Khanittha Uthaipan - Academia.edu (original) (raw)
Uploads
Papers by Khanittha Uthaipan
Cambridge Prisms: Coastal Futures
Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great eff... more Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great efforts to reduce nutrient loading and mitigate associated environmental damages. Symptoms of this crisis have appeared to spread rapidly, reaching developing countries in Asia with emergences in Southern America and Africa. The pace of changes and the underlying drivers remain not so clear. To address the gap, we review the up-to-date status and mechanisms of eutrophication and hypoxia in global coastal oceans, upon which we examine the trajectories of changes over the 40 years or longer in six model coastal systems with varying socio-economic development statuses and different levels and histories of eutrophication. Although these coastal systems share common features of eutrophication, site-specific characteristics are also substantial, depending on the regional environmental setting and level of social-economic development along with policy implementation and management. Nevertheless, e...
Biogeosciences
We examined the evolution of intermittent hypoxia off the Pearl River estuary based on three crui... more We examined the evolution of intermittent hypoxia off the Pearl River estuary based on three cruise legs conducted in July 2018: one during severe hypoxic conditions before the passage of a typhoon and two post-typhoon legs showing destruction of the hypoxia and its reinstatement. The lowest ever recorded regional dissolved oxygen (DO) concentration of 3.5 µmol kg −1 (∼ 0.1 mg L −1) was observed in bottom waters during leg 1, with an ∼ 660 km 2 area experiencing hypoxic conditions (DO < 63 µmol kg −1). Hypoxia was completely destroyed by the typhoon passage but was quickly restored ∼ 6 d later, resulting primarily from high biochemical oxygen consumption in bottom waters that averaged 14.6 ± 4.8 µmol O 2 kg −1 d −1. The shoreward intrusion of offshore subsurface waters contributed to an additional 8.6 ± 1.7 % of oxygen loss during the reinstatement of hypoxia. Freshwater inputs suppressed wind-driven turbulent mixing, stabilizing the water column and facilitating the hypoxia formation. The rapid reinstatement of summer hypoxia has a shorter timescale than the water residence time, which is however comparable with that of its initial disturbance from frequent tropical cyclones that occur throughout the wet season. This has important implications for better understanding the intermittent nature of hypoxia and predicting coastal hypoxia in a changing climate.
Limnology and Oceanography, 2020
Cambridge Prisms: Coastal Futures
Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great eff... more Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great efforts to reduce nutrient loading and mitigate associated environmental damages. Symptoms of this crisis have appeared to spread rapidly, reaching developing countries in Asia with emergences in Southern America and Africa. The pace of changes and the underlying drivers remain not so clear. To address the gap, we review the up-to-date status and mechanisms of eutrophication and hypoxia in global coastal oceans, upon which we examine the trajectories of changes over the 40 years or longer in six model coastal systems with varying socio-economic development statuses and different levels and histories of eutrophication. Although these coastal systems share common features of eutrophication, site-specific characteristics are also substantial, depending on the regional environmental setting and level of social-economic development along with policy implementation and management. Nevertheless, e...
Biogeosciences
We examined the evolution of intermittent hypoxia off the Pearl River estuary based on three crui... more We examined the evolution of intermittent hypoxia off the Pearl River estuary based on three cruise legs conducted in July 2018: one during severe hypoxic conditions before the passage of a typhoon and two post-typhoon legs showing destruction of the hypoxia and its reinstatement. The lowest ever recorded regional dissolved oxygen (DO) concentration of 3.5 µmol kg −1 (∼ 0.1 mg L −1) was observed in bottom waters during leg 1, with an ∼ 660 km 2 area experiencing hypoxic conditions (DO < 63 µmol kg −1). Hypoxia was completely destroyed by the typhoon passage but was quickly restored ∼ 6 d later, resulting primarily from high biochemical oxygen consumption in bottom waters that averaged 14.6 ± 4.8 µmol O 2 kg −1 d −1. The shoreward intrusion of offshore subsurface waters contributed to an additional 8.6 ± 1.7 % of oxygen loss during the reinstatement of hypoxia. Freshwater inputs suppressed wind-driven turbulent mixing, stabilizing the water column and facilitating the hypoxia formation. The rapid reinstatement of summer hypoxia has a shorter timescale than the water residence time, which is however comparable with that of its initial disturbance from frequent tropical cyclones that occur throughout the wet season. This has important implications for better understanding the intermittent nature of hypoxia and predicting coastal hypoxia in a changing climate.
Limnology and Oceanography, 2020