Hydrographic analysis on the multi-time scale variability of hypoxia adjacent to the Changjiang River Estuary

水文学 缺氧(环境) 河口 海洋学 环境科学 季节性 空间变异性 地质学 生态学 生物 氧气 化学 统计 数学 有机化学
作者
Ke Zhu
摘要

The extremely low concentration of dissolved oxygen(DO) phenomenon,also known as hypoxia if DO ≤ 2 mg/L,is extraordinary significant in the near bottom water of the Changjiang River Estuary and its adjacent waters in summer.The area of hypoxic zone in this region has a clear trend of increasing during last decades.The spatial distribution of hypoxic zone shows a significant inter-annual variability.Most of published work has mainly concentrated on the formation of hypoxia while only a few attentions have been paid on the mechanism of hypoxia variability and its association with dynamical factors.To understand the evolution and variability of hypoxia and their relationship with the hydrographic conditions in the above area,data collected during four interdisciplinary cruises in June,August and October 2006 and in August 1999 were comparatively analyzed in this paper.The hypoxia off the Changjiang River Estuary was not significant in early summer(June) but already disappeared in early autumn(October).By contrast it continued along the coastal waters off Zhejiang Province throughout three cruises in 2006.In mid-summer(August),there were two hypoxic zones co-existed in the investigating areas as in 1999.It was obvious that these two low DO zones evolved in different ways with different seasonality.The area of the north hypoxic zone was significantly larger even though it took place later.In the meantime,the DO concentration there was much lower than that of the south part,but endured for a relatively short time.The inter-annual variability was also much stronger especially for the north hypoxic zone.A comparison was conducted to show those variations between the mid-summer of 1999 and 2006 were unprecedentedly large marked by the enormous intensification of northward spreading of the hypoxic zone in 2006.The prominent multi-time scale variability of the hypoxia is associated with variable physical forcing.(1)The seasonal evolution of hypoxia is relevant to the corresponding changes of thermo-and hydro-dynamic factors.The development of vertical stratification is necessary for the formation of the bottom hypoxic condition.(2)The competition among various waters masses,like the Changjiang Diluted Water(CDW) and the Taiwan Warm Current Water(TWCW),result in migrations of hypoxic zone in different years.The distribution of satellite observed sea surface chlorophyll a provides supporting evidence for the changes of waters masses.According to these observations,the 3D primitive equation model-Regional Ocean Modeling Systems(ROMS)-was applied to the East China Sea to examine the variability of the CDW with the agency of sea surface salinity.A set of numerical simulations were conducted to understand the individual and joint effects of three forcing: wind,river runoff and the Kuroshio.The significant disparity between 1999 and 2006 can be explained by the CDW retreat and/or the TWCW expansion induced by these factors,i.e.the change of the wind fields,the tremendous reduction of the freshwater runoff and variant intrusion of the TWCW.Among of which,the changing wind forcing plays the dominant role to the changed CDW.This paper suggests that more attentions need to be paid on the roles of hydrography played on the hypoxia formation and evolutions.
最长约 10秒,即可获得该文献文件

科研通智能强力驱动
Strongly Powered by AbleSci AI
更新
PDF的下载单位、IP信息已删除 (2025-6-4)

科研通是完全免费的文献互助平台,具备全网最快的应助速度,最高的求助完成率。 对每一个文献求助,科研通都将尽心尽力,给求助人一个满意的交代。
实时播报
Singularity举报debuffv求助涉嫌违规
1秒前
852应助含蓄绿兰采纳,获得10
1秒前
Sherry完成签到,获得积分10
1秒前
隐形曼青应助平常的念柏采纳,获得10
2秒前
ppc524发布了新的文献求助50
3秒前
huajianjiuxing完成签到,获得积分10
3秒前
3秒前
在水一方应助巫凝天采纳,获得30
3秒前
善学以致用应助就这样采纳,获得10
3秒前
3秒前
4秒前
爆米花应助dudu10000采纳,获得10
4秒前
麦田的守望者完成签到,获得积分10
4秒前
llyy123完成签到,获得积分10
4秒前
123发布了新的文献求助10
5秒前
6秒前
123发布了新的文献求助10
6秒前
6秒前
6秒前
6秒前
SciGPT应助meng采纳,获得10
7秒前
狂野友梅完成签到,获得积分10
7秒前
7秒前
文艺寄灵完成签到,获得积分10
7秒前
7秒前
听风者发布了新的文献求助10
8秒前
欣喜的成败完成签到,获得积分20
8秒前
panpan111完成签到,获得积分10
9秒前
TL完成签到,获得积分10
9秒前
wu完成签到 ,获得积分10
9秒前
9秒前
我想@科研发布了新的文献求助10
10秒前
10秒前
过pass发布了新的文献求助10
10秒前
zy发布了新的文献求助10
10秒前
11秒前
Vivian完成签到,获得积分10
11秒前
倩迷谜发布了新的文献求助10
12秒前
小荇发布了新的文献求助10
13秒前
小二郎应助ShangNiNE采纳,获得10
13秒前
高分求助中
A new approach to the extrapolation of accelerated life test data 1000
ACSM’s Guidelines for Exercise Testing and Prescription, 12th edition 500
Picture Books with Same-sex Parented Families: Unintentional Censorship 500
Nucleophilic substitution in azasydnone-modified dinitroanisoles 500
不知道标题是什么 500
A Preliminary Study on Correlation Between Independent Components of Facial Thermal Images and Subjective Assessment of Chronic Stress 500
Phylogenetic study of the order Polydesmida (Myriapoda: Diplopoda) 360
热门求助领域 (近24小时)
化学 材料科学 医学 生物 工程类 有机化学 生物化学 物理 内科学 纳米技术 计算机科学 化学工程 复合材料 遗传学 基因 物理化学 催化作用 冶金 细胞生物学 免疫学
热门帖子
关注 科研通微信公众号,转发送积分 3970683
求助须知:如何正确求助?哪些是违规求助? 3515337
关于积分的说明 11178055
捐赠科研通 3250580
什么是DOI,文献DOI怎么找? 1795357
邀请新用户注册赠送积分活动 875790
科研通“疑难数据库(出版商)”最低求助积分说明 805166