Microplastics and the environment

We use a lot of plastic material  in our everyday life.  Once get into the environment, large pieces will turn to small plastic particles or microplastics.   Microplastics in the environment has become an important issue in aquatic environment.

What is microplastics? Microplastics is operational defined according to the size. Generally, plastic particles smaller than 5 mm are defined as microplastics.

Photo credit: http://5gyres.org/

What types of microplastics are there?
(1) primary microplastics -- the plastics that are manufactured to be of a microscopic size. They are usually used in facial cleansers and cosmetics, or in the air blasting technology. In some cases, their use in medicine as vectors for drugs was reported. Microplastics ‘‘scrubbers’’, used in exfoliating hand cleansers and facial scrubs, have replaced traditionally used natural ingredients, including ground almonds, oatmeal and pumice.
(2) secondary microplastics --  from the breakdown of larger plastic debris, both at sea and on land due to physical, biological and chemical processes that reduce the structural integrity of plastic debris

What environmental problems microplastics cause?
Microplastics may pose problems in the marine environment because of the persistence of microplastics (their likely buildup in the future), and the ingestion by marine organisms. Ingestion of microplastics by species at the base of the food web causes concern as little is known about its effects. Potential effects of microplastics on marine organisms after ingestion include:

• physical blockage or damage of digestive tract
• leaching of plastic component chemicals into organisms
• ingestion and accumulation of sorbed chemicals by the organism

Microplastics and POPs
persistent organic pollutants (POPs)can accumulate on microplastics, which may influence the global transport of POPs. The role of microplastics in the transfer of POPs from the environment to organisms is unknown. Because microplastics can possibly act as a carrier for POPs to enter food webs meanwhile it may lower the bioavailability of POPs to organisms in the food web.

Another concerns of microplastics and toxic chemicals is from additives such as plasticizer added to plastics during manufacture. The plasticizers, some of which have endocrine disruptive effect,  may leach out upon ingestion.

Currently, there is no study that test if microplastics can be transferred across trophic levels.

References and read more:
http://5gyres.org/
http://voices.nationalgeographic.com/2013/04/12/new-concerns-about-plastic-pollution-in-great-lakes-garbage-patch/
http://en.wikipedia.org/wiki/Microplastics

How the seawater at different depth of the ocean is sampled?

Ocean is the reservoir for many contaminants.  To analyze these contaminants and assess their ecological risk, the first step is to sample collection. What device is used to sample seawater of different depth ? 

Photo (taken by Xianming Zhang): seawater sampling using a CTD device on the Endeavor Research Cruise.

CTD (conductivity, temperature, and depth) is a package of electronic instruments that measure these properties. The CTD is lowered into the water to measure the salinity, temperature, depth and take samples through the water column. The CTD is attached to a metal frame, which holds water-sampling bottles to collect water at different depths. The sample bottles can be closed with computer control when the CTD is at a give depth. 

Along with seawater, gorgeous scenery is also sampled:  

(Photo of sunset from the research cruise close to the coast of New Jersey)