Nitrogen cycling in a deep ocean margin sediment (Sagami Bay, Japan)
Nitrogen cycling in a deep ocean margin sediment (Sagami Bay, Japan)
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DOI：
10.4319/lo.2009.54.3.0723
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发表时间：
2009-05-01
影响因子：
4.5
通讯作者：
Kitazato, Hiroshi
中科院分区：
文献类型：
--
作者：
Glud, Ronnie N.;Thamdrup, Bo;Kitazato, Hiroshi
基于原位硝酸盐（NO₃⁻）微剖面和培养箱培养，并结合对厌氧氨氧化和反硝化作用的实验室评估，我们评估了水深1450米的海洋边缘沉积物的氮周转情况。水平间隔12毫米的原位硝酸盐剖面反映出硝酸盐穿透深度、硝酸盐消耗速率和硝化作用具有高度变异性。平均而言，孔隙水硝酸盐库的周转时间约为0.2天。矿化过程中铵离子（NH₄⁺）的净释放量（0.95毫摩尔每平方米每天）维持了氨的净流出（53%）、硝化作用（24%）和厌氧氨氧化活性（23%）。该沉积物具有相对较高的原位硝酸盐净流入量（1.44毫摩尔每平方米每天），这与船上示踪实验所评估的氮气（N₂）产生量相平衡。氮气产生归因于原核生物反硝化作用（59%）、厌氧氨氧化（37%）以及基于有孔虫的反硝化作用（4%）。因此，厌氧氨氧化是一个重要的营养汇，但氮气产生主要由反硝化作用主导。尽管有孔虫体内储存的硝酸盐约占底栖硝酸盐总库的80%，但细胞内硝酸盐周转缓慢，平均而言，其维持有孔虫代谢的时间为12 - 52天，对整体氮气产生的贡献较小。表层沉积物中的微生物活动是一个约为1.1毫摩尔氮每平方米每天的净营养汇，这与在沿海和大陆架环境中进行的许多研究结果一致。大陆边缘区域可作为重要的氮汇，并在区域氮收支中发挥重要作用。
On the basis of in situ NO3- microprofiles and chamber incubations complemented by laboratory-based assessments of anammox and denitrification we evaluate the nitrogen turnover of an ocean margin sediment at 1450-m water depth. In situ NO3- profiles horizontally separated by 12 mm reflected highly variable NO3- penetration depths, NO3- consumption rates, and nitrification. On average the turnover time of the pore-water NO3- pool was similar to 0.2 d. Net release of NH4+ during mineralization (0.95 mmol m(-2) d(-1)) sustained a net efflux of ammonia (53%), nitrification (24%), and anammox activity (23%). The sediment had a relatively high in situ net influx of NO3- (1.44 mmol m(-2) d(-1)) that balanced the N-2 production as assessed by onboard tracer experiments. N2 production was attributed to prokaryotic denitrification (59%), anammox (37%), and foraminifera-based denitrification (4%). Anammox thereby represented an important nutrient sink, but the N2 production was dominated by denitrification. Despite the fact that NO3- stored inside foraminifera represented similar to 80% of the total benthic NO3- pool, the slow intracellular NO3- turnover that, on average, sustained foraminifera metabolism for 12-52 d, contributed only to a minor extent to the overall N-2 production. The microbial activity in the surface sediment is a net nutrient sink of similar to 1.1 mmol N m(-2) d(-1), which aligns with many studies performed in coastal and shelf environments. Continental margin areas can act as significant N sinks and play an important role in regional N budgets.