If you’ve ever watched a solitary ant explore your countertop, you might have marveled at its tiny size. You also might have questioned how something seemingly insignificant can be such a nuisance in your aspiringly sterile kitchen. Then you remember what your tiny pioneer heralds — the impending arrival of thousands of her sisters — and she suddenly seems like a more formidable adversary.
At a few millimeters short of a typical carpenter ant, microplastics are another case of both extreme smallness and overwhelming magnitude. Microplastics are the fragments, pellets, sheets, fibers, microbeads and polystyrene that begin as improperly discarded plastic bottles and trash that get washed into our waterways. At less than five millimeters in length, they are nearly imperceptible. But plastic doesn’t degrade like most organic material, meaning the total amount of plastic in the environment doesn’t really change as it breaks down, allowing microplastics to persist in most surface waters around the globe, including the Chesapeake Bay.
University of Maryland Professor Dr. Lance Yonkos is the primary author on a study of microplastics collected from four tributaries of the Chesapeake Bay — the Patapsco, Magothy, Rhode, and Corsica Rivers. Of the 60 samples taken by the National Oceanic and Atmospheric Association (NOAA) Marine Debris Program, all but one contained microplastics.
To Yonkos, it’s not really a surprise there are microplastics in the Bay.
“We have many of the prime sources for creating and introducing microplastics to aquatic environments,” Yonkos said. Roads are a main contributor because they promote physical degradation of plastics and provide easy transport via storm drains to Bay tributaries. Yonkos listed wastewater treatment plant effluent and substantial shipping traffic.
As plastic fragments become smaller, a greater number of animals are able to swallow them—as exemplified by the recent case of a whale killed by a shard from a DVD case. When these materials break down enough reach the level of microplastics, even filter feeders like oysters can consume them.
Smaller pieces also mean more surface area, Yonkos said, which could mean more leaching, either of chemicals from the plastic itself or of the environmental contaminants that cling to its surface.
“In this way, microplastics might serve as a vehicle for introducing bioaccumulative contaminants to the food chain,” Yonkos said. The concentration of such toxic contaminants can become magnified at higher levels of the food web.
But, the science isn’t clear yet on whether microplastics represent a serious environmental or human health concern.
“Since we don’t really know yet, it is a little disconcerting to think that most of the plastics we have created over the past 70 years are still in the environment,” Yonkos said.
And microplastics are here to stay. With no feasible method for removing microplastics that are already in the environment, measures like improved recycling and decreased use of offending products — like those that include microbeads, which would be banned by the state of Maryland according to legislation passed recently — could improve the situation going forward.
“The take home message is prevention,” Yonkos said. “If we want to reduce microplastics in the oceans we need to limit their release at the source.”
To view more photos, visit the Chesapeake Bay Program's Flickr page.
A new report from an advisory committee of scientific experts recommends the Chesapeake Bay Program’s Watershed Model be adjusted to better account for the influence of stream corridors and tree canopy on pollution from urban areas.
In the report, experts from the Bay Program’s Scientific and Technical Advisory Committee (STAC) suggest accounting for the effects of stream corridors and urban trees to improve the model’s accuracy and allow managers to better target pollution-reducing best management practices.
Trees and stream corridors interact with nutrient and sediment pollution in ways that are unique compared to other urban land covers, the study suggests. The erosion of stream channels can significantly increase the amount of sediment pollution associated with an urban area, while trees can help reduce the volume of polluted runoff.
The Watershed Model is used by Bay Program partners and stakeholders to estimate the amount of nutrients and sediment reaching the Bay. The model currently includes three urban land use categories: impervious (paved) surfaces like buildings, roads or parking lots; pervious (porous) surfaces like lawns or landscaping; and construction sites.
The federal agencies leading the watershed-wide effort to restore the Chesapeake Bay have released a progress report highlighting work completed in the last year, as well as a summary of achievements from the past five years.
Last year, federal agencies and their state and local partners opened more than 150 miles of rivers and streams to migratory fish, providing passage to key species such as American shad, river herring and American eel. They established conservation practices across farms and forests, protecting soil and water resources throughout the Bay region. And they launched efforts to respond to the emerging threats of toxic contaminants and climate change and their effects on fish, wildlife and local communities.
Since the signing of the Chesapeake Bay Executive Order in 2009, the federal agencies and their partners have helped make significant progress toward restoring the health of the Bay, including the permanent protection of more than 500,000 acres of land, the opening of 86 public access sites and the development of the nation’s largest oyster restoration project at Harris Creek. Over the last five years, federal agencies on the Federal Leadership Committee for the Chesapeake Bay have spent more than $2 billion on Bay restoration and protection.
The 2014-15 progress report marks the final report exclusive to the Federal Leadership Committee for the Chesapeake Bay; federal partners will continue to track their protection and restoration efforts as part of the new Chesapeake Bay Watershed Agreement and its associated management strategies. Draft versions of these strategies are available for public feedback through April 30, 2015.
Learn more about the 2014-15 progress report on the Chesapeake Bay Executive Order website.
While pollution controls put in place over the last five years have lowered the amount of nutrients and sediment entering the nation’s largest estuary, new data show that agricultural sources have sent more nitrogen and sediment into the Bay since 2007 than previously thought.
Excess nitrogen, phosphorus and sediment can impair water quality: nitrogen and phosphorus can fuel the growth of harmful algae blooms, while sediment can suffocate shellfish and block sunlight from reaching underwater plants.
Each year, the seven watershed jurisdictions report the steps they have taken to lower the nutrients and sediment entering rivers and streams. Bay Program experts run this information through a suite of computer simulations, which generate pollution load estimates that show us how far our partners have come toward meeting the Bay’s “pollution diet.” When bolstered with new data on population size, land use and agricultural commodities, these simulations show a drop in pollution since 2009—including a six percent drop in nitrogen, an 18 percent drop in phosphorus and a 4 percent drop in sediment—but a two percent rise in nitrogen and sediment loads between 2013 and 2014.
A shift in agricultural commodities could explain this rise in nitrogen and sediment loads. According to data from the U.S. Department of Agriculture’s Census of Agriculture, several states have seen a surge in corn plantings since 2007. Because corn requires nitrogen-rich fertilizer that can leach off the ground and into local waterways, more corn plantings led to more nitrogen loadings than anticipated when pollution targets and reduction milestones were set.
The Bay Program uses the best possible data and information to track our progress toward restoring water quality. By incorporating new data into our computer simulations and pollution load estimates, we are allowed a more accurate picture of pollution in the watershed and a better understanding of the actions that are needed to reach our clean water goals. Because these computer simulations generate pollution load estimates using long-term average weather conditions, it’s possible for these estimates to differ from those that are based on water quality monitoring data; the latter can vary with the amount of rainfall in a given year.
“Each year, we employ the most current data and up-to-date science [to] offer the highest quality information to the public on pollution reductions resulting from Chesapeake Bay Program partners’ continued efforts. While we… have a lot of work to do… we are making steady progress toward meeting water quality goals,” said Bay Program Director Nick DiPasquale in a media release.
These pollution load estimates are just one in a suite of tools the U.S. Environmental Protection Agency (EPA) uses to evaluate whether jurisdictions are on track to meet the Total Maximum Daily Load (TMDL) and its two-year milestone commitments. The EPA also considers data and information on best management practice implementation, best management practice effectiveness and jurisdictions’ progress toward putting programs in place to achieve pollution cuts. It is expected to release interim assessments of jurisdictions’ work in May and conduct the next full two-year assessment in 2016.