THE IMPORTANCE OF THE DIFFUSIVE PERMEABILITY OF ANIMAL BURROW LININGS IN DETERMINING MARINE SEDIMENT CHEMISTRY
THE IMPORTANCE OF THE DIFFUSIVE PERMEABILITY OF ANIMAL BURROW LININGS IN DETERMINING MARINE SEDIMENT CHEMISTRY
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DOI：
10.1357/002224083788520225
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发表时间：
1983-01-01
影响因子：
0.5
通讯作者：
ALLER, RC
中科院分区：
文献类型：
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作者：
ALLER, RC
动物在海洋沉积物中形成的许多丰富的洞穴都有薄薄的有机物质层。这些衬里对溶质扩散的渗透性可以是周围沉积物和洞穴栖息地化学成分的重要决定因素。通过对8种海洋无脊椎动物[圆形两栖动物、长形两栖动物、美洲角蕨、变异毛羽蝶、铜斑蝶、加拿大绿鳍蝶、jenneri Onuphis和Schizobranchia insignis]穴道衬里的扩散渗透率测量，发现细小无机溶质在衬里的扩散系数约为。是自由溶液的10-40%。相对于以NH4+为代表的阳离子，以Br-为代表的阴离子的扩散受到一定程度的阻碍，这表明在天然水体的pH值下，衬里有带负电的区域。通过衬里的扩散的时间依赖性受到衬里材料内简单离子交换的影响。对NH4+和Si(OH)4等溶质的吸附常数[K]在K .apprx范围内。2-8（相对孔隙水体积）。在某些情况下，二氧化硅显示出除可逆离子交换外的相互作用的证据。根据控制周围沉积物中特定溶质的不同反应类型，衬里的渗透率会对沉积溶质分布产生不同的影响。发生零级反应的溶质浓度受衬里渗透性的影响很大，但通过衬里的净通量（稳态）不受影响。溶质发生一阶或高阶浓度依赖性反应时，情况正好相反。假设洞穴衬里可以起到分子筛的作用，那么某些类别的溶质将受到灌溉洞穴存在的强烈影响，而其他类别的溶质将分布在沉积物中，就好像洞穴完全不存在一样。这可能使沉积溶质分布大为复杂化。
Many of the abundant burrows formed by animals in marine sediments are lined with thin layers of organic material. The permeability of these linings to solute diffusion can be an important determinant of the chemical composition of surrounding sediment and the burrow habitat. Measurement of the diffusive permeability of burrow linings from 8 spp. [Amphitrite ornata, Asychis elongata, Ceriantheopsis americanus, Chaetopterus variopedatus, Diopatra cuprea, Eudistyla vancouverensis, Onuphis jenneri and Schizobranchia insignis] of marine invertebrates indicates that the diffusion coefficients of small inorganic solutes within linings are .apprx. 10-40% that in free solution. The diffusion of anions, represented by Br-, is hindered somewhat relative to cations, represented by NH4+, indicating that linings have negatively charged regions at the pH of natural waters. The time dependence of diffusion through linings is affected by simple ion exchange within the lining material. Adsorption constants [K] for solutes like NH4+ and Si(OH)4 are in the range of K .apprx. 2-8 (relative to pore water volume). Silica shows evidence of interaction other than reversible ion exchange in some cases. The permeability of linings can affect sedimentary solute distributions differently depending on the types of reactions controlling a particular solute in surrounding sediment. The concentrations of solutes subject to zeroth-order reactions are greatly influenced by lining permeability but net fluxes (at steady state) across the lining are not. The opposite is true for solutes subject to first or higher order concentration-dependent reactions. Assuming burrow linings can act as molecular sieves, then some classes of solutes will be strongly influenced by the presence of irrigated burrows while others will be distributed in a deposit as though burrows were completely absent. This may greatly complicate sedimentary solute distributions.