STUDY ON THE FORMATION OF LARGE SCALE ANOXIDATION AND OUTSIDE WATER INTRUSION IN URANOUCHI BAY

浦之内湾大规模氧化及外部水入侵的形成研究

基本信息

批准号：
04650465
负责人：
MUNEKAGE Yukihiro
金额：
$ 1.02万
依托单位：
KOCHI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04650465/
关键词：
Anoxidation DO production and consumption Intrusion Vertical mixing DO budget daylight hours DO consumption by hydrogen sulfide migration of dinoflagellate 亜表層部の貧酸素化異常気象プランクトンによるDO消費赤潮 DO消費速度密度流物質収支海水交換

项目摘要

In Uranouchi Bay, strong anoxic water mass was formed in the bottom and subsurface layrs in summer. A large number of cultured yellowtail fish were killed.(1)Anoxic water in the bottom grew with the development of pycnocline from June to September, and disappeared for a while after intrusion. Intrusion upwelled the bottom nutrient water, and made worse the upper water quality.(2)Hydrogen sulfide (H2S), which was produced at the bottom surface with the development of anoxic water, was transported to the upper layr through vertical mixing, and immediately oxidized. Oxidation of H2S reduced the dissolved oxygen (DO) concentration in the bottom layr by 2.4ppm during August, and further promoted the anoxidation.(3)Gymnodinium nagasakiense red tide plankton began to grow at the middle layr in the center of Uranouchi Bay with the development of anoxic water in the bottom. When external saline water intruded, abnormal multiplication immediately occurred in the whole layrs, red tide was formed at the surface.(4)Anoxidation in the subsurface was formed at the beginning of September, 1988, the middle of August and September, and the beginning of November, 1993. These were formed from just after the sudden decrease of daylight hours. At the beginning of anoxidation, red tides of dinoflagellates and outside water intrusion were developed.(5)Dinoflagellates were appeared in the surface in the daytime, but migrate into the depth of 8-15m in the nighttime, and consumed abundant DO in the subsurface and middle layrs.(6)DO concentration in the subsurface layr was controlled by the production due to phytoplankton and consumption in water. DO supply due to mixing and intrusion was negligible. When the daylight hours decreased, anoxidation were formed in the subsurface, because DO production in the subsurface layr decreased, and DO consumption were increased due to the migration of dinoflagellates.

夏季，浦之内湾底层和次表层形成强烈缺氧水团。养殖黄尾鱼大量死亡。(1)6-9月底层缺氧水体随着密斜线的发展而增长,入侵后暂时消失。入侵使底层营养水上涌，使上层水质恶化。(2)随着缺氧水体的发展，底层表面产生的硫化氢(H2S)通过垂直混合输送到上层，立即被输送到上层。被氧化。 8月份H2S的氧化使底层溶解氧(DO)浓度降低了2.4ppm，进一步促进了缺氧。(3)浦之内湾中部中层赤潮浮游生物Gymnodinium nagasakiense开始生长，底部缺氧水的发展。当外部咸水侵入时，全层立即发生异常繁殖，地表形成赤潮。(4)1988年9月初、8、9月中旬和年初，形成地下氧化层。 1993 年 11 月。这些是在白天时间突然减少后形成的。缺氧初期，甲藻赤潮和外界水体侵入。(5)甲藻白天出现在表层，夜间向8～15m深处迁移，消耗地下丰富的DO。 (6)地下层DO浓度受浮游植物的产生和水的消耗控制。由于混合和侵入而产生的溶解氧供应可以忽略不计。当日照时间减少时，地下形成缺氧现象，原因是地下层DO产生减少，而甲藻的迁移导致DO消耗增加。