The extent and temporal variability of denitrification activity was measured in Yaquina Bay, Oregon, over a year using sediment cores collected approximately monthly from August 2003 through August 2004. Denitrification rates in sediments from a marine-dominated intertidal sand flat near the mouth of the estuary averaged 0.181 ± 0.114 mmol N m⁻² day⁻¹, whereas sediments within the estuary and river averaged 0.626 ± 0.141 mmol N m⁻² day⁻¹. Sediments from all sites had denitrification rates throughout the year that were within the values reported for other temperate estuaries. Denitrification rates decreased with depth from 0.4 mmol N m⁻² day⁻¹ in the upper 2 to 5 cm of sediment to 0.006 mmol N m⁻² day⁻¹ at 28 cm sediment depth, indicating that denitrification was greatest in the upper 5 cm. Denitrification rates were lowest in areas with low sediment carbon content, particularly in the sandy intertidal areas at the mouth of the estuary. The results suggested that denitrification rates in this estuary were influenced by the availability of organic carbon (r² = 0.84). Denitrification removed an estimated 8.7% of the annual Yaquina River nitrate load for August 2003 through August 2004. The relatively low percent lost via denitrification may be due to high river discharge during winter storm events when the nitrate load was greatest and dissolved nitrogen was exported directly from the estuary into the Pacific Ocean. For this reason, a direct relationship between denitrification rate and nitrate concentrations in the overlying water column was not observed. Carbon isotopic data used to investigate the carbon source indicated that δ¹³C increased from − 27 ‰ in the freshwater river sediments to − 21.5 ‰ δ¹³C at the seawater site, reflecting a change from terrestrial plant vegetation in the river to phytoplankton carbon sources at the mouth of the estuary. Similar values for δ¹³C between suspended and benthic sediments suggested that resuspension and mixing occurred frequently during tidal inflow.

中文翻译：

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俄勒冈州亚奎那湾北温带河口的反硝化率。

使用从2003年8月至2004年8月大约每月收集一次的沉积岩心，在俄勒冈州的亚奎那湾，对反硝化活动的程度和时间变化进行了测量。从河口附近的一个以海洋为主的潮间带沙滩中，沉积物的反硝化率平均为0.181±0.114 mmol N m ^-2 天^-1，而河口和河流内的沉积物平均为0.626±0.141 mmol N m ^-2 天^-1。全年所有地点的沉积物的反硝化率均在其他温带河口的报告值范围内。从0.4 mmol N m ^-2 天^-1开始，反硝化速率随深度降低在沉积深度2至5厘米处深度为0.006 mmol N m ^-2 天^-1时，沉积深度为28厘米，这表明在上方5厘米处反硝化作用最大。在含沙量低的地区，特别是在河口口的潮间带地区，反硝化率最低。结果表明，该河口的反硝化率受有机碳（r ² = 0.84）。从2003年8月到2004年8月，反硝化作用消除了Yaquina河年度硝酸盐负荷的8.7％。通过反硝化作用损失的百分比相对较低，可能是由于冬季暴风雨期间硝酸盐负荷最大且溶解氮直接出口而导致河水流量大。从河口到太平洋。因此，未观察到上方水柱中反硝化率与硝酸盐浓度之间的直接关系。用于研究碳源碳同位素数据表明，δ ¹³ C来自增加- 27‰在淡水河流沉积物- 21.5‰δ ¹³海水中的碳，反映了河中陆生植物植被到河口处浮游植物碳源的变化。对于δ类似值¹³悬浮和底栖沉积物℃之间建议再悬浮和潮汐流中的混合经常出现。