Lander Merma-Mora , François Colas , Jorge Cardich , Sonia Sánchez , Edgart Flores , Alberto Lorenzo , Arturo Aguirre-Velarde , David Correa , Dimitri Gutiérrez
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引用次数: 1
Abstract
Coastal hypoxia can occur naturally in inshore areas of the Eastern Boundary Upwelling Systems, influenced by the nutrient-rich and low-oxygen upwelling waters. This study aims to explore the influence of water stratification and winds on bottom-water hypoxia of the Paracas Bay, an area subjected to the most intense alongshore winds and active coastal upwelling in the Peruvian coast. Monitoring data of the Pisco-Paracas water properties (dissolved oxygen, temperature, salinity and estimated stratification), the Pisco River flow, and the intensities of surface winds of the outside upwelling area, and of the local area, were analysed for the period 2006 to 2015. Bottom waters deeper than 8 m in the bay were shown undergoing a hypoxic regime (oxygen <1.4 mL L−1) that becomes more frequent towards austral summer and less frequent towards winter. This seasonal difference was associated with changes in the oxygen content of incoming upwelling waters and changes in the intensity of both local and upwelling winds that drive the hydrodynamics of the bay. High frequency data analysis revealed that synoptic time-scale fluctuations of the upwelling-favourable and local winds modulate the intra-seasonal variability of hypoxia. Fluctuations of the former drive the inshore expansion of mixed and less hypoxic upwelling waters during June–September, whereas fluctuations of the latter during December–April drive the entrance and circulation of more hypoxic upwelling waters, and the development of stratification events that contribute to the persistence of bottom hypoxia.
沿海缺氧可能自然发生在东部边界上升系统的近海地区,受营养丰富和低氧上升流水域的影响。本研究旨在探讨水分层和风对帕拉卡斯湾底层水缺氧的影响。帕拉加斯湾是秘鲁海岸沿岸风最强烈、海岸上升流最活跃的地区。分析了2006年至2015年期间Pisco Paracas水质(溶解氧、温度、盐度和估计分层)、Pisco河流量以及外部上升流区域和当地的表面风强度的监测数据。海湾中深度超过8米的底层水域显示出缺氧状态(氧气<1.4 mL L−1),这种情况在南半球夏季变得更频繁,在冬季变得不那么频繁。这种季节性差异与进入上升流水域的氧气含量的变化以及驱动海湾流体动力学的局部风和上升流风强度的变化有关。高频数据分析表明,上升流有利风和局地风的天气时间尺度波动调节了缺氧的季节内变化。前者的波动在6月至9月期间驱动混合和缺氧性较低的上升流水域的近海扩张,而后者在12月至4月期间的波动则驱动缺氧性较高的上升流水体的进入和循环,以及导致底部缺氧持续存在的分层事件的发展。
期刊介绍:
The Journal of Marine Systems provides a medium for interdisciplinary exchange between physical, chemical and biological oceanographers and marine geologists. The journal welcomes original research papers and review articles. Preference will be given to interdisciplinary approaches to marine systems.