The street where I grew up |
A lake near my house |
My
first project here was to familiarize myself with the concept of beach water
safety and flagging system. The Massachusetts Water Resources Authority (MWRA)
tests Enterococcus (a bacterial which can be an indicator for harmful bacteria
in water) level in beach water daily or weekly, and if the amount exceeds a
standard, then the water is deemed as not swimmable; the Department of
Conservation and Recreation (DCR) advises the public’s beach
activities by posting flags on beaches from the tested results. It sounds a
perfect system, but I was surprised that the beaches were flagged based on the
samples taken on the previous day. However, it is unavoidable because it takes
the lab 24 hours to process the sample and release the result. Given the fact
that marine water is unlike fresh water—the tides could entirely change the
water quality, it is unlikely that today’s water quality remains consistent
with that of the previous day. This puts the flagging system on a questionable
ground, which speaks for the reason that the flagging accuracy for existing
system is needed. However, the good news is that most of the time the water is
clean during the swimming season (May-Sep). For example, only 1 day exceeds the
standard during the swimming season of 2012 for Pleasure Bay in South Boston.
The
other project I’ve worked on is sanitary survey, and the goal is to investigate
the potential contamination source for Enterococcus in beach water. Sewage
leakage from old and broken pipes, illegal connections to the pipeline, or even
the storm water runoff carrying pollutants could make their contributions to
the bacterial level in the nearby water body. But for some beaches, like
Pleasure Bay, the infrastructure problem was pretty much settled but there were
still occasionally bacterial exceedances in the water during the swimming
season, like I mentioned earlier. How did this happen? Is there any neglected pollution
source? And the answer is YES! As audience mentioned that Pleasure Bay was
quite popular among dog walkers at 2014 Metropolitan Beaches Commission public
hearing, we paid a visit to Pleasure Bay in March. Unsurprisingly, we found
numerous dog poop piles left behind on the beach and quite a few dogs walked by
their owners during weekends, which provides us a reasonable guess that dog may
cause the problem!
I was surrounded by dogs at Victory Park |
When
we had those preliminary clues for dog problems, another thing needed to work
on is to get an idea of how much pollution dog poop can generate. Take Pleasure
Bay as an example, I performed calculations to estimate the required amount of
dog poop to raise the entire bay’s Enterococcus level to the swimming standard,
assuming that all bacterial released and mixed thoroughly in the water. As a
result, 54 pounds of dog poop or 288 dog poop events is needed. It is not a
huge amount of poop, and the common sense tells us that it couldn’t be the reality
that 54 pounds of dog poop is washed into the ocean, mixed uniformly and stay
for long time. However, it is likely that one or several dog poop piles would
have the ability to pollute a stretch of beach for many hours. This is what the
general public may not be aware of, when they are walking their dogs on a sunny
day, not cleaning up after the dogs, probably thinking that a poop event won’t
have much impact on the water quality, however, they are wrong. And this is why
we are doing the work, using scientific knowledge to educate the public, and to
make a better world!
Yudan Jiang
Yudan Jiang
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