5 things to know about… the global water supply

Huichun (Judy) Zhang

Just a few miles from campus is Lake Erie—the source of Cleveland’s drinking water, a prime spot for outdoor activity and, at Case Western Reserve, a hotbed for research.

Huichun (Judy) Zhang, the Frank H. Neff Professor of Civil and Environmental Engineering at Case School of Engineering, specializes in environmental chemistry and engineering and has conducted considerable research on Lake Erie.

Huichun (Judy) Zhang

Huichun (Judy) Zhang

So in recognition of World Water Day—the annual United Nations observance that celebrates water and raises awareness of the 2 billion people living without access to safe water—The Daily reached out to Zhang to better understand the water all around us. 

Zhang and colleagues at several other universities and the U.S. Department of Agriculture have been working on several Lake Erie-related pollution challenges, including developing new methods to test for and remove contaminants in livestock manure that end up in groundwater and then the lake. Together, they’re seeking new ways to remove excess nutrients like phosphorus from agricultural runoffs.

Her team is also developing the latest artificial intelligence and machine-learning tools to develop forecast models for what are known as harmful algal blooms (HAB) in Lake Erie and other water bodies. The proposed models could lead to better bloom control and management.

Today Zhang, with support from graduate students in her lab, shares five water-themed ideas to help bring World Water Day closer to home.

1. All water is connected.

Water is an essential ingredient to life on Earth. Although the total mass of water is fairly constant over time due to the Earth’s gravity, the combined processes of evaporation, transportation, condensation and precipitation result in a continuous cycle of all the water in the world. 

About 97% of the Earth’s water is in the oceans, while about 1.7% is stored in polar ice and glaciers. Only about 1.7% is present in commonly accessible reservoirs, including rivers, lakes and aquifers. 

Groundwater in aquifers may seem invisible to us, but it plays a critical role in the ecosystem. Compared to surface water, groundwater suffers less from seasonal changes and is generally less directly and more slowly affected by climate change. To better manage this precious resource, more efforts are needed to make it more sustainable.

2. The Great Lakes, including Lake Erie, are a critical resource for Northeast Ohio and beyond.

The Great Lakes, including Lakes Erie, Huron, Michigan, Ontario and Superior, compose the largest freshwater system on Earth. The system contains about 21% of the surface freshwater by volume in the world.

Around 34 million people are living in the Great Lakes basins. Among them, the Lake Erie Basin is the most populated, with 12 million people dependent on it for drinking water and for fishing and other recreation. 

Lake Erie’s health is strongly linked to the welfare of the residents. Without proper care, Lake Erie can’t always be a reliable source of drinking water or home to thousands of species.

3. Our water supply remains at risk even after decades of clean-up.

Since last century, point-source pollutions (think sewage water discharge and wastes from confined animal feeding operations) have been largely well controlled. 

However, what is known as “nonpoint source” pollution (generally from less easily defined sources such as storm-water runoffs, precipitation, atmospheric deposition and more) is now the leading problem in water quality control. 

During nonpoint source pollution, contaminants can be carried by rainfall or snowmelt from different sources and finally enter surface waters and groundwater to cause water contamination.

4. Lake Erie algal blooms are an indicator of problems on land and water.

A prime example of nonpoint pollution are the HABs previously mentioned, which have been a problem in Lake Erie in recent decades. When HABs break up in the water, they not only release excess toxins, which can poison aquatic lives and endanger human health, but also cause oxygen depletion and turn the water body into a “dead zone” of low or no oxygen. 

The worst case: Because of the HABs and excess amounts of toxins released, the drinking water was cut off for over half-a-million residents in Toledo, Ohio, in 2014. 

Scientists often look to an excess of phosphorus as a major contributor to the widespread algal blooms. In total, the Lake Erie basin was found to receive 44% of all phosphorus deposited into the Great Lakes, much more than any other Great Lake. 

This phosphorus overload has negatively impacted a $11.5 billion tourism industry in the Lake Erie basin and significantly increased costs to treat public drinking water. To eliminate these negative impacts, the Ohio Environmental Protection Agency set a goal of 41% reduction of phosphorus going into the Maumee River. 

5. What’s next: Microplastics and an emerging issue.

Human life has greatly benefited from the use of various plastics such as polyethylene, polypropylene, polyethylene terephthalate (PET), etc. In fact, almost everything around us contains some plastics—from plastic packages, to food containers, to water bottles.

However, microplastics that form due to unsuitable treatment of used plastics have increasingly become a serious environmental problem and are now being found in the bodies of various aquatic organisms such as fish, turtles and whales. 

These small particles cannot be digested or excluded from the body of these aquatic organisms, and the accumulation of microplastics would further lead to physical or biological harm to these animals. 

Further, because most microplastics are hydrophobic (do not like to be associated with water), studies have found that microplastics can adsorb large quantities of organic pollutants, such as pesticides and pharmaceuticals. That means the pollutants could migrate with water flow and transfer pollutants from one place to another. 

This is a problem for lakes like Lake Erie, too.

Lake Erie is not only the home of various animals but also a very important water source for the residents in the region. The microplastics problem in Lake Erie deserves not only the attention of the scientific community, but also everyone who lives in or around the great lake region.