秋季雷州半岛近海营养盐和叶绿素a浓度空间分布及其相互关系

The Concentration of Nutrients and Chlorophyll a in the Offshore of Leizhou Peninsula in Autumn Spatial Distribution and Their Relationship

【目的】研究秋季雷州半岛海域东西部水体营养盐和叶绿素a(Chl-a)空间变化特征及其相互关系。【方法】根据2017年10月(秋季)的现场调查资料,分别采用镉铜柱还原-重氮偶氮法、重氮偶氮法和硅钼蓝法测定硝酸盐、亚硝酸盐、磷酸盐和硅酸盐,以及萃取荧光法测定Chl-a浓度,深入探讨雷州半岛Chl-a浓度空间变化的调控机制。【结果】2017年秋季,研究区域近岸Chl-a及营养盐浓度大致呈现近岸高离岸低的分布特点;雷州半岛东部海域与西部海域相比,Chl-a浓度、DIN、Si O32-,nDIN/nP比较高,而nSi/nDIN和PO43-在西部略高于东部;营养盐对浮游植物生长的可能限制因子分析结果,在雷州半岛东西部环境因子对Chl-a浓度的影响程度不同,其中盐度和亚硝酸盐是影响Chl-a浓度的主要因子。在浮游植物生长的限制因素方面,雷州半岛东部海域表现为明显的磷限制,西部海域表现为明显的氮限制。【结论】秋季调查海域营养盐和Chl-a结构变化主要受海域水文情况(河流径流,潮汐类型)和人类活动的影响。调查海域东部受到河流径流和不规则半日潮的影响,营养盐、Chl-a浓度以及营养盐比值(PO43-和nSi/nDIN除外)都比较高。西部海域由于河流径流量小、人类活动较少以及受到规则的全日潮的影响,营养盐、Chl-a浓度以及营养盐比值含量较低且分布较均匀。

【Objective】The spatial variation characteristics of nutrients and chlorophyll a(Chl-a) in the waters of the eastern and western Leizhou Peninsula were studied and their relationship was analyzed.【Method】According to the field investigation data of October 2017(autumn), the determination of nitrate, nitrite, phosphate and silicate by cadmium copper column reduction-diazo azo method, diazo azo method and silicon molybdenum blue method were respectively carried out. And the extraction fluorescence method to determine the concentration of Chl-a, and to explore the regulation mechanism of the spatial variation of Chl-a concentration in Leizhou Peninsula.【Result】In the fall of 2017, the near-shore Chl-a and nutrient concentrations in the study area were generally distributed near the shore and low offshore;the eastern part of the Leizhou Peninsula was compared with the western sea, Chl-a concentration, DIN, Si O32-and nDIN/nP were relatively high, while nSi/nDIN and PO43-are slightly higher in the west than in the east. Further analysis of the possible limiting factors of nutrient salt on the growth of phytoplankton in the sea area showed that the influence of environmental factors on the concentration of Chl-a in the eastern and western parts of Leizhou Peninsula is different. Among them, salinity and nitrite are the main factors affecting the concentration of Chl-a. It also showed obvious phosphorus limitation in the eastern waters of the Leizhou Peninsula and obvious nitrogen limitation in the western waters.【Conclusion】The change of the nutrient salt and Chl-a structure in the autumn survey area are mainly affected by the hydrological conditions(river runoff, tidal type) and human activities in the sea.In the eastern part of the survey, affected by river runoff and irregular half-day tides. Nutrient salts,Chl-a concentrations and nutrient ratios(except PO43-and nSi/nDIN) were relatively high. In the western seas, nutrient salts, Chl-a concentrations and nutrient ratios are low and evenly distributed due to small river runoff, low human activities and regular daytime tides.