Mishra R K, Shaw B P, Sahu B K, Mishra S, Senga Y
School of Marine Science and Technology, Tokai University, Shizuoka, Japan.
Environ Monit Assess. 2009 Feb;149(1-4):261-73. doi: 10.1007/s10661-008-0200-2. Epub 2008 Feb 27.
Characteristics of the monsoonal bloom of phytoplankton at Orissa Coast in the Bay of Bengal were studied through bimonthly observation from April 2001 to December 2002. Three photosynthetic pigments chlorophyll-a (Chl a), chlorophyll-b (Chl b) and carotenoid (Car) were analyzed by absorption spectroscopic method. The seasonal variation of Chl a included phytoplankton bloom in the coastal area during monsoon period. The water column integrated Chl a reached to 68 mg m(-2) at the station-1(St1), and amounted to 20 mg m(-2) at 30 km off the river mouth during August 2001. In contrast the same amount was found at 15 km off the Mahanadi river mouth during August 2002. Salinity during this period varied from 5 psu at the St1 to 27 psu at the edge of the bloom area. The total amount of river discharge in the monsoon period calculated from daily river discharge data reported by Water Resources Department in India was 84 x 10(9) m(3) during 2001 and 20 x 10(9) m(3) during 2002. Both nitrate and phosphate concentrations showed negative quadratic relationship with salinity throughout the observation period. Extrapolated nitrate and phosphate concentration discharge from the Mahanadi river were 10.8 and 4 microg-at l(-1), respectively. Microscopic identification revealed dominance of fluvial Chlorophyceae and diatoms during the monsoon period showing influence of the freshwater discharge.
通过2001年4月至2002年12月的双月观测，研究了孟加拉湾奥里萨海岸浮游植物季风雨季大量繁殖的特征。采用吸收光谱法分析了叶绿素a（Chl a）、叶绿素b（Chl b）和类胡萝卜素（Car）这三种光合色素。Chl a的季节变化包括季风期沿海地区浮游植物的大量繁殖。2001年8月，1号站（St1）水柱积分Chl a达到68 mg m(-2)，在河口外30公里处为20 mg m(-2)。相比之下，2002年8月在默哈讷迪河河口外15公里处发现了相同的数量。在此期间，盐度从St1的5 psu到大量繁殖区域边缘的27 psu不等。根据印度水资源部报告的每日河流流量数据计算，2001年季风期河流总流量为84×10(9) m(3)，2002年为20×10(9) m(3)。在整个观测期内，硝酸盐和磷酸盐浓度与盐度均呈负二次关系。默哈讷迪河的硝酸盐和磷酸盐浓度外推排放量分别为10.8和4微克-at l(-1)。显微镜鉴定显示，季风期河流绿藻科和硅藻占优势，表明受到淡水排放的影响。
