Nitrogen Cycling in Marine Sediments: Isotope Fraction- ation Effects

提出了一项初步研究，以评估的有用性， 15/N/14 N比值研究沉积物氮循环。 海洋沉积物中的反硝化作用，特别是 大陆架是氮化合物的主要汇 除了硝化作用外， 强分馏氮同位素 对于沉积物， 硝化反硝化与通量输运控制 很可能会强烈地改变这些分馏效应。 最初的目标将是确定氮是否 同位素信号足够大，使得它们都是 连贯性和可解释性。 模型分析表明， 将会是这样。 位于马萨诸塞州巴扎兹湾的研究点，沿着 将研究缅因州和百慕大。 孔隙水的15 N值 NO3-、NH 4+和沉积物PN将在岩芯下测定， 将进行通量室实验，以确定 相对于水柱的净同位素效应。 将进行岩心切片的孵育实验， 确定微生物分级因子。

A pilot study is propoosed to evaluate the usefulness of 15/N/14N ratios for studying the sedimentary nitrogen cycle. Denitrification in marine sediments, particularly on continental shelves, is a principal sink for combined nitrogen from the ocean and in addition to nitrification is known to strongly fractionate nitrogen isotopes. For sediments, coupled nitrification-denitrification and transport control of fluxes are likely to strongly modify these fractionation effects. Initial objectives will be to determine whether nitrogen isotopic signals are sufficiently large such that they are both coherent and interpretable. Model analysis suggests that this will be the case. Sites in Buzzards Bay-MA, along a transect between the Gulf of Maine and Bermuda will be studied. 15N values for pore-water NO3-, NH4+, and sediment PN will be determined downcore and flux chamber experiments will be carried out to determine the net isotopic effect with respect to the water column. Incubation experiments of core slices will be carried out to determine microbial fractionation factors.