大亚湾养殖海区沉积物中营养盐的解吸-吸附

研究了天然海水体系大亚湾养殖海区表层沉积物营养盐的解吸 -吸附规律。结果表明 :沉积物中磷酸盐和硅酸盐解吸 2h基本达到平衡 ,而铵盐、硝酸盐和亚硝酸盐 0 5h内基本达到平衡 ;各营养盐的解吸随pH值 (小于 8)降低而增大 ,随pH值 (大于 8)升高略有增加 ;盐度仅在低于 1 0时对各营养盐的解吸有影响。研究了磷酸盐在沉积物上的吸附等温线。     

大亚湾养殖海区沉积物中营养盐的解吸——吸附

研究了天然海水体系大亚湾养殖海区表层沉积物营养盐的解吸－吸附规律。结果表明,沉积和扣磷酸盐和硅酸盐解吸２小时基本达到平衡,而铵盐、硝酸盐和亚硝酸盐０．５小时内基本达到平衡;各营养盐的解吸随ＰＨ值（小于８）降低而增大,随ＰＨ值（大于８）升高略有增加;盐度仅在低于１０时对各营养盐的解吸有影响。研究了磷酸盐在沉积物上的吸附等温线。     

中国东海陆架海域柱状沉积物对磷的吸附行为

通过研究磷在海洋柱状沉积物上的吸附动力学曲线和吸附等温线,并结合沉积物表面电荷性质以及磷形态分析,考察了我国东部陆架海域沉积物对磷的吸附特征。结果表明,所研究海域沉积物对磷的吸附过程明显分为快慢两段,48h后吸附可达到平衡;吸附后的磷主要为可交换态磷,吸附过程以物理作用为主;吸附等温线可用Langmuir交叉型模式描述,在磷初始浓度较低时,沉积物对磷存在解吸现象;沉积物对磷吸附参数的垂直分布较为复杂,受自身性质影响较大;盐度增大,沉积物对磷的吸附能力呈下降趋势。     

溶解性石油烃在砂上的吸附和解吸研究

采用海滨浴场的沙为吸附剂,0号柴油为吸附质,研究了溶解性石油烃（DPHs）在砂上的吸附及解吸规律.研究发现,砂对DPHs的吸附和解吸均符合一级反应模式;油的解吸速率比吸附速率慢13倍,并且有约25%的油残存于砂上, 因而污染威胁会在较长时间内存在.砂对海水中DPHs的吸附等温线可以用Henry型等温式描述,温度越高,海水中的油向砂上转移的量越小.通过吸附热力学分析,得出该吸附属于物理吸附范畴.     

黄河口海域沉积物对重金属的吸附

以黄河口海域表层沉积物为研究对象,研究沉积物对重金属Cu、Pb的吸附特性,将沉积物筛分为4种粒级,探讨粒度、pH值、吸附时间和吸附剂初始浓度对重金属吸附的影响。结果表明:沉积物粒径越小,对重金属的吸附量越大;吸附平衡时间有所差异,但在1.5h均能达到吸附平衡;吸附量均随pH值升高而逐渐增加,但铜的吸附较铅的吸附速度快;铜的吸附量与吸附剂初始浓度呈线性关系,而铅的吸附量在初始浓度较低时变化明显,随初始浓度增加吸附量增加减小;沉积物对铜吸附等温线符合Langmuir型,铅吸附等温线符合Freundlich型,吸附类型存在差异。重金属在沉积物中的吸附规律研究为黄河口海域污染调查及治理提供了科学依据。     

胶州湾沉积物表面酸碱性质及对铜的吸附

选取胶州湾海域2个站点的沉积物进行了表面酸碱电位滴定实验,并考察了人工海水介质中对铜离子的吸附性能,比较了介质的盐度和温度等对吸附动力学曲线和吸附等温线的影响.结果发现:2个站点的沉积物随pH值由3增大到10表面质子电荷密度的值由正转负,零净质子电荷点pHPZNPC均在4.0～4.5之间,表面位浓度Hs在1.34×104～1.90×10-4 mol·L-1之间;沉积物对铜离子的动力学吸附曲线可用伪一级动力学方程、伪二级动力学方程、Elovich方程、双常数速率方程拟合,其中伪二级动力学方程符合较好,吸附在2h左右达到平衡;吸附等温线可用Langmuir等温式拟合.零净质子电荷点低、表面位浓度大的沉积物对铜离子的吸附能力较强.蒸馏水介质中,沉积物对铜离子的饱和吸附量小于在稀释人工海水中和人工海水中的结果;较高的温度使饱和吸附量增大.     

胶州湾沉积物表面酸碱性质及对铜的吸附

选取胶州湾海域2个站点的沉积物进行了表面酸碱电位滴定实验,并考察了人工海水介质中对铜离子的吸附性能,比较了介质的盐度和温度等对吸附动力学曲线和吸附等温线的影响。结果发现:2个站点的沉积物随pH值由3增大到10表面质子电荷密度的值由正转负,零净质子电荷点pHPZNPC均在4.0～4.5之间,表面位浓度HS在1.34×10-4～1.90×10-4mol.L-1之间;沉积物对铜离子的动力学吸附曲线可用伪一级动力学方程、伪二级动力学方程、Elovich方程、双常数速率方程拟合,其中伪二级动力学方程符合较好,吸附在2 h左右达到平衡;吸附等温线可用Langmuir等温式拟合。零净质子电荷点低、表面位浓度大的沉积物对铜离子的吸附能力较强。蒸馏水介质中,沉积物对铜离子的饱和吸附量小于在稀释人工海水中和人工海水中的结果;较高的温度使饱和吸附量增大。     

不同海域沉积物对尿素吸附的实验模拟研究

本文对采自渤海、黄海和东海3个典型海域的沉积物进行了尿素吸附/解吸的实验室模拟研究，用Freundlich吸附模型和Henry吸附模型分析了不同沉积物对尿素吸附的热力学特性，并研究了温度、沉积物粒径、有机质含量等因素对尿素在沉积物表面吸附的影响。结果表明，沉积物对尿素的吸附/解吸过程总体呈现3个阶段:快速吸附阶段（0~5 h）—慢速吸附阶段（5~12 h）—平衡阶段（12 h之后）。当水体中的尿素浓度较低时，沉积物解吸释放尿素，随着上覆水中尿素浓度逐渐增加，沉积物对上覆水中的尿素产生吸附行为，各海区沉积物对尿素的吸附能力由强至弱依次为渤海、东海、黄海，这可能与沉积物的类型有关。Freundlich方程和Henry方程均可模拟沉积物对尿素的吸附，温度、粒径以及沉积物中有机质含量等因素均对尿素在沉积物上的吸附产生影响，随着温度升高，尿素在沉积物上的吸附量变小，沉积物粒径越小，有机质含量越高，吸附尿素的能力越强，因此，揭示尿素在沉积物表面的环境行为时，必须考虑以上因素的影响。     

两种铁氧化物对无机磷的吸附特征分析

沉积物是海洋生态系统磷循环的载体之一,铁氧化物作为海洋沉积物活性组分的重要部分,对磷在沉积物上的吸附解吸有着重要贡献,进而影响着磷在沉积物-水界面的交换。本文利用自行合成的α-Fe_2O_3和无定形氧化铁,研究了无机磷(以KH_2PO_4为例)在其上的吸附特征,并考察了离子强度等对该吸附过程的影响。结果表明,无定形氧化铁对无机磷的吸附平衡时间较短且吸附量较大,这与其较差的结晶度,较大的比表面积有关。无机磷在氧化铁上的吸附等温线符合Freundlich吸附等温式,研究发现两种铁氧化物的吸附热力学函数均为ΔH~θ0,ΔG~θ0,ΔS~θ0,说明整个吸附过程是吸热、自发、熵增加的过程;随着离子强度的增大,无机磷在两种铁氧化物上的平衡吸附量增加,吸附pH边曲线实验发现,无定形氧化铁对无机磷的吸附量随着pH的升高而减小。     

黄河口磷酸盐缓冲机制的探讨──Ⅰ.黄河口悬浮物对磷酸盐的吸附-解吸研究

以黄河口为研究对象,通过对温度、盐度、平衡时间、悬浮物含量等模拟河口现场条件,对黄河口磷酸盐的缓冲机制进行了探讨。黄河口悬浮物对磷酸盐的吸附和解吸一般在4－5h后就已趋于平衡;随着水体悬浮物含量的增加,对磷酸盐的吸附-解吸量呈指数形式下降,粒度减小使吸附量-解吸量呈指数形式增加;盐度对解吸量的影响程度大于吸附量,最大吸附和最小解吸出现在低盐度区;温度对吸附-解吸平衡的影响较大,随温度升高吸附量和解吸量均呈线性关系增加,且平衡时间有所延长。     

沉积物对磷酸盐的吸附与释放

本实验研究黄河口水文站沉积物对黄河水磷的吸附释放过程和东海１１１号站位沉积物对海水磷的吸附释放过程。并摸拟黄河沉积物在海水中磷的吸附释放过程。结果表明：底沉积物对磷的吸附相当迅速，无论是河泥还是海泥在２４ｈ内均能达到吸附平衡。吸附量与沉积物的量和水中原有磷的浓度有关，在不同的ｐＨ条件下，沉积物对磷的吸附是有显著差别的     

Adsorption–desorption reactions and bioturbation transport of 224Ra in marine sediments: a one-dimensional model with applications

The distribution of trace metals in sediments and their exchange between sediments and overlying water is governed by multiple processes including molecular diffusion, bioturbation (porewater advection, porewater mixing, and particle mixing), chemical reactions and adsorption–desorption. To understand these processes and their relative contributions, a one-dimensional model was built, which includes bioturbation and adsorption–desorption processes, to describe the transport of ²²⁴Ra. Because ²²⁴Ra is adsorbed on MnO₂, ²²⁴Ra may serve as a proxy for trace metal transport. Three sites were sampled and both dissolved and adsorbed ²²⁴Ra were analyzed and modeled to understand the transport and exchange processes. It was found that particle transport of adsorbed ²²⁴Ra followed by desorption at the sediment/water interface typically represents the dominant flux. We have further been able to define conditions where the porewater transport for adsorption reactive metals like ²²⁴Ra (and other metals) may be out of the sediments whereas the active scavenging of ²²⁴Ra from the water column at the sediment water interface via adsorption reactions can result in a flux of ²²⁴Ra into the sediment. These processes are both predicted by the model and observed in sediment samples.     

Adsorption–desorption reactions and bioturbation transport of Ra in marine sediments: a one-dimensional model with applications

The distribution of trace metals in sediments and their exchange between sediments and overlying water is governed by multiple processes including molecular diffusion, bioturbation (porewater advection, porewater mixing, and particle mixing), chemical reactions and adsorption–desorption. To understand these processes and their relative contributions, a one-dimensional model was built, which includes bioturbation and adsorption–desorption processes, to describe the transport of ²²⁴Ra. Because ²²⁴Ra is adsorbed on MnO₂, ²²⁴Ra may serve as a proxy for trace metal transport. Three sites were sampled and both dissolved and adsorbed ²²⁴Ra were analyzed and modeled to understand the transport and exchange processes. It was found that particle transport of adsorbed ²²⁴Ra followed by desorption at the sediment/water interface typically represents the dominant flux. We have further been able to define conditions where the porewater transport for adsorption reactive metals like ²²⁴Ra (and other metals) may be out of the sediments whereas the active scavenging of ²²⁴Ra from the water column at the sediment water interface via adsorption reactions can result in a flux of ²²⁴Ra into the sediment. These processes are both predicted by the model and observed in sediment samples.     

Adsorption and desorption of proteins and polyamino acids by clay minerals and marine sediments

The adsorption and desorption of proteins and polyamino acids on illite, montmorillonite, goethite, and marine sediments was investigated. Three ¹⁴C-labeled hydrophilic proteins, Rubisco from C. reinhardtii, and GroEL and GroES from genetically modified Escherichia coli, were synthesized and purified for this study. The proteins were strongly and rapidly adsorbed by the clay minerals and marine sediments, and much of the adsorbed protein was not readily desorbed. Sodium dodecyl sulfate (SDS) extraction and separation by SDS-polyacrylamide gel electrophoresis (PAGE) and sucrose density gradients showed that Rubisco and GroEL were adsorbed on illite and sediments in their original forms. The apparent adsorption partition coefficients of the proteins were on the order of 10² l/kg on illite, 10³–10⁴ l/kg on goethite and montmorillonite, and 200 and 75 l/kg on Skan Bay and Resurrection Bay (Alaska) sediments, respectively. These partition coefficients are sufficiently large to permit sedimentary protein preservation via an adsorptive mechanism. Generally, basic polyamino acids had greater adsorption partition coefficients than acidic polyamino acids. Molecular size did not affect the electrostatic interaction between polyamino acids and mineral surfaces. Adsorption of bovine serum albumin (BSA) and negatively charged polyamino acids inhibited Rubisco adsorption, while positively charged cytochrome c and polyamino acids increased Rubisco adsorption. These results indicate that electrostatic interactions dominated in protein adsorption.     

长江口潮滩表层沉积物对NH4+-N的吸附特征

沉积物对NH₄+-N的吸附是氮素生物地球化学循环的关键过程之一,它在河口潮滩生态系统内氮素循环过程中起着非常重要的作用.以长江口滨岸潮滩为研究区域,运用实验模拟的方法,研究了沉积物对NH₄+-N的吸附特征,结果表明,在长江口潮滩上覆水和孔隙水中NH₄+-N含量的变化范围内,沉积物对NH₄+-N的吸附呈线性变化;研究区域内沉积物对NH₄+-N的吸附系数为3.81~9.00,且与沉积物中有机碳(TOC)含量有良好的相关关系,它揭示了有机质控制着长江口潮滩沉积物中NH₄+-N的吸附行为.实验模拟与实测结果对比发现,在潮滩自然环境条件下,研究区域内沉积物对NH₄+-N的吸附处在非热力学平衡状态过程中.盐度是影响NH₄+-N吸附过程的重要环境因子,且导数方程关系式在低盐度范围内,盐度的微小变化对NH₄+-N的吸附有显著的影响.     

环境因子对菲在黄河口沉积物上吸附的影响

为研究多环芳烃从河口到近海的环境归趋行为与生态风险,考察了沉积物质量浓度、溶解性有机质、温度、盐度4种典型环境因子对菲在黄河口沉积物上吸附的影响,比较了黄河口与近海两种沉积物对菲的吸附性能。研究结果表明,沉积物质量浓度越低,单位质量颗粒物的菲吸附量越高;共存的溶解性有机质对菲的吸附具有增促作用,且腐殖酸比黄腐酸的作用更显著;温度的升高不利于菲的吸附,而盐度的增加有利于菲的吸附。菲在沉积物上的吸附是分配作用与表面吸附两种行为的耦合,其中黄河口沉积物以表面吸附为主,而近海沉积物以分配作用为主。近海沉积物菲吸附量显著高于黄河口沉积物菲吸附量。基于此,菲从河口到近海的迁移过程中,更易于在沉积物表面发生吸附沉降,从而可能降低水相中的生态危害,但对近海底栖生物具有潜在的健康生态风险。     

Vegetable oil spills on salt marsh sediments; comparison between sunflower and linseed oils

The effects of a simulated spill of sunflower oil in salt marsh sediments were compared with an experiment with linseed oil. Sunflower and linseed oil penetrated the sediments at the same rates but different adsorption of the oils onto sediment particles resulted in the establishment of anaerobic conditions at shallower depths in sediments contaminated with linseed oil than with sunflower oil. The total lipid content of sunflower oil contaminated sediments remained almost stable for 6 months, whilst only 40% of linseed oil remained in the sediment after 2 months. Numbers of culturable heterotrophic bacteria and aerobic oil degrading bacteria in muddy sediment increased rapidly in response to the presence of the oils but bacterial numbers in sandy sediments increased more slowly for sunflower oil. Changes in fatty acid composition indicate similar degradation pathways for both oils but sunflower oil degraded more slowly than linseed oil and thus has the potential for longer lasting effects in marine environments.     

New perspectives on radium behavior within a subterranean estuary

Over the past decade, radium isotopes have been frequently applied as tracers of submarine groundwater discharge (SGD). The unique radium signature of SGD is acquired within the subterranean estuary, a mixing zone between fresh groundwater and seawater in coastal aquifers, yet little is known about what controls Ra cycling in this system. The focus of this study was to examine controls on sediment and groundwater radium activities within permeable aquifer sands (Waquoit Bay, MA, USA) through a combination of field and laboratory studies. In the field, a series of sediment cores and corresponding groundwater profiles were collected for analysis of the four radium isotopes, as well as dissolved and sediment associated manganese, iron, and barium. We found that in addition to greater desorption at increasing salinity, radium was also closely tied to manganese and iron redox cycling within these sediments. A series of laboratory adsorption/desorption experiments helped elucidate the importance of 1) contact time between sediment and water, 2) salinity of water in contact with sediment, 3) redox conditions of water in contact with sediment, and 4) the chemical characteristics of sediment on radium adsorption/desorption. We found that these reactions are rapid (on the order of hours), desorption increases with increasing salinity and decreasing pH, and the presence of Fe and Mn (hydr)oxides on the sediment inhibit the release of radium. These sediments have a large capacity to sorb radium from fresh water. Combined with these experimental results, we present evidence from time series groundwater sampling that within this subterranean estuary there are cyclic periods of Ra accumulation and release controlled by changing salinity and redox conditions.