渤海无机氮年际变化分析

根据1985－1998年渤海断面资料分析，高浓度无机氮水体从断面近岸海域通过底层水体逐年向渤海中剖迁移和扩散。断面海域底层一无机氮浓度的年际变化可以比较稳定地反映水体的富营养化程度。渤海断面海域硝酸盐氮、亚硝酸盐氮年际变化的主要部分原本呈现准平衡态变化，由于海水污染程度的持续增长，破坏了这种准平衡态年际变化，海洋生物－化学过程仅能够维持其年际变化的次要部分呈现准平衡态变化，但是不足以阻止其主要部分脱离准平衡态变化。海洋生物的繁殖和聚集密度对无机氮浓度的空间分布有重要影响。     

渤海浮游植物群落结构时空分布及其影响因素

浮游植物群落结构的时空变化对生物地球化学循环、全球气候及渔业资源具有重要的影响。本文采用ROMS-CoSiNE高分辨率数值模拟结果,分析了渤海浮游植物生物量和群落结构的时空分布特征,讨论了浮游植物群落结构时空差异的主要影响因素。结果表明,渤海表层叶绿素浓度和甲硅藻比在冬季最低、夏季最高。叶绿素浓度呈条带状分布,甲硅藻比呈斑块状分布。冬季、春季和秋季浮游植物群落结构均以硅藻占绝对优势,夏季以硅藻和甲藻共同占优。不同因素对浮游植物群落结构的影响具有时空差异性。在辽东湾、渤海湾、莱州湾和渤海中部,各个季节浮游植物群落结构差异分别受磷酸盐、氮磷比、硅氮比、溶解无机氮的影响最大。在冬季、夏季和秋季,各个区域浮游植物群落结构差异均受溶解无机氮的影响最大,在春季则受硅氮比的影响最大。总体上,营养盐浓度及结构是浮游植物群落结构时空差异的主要影响因子。     

渤海悬浮物分布的遥感研究渤海悬浮物分布的遥感研究

利用渤海湾和莱州湾现场实测的悬浮物含量和光谱数据，建立了基于555和670 nm波段遥感反射率的悬浮物含量遥感反演模型。经检验，模型平均相对误差优于20%，对输入端误差不敏感。基于该模型，利用ENVISAT MERIS遥感数据，从空间分布格局、大风过程的短期扰动以及季节性差异等方面分析了渤海悬浮物的时空分布特征。（1）渤海悬浮物含量的高值区集中分布在莱州湾（尤其是黄河口和莱州湾湾底）和渤海湾沿岸，此外在辽东湾沿岸海域悬浮物含量也相对较高，而在渤海大部水体悬浮物含量较低。（2）大风过程可在短期内（约1~3 d）显著改变全渤海的悬浮物空间分布格局，其中渤海湾和莱州湾响应最为强烈，辽东湾响应相对较弱，这与其各自的水深条件、底质类型和悬浮物粒径等因素有关。（3）渤海悬浮物含量总体上呈春夏低、秋冬高的分布特征；季节性差异最显著的区域是渤海湾、莱州湾和辽东湾，差异性最小的是秦皇岛近岸海域；风力等气候因素是悬浮物分布呈现季节性差异的主要原因，入海径流是另一重要因素     

渤海近岸水体有色溶解有机物的光吸收特征及其分布

依据2011-08和2012-05的现场调查资料,分析渤海水体有色溶解有机物(CDOM)的光谱吸收特性,研究其分布变化特征及影响因素。结果表明:渤海水体a_(355)的变化范围为0.38~4.15m~(-1),均值为1.33m~(-1),表现为莱州湾渤海湾辽东湾,春季夏季的时空变化特征;表层海水a_(355)的水平分布基本呈近岸及河口区高、远岸稍低的变化规律。光谱斜率S_(275~295)和S_(350~400)的变化范围分别为0.011~0.074nm~(-1)和0.012~0.195nm~(-1),春季整体高于夏季。光谱斜率比S_R的变化范围为0.25~2.25,平均值为0.88,夏季略高于春季,其中春季渤海湾最高,莱州湾次之,辽东湾最低;夏季则莱州湾高于渤海湾。渤海春季水体CDOM主要来源于生物现场生产和底层沉积物再悬浮释放,夏季则主要受陆源径流输入的影响。不同时空条件下CDOM在咸淡水的混合过程中也有着不同的表现,春季多呈非保守行为;夏季莱州湾呈保守行为,渤海湾则呈非保守行为。     

獐子岛养殖海域颗粒有机碳、颗粒氮的时空分布特征

2011年8月、10月、12月和2012年4月对大连獐子岛养殖海域共14个站位进行了大面调查。对其中颗粒有机碳(POC)和颗粒氮(PN)的时空分布特征进行了研究。结果表明,獐子岛养殖海域水体中POC质量浓度的季节变化趋势是:夏季秋季春季冬季。夏季POC质量浓度最高,表、底层的质量浓度分别为0.159~1.672 mg/L和0.045~0.834 mg/L,平均值分别为(0.867±0.451)mg/L和(0.319±0.204)mg/L。冬季表、底层POC质量浓度最低,表、底层POC质量浓度分别为0.020~0.530 mg/L和0.061~0.458 mg/L。平均值分别为(0.240±0.125)mg/L和(0.221±0.129)mg/L。四个季节的POC质量浓度平面分布较为均匀。PN质量浓度的季节变化趋势是:夏季秋季冬季春季。夏季PN的质量浓度最高,表、底层PN的质量浓度分别为0.026~0.439 mg/L和0.020~0.393 mg/L,平均值分别为(0.193±0.067)mg/L和(0.172±0.060)mg/L。春季表、底层PN质量浓度最低,表、底层PN质量浓度分别为0.059~0.178 mg/L和0.024~0.212 mg/L,平均值分别为(0.120±0.047)mg/L和(0.100±0.050)mg/L。PN与POC的分布特征相似,空间分布均匀。叶绿素a(Chl-a)质量浓度的变化趋势为:夏季秋季春季冬季。POC、PN和Chl-a的垂直分布规律相似,春季底层质量浓度高于表层,夏秋两季表层质量浓度高于底层,冬季表、底层质量浓度基本一致。根据C/N以及POC/Chl-a的比值对POC的来源进行初步分析,表明该海域的POC主要来源于海洋生物,并且受陆源的影响较小。     

车由岛附近海域营养盐分布特征

由于车由岛周海域水比较浅，上下层混合得比较充分，营养盐的垂直分布较均匀，但在水平方向上差别较大。各种营养盐受生物活动、降雨和陆地经流的影响，有明显的季节变化。活性磷、硝酸盐和亚硝酸盐的浓度在冬季最高，春季最低；氨氮和活性硅的浓度则相反，夏季最高，秋季最低。     

车由岛附近海域营养盐分布特征

由于车由岛周海域水比较浅，上下层混合得比较充分，营养盐的垂直分布较均匀，但在水平方向上差别较大。各种营养盐受生物活动、降雨和陆地经流的影响，有明显的季节变化。活性磷、硝酸盐和亚硝酸盐的浓度在冬季最高，春季最低；氨氮和活性硅的浓度则相反，夏季最高，秋季最低。     

厦门海域秋、冬季溶解有机氮时空分布及总溶解态氮的组成

根据2015年10月(秋季)和2016年1月(冬季)对厦门海域开展的2次水质调查,研究了该海域中溶解有机氮(DON)的时空分布特征及总溶解态氮(TDN)的组成,并探讨了DON与环境要素的相关性及其来源.结果表明:厦门海域DON浓度平均值冬季大于秋季,表层高于底层,整体呈内湾、河口区较高,湾口区低的分布格局.秋季DON浓度的空间分布为同安湾西海域九龙江口邻近海域东南海域大嶝海域,冬季为西海域同安湾九龙江口邻近海域东南海域大嶝海域.该海域秋、冬季DON浓度占比(CDON/CTDN)分别为56%和53%,DON浓度占比整体呈湾口区大、河口区及内湾小的分布特征.相关性分析表明,该海域秋、冬季表、底层DON浓度与盐度均呈极显著负相关,与磷酸盐、硅酸盐含量为极显著正相关,与叶绿素a、溶解氧、p H值存在一定相关性.厦门海域DON的来源主要有九龙江河流、城市生活污水、工农业废水等陆源输入和浮游植物活动等海源生成.     

基于GOCI影像进行渤海表层悬浮泥沙浓度估算的新方法

针对现场观测数据缺乏的情形,提出了一种新的利用GOCI影像反演渤海海域表层悬浮泥沙浓度(SSC)的方法。应用mMUMM大气校正算法对GOCI数据进行大气校正处理得到的GOCI遥感反射率产品后,以MODIS影像反演得到的表层悬浮泥沙浓度(SSC)作为参考值,对已应用于渤海的4种SSC反演模型进行参数化拟合,最后通过对比确定了效果最好的参数化SSC经验模型并且进行了验证。验证结果显示最优参数化模型的平均相对误差绝对值(16.0%)和均方根误差(12.2 mg/L)均相对较低,表明该模型可适用于渤海海域GOCI数据的SSC反演。通过采用建立的最优参数化SSC反演算法对2015年12月至2016年11月的GOCI数据对渤海海域的季节平均SSC进行了估计和分析。相比其他区域,渤海湾、莱州湾、辽东湾等3个海湾和黄河口附近沿岸SSC相对较高;3个海湾水体区域,从沿岸向离岸方向SSC由高变低,具有明显的浓度梯度;季节上,整个渤海海域SSC在冬季最高,夏季最低,春季与秋季相差不大。渤海SSC这些明显的空间分布特征、季节变化特性与前人研究结果一致,表明该算法应用于渤海可行。     

渤海湾水环境氮、磷营养盐分布特点

渤海是一个半封闭的陆架边缘海,主要由辽东湾、渤海湾、莱州湾及中央海区组成,面积为7.7×104 km2,平均水深18 m[1].近些年富含氮、磷营养盐的工农业废水的大量排放使得渤海湾营养盐结构发生了很大变化,同时导致渤海湾局部海域“赤潮”频繁发生.营养物质进入水体后,将会在水与沉积物之间发生迁移,其中一部分可以与钙、铁或铝络合形成沉淀,或吸附到矿物颗粒的表面而转移到沉积物中.近海沉积物可以看作营养物质的“蓄积库”.沉积物中营养物质的再生,对水体中营养盐的收支和营养盐循环动力学有着及其重要的作用[2].     

Seasonal Cycle Analysis of the Nitrate Nitrogen and Nitrite Nitrogen in the Bohai Sea

During 1985～1987,the concentration of nitrate nitrogen was higher in the Laizhou Bay and the Bohai Bay while that of nitrite nitrogen was higher in the Liaodong Bay and the Bohai Bay,The concentration of nitrate nitrogen was highest in winter and lowest in summer while that of nitrite nitrogen was highest in autumn and lowest in spring .the seasonal variation of the concentration of nitrate nitrogen was maximum in the Laizhou Bay and the Bohai Bay while that of the concentration of nitrite nitrogen was maximum in the Liaodong Bay.There was a great difference in the concentration of nitrate nitrogen between the surface and the bottom in autumn and in the concentration of nitrite nitrogen between the surface and the bottom in summer.The main reason for the seasonal variations of the concentration of nitrate nitrogen and nitrite nitrogen was the marine biochemical process.The nitrate nitrogen and nitrite nitrogen in the Bohai Sea basically maintained a quasi-equilibrium state seasonal cycle,The quesi-equilibrium state seasonal cycle of nitrate nitrogen and nitrite nitrogen at the bottom was stable while that at the surface was liable to variations caused by other factors.     

Nitrogen and phosphorus in the Ngongotaha Stream

This paper gives the data and methods used to calculate the nitrogen and phosphorus loads of the Ngongotaha Stream, near Rotorua, New Zealand. The variations in concentration with time and with flow rate are given in some detail, as examples of what may happen in other streams of the central volcanic plateau, and a novel way to define a flow‐concentration curve is described. Nitrate, ammonia, dissolved reactive phosphorus (DRP), total phosphorus (TP), and total Kjeldahl nitrogen (TKN) concentrations were measured, and mean concentrations in 1976 base flow were found to be 527, 25, 32, 48, and 162 mg m^‐3 respectively. Nitrate concentrations showed seasonal variations, and although changes occurred during floods, they were not correlated with flow rate. DRP concentrations showed little variation, except that they dropped at the peak of the largest floods. TP was strongly correlated with flow rate during floods, and TP loads could best be calculated by allowing for a curvilinear relationship between concentration and flow rate. The logarithms of the TP load carried by a flood and the peak flow rate of the flood were highly correlated (R = 0.984). The annual loads of nitrate, ammonia, DRP, TP, and TKN were estimated to be 34, 1.3, 2.9, 6.0, and 26 tonnes in 1976.     

An Ecosystem Model Including Nitrogen Isotopes: Perspectives on a Study of the Marine Nitrogen Cycle

We have developed an ecosystem model including two nitrogen isotopes (¹⁴N and ¹⁵N), and validated this model using an actual data set. A study of nitrogen isotopic ratios (δ¹⁵N) using a marine ecosystem model is thought to be most helpful in quantitatively understanding the marine nitrogen cycle. Moreover, the model study may indicate a new potential of δ¹⁵N as a tracer. This model has six compartments: phytoplankton, zooplankton, particulate organic nitrogen, dissolved organic nitrogen, nitrate and ammonium in a two-box model, and has biological processes with/without isotopic fractionation. We have applied this model to the Sea of Okhotsk and successfully reproduced the δ¹⁵N of nitrate measured in seawater and the seasonal variations in δ¹⁵N of sinking particles obtained from sediment trap experiments. Simulated δ¹⁵N of phytoplankton are determined by δ ¹⁵N of nitrate and ammonium, and the nitrogen f-ratio, defined as the ratio of nitrate assimilation by phytoplankton to total nitrogenous nutrient assimilation. Detailed considerations of biological processes in the spring and autumn blooms have demonstrated that there is a significant difference between simulated δ¹⁵N values of phytoplankton, which assimilates only nitrate, and only ammonium, respectively. We suggest that observations of δ ¹⁵N values of phytoplankton, nitrate and ammonium in the spring and autumn blooms may indicate the ratios of nutrient selectivity by phytoplankton. In winter, most of the simulated biogeochemical fluxes decrease rapidly, but nitrification flux decreases much more slowly than the other biogeochemical fluxes. Therefore, simulated δ¹⁵N values and concentrations of ammonium reflect almost only nitrification. We suggest that the nitrification rate can be parameterized with observations of δ¹⁵N of ammonium in winter and a sensitive study varying the parameter of nitrification rate.     

Nitrogen and phosphorus budgets in the Baltic Sea

The paper reports the budgets of inorganic and total nitrogen and phosphorus based on a recalculation of the existing water balance. The nitrogen budgets indicate that humus carried by river runoff probably dominates in the sedimentation of nitrogenous organic matter, while the excess transferred to the layer below the halocline is controlled by the amounts added by river runoff and waste disposal. The budgets appear to be considerably influenced by eutrophication and human activity. The phosphorus budget indicates that the supply of organic phosphorus and oxygen in the layers below the halocline are in a precarious balance with each other. Phosphorus and nitrogen compounds appear to sediment in almost the same proportions as their concentrations in the bottom water.     

黄海南部的溶解无机氮

根据 1998年 5月的调查资料 ,分析并讨论了春季黄海南部海区溶解无机氮的分布特征。结果表明 :( 1)因受长江冲淡水及沿岸流的影响 ,NH+4 - N、NO-2 - N浓度的平面分布基本呈周边高、中央低 ,NO-3 - N的浓度则基本呈长江口外海域高、中北部深水区低的分布规律。 ( 2 )调查海域深水区的溶解无机氮存在明显的层化现象 ,且底层等值线上凸密集。 10 m以浅水体 ,NO-3 - N的浓度分布均匀 ,10 m以深水体 ,NO-3 - N的浓度急剧增加 ,且呈现出随深度增加而增加的趋势 ,NH+4 - N、NO-2 - N浓度的垂直分布比较均匀。 ( 3)黄海南部表层叶绿素 a的浓度呈现周边高、中央低的分布特征。     

Nitrogen dynamics during the Arabian Sea Northeast Monsoon

This investigation focused on the weaker and less well understood of the two Arabian Sea monsoonal wind phases, the NE Monsoon, which persists for 3–4 months in the October to February period. Historically, this period has been characterized as a time of very low nutrient availability and low biological production. As part of the US JGOFS Arabian Sea Process Study, 17 stations were sampled on a cruise in January 1995 (late NE Monsoon) and, 15 stations were sampled on a cruise in November 1995 (early NE Monsoon). Only the southern most stations (10° and 12°N) and one shallow coastal station were as nutrient-depleted as had been expected from the few relevant prior studies in this region. Experiments were conducted to ascertain the relative importance of different nitrogenous nutrients and the sufficiency of local regeneration processes in supplying nitrogenous nutrients utilized in primary production. Except for the southern oligotrophic stations, the euphotic zone concentrations of NO₃⁻ were typically 5–10-fold greater than those of NO₂⁻ and NH₄⁺. There was considerable variation (20–40-fold) in nutrient concentration both within and between the two sections on each cruise. All nitrogenous nutrients were more abundant (2–4-fold) later in the NE Monsoon. Strong vertical gradients in euphotic zone NH₄⁺ concentration, with higher concentrations at depth, were common. This was in contrast to the nearly uniform euphotic zone concentrations for both NO₃⁻ and NO₂⁻. Half-saturation constants for uptake were higher for NO₃⁻ (1.7 μmol kg⁻¹ (s.d.=0.88, n=8)) than for NH₄⁺ (0.47 μmol kg⁻¹ (s.d.=0.33, n=5)). Evidence for the suppressing effect of NH₄⁺ on NO₃⁻ uptake was widespread, although not as severe as has been noted for some other regions. Both the degree of sensitivity of NO₃⁻ uptake to NH₄⁺ concentration and the half-saturation constant for NO₃⁻ uptake were correlated with ambient NO₃⁻ concentration. The combined effect of high affinity for low concentrations of NH₄⁺ and the effect of NH₄⁺ concentration on NO₃⁻ uptake resulted in similarly low f-ratios, 0.15 (s.d.=0.07, n=15) and 0.13 (s.d.=0.08, n=17), for early and late observations in the NE Monsoon, respectively. Stations with high f-ratios had the lowest euphotic zone NH₄⁺ concentrations, and these stations were either very near shore or far from shore in the most oligotrophic waters. At several stations, particularly early in the NE Monsoon, the utilization rates for NO₂⁻ were equal to or greater than 50% the utilization rates for NO₃⁻. When converted with a Redfield C : N value of 6.7, the total N uptake rates measured in this study were commensurate with measurements of C productivity. While nutrient concentrations at some stations approached levels low enough to limit phytoplankton growth, light was shown to be very important in regulating N uptake at all stations in this study. Diel periodicity was observed for uptake of all nitrogenous nutrients at all stations. The amplitude of this periodicity was positively correlated with nutrient concentration. The strongest of these relationships occurred with NO₃⁻. Ammonium concentration strongly influenced the vertical profiles for NO₃⁻ uptake as well as for NH₄⁺ uptake. Both NO₂⁻ and NH₄⁺ were regenerated within the euphotic zone at rates comparable to rates of uptake of these nutrients, and thus maintenance of mixed layer concentrations did not require diffusive or advective fluxes from other sources. Observed turnover times for NH₄⁺ were typically less than one day. Rapid turnover and the strong light regulation of NH₄⁺ uptake allowed the development and maintenance of vertical structure in NH₄⁺ concentration within the euphotic zone. In spite of the strong positive effect of light on NO₂⁻ uptake and its strong negative effect on NO₂⁻ production, the combined effects of much longer turnover times for this nutrient and mixed layer dynamics resulted in nearly uniform NO₂⁻ concentrations within the euphotic zone. Responses of the NE Monsoon planktonic community to light and nutrients, in conjunction with mixed layer dynamics, allowed for efficient recycling of N within the mixed layer. As the NE Monsoon evolved and the mixed layer deepened convectively, NO₂⁻ and NO₃⁻ concentrations increased correspondingly with the entrainment of deeper water. Planktonic N productivity increased 2-fold, but without a significant change the new vs. recycled N proportionality. Consequently, NO₃⁻ turnover time increased from about 1 month to greater than 3 months. This reflected the overriding importance of recycling processes in supplying nitrogenous nutrients for primary production throughout the duration of the NE Monsoon. As a result, NO₃⁻ supplied to the euphotic zone during the NE Monsoon is, for the most part, conserved for utilization during the subsequent intermonsoon period.     

细菌对海水中各形态氮的影响

海洋细菌生长过程中,不但能利用体系中的有机物质,而且也能利用无机营养盐。本论文通过小麦岛细菌接种实验发现,细菌大量繁殖时吸收利用体系中的营养物质,生成颗粒态氮(PN)和溶解有机氮(DON),体系中溶解无机氮(DIN)、总溶解氮(TDN)降低至最低值。进入细菌指数生长期和稳定期后,颗粒态和有机态氮不断降解向体系中释放出无机营养盐,DIN和TDN呈现回升趋势,颗粒氮(PN)与细菌数量变化正相关。体系中,初始氮源的量决定了细菌体内POC/PN的比值,氮源充足,细菌繁殖数量多,POC/PN值低,氮源不足,细菌数量相对较少,POC/PN比值高。     

Nitrogen uptake kinetics in the Ross Sea, Antarctica

The first estimates of uptake kinetic parameters for NH₄⁺, NO₃⁻, and urea in the Ross Sea, Antarctica were measured on three cruises during austral late winter–early spring 1996 (pre-bloom), late spring 1997 (bloom development), and summer 1997 (bloom decline). Nitrogen (N) uptake experiments were conducted with water collected at the 50% light penetration depth using trace-metal clean protocols and ¹⁵N tracer techniques. At all sites, ambient NO₃⁻ concentrations ranged from 5.8 to 30.5 μg-at N l⁻¹ and silicic acid concentrations were greater than 62.0 μg-at Si l⁻¹. The following trends were observed. First, based on maximum uptake rates (V_max), apparent N utilization followed the order NO₃⁻>NH₄⁺>urea during the pre-bloom and bloom development cruises. During the summer cruise, as the bloom was declining, the apparent order of utilization was NH₄⁺>NO₃⁻>urea. Second, evidence for possible repression of NO₃⁻ uptake by elevated NH₄⁺ concentrations was only observed at one site. Third, the kinetic parameters of NH₄⁺ uptake rates corrected for isotope dilution were compared with the kinetic parameters determined from uncorrected rates. In this comparison, the measure of substrate affinity, α (α=V_max/K_s) increased by an average of 4.6-fold when rates were corrected for isotope dilution, but values of V_max remained unchanged. Fourth, using bacterial production data, the magnitude of bacterial N uptake was estimated. Assuming that all bacterial N demands were met with NH₄⁺, the estimated bacterial portion of NH₄⁺ uptake ranged from <1%, when the ratio of bacteria to autotrophic biomass was low, to 35%, when bacterial abundance and biomass were highest. Finally, dramatic changes in NH₄⁺ uptake capacity were observed at one station (Stn. O), where kinetic parameters were measured during all three cruises. We hypothesize that a mutualistic relationship exists between phytoplankton and heterotrophic bacteria, and that the creation of microzones of high NH₄⁺ concentrations contributed to the changes seen at this station.     

Nitrogen Assimilation and Partitioning in the Mediterranean Seagrass Posidonia oceanica

Abstract. The supply of nitrogen (N) often limits the productivity of marine macrophytes. In vitro and in vivo assays of glutamine synthetase (GS) activity were employed to investigate patterns of N assimilation by the Mediterranean seagrass Posidonia oceanica (L.) DELILE. Biomass-specific GS activity wa measured in root tissue, in leaves within a shoot, in shoots collected at two sites during two season and over a depth range of 5–33 m. Root tissue was less important than shoot tissue in assimilating inorganic N in P. oceanica , due both to the small roots' biomass (ca. 3% of total plant biomass and greatly lower (10- to 50-fold) GS activities. While the GS activity and N assimilatory potentia (biomass × GS activity; μmol N-h-^-1) were greatest in leaf 2, leaves 1 and 3–5 assimilated N a significant rates. Shoots from a site characterized by elevated N availability in the winter water column and no significant sediment N reservoir exhibited GS activities that were 9-times higher than shoot from a more oligotrophic site. Shoot GS activities in July increased linearly from 5 to 33 m and wer correlated with light availability as defined by H^sat, (daily period during which photosynthetic reaction are light-saturated). This may represent metabolic compensation by P. oceanica to maintain N influx. Factors contributing to the ecological success of P. oceanica include the ability to assimilate N under conditions of severe light limitation (< 35 μmol photons. m^-2. s^-1), and metabolic plasticity to ensur the de novo generation of N-containing organic compounds.