Human, swine waste pose dual threats to water quality after flooding


Date:
August 24, 2021
Source:
North Carolina State University
Summary:
A study that monitored surface waters in the wake of 2018's
Hurricane Florence finds that waters contaminated by fecal bacteria
were affected by both human and swine waste.



FULL STORY ==========================================================================
A study that monitored surface waters in the wake of 2018's Hurricane
Florence finds that waters contaminated by fecal bacteria were affected
by both human and swine waste.


==========================================================================
"We found that surface waters in eastern North Carolina were more likely
to face dual contamination than to be contaminated by either human
waste or swine waste by themselves," says Angela Harris, corresponding
author of the study and an assistant professor of civil, construction
and environmental engineering at North Carolina State University.

"This means people are dealing with multiple hazards," Harris says. "It
also means there are two sources of fecal contamination that need to
be addressed.

It's not just the swine industry, and it's not just wastewater treatment
plants or septic systems." For the study, researchers collected surface
water samples at 40 sites across eastern N.C. Samples were collected
one week after Hurricane Florence made landfall in September 2018, and
again one month after landfall. These samples are referred to as Phase
1 and Phase 2, respectively.

The researchers tested the water samples for a variety of bacteria.

Specifically, the samples were tested for: E. coli -- an indicator species
used to identify fecal contamination and the likelihood that there are pathogens present; pathogens such as Arcobacter butzleri and various Listeriaspecies; and bacterial species associated specifically with
either swine or humans, so that researchers could trace contamination
back to its source.

"About 30% of the surface water sites we tested had levels of bacteria
that would have made those waters unsafe for swimming," Harris said.

The most commonly found pathogen was Arcobacter, a finding the research
team published late last year. The new study reports that the presence
of Arcobacterwasn't associated with human or swine fecal markers. In
other words, it's not clear where the pathogen is coming from.

Another mystery was that the levels of E. coli in Phase 2 samples taken
from permanent water channels (as opposed to floodplains) were actually
higher than the levels of E. coli in the Phase 1 samples.

"We're not sure why E. coli levels jumped in those Phase 2 samples,"
Harris says. "It could be because water levels were decreasing, so there
was less dilution. It could be due to temporary changes in regulatory requirements in the wake of the hurricane. It could be some other variable
we haven't identified. We need a lot more monitoring data to begin to
tease that apart.

"A lot of post-flooding work has been done in urban areas," Harris
says. "This is one of the few studies that looks at post-flooding water
quality impacts in rural, agricultural areas. And our findings suggest
that this merits a much closer look. This work highlights the need for
more routine water quality monitoring in these areas that tests for the bacteria we were looking at here.

That could help us establish broader baseline measures for water quality.

"This is particularly important given concerns around antibiotic-resistant pathogens and the likelihood that we'll be seeing more extreme wet weather events in the future." The study was done with support from the National Science Foundation, under grants 1901588 and 1901202; the North Carolina
Policy Collaboratory; and the International Life Sciences Institute.

========================================================================== Story Source: Materials provided by
North_Carolina_State_University. Original written by Matt Shipman. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Angela R. Harris, Emine N. Fidan, Natalie G. Nelson, Ryan
E. Emanuel,
Theo Jass, Sophia Kathariou, Jeffrey Niedermeyer, Mahmoud
Sharara, Francis Lajara de los Reyes, Diego A. Riveros-Iregui,
Jill R. Stewart.

Microbial Contamination in Environmental Waters of Rural
and Agriculturally-Dominated Landscapes Following Hurricane
Florence. ACS ES&T Water, 2021; DOI: 10.1021/acsestwater.1c00103 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210824104136.htm

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