中国科学院海洋研究所机构知识库

基于2014年春季、2014年秋季及2015年夏季对台湾以东黑潮主流径及台湾东北部黑潮上升流海域的调查，在系统研究该区域海水中溶解无机态、溶解有机态及颗粒态的氮（N）、磷（P）、硅（Si）等生源要素及相关参数的垂直分布特征的基础上，定量评估了黑潮输入对东海陆架区营养物质分布格局的影响。获得如下的系列结果和认识：

1.春、夏、秋三个季节黑潮主流径及台湾东北部上升流水体中各形态N、P、Si等生源要素的浓度在不同深度水层差异明显，受到水体交换、浮游植物生产、颗粒物沉降、有机物矿化分解等过程的综合影响，但不同季节的影响因素有所差异。

黑潮主流径水体中溶解无机态生源要素（NO₃-N、NO₂-N、PO₄-P、SiO₃-Si）、溶解有机态生源要素（DON、DOP）和颗粒态生源要素（PIN、PIP、PON、POP）浓度在不同深度水层差异明显：NO₂-N在50~150 m水深范围内存在一高值区；NO₃-N、PO₄-P及SiO₃-Si在表层水中浓度最低，在次表层水、中层水中浓度随水深增加而迅速升高，在深层水中浓度最高且较为均一；DON、DOP、PON及POP在表层水中浓度最高，在次表层水中浓度随水深增加而逐渐降低，在中层水及深层水中浓度最低且分布较为均一；而PIN、PIP在全水深范围内浓度较低，垂直变化趋势不甚分明。各形态生源要素的浓度及分布趋势受到水体交换、浮游植物生产、颗粒物沉降、有机物矿化分解等诸多生物地球化学过程的影响，其季节变化表明不同季节影响因素有所差异。

TW0-1站位处于台湾东北部黑潮上升流核心区域，其各形态生源要素浓度及分布趋势受不断涌升的黑潮次表层水及中层水影响极大。其中NO₃-N、PO₄-P、SiO₃-Si及PON、POP的浓度基本高于黑潮主流径水体对应水层中浓度，而DON、DOP浓度基本低于黑潮主流径水体对应水层中浓度，正是上升流水体生源要素分布特征。

2.黑潮主流径及台湾东北部上升流区域水体内各形态N、P的组成在春、夏、秋三季大体相似，在浅层水体中以溶解有机态为主要存在形态，在深层水体中以溶解无机态为主要存在形态。

黑潮表层水中，DON、DOP是N、P主要存在形态，分别占TN、TP的约90%、80%；其次以颗粒态形式存在，PN（PIN+PON）、PP（PIP+POP）分别占总量的10%左右；溶解无机态含量最少。随水深增加，溶解有机态及颗粒态的N、P浓度降低，而溶解无机态N、P浓度增加。至黑潮深层水中，溶解无机态成为N、P的最主要存在形态，DIN（NO₃-N+NO₂-N）、DIP（PO₄-P）分别占TN、TP的90%左右；溶解有机态为次要存在形态；而颗粒态组分所占比例已不足1%。

上升流水体中，N、P在表层水中以溶解有机态为主要存在形态，在深层水中以溶解无机态为主要存在形态，且各组分所占比例受到黑潮涌升水影响。

3.黑潮水向东海陆架区的入侵向东海输送大量的营养物质，夏半年（5月~10月）间跨陆架边缘向东海输入N、P、SiO₃-Si营养物质的通量分别为17.17、0.93、14.71 kmol/s；冬半年（11月~次年4月）间跨陆架边缘向东海输入N、P、SiO₃-Si营养物质的通量分别为15.70、0.75、9.73 kmol/s。值得注意的是，N、P输送通量中溶解有机态、颗粒态的N、P贡献近半，不容忽视。黑潮向东海输送营养物质通量，受黑潮自身营养物质分布及黑潮向东海输入水通量两方面的共同影响。

黑潮水向东海陆架区的入侵向东海输送大量的营养物质，由于黑潮自身营养物质分布存在季节变化，且营养物质含量各不相同的黑潮各水层（黑潮表层水、黑潮次表层水和黑潮中层水）的入侵程度存在季节差异，因此不同季节黑潮向东海输送营养物质的通量有所不同。根据水-盐平衡箱式模型估算得到了各季节黑潮跨陆架边缘向东海输送各形态营养物质的通量。黑潮向东海输送DIN、DIP、SiO₃-Si、DON、DOP、PN、PP通量在春季分别为13.70、0.98、23.03、10.65、0.38、0.66、0.04 kmol/s；夏季分别为4.24、0.27、6.38、4.84、0.18、0.25、0.02 kmol/s；秋季分别为5.25、0.37、9.73、9.80、0.34、0.65、0.04 kmol/s。夏半年（5~10月）中DIN、DIP分别占N、P总输入通量的52%、67%，冬半年（11月~次年4月）中DIN、DIP分别占N、P总输入通量的33%、50%。除溶解无机态营养物质外，黑潮向东海输送了大量的溶解有机态及颗粒态营养物质，这两种形态的营养物质对东海陆架区营养物质的分布格局也有重要影响。

4.夏半年、冬半年间的黑潮入侵水输入营养物质通量的DIN/DIP比值分别为14.36、14.08，而TN/TP比值分别为18.41、20.91。携带大量营养物质尤其是含有较高浓度DIP的黑潮入侵水可以经近岸黑潮底层分支入侵至东海闽浙近海海域，进而缓和河流输入所造成的东海近海高N/P情况，对东海营养物质分布格局造成一定的影响。

在夏半年（5月~10月），黑潮输入DIN、DIP、SiO₃-Si、DON、DOP、PN、PP分别是东海陆架区N、P、SiO₃-Si总收入（黑潮输入、台湾海峡水输入及河流输入之和）的23%、34%、42%、20%、15%、1%、2%，是东海陆架区营养物质的极重要来源。在冬半年（11月~次年4月），黑潮输入DIN、DIP、SiO₃-Si、DON、DOP、PN、PP分别是东海陆架区N、P、Si总收入（黑潮输入、台湾海峡水输入及河流输入之和）的18%、25%、37%、33%、22%、2%、3%，其溶解无机态营养物质输入通量低于夏季，溶解有机态及颗粒态营养物质输入通量高于夏季。

黑潮入侵水在夏半年和冬半年向东海输送DIN、DIP、SiO₃-Si、DON、DOP、PN、PP等形态营养物质的通量分别是同期河流输入通量的2.55、37.77、2.93、10.68、9.33、0.63、0.63倍和5.04、45.67、5.22、40.70、33.74、5.57、1.08倍。而夏半年、冬半年间的河流输入DIN/DIP比值分别为212.31、127.50，黑潮入侵水输入DIN/DIP比值分别为14.36、14.08。携带大量营养物质尤其是含有较高浓度DIP的黑潮入侵水可经近岸黑潮底层分支入侵至东海闽浙近海海域，可以缓解河流输入所造成的东海近海高N/P比值，进而对东海营养物质分布格局产生一定的影响。

Based on the investigations in the Kuroshio mainstream and the upwelling zone northeast of Taiwan island during spring 2014, autumn 2014, and summer of 2015, the vertical distribution patterns of dissolved inorganic froms, dissolved organic froms and particulate forms of Nitrogen (N), Phosphorus (P) and Silicon (Si), and their relevant parameters were systematically studied. The nutrients fluxes from the Kuroshio to the East China Sea (ECS) shelf area were estimated, and the impact of the Kuroshio intrusion water to the distribution pattern of biogenic elements in the ECS was preliminary evaluated. A series of results and recognition obtained in this study are as follows:

1. The contents of different forms of biogenic elements in the Kuroshio mainstream and the upwelling water northeast of Taiwan island were distinctly varied with water depth in spring 2014, autumn 2014, and summer of 2015. Their distribution patterns, which were subjected to the combined influences of exchange of water masses, primary production, settling of paticulate matters, remineralization of organic matters and so on, vaired with different seasons, indicating that the influence factors vaired with different seasons.

In the Kuroshio main stream, the contents of dissolved inorganic biogenic elements (NO₃-N, NO₂-N, PO₄-P and SiO₃-Si), dissolved organic biogenic elements (DON and DOP) and particulate inorganic and organic biogenic elements (PIN, PIP, PON and POP) distinctly varied with water depth: NO₂-N has a high value zone in 50~150 m layer; the contens of NO₃-N, PO₄-P and SiO₃-Si are lowest in the Kuroshio Surface Water (KSW), then increase with the increase of water depth in the Kuroshio Subsurface Water (KSSW) and Kuroshio Intermidiate Water (KIW), and have uniform and the highest values in the Kuroshio Deep Water (KDW); the contents of DON, DOP, PON and POP have the highest values in the KSW, then decrease with the increase of water depth in the KSSW, have uniform and lower values in the KIW and KDW; the contents PIN and PIP are relatively low throughout the water column. Their contents and vertical distribution patterns, which were subjected to the combined influences of exchange of water masses, primary production, settling of paticulate matters, remineralization of organic matters and so on, vaired with different seasons, indicating that the influence factors varied with different seasons.

Staion TW0-1 locatted in the Kuroshio upwelling zone northeast of Taiwan island, its contents of biogenic elements are strongly influenced by the upwelling of KSSW and KIW. The contents of NO₃-N, PO₄-P, SiO₃-Si, PON and POP are basically higher than the contents in the corresponding layer of the Kuroshio water, while DON and DOP contents are basically lower than the contents in the corresponding layer of the Kuroshio water, which consist with the distribution patterns of biogenic elements in upwelling water.

2. The composing characteristics of different forms of N and P in the Kuroshio mainstream and the upwelling zone northeast of Taiwan island were broadly similar in spring, summer and autumn: DON and DOP were main existing forms in upper water, while DIN and DIP were main existing forms in deep water.

In the KSW, DON and DOP were the main existing forms of N and P, which accounted for about 80% and 66% of the TN and TP respectively; secondly was particulate forms, PN (PIN+PON) and PP (PIP+POP) accounted for around 10% of the TN and TP, respectively; the contents of DIN (NO₃-N+NO₂-N) and DIP (PO₄-P) were the lowest. Then increased with water depth, the contents of dissolved organic and particulate forms of N and P decreased, while the contents of dissolved inorganic forms of N and P increased. In KDW, DIN and DIP were the main existing forms of N and P, respectively; dissolved organic forms took the second place; and particulate forms accounted less than 1%.

In the Kuroshio upwelling water, DON and DOP were main existing forms in the upper water, DIN and DIP were main existing forms in the deeper water, and their composing characteristics were influenced by the intrusion KSSW and KIW.

3. The Kuroshio water intrudes and imports large amounts of nutrients into the ECS shelf area. The influxes of N, P and SiO₃-Si from the Kuroshio to the ECS are respectively 17.17, 0.93 and 14.71 kmol/s during rainy season (May to October); and respectively 15.70, 0.75 and 9.73 kmol/s during dry season (November to April). What’s noticeable is that dissolved organic and particulate forms of N and P influxes, which accounted for nearly half of the TN and TP influxes, can not be ignored. The nutrients influxes from the Kuroshio to the ECS are influenced by the contents of biogenic elements in the Kuroshio and the water flux of the intrusion Kuroshio water.

The Kuroshio import large amounts of nutrients into the ECS, and the influxes varies with seasons beacused of the seasonal variations of both the contents of nutrients and the intrusion water fluxes. Based on the box modle about water-salt balance, the influxes of different forms of nutrients from the Kuroshio to the ECS are estimated. The Kuroshio imports respectively 13.70, 0.98, 23.03, 10.65, 0.38, 0.66 and 0.04 kmol/s of DIN, DIP, SiO₃-Si, DON, DOP, PN and PP in spring, imports respectively 4.24, 0.27, 6.38, 4.84, 018, 0.25 and 0.02 kmol/s in summer, and imports respectively 5.25, 0.37, 9.73, 9.80, 0.34, 0.65 and 0.04 kmol/s in autumn. Influxes of DIN and DIP accounted for 52% and 67%, respectively, of the total influxes of N and P in rainy season (May to October); and influxes of DIN and DIP accounted for 33% and 50%, respectively, of the total influxes of N and P in dry season (November to April). As well as dissolved inorganic forms of N and P, dissolved organic and particulate forms of N and P also plays importan role in the N and P distribution patterns in the ECS shelf area.

4. During the rainy and the dry season, the DIN/DIP ratio of the nutrients influxes from Kuroshio intrusion water are 14.36 and 14.08, respectively; while the TN/TP ratio of the nutrients influxes are 18.41 and 20.91, respectively. The intrusion Kuroshio water, which is featured by high concentrations of nutrients, especially DIP, could intrude into the ECS coastal area nearby the Fujian and Zhejiang Province and mitigate the extreamly high DIN/DIP ratio caused by the river input, and therefore impact the distribution pattern of nutrients in the ECS.

 During the rainy season (May to October), the DIN, DIP SiO₃-Si, DON, DOP, PN and PP accounted for 23%, 34%, 42%, 20%, 15%, 1%, 2%, respectively, of the total influxes of N, P and SiO₃-Si (the sum of the Kuroshio influxes, Taiwan Strait influxes and river influxes). During the dry season (November to April), the DIN, DIP, SiO₃-Si, DON, DOP, PN and PP accounted for 18%, 25%, 37%, 33%, 22%, 2%, 3%, respectively, of the total influxes of N, P and SiO₃-Si. The influxes of DIN, DIP, and SiO₃-Si in dry season are lower than those in rainy season, while influxes of DON, DOP, PN and PP in dry season are higher than those in rainy season.

The influxes of DIN, DIP, SiO₃-Si, DON, DOP, PN and PP from Kuroshio intrusion water are 2.55, 37.77, 2.93, 10.68, 9.33, 0.63 and 0.63 times of the riverine influxes during the rainy season, and 5.04, 45.67, 5.22, 40.70, 33.74, 5.57 and 1.08 times of the riverine influxes during the dry season. The DIN/DIP ratio of riverine influxes during the rainy and dry season are 212.31 and 127.50, respectively, while the DIN/DIP ratio of Kuroshio influxes during the rainy and dry season are 14.36 and 14.08, respectively. The intrusion Kuroshio water, which is featured by high contents of nutrients, especially DIP, could intrude into the ECS coastal area nearby the Fujian and Zhejiang Province and mitigate the extreamly high DIN/DIP ratio caused by the riverine input, and therefore impact the distribution pattern of nutrients in the ECS.