//
you're reading...

Biogeochemistry

On a mission to partition: the likelihood of flame retardants to bind to marine organic matter

Wei-Haas, M. L., Hageman, K. J., & Chin, Y.-P. (2014). Partitioning of Polybrominated Diphenyl Ethers to Dissolved Organic Matter Isolated from Arctic Surface Waters. Environmental Science & Technology. doi:10.1021/es405453m

Background

Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants that are classified as persistent organic pollutants (POPs) and found ubiquitously in the environment. They are now banned in many regions of the world, however certain mixtures of PBDEs are still widely produced and used in the United States and can be found in all sorts of products from couches to roof shingles to pajamas.

Marine dissolved organic matter (DOM) is a complex mixture of organic matter found in seawater. Largely it consists of (and as such is measured by) a huge pool of organic carbon in the oceans that is of a very small size that can pass through a very small filter (i.e. < 0.5 microns). However it is important to note that in addition to carbon, there are thousands of complex molecules within the DOM pool that often make it difficult to completely characterize.

PBDEs are largely hydrophobic molecules, meaning they hate the water. Thus, they are much more likely to bind or sorb to something they have a greater affinity, or liking, to such as organic matter or fatty tissues in organisms (e.g. fish or humans). There are various different methods we can use to measure how likely organic contaminants, such as PBDEs, are to be bound or sorbed to a certain material – these are referred to as partition coefficients, and are usually denoted with the letter “K.” When you see Kow, it is referring to the partitioning between octanol and water, or the ratio of the compound you will find in octanol versus water. Octanol in many cases is used as a proxy, or substitute, for fatty tissue; so if you see a compound with a high Kow, you might expect that it will really want to be in an organism versus the water. In a similar sense, a compound Koc, is the ratio of a contaminant you see in organic carbon versus water. In most cases, compounds with high Kow values will also have high Koc values. This study aims to find Kdoc values for 6 different PBDEs, which means the focus it only on the dissolved component of organic carbon.

Wei-Haas - BDE structure image

This Study

Since we know PBDEs are largely hydrophobic and don’t like to exist in water, we want to know where they might end up. Some options, and often where we find them, are bioaccumulating up the food chain through organisms and binding to sediment. The authors of this paper focus on the Arctic environment and investigate dissolved organic matter (DOM) and the interaction that PBDEs might have with it. Interactions have been proven in the past between DOM and other hydrophobic contaminants that link to altered environmental mobility, bioavailability, and degradation in the environment. If PBDEs, which have typically high Kow values, are likely to bind to DOM, their transport and fate may be greatly affected.

How they did it

DOM is extremely complex and its composition may vary, depending on the region of interest.  Structures of DOM can range from high aromaticity and molecular weight, which often comes from land-derived sources, to low aromaticity and molecular weight, which is often indicative of marine sources such as phytoplankton and microbial action. In simpler terms, the level of complexity of DOM can affect the sorption of hydrophobic contaminants, such as PBDEs.

The authors collected and isolated DOM from the North Slope of Alaska using what’s called a ‘solubility enhancement method and PPL solid phase extraction cartridges’ (fancy terminology for the lab work performed), choosing to look at the interactions of 6 PBDE congeners or varying bromination (BDE-28, -47, -77, -99, -153, and -190) with the isolated Arctic DOM as well as laboratory standards. They analyzed their observations and compare them to predicted values using what’s called a poly-parameter linear free energy relationship, or pp-LFER. This is basically just a way of plotting a combination of various parameters of the compounds (such as how many hydrogens it’s willing to donate or accept) in logarithmic form to come up with a KDOC.

What they found

DOM concentrations in the Arctic surface waters are high and high Kdoc values were measured for the PBDEs observed in this study. When you link high amounts of DOM and high Kdoc values, you can get as much as 70% of the dissolved mass of higher brominated PBDEs partitioning to DOM, which may largely affect the fate and bioavailability of the compound.

Wei-Haas Figure 4

It is clear that PBDEs are unique and do not always follow the same trends as observed in other hydrophobic compounds. However, certain trends observed were that the Log Kdoc increased with increasing bromine substitution, but when looking at molecules with the same number of bromines, the Log Kdoc  may also be affected by the position of the bromine on the molecule (i.e. if it’s in the “ortho” position on the molecule). Values determined for KDOC in this experiment are 1-2 orders of magnitude lower than what has been reported previously in the literature, which illustrates the complexity of aquatic DOM and demonstrates that using laboratory derived standards for organic matter may not always be the best option.

 

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 4 days ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 1 month ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 2 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 2 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 4 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 5 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 5 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 6 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 6 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 7 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 7 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 8 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
  • by oceanbites 8 months ago
    Feeling a bit flattened by the week? So are these summer flounder larvae. Fun fact: flounder larvae start out with their eyes set like normal fish, but as they grow one of their eyes migrates to meet the other and
  • by oceanbites 8 months ago
    Have you seen a remote working setup like this? This is a photo from one of our Oceanbites team members Anne Hartwell. “A view from inside the control can of an underwater robot we used to explore the deep parts
WP2Social Auto Publish Powered By : XYZScripts.com