Spatio-temporal distribution of chlorophyll - a concentration in Hong Kong's coastal waters

Abstract

選取香港海域7個水環境控制區在1988 ~ 1999年期間每月或每半月定位連續取樣的37個水質測站,每個測站選用17個水質參數,研究香港海域海岸帶水體葉綠素-a濃度及其相關因子的時空分布規律。對37個測站17個參數作聚類分析,結果表明,香港海域東部由半封閉海灣組成的水域控制區,其赤潮發生頻率較高;西部水域屬于河口環境。多變量分析結果表明,BOD5對葉綠素-a濃度普遍存在顯著性影響,氮和光照條件在東部海域對葉綠素-a濃度的影響比西部海域更顯著,而磷以及包括鹽度、溫度、溶解氧和pH在內的海洋物理化學條件在西部海域有更顯著的影響。在整個香港海域,年內平均最高葉綠素-a濃度主要出現在冬末春初和夏末秋初,東部海域的年平均葉綠素-a濃度一般高于西部海域。香港海域的葉綠素-a濃度普遍存在一個8~10年的周期性變化規律。 Seven Water Control Zones in Hong Kong’s coastal waters with sampling data of 17 parameters collected at 37 monitoring stations from 1988 to 1999 were selected to analyze the spatio-temporal variations of chlorophyll-a concentration. The results suggest that frequent red tides occurred in eastern Hong Kong’s coastal waters, and less red tides occurred in an estuarine environment in the west. In all coastal waters, the organic contents indicator, BOD 5 , was a common significant influential factor of the chlorophyll-a level. Nitrogen and light penetration condition related to turbility, total volatile solids and suspended solids had greater influence on the cholophyll-a level in the east than in the west, while phosphorus and oceanographic condition associated with salinity, temperature, dissolved oxygen and pH was more important in west than in east. Generally, there was a higher average chlorophyll-a level in the late winter and early spring, and late summer and early autumn in a year. The chlorophyll-a level was higher in the east than in the west among all seasons in general. The chlorophyll-a concentration has a fluctuation period of 8-10 years generally in the whole region.