Caoxin Sun

Caoxin Sun has written 18 posts for oceanbites
Figure 2. "Deep ocean!" PFASs shout. (picture from Hastings water works)

Pollutants have fun sliding downhill in submarine canyons!

Many of us believe that the deep ocean is pristine and not affected by any human activities; the fact that pollutants such as perfluoroalkyl substances can reach deep ocean gives us a warning sign. It was estimated that around 60 kg of these chemicals was transported during the sampling periods.

Figure 2. Snow melting may be the major input of volatile methyl siloxanes to the Antarctic ecosystem.

These Volatile Pollutants Can’t Fly, but Can They Hop?

Volatile methyl siloxanes can be easily found in personal care products (e.g. shampoo, lotion and cream) . Recently, scientists detected these compounds in soils, vegetation, phytoplankton, and krill samples from the Antarctic Peninsula region. This finding brings into question the belief that these compounds are not able to reach remote terrestrial and marine surfaces.

Figure 5. Plane spreading oil dispersants over floating oil.

“Magic Sand” Cleans up floating oil

Currently, spreading dispersants is the most common way to stabilize surface oil after oil spill. These dispersants divide oil into small droplets which are more available to bacteria. However, this application of dispersants is not applicable near the coast and the toxicity of dispersants remains to be studied. Natural granular material could be a more eco-friendly tool in fixing coastal floating oil.

Figure 1. A time line of the 5 most pressing problems affecting the global ocean.

Global change and the future ocean

The Growing number of environmental changes, such as contamination of seafood, shortage of water and increased frequency of extreme weather (floods, drought, hurricanes, etc), has raised people’s concerns about the Earth’s ability to sustain human populations.

Figure 4. Cycling of MMHg and DMHg in the Arctic Marine Boundary Layer.

Methylated Mercury Cycling in the Canadian Arctic Marine Boundary Layer

Monomethylmercury (MMHg) is the most toxic form of mercury (Hg) to humans and wildlife. In the environment it concentrates (or “bioaccumulates”) in fish and shellfish. This increase in methylmercury concentration is further amplified up the food chain when, for example, people consume seafood. Mercury (Hg) found in Arctic marine mammals and fish are on the rise, raising concerns over the potential impacts on the environment and human health. However, our understanding of Arctic Hg biogeochemistry remains incomplete.

Figure 6. Beautiful scenery of one of the Pacific Islands.

How Does Pacific Island Climate Change Under Various El-Niño

El Niño impacts vary among different geographic regions and El Niño types. A single El Niño event may bring drought to one Pacific Island country while increasing rainfall in another.

Figure 1. Salmon attacked by parasites. (From FIS)

Passive Sampling for Antiparasitics near a Chile Salmon Farm

An increase in the number of positive cages and cage-level abundance of sea lice in southern Chile was shown since 2004. The prevalence of sea lice in the fish farms was 53.4%, and the average sea lice abundance was 11.8 per fish (poor salmon)! In order to gain control over parasites, synthetic pyrethoid has been invented and put into use. However, pyrethoid is released to the ocean after treatment and has the potential to harm non-target organism, such as copepods, benthonic crustaceans and mussels. Passive sampling is a promising way for monitoring these compounds in the water. It is much cheaper and simpler than actively collecting liters of water!

Fig 1. An example of oil slicks on Lake Maracaibo, Venezuela in January 2013. The scene shows oil slicks (the various dark patches) in the south-eastern portion of the lake. The slicks come from leaks in the various oil production and storage platforms located on Lake Maracaibo.  
From: http://earthobservatory.nasa.gov/IOTD/view.php?id=3533

The first day after an oil spill

Crude oil is mostly composed of n-alkanes and polycyclic aromatic hydrocarbon (PAHs) which are toxic to organisms. After an oil spill, it is crucial to investigate the fractionation of compounds partitioning into the air and water to aid in predicting their threat to downwind population and the marine community.

Fig 1. Detection frequencies  of compounds with df > 10% in all samples (n = 153). Only the compounds analyzed in all samples were considered in the calculation.

Fish don’t need to lineup at Starbucks to get their morning coffee – they’re swimming in it!

Pharmaceuticals, corrosion inhibitors, biocides and stimulants are some of the most frequently detected micropollutants in the aquatic environment. They are toxic, bioaccumulative and hard to degrade. They can pose risks to the local ecosystem or even human health.


Seafood? Yes! Plastics? No!

Seafood is an important part of people’s diets worldwide, so it is crucial to understand the presence of microplastics in seafood. Van Cauwenberghe and Janssen measured plastics ingested by the mussel Mytilus edulis and the oyster Crassostrea gigas because of their filter-feeding behaviors.


Ocean Ecosystem Stressors Influence Human Health

Healthy coastal and marine environments are of great importance to human beings. They provide many ecosystem services, which are water and food supply, temperature maintenance, storm protection, recreation etc; yet currently, many of these environments are being degraded by several environmental stressors.


Arctic Feels Hotter than Other Parts of the World

Speaking of climate change, you can easily picture a scene in which big ice sheets are melting and poor polar bears standing on the last piece of ice finding nowhere to live. To some extent this is true, since impact from global warming can be amplified in Arctic region.

Fig 2. Locations of core sites.

Rapid Reductions in North Atlantic Deep Water during the Peak of the Last Interglacial Period

North Atlantic deep water forms primarily in more extreme northern latitudes due to the colder, saltier water with a higher density. When this flow of water goes south it mixes with the cold Antarctic water and then redistributes into other parts of the world. As high latitude warming and ocean refreshing reduce water density, North Atlantic Deep Water (NADW) formation can be prohibited.

Fig. 1. The Svalbard gas hydrate province is located on the western margin of the Svalbard archipelago (inset). At water depths shallower than 398 m, numerous gas flares have been observed in the water column (color-coded dots for different surveys) by using EK60 echo sounders and high-resolution side scan sonar. The gas flares are located between the contour lines at which gas hydrate is stable in the subsurface at 3° (brown) and 2° (blue) C average bottom water temperature. The black lines show the location of PARASOUND profiles with 40-m separation, that is, complete coverage, for flare mapping. The black arrows point to the location of submarine dives. The red line shows the location of the modeling transect. The large cluster of seeps at the northern limit of the gas flare line at a water depth of 240 to 260 m can be explained by the presence of an elsewhere-absent glacial debris flow deposit that is deviating gas laterally within the prograding debris flow deposits and cannot have anything to do with gas hydrate dynamics (16, 23). CTD, conductivity, temperature, and depth.

Reevaluating of Hydrate-Controlled Methane Seepage from Study off Svalbard

Methane, which is an even more powerful greenhouse gas than carbon dioxide, has been a great concern as climate change may lead to large quantities of emissions of methane. Due to the temperature-dependent stability of methane, it is claimed that a fraction of methane would be released from the warming up ocean water.


Sea ice leads cause changes in mercury and ozone levels in the Arctic

In our changing climate, the opening and closing of sea-ice is occurring more frequently, resulting from thick perennial Arctic sea ice shifting into thin seasonal ice sheets. This physical phenomenon can not only affect the energy balance in the Arctic, but can also have some influence on its atmospheric chemistry involving components such as mercury and ozone.


Is Aragonite Saturation State (Ωa) the Best Way to Describe Calcification Rate?

Nearly every scientific report concerning the effects of ocean acidification on coral reefs describes changes in calcification as a function of the aragonite saturation state (Ωa). Is this the best parameter that we can use to represent calcification condition? Are there any other options?


Perfluorooctanoic acid (PFOA) Entering Deeper Ocean via Vertical Eddy Diffusion

The ocean is home to many creatures: plankton, fish, mammals, etc. But it is also ‘home’ to a number of persistent organic pollutants (POPs), which are usually at low concentrations in the water but have the potential to bioaccumulate. Where do these pollutants end up? Do they stay in the surface water or do they sink into the deep?


Coral Reefs Suffering from Ocean Acidification

Researchers investigated natural trends in carbonate chemistry of the Davies Reef flat in the central Great Barrier Reef on diel and seasonal timescales. They found the reef flat is below a calcification threshold, which implies that a transition in the reef may occur from a state of net calcification to dissolution, around 26.9% of the time during the summer and 14.1% of the time in the winter.

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