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Photo of Christy Remucal
May 11, 2017

Improving the world’s water

Written By: Will Cushman

The eel-like parasitic sea lamprey is essentially an ancient Homeric sea monster brought to life, but in miniature. “They’re scary and pretty gross,” says Christy Remucal, an assistant professor of civil and environmental engineering.

The gross-out factor revolves around the lamprey’s mouth: It lacks a jaw, instead possessing a suction-cup-like mouth filled with rings of sharp, thorny teeth that surround a razor sharp tongue. The grotesque mouth is perfectly engineered for the sea lamprey’s parasitic existence: The sharp teeth maintain a firm grasp on the body of host fish while the razor tongue slices the host’s flesh. Voila! The lamprey has a constant source of nourishment—that is, until the host fish dies. Upon the host’s death, the sea lamprey simply detaches and finds another host.

 sea lamprey
Sea lamprey (Petromyzon marinus). Credit: T. Lawrence, Great Lakes Fishery Commission.

Sea lampreys are a sort of physical manifestation of the general scourge of invasive species—plants and creatures that infest ecosystems and wreak havoc by outcompeting or killing native species and destroying habitats. The sea lamprey is native to the North Atlantic, and—similar to salmon—it’s a versatile fish, capable of thriving in both fresh and sea water. That capability has allowed sea lampreys to invade inland freshwaters, including the Great Lakes, where they’ve preyed on native and game fish, including trout and salmon, for decades.

A joint U.S.-Canadian effort has been fighting back against the invasive sea lampreys for nearly as long as they’ve called the Great Lakes a second home. The method is surprising: Every year, fish and wildlife personnel apply two pesticides—known as lampricides—in some of the 400 Great Lakes tributaries from Quebec to Wisconsin where the sea lampreys spawn.

One of the two lampricides used, a chemical compound called 3-trifluoromethyl-4-nitrophenol—TFM for short—is remarkably effective in targeting sea lampreys in their larval stage while avoiding ill effects on other species. The other lampricide—niclosamide—is less selective, yet is considered safe for widespread use. Still, both TFM and, to a greater extent, niclosamide have been shown to have negative effects on other fauna, and researchers haven’t known much about how the chemical compounds degrade and transform in aquatic environments. That’s where Remucal comes in.

Remucal’s lab, housed in the Water Science and Engineering Laboratory on Lake Mendota, studies the two lampricides and how sunlight breaks them down into other chemical compounds, called transformation products. The goal is to determine how long the lampricides persist in tributaries, and how their exposure to sunlight in aquatic ecosystems may affect aquatic life.

It’s all part of Remucal’s greater focus on the fundamentals of water chemistry and how tiny dissolved contaminants can affect water quality. Remucal also studies ways to remove organic contaminants from water. “These organic contaminants could be everything from pesticides to pharmaceuticals to personal products, such as caffeine,” Remucal says.

 Christy Remucal
Christy Remucal

And our surface freshwaters are teeming with these contaminants. “For example, we study how sunlight causes chemicals to break down in a lake,” Remucal says.

With more than 15,000 lakes in Wisconsin (not to mention Lakes Michigan and Superior), Remucal and her students have plenty of potential field sites from which to choose. The sheer number of freshwater lakes in the state also demonstrates the importance of Remucal’s work—organic contaminants are present in even the most pristine bodies of water, and it behooves us to better understand how natural processes affect and alter them.

Remucal also conducts research that has very real consequences for public utility operators, who are coming under increasing security after drinking water crises like the recent lead contamination in Flint, Michigan. Remucal doesn’t study lead contamination, but there are many chemicals that could spoil a municipal drinking water system.

“Our current drinking water treatment is really good at getting rid of particles and pathogens that can make you sick, like E. coli,” says Remucal. “But the treatment processes aren’t very good at getting rid of many of these organic contaminants.”

So she and her students are studying advanced ways to do just that. Right now, they’re investigating the potential of a treatment system called chlorine photolysis. In a way, it’s related to her research on lampricides and other organic contaminants in surface waters. That’s because the treatment works by combining the chemical chlorine with the power of light, which transforms it into a sort of super disinfectant.

“If you shine light on chlorine, it produces a bunch of radicals,” Remucal says. “These are really powerful oxidants that can break down chemicals that we want to get rid of.”

The basic idea of Remucal’s chlorine photolysis project is to see if utility operators could simply add light to their chlorine disinfection unit, transforming it into an advanced oxidation—and advanced disinfection—process. The process could be useful in safeguarding drinking water from chemical spills or toxic algae blooms, Remucal says.

“This could either be a way to upgrade existing infrastructure or to deal with occasional problems where you need to improve what you’re doing to treat the drinking water,” Remucal says.

And though the application of chlorine photolysis research is promising, Remucal is focused on the fundamental chemistry of the process. Other engineers specialize in designing treatment systems that include the process.

Paul Block (right) with postdoc Solomon Tassew Erkyihun
Paul Block (right) with postdoc Solomon Tassew Erkyihun

Remucal is one of many researchers on campus whose primary concern is water. UW-Madison historically is well known for its water-related research: The university’s Center for Limnology is considered the birthplace of inland water research in North America, and Lake Mendota is often called the most studied lake in the world. But the true depth (forgive the pun) and breadth of the research conducted at UW-Madison on this most important element for life goes far beyond the study of lakes.

Reflecting the ubiquity of water in our lives, the diversity of water research here is impressive, and much of that research occurs in the College of Engineering. From advanced computer modeling to old-fashioned fieldwork, engineers use a diverse set of scientific methods and tools in their efforts to improve the human relationship to water.

Paul Block’s research takes him from hydroelectric dams in South America to the famine-prone fields of Ethiopia. Block, an assistant professor of civil and environmental engineering, spends a lot of time considering the water systems (both natural and those altered and harnessed by humans) that affect these regions and others.

“My research is focused on a broader view, or what we often call a systems view,” says Block. “Instead of some individual component, we will look at how if something in our system changes, how does that perturb other aspects within the system.”

This broader view is essential when considering the climate—a hugely complex system that affects just about everything else on Earth. While Block and his research group don’t necessarily think on the global scale, their systems approach is crucial for answering questions on the watershed scale.

These questions will become increasingly important as climate change affects agricultural regions and water supply systems. And the questions will often have significant economic and geopolitical consequences.

“If you extract water farther up within a basin—say if you irrigate some fields or some farms—what does that mean downstream?” Block poses. “You obviously have less water, but how does that water balance carry out? Does somebody have less water, or are you storing some water somewhere?”

These questions might seem mundane to those of us who are accustomed to what seems like a limitless supply of cheap, fresh water—but they are hugely important questions in more arid areas of the world, where states and nations squabble over water resources and reservoir operators must deal with the uncertainty of fickle weather patterns and a changing climate.

In his systems-focused work, Block attempts to reduce the uncertainty for reservoir operators and farmers by combining various models—climate, rainfall runoff—to come up with seasonal forecasts that can help water resource decision makers. “If you’re a farmer or you’re a reservoir operator, and you had some sense of whether summer is going to be wet or dry in advance, would you make a different decision?” Block asks.

Old-fashioned water resources management depends on averages to make decisions. It’s a risky method that can lead to crises in years of weather extremes.

“We’re used to saying we know what’s happened for the last 50 years, so we take the average of that and we say, ‘Well, we don’t know anything better, let’s use it,’” Block says. “But that’s pretty inefficient, and it’s hardly ever an average year.”

That’s increasingly becoming the case as climate change leads to less and less dependable rainfall “averages.” Consider southern Louisiana, which experienced devastating flooding in summer 2016—that was the result of rainfall so outside of the average that it was considered a 1 in 1,000-year event. And many locales are experiencing similar 500-year or 1,000-year floods at a much more frequent rate than every 500 or 1,000 years.

So Block and his colleagues are using systems modeling methods to attempt to more accurately forecast climate conditions for risk-prone regions where crops and potable water are at stake.

One region where these forecasts inform water resource decisions is in the arid portions of Peru and Chile, where reservoir operators need reliable forecasts of stream flow to assist in their allocation of water rights within the region. Another area is in Ethiopia, where Block uses modeling to assist in precipitation predictions. “The idea there is to say if it’s going to be wetter or drier, these farmers may want to plant something different or they may want to use a drought-resistant seed if it’s going to be dry,” Block says.

And these are high stakes for the mostly subsistence farmers who depend on increasingly erratic rainfall to support their crops.

“But they also want to know if it’s going to be wetter,” Block explains. “Because they wouldn’t want to pay the premium for the drought-resistant seed then, and maybe then they’ll use fertilizer because you’ll get your return on that.”

Block says the decisions are somewhat constrained by cultural considerations, like the need to grow teff every year, which is the primary ingredient in injera, a flatbread ubiquitous in the region. That means their models must incorporate social science as well systems research must include all these considerations.

“But if it’s going to be dry, we ask, ‘Can we assist in suggesting what might be good cropping strategies?’ says Block. “So we also have an agriculture economic model that we’re feeding this info into. What if X percent of farmers adopt this policy; what does this mean for, in this case, poverty? What does this mean for agriculture and GDP? There’s a whole adoption piece of this, which is in the social science realm. Why do these farmers make the decisions they make, or why do they choose to ignore forecasts?”

So Block has teamed up with a group of ethnographers living in the villages he’s working with. “They’re really trying to understand the decision-making processes, and how this information—in our case particularly related to forecasts—is passed to farmers,” he says. “How are they receiving this, or not? Are they taking action based on this, or not?”

In the case that the farmers do not heed the forecasts, Block says the team’s goal is then to figure out what it can do to increase uptake. Do the researchers need to improve the forecasts? Or do they simply need to tailor the forecasts to be more specific? Or perhaps it’s a governance or communication issue; the forecasts are fine, but they aren’t reaching the right audiences. The ultimate goal is to encourage more farmers to plan ahead with the use of the forecasts, which can be difficult when the forecasts aren’t perfect.

“So one year we say, ‘Oh, it’s going to be real wet,’ but it turns out to be dry. There’s a lot of noise in the climate system, so there will be years when the predictions are not correct,” Block says. “So what happens then? Do we lose trust? Do farmers not rely on the forecasts anymore? What are those dynamics?”

The task is to link this cognitive aspect that might limit adoption to the technical and economic forecast to ultimately encourage adoption. “So really we’re moving beyond just engineering,” Block says.

The National Science Foundation has started referring to this new type of trans- or interdisciplinary research as “convergence.”

“It’s a nice way to describe what we’re doing,” says Block. “We team with climate scientists and social scientists, and we all have to kind of converge to an extent both in the understanding of each other’s fields, but also converge to a point where we may be able to offer something of value collectively, in this case to farmers. Can we do that or not?”

Block’s project in Ethiopia is planned for five years and just beginning. The ultimate goal is to refine the models and build a mobile app that uses the forecast data to assist farmers in their decisions. “It’s really exciting for me,” says Block. “It’s the same thing with the reservoir operator: These farmers are optimizing a lot of different things. And this is hopefully one piece of information that we can provide.”