Bacteria can defuse dangerous chemical in Rassaic River
Study suggests pollutant's toxicity could be decreased

Date:
August 19, 2020
Source:
Rutgers University
Summary:
Bacteria that can help defuse highly toxic dioxin in sediments
in the Passaic River - a Superfund hazardous waste site - could
eventually aid cleanup efforts at other dioxin-contaminated sites
around the world, according to scientists.



FULL STORY ========================================================================== Bacteria that can help defuse highly toxic dioxin in sediments in the
Passaic River -- a Superfund hazardous waste site -- could eventually
aid cleanup efforts at other dioxin-contaminated sites around the world, according to Rutgers scientists.


========================================================================== Their research, published in the journal Environmental Science &
Technology, needs further work to realize the full potential of the
beneficial bottom- dwelling microbes.

"The bacteria-driven process we observed greatly decreases the toxicity
of dioxin," said senior author Donna E. Fennell, a professor who chairs
the Department of Environmental Sciences in the School of Environmental
and Biological Sciences at Rutgers University-New Brunswick.

"Our results showed that although the process is quite slow, it can be
enhanced and may even have the potential to remove all toxic chlorines
from the compound," said lead author Rachel K. Dean, a Rutgers doctoral student.

In a process known as dechlorination, the bacteria remove chlorine atoms
from 2,3,7,8-Tetrachlorodibenzo?p?dioxin (TeCDD), the most toxic of the
many dioxins, according to the study.

These chemicals can cause cancer, reproductive and developmental problems
and immune system damage, according to the U.S. Environmental Protection Agency.

They also can interfere with hormones in the body.



==========================================================================
In New Jersey, the decades-old Diamond Alkali Superfund site includes
a former chemical manufacturing facility in Newark, a 17-mile tidal
stretch of the Passaic River and tributaries, Newark Bay and portions of
the Hackensack River, Arthur Kill and Kill van Kull, according to the EPA.

The 2,3,7,8-TeCDD dioxin is a byproduct of combustion and chemical
product manufacturing, including the herbicides in Agent Orange. Sampling revealed high levels of dioxin in 1983 and the site landed on the
Superfund National Priorities List a year later. Dioxin, polychlorinated biphenyls, metals, polycyclic aromatic hydrocarbons and pesticides were
found in sediment in the Lower Passaic River.

Though dredging is required to remove the most highly contaminated
sediments in the Passaic River, some contamination has spread and will
remain in the river and estuary, where it could be transformed by the
bacteria over time, according to the Rutgers scientists.

In the study, scientists took solid material from the river bottom
and mixed it with water and other nutrients in the lab to make
mud in bottles. Then they added 2,3,7,8-TeCDD and another chemical (dichlorobenzene) that boosted dechlorination by bacteria.

The Rutgers scientists revealed bacteria that are likely involved in
the dechlorination process -- a novelDehalococcoidia bacterium -- by
sequencing their DNA from the dioxin-tainted mud. It is possible that 2,3,7,8-TeCDD could be completely dechlorinated in the Passaic River
and estuary.

The next goal is to try to identify the enzymes involved in
dechlorination so cleanup technologies could be developed that lead to
more dechlorination at this and other contaminated sites, the study says.

Rutgers co-authors include Cassidy R. Schneider, who earned bachelor's
and master's degrees at Rutgers; Haider S. Almnehlawi, who is earning a doctorate at Rutgers and is a faculty member at Al-Muthanna University;
and Professor Katherine S. Dawson, an assistant professor in the Rutgers Department of Environmental Sciences.


========================================================================== Story Source: Materials provided by Rutgers_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Rachel K. Dean, Cassidy R. Schneider, Haider S. Almnehlawi,
Katherine S.

Dawson, Donna E. Fennell. 2,3,7,8-Tetrachlorodibenzo-p-dioxin
Dechlorination is Differentially Enhanced by Dichlorobenzene
Amendment in Passaic River, NJ Sediments. Environmental Science &
Technology, 2020; 54 (13): 8380 DOI: 10.1021/acs.est.0c00876 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200819110915.htm

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