From the RENSSELAER POLYTECHNIC INSTITUTE and the “sunlight is always the best disinfectant” department
An increase in extreme rainfall makes it more difficult for UV light to kill pathogens
Troy, N.Y. – Increasing organic runoff as a result of climate change may be reducing the penetration of pathogen-killing ultraviolet (UV) sunlight in inland lakes, rivers, and coastal waters, according to a new study in the journal Scientific Reports. The findings, from a team including researchers at Rensselaer Polytechnic Institute, points to the potential for an increase in waterborne pathogens.
Rensselaer
Scientists have already measured an increase in “browning” of the world’s waters, a phenomenon caused by more organic matter washing in from the surrounding land. The new study, led by Miami University in Ohio, analyzed water samples and used a model based at the National Center for Atmospheric Research (NCAR) to quantify, for the first time, the impact of dissolved organic matter on the potential for UV radiation from the sun to kill pathogens in the water.
Not only does an increase in dissolved organic matter make it more difficult for sunlight to disinfect bodies of water, it also makes it more difficult for water treatment plants to work effectively, said lead author Craig Williamson, a Miami University ecologist. In the United States, 12 to 19 million people already become ill from waterborne pathogens annually.
Kevin Rose, the Frederic R. Kolleck ’52 Career Development Chair in Freshwater Ecology at Rensselaer, gathered much of the data on dissolved organic matter in water samples to assess the potential of UV radiation to kill pathogens.
“Water clarity is dropping in many regions due to factors such as browning, and this research demonstrates that this change is likely decreasing natural disinfection of potentially harmful pathogens,” said Rose.
The team used samples of water from lakes around the world, from Pennsylvania and Wisconsin, to Chile and New Zealand. Tests determined the amount of dissolved organic matter contained in each sample, and the wavelengths of light — including ultraviolet wavelengths — absorbed by that organic matter.
Using the Tropospheric Ultraviolet-Visible model — which simulates how UV light is scattered and absorbed as it passes through Earth’s atmosphere — researchers determined how much UV light hits the surface of the lakes throughout the year. Researchers also analyzed reflection and refraction off each lake’s surface to calculate how much light penetrates the lakes and then, finally, how deeply it reaches.
The Tropospheric Ultraviolet-Visible model also calculates the expected disinfecting power of UV light in a particular body of water based on its dissolved organic matter and other characteristics, a measurement known as “solar inactivation potential (SIP).” In some cases, researchers calculated the SIP across different parts of, or for different time periods in, the same lake.
The results allowed scientists to quantify the impacts of dissolved organic matter. For example, the summertime SIP for one lake in northeastern Pennsylvania — which, along with other regional lakes has undergone significant browning in recent decades — dropped by about half between 1994 and 2015.
In California’s Lake Tahoe, the SIP in the relatively pristine center of the lake can be as much as 10 times greater than at Tahoe Meeks Bay, an area at lake’s edge that is heavily used by humans and has a much higher level of dissolved organic matter.
The scientists also showed how SIP can dramatically decrease after a heavy rainfall event using water samples collected from the region where the Manitowoc River flows into Lake Michigan, which supplies drinking water to more than 10 million people. Modeling based on samples taken before and after a strong storm moved through on June 21, 2011, showed that the SIP may have dropped by as much as 22 percent due to the extra dissolved organic matter that washed into the area in this single storm event.
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The study was an outgrowth of collaboration among multiple scientists from different disciplines who serve on the United Nations Environment Programme Environmental Effects Assessment Panel (UNEP EEAP). The data collection and modeling foundations used in this study were funded by multiple grants from the National Science Foundation.
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Limnology & Oceanography Letters
Centennial-long trends of lake browning show major effect of afforestation
Emma S. Kritzberg
5 June 2017
http://onlinelibrary.wiley.com/doi/10.1002/lol2.10041/full
[…]
To fully disentangle the relative importance of land-use, climate change and S deposition to lake DOC and water color, modeling with site specific information on land-use would be the best way forward. The results presented here suggest that the major transition in land-use in this region is likely a major factor driving lake browning, and that this browning has been augmented by climate change [esp., “increased growing days” and “climate mediated greening”]. While historical changes in S deposition have not been the sole driver, it has most probably played an important role by delaying the browning through enhanced adsorption of organic matter during the period of high deposition. Thus, the high rate at which water color has increased in the past few decades should be highly influenced by reduced S deposition. The data and analysis presented here is specific for this particular region, but it should be noted that the transition to forestry was facilitated by the introduction of artificial fertilizers, which reduced the land area required for cultivating crops and supporting animals that produce manure—a development common to many parts of northern Europe.
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Meanwhile, diseases of almost every kind continue to decrease around the world thanks greatly to the increase of cheap fossil fuel energy used per capita.
No matter what they can think of, it is bad, it is getting worse, it is caused by Climate Change, it never happened when climate used to just change all the time by itself, it is all our fault, and it needs more study…lots more study, so they can work out a few more of the maybe’s, could’s, and perhaps’s.
If only these groups of people groping for more money would stop using the subjunctive… the use of ‘would, could, should,’ or ‘may’ is a dead giveaway to their real goal.
If they get enough cash from the cash cow (taxpayers) they can do another bit of formulating and come up with another way to use the subjunctive approach to ensure a well-fed bank account.
A “What if?” study strikes again. When will they end? Based on an untested hypothesis of a very low probability out-of-control global warming event, we now should be concerned about an untested hypothesis of very low probability infected lakes. Give us a break! More tax dollars down the drain. Research at universities is completely out-of-control. To quote Bob McNair, “We can’t have the inmates running the prison.” (Don’t have a conniption. It’s a figure of speech.)
Why is it that AGW only causes bad things to happen. You would think there would have to be some positives.
In point of fact, higher CO2 and a warmer planet is good news all the way down.
Studying CACA, on the other hand, causes a pathological and enfeebling thickening of the bony layers of the cranium, and seems to cause actual knowledge to abandon the brain like A-list stars from an accused Hollywood producer.
In fact, the effect is so powerful, merely identifying as a “climate scientist” causes a condition that closely resembles what has been called “going full retard”.
CACA produces brown water.
Who knew?
Need to ban walking, hiking, biking, etc, in these watersheds. No more eco-tourists or people enjoying nature.Causes erosion leading to brown water.
First the nuts claim “carbon” is polluting the air (in the form of CO2), now the claim “carbon” is polluting the water (in the form of natural organics).
I have to wonder what they see when they look in a mirror?
PS I hold EPA certifications for both water and wastewater treatment.
I know which certification is best suited for the treatment of this study.
I believe it’s a whole lot better now than when that “Sea of buffalo” existed in the plains. All that defecation in the water must have been nasty.
Even pure water absorbs UV light quite strongly. Which is fortunate because otherwise it might actually kill aquatic organisms.
This is why we need more wind turbines. The old kind that chop up birds. Birds poop every where. They seem to have an affinity for my sail boat. The windfarms on both sides of the river do seem to make a difference.
A few years ago our small yacht club got a government grant for a pump out station. It was the brainstorm from the member who works at the local college. While I thought the project was a waste money and voted against it, I said nothing.
I wanted to ask a rhetorical question, do bears sh!t in the woods? Will the goverment mandate fish and birds use the dump station?
I think clean drinking water is a basic human right. I have only read about epidemics from water borne pathogens because I live when we have clean drinking water.
Do not drink untreated surface water.
or eat yellow snow.
Yellow might be OK.
But brown snow? 😎
So, class think of all the things that could be bad about:
1)lots of sunny days
2) lots of cloudy days
3)no wind
4)no calm
5)cold
6) warm
…
Yes. I guess that all the extra run-off in their model indicates that there is no drought caused by this particular version of global warming. These authors seem to have got hold of the flooding version.
Of course somebody else will have a different version of global warming that predicts the exact opposite, but they are never expected to be consistent with either each other, or reality. That would require a much larger grant.
Increased organic matter in water means more life. That increased organic matter had to come from somewhere – and there’s no evidence that any place else is being depleted, therefore there must have been a net increase. So according to their own hypothesis, climate change is good for living things.
Now, let’s challenge their assessments and methodology. How much of this is “climate change” and how much is all the rest of the meddling and messing that we humans do to the environment? From their own press release, two areas of the same lake (and presumably experiencing identical climate changes) exhibit vastly different rates of organic matter with the much higher levels at the site with the most human interaction. Wouldn’t a first hypothesis be that it was the human interaction (agricultural runoff, waste discharges, land-use changes that increase erosion, etc) rather than the climate that caused the difference?