秋季东海二甲基硫和二甲巯基丙酸内盐浓度分布及降解速率研究   总被引：1，自引：0，他引：1  

杨桂朋  刘龙  张洪海 《中国海洋大学学报(自然科学版)》2014,44(10):86-91

于2013年10~11月现场测定了东海中二甲基硫(DMS)及其前体物质二甲巯基丙酸内盐(DMSP,分为溶解态DMSPd和颗粒态DMSPp)的含量,研究其水平分布特征、DMSPp的粒径分布及DMSPd的降解速率,并对DMS的海-气交换通量进行了探讨。研究结果表明,表层海水中DMS、DMSPd和DMSPp的浓度平均值分别为(4.84±0.40)、(5.84±0.93)和(13.01±0.52)nmol·L-1。海水中DMSPd的降解速率在2.59~16.36nmol·L-1·d-1之间,平均值为(6.78±0.84)nmol·L-1·d-1。调查海域范围内,小型浮游植物(20μm)是DMSPp和叶绿素a(Chl a)重要贡献者。此外,秋季东海表层海水DMS的海-气交换通量为0.66~31.73μmol·m-2·d-1,平均值为(11.63±0.71)μmol·m-2·d-1。  相似文献   

Dynamics of communal land degradation and its implications in the arid mountains of pakistan: A study of District Karak,Khyber Pakhtunkuwa     

Iffat TABASSUM  Fazlur RAHMAN  Fazlul HAQ 《山地科学学报》2014,11(2):485-495

Similar to other areas of Pakistan, land resources in Khyber Pakhtunkhwa （KP） is kept under various ownership regimes for socio-economic and ecological benefits. For the last three to four decades, communal lands and resources are subjected to high rate of degradation and deterioration, which is leading to multifarious socio-economical and ecological implications. This paper intends to look into factors that are responsible for the degradation of communal land and the adaptability of the management mechanisms developed by the local inhabitants to conserve these resources. Moreover, this study also explores the sustainability of these adopted strategies in present circumstances. Data regarding socio-economic parameters of the inhabitants and their interactions with communal lands were collected through questionnaire cum interview method. As long-term climatic data for the area do not exist therefore focus group discussions were conducted to document the changing trend in rainfall regimes and temperature variations for the last about four decades. Results indicate that communal lands are highly vulnerable to degradation due to biophysical and anthropogenic factors. Local inhabitants have developed suitable measures to control the situation, however, accelerated socio-economic transformations in the area have weakened the role of local institutions and that led to further degradation of these resources. Nevertheless, a number of locally formulated rules have been revived and implemented and it is hoped that these threatened resources would be conserved.  相似文献   

热处理改性天然闪锌矿的可见光催化性能研究     

殷义栋  李艳  颜云花  鲁安怀 《岩石矿物学杂志》2013,32(6):825-832

天然闪锌矿是一种具有良好可见光催化性能的半导体光催化剂,然而其结构缺陷会成为光生电子的捕获阱,导致其光催化反应效率降低。为了进一步提高其可见光催化效率,本文在空气气氛下对天然闪锌矿进行了500～1 200℃的热处理改性实验研究,并利用X射线衍射(XRD)、紫外-可见漫反射吸收光谱(UV-Vis DRS)对热改性后样品的半导体物理化学性质进行了初步的表征分析;然后以甲基橙为目标降解物进行了热处理样品的光催化实验研究。研究结果显示,空气气氛下的热处理随着温度的逐渐升高,闪锌矿物相先转变为氧化硫酸锌,再转变为红锌矿和锌铁尖晶石,到1 100～1 200℃时样品完全转变为红锌矿-锌铁尖晶石二元复合半导体光催化剂,此时样品在可见光下对甲基橙的降解率从原样的54.2%提高到99.7%,1 100～1 200℃改性后样品的可见光催化性能最好。  相似文献   

磁性4A分子筛的制备及其对氨氮的吸附动力学研究     

杨哲  庆承松  陈冬  彭书传  舒林  郑思灿  陈天虎 《岩石矿物学杂志》2013,32(6):935-940

以高岭土为原料,采用水热法在晶化前加入合成磁铁矿制得Fe₃O₄含量为 4.48%的磁性4A分子筛。通过X 射线粉末衍射分析(XRD)、磁化率分析(MS)及磁回收效果实验对制备的磁性4A分子筛进行物性分析,并将该吸附材料应用于氨氮吸附实验,将吸附实验数据根据相应吸附等温方程进行拟合,随后使用动力学分析手段考查了其吸附过程反应机理。表征结果表明,Fe₃O₄的载入对分子筛的晶体结构影响不大,磁性4A分子筛磁化率稳定,可用来重复使用。该分子筛可以通过磁性分离进行回收,且磁性分离快速高效。吸附实验结果表明磁性4A分子筛容易吸附水中的氨氮,Fe₃O₄的载入对于分子筛本身的吸附容量影响较小。在Langmuir、Freundlich两种等温吸附模型拟合结果中,Freundlich曲线拟合效果更好。Lagergren准二级吸附动力学拟合结果表明,NH⁺₄在磁性4A分子筛上的吸附过程遵循准二级动力学反应机理。  相似文献   

暂堵型钻井液的试验研究   总被引：1，自引：0，他引：1  

蔡记华  乌效鸣  潘献义  李新夫 《地质科技情报》2004,23(3):97-100

针对钻井工程中出现的护壁堵漏与保护地层渗透性的矛盾,提出了利用羧甲基纤维素钠、胍尔胶、魔芋等聚合物,并结合现代生物技术中聚合物的断链降解原理,开发出适合于石油、天然气、地下水等钻井领域的自动降解无伤害钻井液--暂堵型钻井液,与传统的暂堵剂不同,它在钻进完成后不需要采用解堵工艺,如压力解堵、酸化解堵、油溶解堵、破胶等,从根本上改进了解堵工艺;分析了暂堵型钻井液的基本原理和两种典型聚合物的酶降解原理,并介绍了室内的粘度实验、渗透性恢复测试实验和在甘肃张掖和广西柳州的现场试验;理论和实践均证明,暂堵型钻井液能自动降解,对产层无伤害,在进行有效护壁堵漏的同时,还能在可控制的时间内显著地恢复地层的渗透性,因此具有推广价值.  相似文献   

Leaf litter degradation in highly turbid transitional waters: preliminary results from litter-bag experiments in the Gironde Estuary     

A. Fuentes-Cid  E. Chauvet  H. Etcheber  E. De-Oliveira  A. Sottolichio  S. Schmidt 《Geodinamica Acta》2013,26(1):60-66

The rates of decomposition of oak (Quercus robur) leaves have been examined using litter bags in a very high turbidity macrotidal estuary, the Gironde Estuary (S.W. France). The first experiments show a marked decrease in the decomposition rate of oak leaves at the water-sediment interface (mud-contact: anoxic conditions, reduced physical fragmentation) in comparison to the water column. The results point out the impact of hydrodynamic conditions on leaf litter degradation in such fluvio-estuarine systems. Regarding the aquatic-terrestrial linkage, our observations suggest direct changes in leaf decomposition kinetics and then, a potential delay on the recycling and transport processes of coarse particulate organic matter, especially in a context of modification of the natural water flow, due to global and land use changes.  相似文献   

CO2-Water-Rock Interactions during Geological CO2 Storage     

ZHU Chen  JI Xaioyan 《《地质学报》英文版》2013,87(Z1):987-987

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Acetate in recent anoxic sediments: Direct and indirect measurements of concentration and turnover rates     

David G. Shaw  Douglas J. McIntosh 《Estuarine, Coastal and Shelf Science》1990,31(6)

While acetate is generally regarded as an important intermediate in the mineralization of organic matter in anoxic sediment systems, some quantitative studies in marine systems (including our own) have measured acetate oxidation rates in excess of sulphate reduction rates where sulphate is known to be the principal electron acceptor. We revisited Skan Bay, Alaska, where we had previously made such observations, for a reexamination of acetate turnover. Measurements of acetate concentrations, production rate, oxidation rate and sulphate reduction rate as well as bioenergetic considerations led to the conclusion that acetate oxidation rate in 15–18-cm deep sediment is 1·1–1·5 μM h⁻¹. The possibility that previous measurements were high because of a non-citric-acid-cycle pathway of acetate oxidation (suggested by recent laboratory studies) was excluded. It appears that our previous turnover measurements were high mainly because of high acetate concentrations. Procedures used for the isolation of porewater for acetate determination may influence results to an extent not previously recognized.  相似文献   

Organic Matter Derived from a Seagrass Meadow: Origin, Properties, and Quality of Particles   总被引：1，自引：0，他引：1  

Branko  Velimirov 《Marine Ecology》1987,8(2):143-173

Abstract. An investigation of the properties of particles found in wrack beds and suspended in the water body of a Posidonia oceanica system led to the following conclusion: except for the period of the leaf fall and at times of strong water movement (e. g. winter storms), the majority of the particles in the water show no similarity with seagrass particles. This is based on the comparison of C: N ratios and SEM inspection. Information on the magnitude of DOC fluxes in this system led to the formulation of the phase shift hypothesis from DOM to POM. Because wrack particles were shown to have relatively fast settling rates, it is expected that processes like adsorption onto inorganic particles, micellation and aggregate formation have more importance in regulating particle density in the water body than the resuspension of directly fractionated Posidonia debris. The implication of these findings are discussed and the importance of the Mediterranean seagrass P. oceanica as an energy source supporting secondary production in adjacent ecosystems is questioned.  相似文献   

厦门筼筜湖污染疏浚物中铜在海水的释放动力学     

陈松  林汝健 《台湾海峡》1993,(1)

本工作模拟研究了厦门筼筜污染疏浚物中的Cu 在海水中的释放动力学。Cu 在海水中的释放比较缓慢,在一周内才基本达到平衡.平衡溶出率约10%,平衡时Cu 的质量浓度达13μg/dm~3。溶出过程可用交换吸附动力学模式描述。测得溶出速率常数k_2为0.04～0.20d~(-1),表现活化能E_2≈121kJ/mol,表明Cu 与疏浚物主要以化学作用形式相互结合。本研究结果为疏浚物海上倾倒的环境评估和预测提供定量依据。  相似文献