大潮期におけるマングローブ水域の溶存酸素と栄養塩の時空間変動

摘要

In the Fukido-river mangrove area in Ishigaki Island, Japan, field observations and water, sediment analyses were conducted to investigate spatial and temporal variations of physical environment (salinity, Dissolved Oxygen) and dissolved nutrient (NO_3-N, NO_2-N, NH_4-N, PO_4-P, SiO_2-Si, DOC-C). In addition, through experiments in the field, we quantified the nutrient release from sediments in mangrove creeks. DO in mangrove creeks increased with high DO seawater flowing into creeks, and decreased during ebb tide by consumption. Continuous observations in mangrove creeks showed NO_3-N and DOC-C increased in the dense mangrove area. PO_4-P also increased there, but was adsorbed to particulate matter and more likely to be diluted with seawater. Under aeration system, the release of NH_4-N increased obviously and the average release rate was 28 mgN/m~2/day. This gave close agreement with NH_4-N increase in creeks.