Abstract: A seasonal investigation was conducted on the chlorophyll-a (Chl-a) and phaeophorbidea (Pha-a) contents in the sediments of mangroves in Dongzhai Bay of Hainan Province from September, 2010 to June, 2011. There was an obvious difference in the horizontal distribution of chl-a and pha-a in the sediments between different sampling points. The chl-a content was 1.59-6.82 μg·g^-1, with an average of 2.98 μg·g^-1, and decreased with increasing sediment depth, being 1.59-6.82, 0.70-5.93, and 0.60-4.49 μg·g^-1 in 0-2,  2-5, and 5-8 cm layers, respectively. The average chl-a contents in different sampling points had the similar seasonal variation pattern, with the highest chla content in 0-2 cm layer in September (6.82 μg·g^-1), and in 2-5 and 5-8 cm layers in June (5.93 and 4.49 μg·g^-1, respectively). The pha-a in the sediments had the similar distribution trend to chl-a. The pha-a content was 1.81-14.22 μg·g^-1, being the highest (14.22 μg·g^-1) at E station in June, 2011.

Key words: Si, phytolith, Moso bamboo, parent rock., phytolith-occluded carbon (PhytOC)