|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!