOB活性始终高于NOB活性,且AOB和NOB菌属活性(η)强弱关系差异较大,AOB活性强弱关系:η_(RExceed)η_(RExact)η_(RAhead),其值分别为104.4%、100%和85.8%,NOB活性强弱关系:η_(RExceed)η_(RExact)η_(RAhead),其值分别为71.2%、64.9%和50.2%. 相似文献