반 폐쇄성내만에서 유기물 분해능 및 분해경로중 저서동물의 영향

Abstract

The objectives of our study were to examine the macrofauna effect on biobeochemistry cycle through seasonal variation of burrow density and anaerobic mineralization rates of organic matter in a unique coastal environment where don’t have any river and terrestrial material. Burrow density at the site 1 (65-249 No. m-2) always exceed that of the site 2 (17-34 No. m-2) by about two-eight times at each season. The solid phase Fe(III) at the site 1 (2465-4514 mmol m-2) were remarkably higher than that of the site 2 (841-1607 mmol m-2) at all season. In contrast to Fe(III), solid phase Fe(II) at the site 2 (1760-2184 mmol m-2) exceed Fe(II) of the site 1 (441-1423 mmol m-2) by about two-four times at each season. The distribution of solid phase Fe(III) matched with the FeRRs (Fe(III) reduction rates), showing that more FeRRs observed where Fe(III) concentration higher. Consequently, in this study area, the seasonal variation of FeRRs was controlled by Fe(III), which could enhance the reoxidation of Fe(II) by macro-fauna activity. Contrasting FeRRs, even though SRRs (sulfate reduction rates) showed a large seasonal variation, little spatial variation was observed.Annually average anaerobic respiration rates were 39.0 and 30.0 mmol m-2 d-1 at site S1 and S2, respectively . Despite low POC concentration relatively, in sediment at Taean Bay, anaerobic respiration rates exceed rates of other intertidal mudflat. The organic matter in Taean Bay, where is no river and influx of organic matter with semi-closed bay, actually originated from autochthonous organic matter with eight or less in average, C/N ratio including the organic matter generated by those of ocean, rather than terrigenous organic matter. Overall results suggested that anaerobic respiration rates were mainly affected by organic matter quality rather than the quantity in the study area.