Environmental Science

<a href='mailto:dcall@enviro-analysts.com'>Daniel Call, Ph.D.</a>
  • Daniel Call, Ph.D.
  • SCN Environmental Science Writer
    Environmental Research and Information Analysts, LLC
  • Dr. Call is co-founder and principal of Environmental Research and Information Analysts, LLC, which assists clients in finding solutions to environmental issues based on research and data analysis. For 31 years, he taught environmental science and aquatic biology at several Midwestern colleges, retiring in 2010 as Professor of Environmental Science at the University of Dubuque. He has published numerous journal articles on aquatic toxicology. He received his B.A. degree in biology and chemistry from St. Olaf College, and his M.A. and Ph.D. degrees in biology from the University of South Dakota. He lives in Dubuque with his wife, Jacquie.
Wednesday 01/02/2013
Could Urban Gardens Help Save the Honey Bee?

How about a New Year's resolution for your city to become bee-friendly in 2013? Seriously! Bees are in big trouble here in the U.S., as well as in many other countries around the world. And I think that cities might be able to help with their survival.

Populations of honeybees and several species of bumblebees have declined in recent years – precipitously. The website BeeFriendlySanDiego.com led me into some interesting resources on the plight of bees. In fact, a PBS video entitled “Silence of the Bees”, states that if the honeybee decline continues, we won’t have them around by 2035. That is only a little more than 20 years away!

Can you imagine a world without bees to pollinate our fruit and nut trees, vegetables and flowers? They are said to pollinate approximately one-third of the food produced in America, with a value of more than $15 billion per year.

It is much preferred to have bees around to perform this essential duty of pollination than for man to do it by hand. This has been learned in a pear-growing region of China, where local residents dust pollen grains onto each of the several hundred flowers in each pear tree of their region. This is done due to the loss of honeybees from past long-term pesticide use. The cost would be astronomical in this country to pay for labor to pollinate the various orchards and other food crops that bees normally pollinate. An estimate in the PBS report was placed at more than $90 billion per year.

What has happened to the bees? It is not exactly known yet, but some experts point to a multitude of possible causes coming together to create the “perfect storm” that is wiping them out. It has been known for a number of years now, since around 2006, that honeybee colonies have been dying out due to a condition called colony collapse disorder (CCD). The colonies in beehives die out quickly, leaving little evidence around in the form of dead bees in the hives or on the ground around the hives. Essentially, the bees just disappear. This has hindered investigations to determine the cause(s).

Hypotheses regarding possible causes of CCD include (1) wildflower and habitat loss associated with farming changes that have occurred in recent years, (2) malnutrition of the bees due to competition, (3) parasites such as the varroa mite, (4) disease agents such as the exotic Israeli acute paralysis virus (IAPV) or single-celled fungi, (4) mortalities from direct contact with insecticides, (5) weakened immune systems due to sublethal contact or ingestion of insecticides, particularly the fairly recently registered systemic neonicotinoid insecticides, with resultant increased susceptibility to disease organisms, and (6) neurological effects due to environmental factors that affect their normal behavior patterns and ability to return to the hive after foraging.

While researchers from around the world are learning more about the causes and seeking solutions, the rapid population losses make it critical that the precautionary principle be applied with regard to possible causes, and proactive steps be taken to help reverse the trend. Application of the precautionary principle would appear to involve eliminating or reducing the use of specific insecticides in agriculture and in households that have been implicated in the declines until more is learned about their possible roles, examining and strengthening regulations involving imported bees that might introduce pathogens into healthy colonies, and destroying parasite- and pathogen-infected colonies.

Your community can take a proactive step to help the bees. Many cities and counties have wonderful flower gardens and plots of greenspace within their jurisdictions. Most cities already plant flowers, shrubs and trees in their boulevards. If not already being done, these areas can be made more bee-friendly by substituting types of plants that benefit bees for those that are not as beneficial. Small plots of perennial wildflowers can be planted in corners of city lawns that do not get much traffic. Excellent resources for bee-friendly, flowering plants of all types and sizes can be found on the Xerces Society's website.

Another proactive step would be to encourage the placement of hives at locations in the city that would allow bees to forage in the greenspace and find drinking water. Bees work hard and need a lot of water. It's important to place hives where the bees will not create a problem for local residents or be in danger of flying across busy highways. The PBS report highlighted the city of Paris. The French are particularly fond of honey and are concern for the welfare of bees. There, hives were placed on flat roofs of multi-storied buildings within the city. What a great idea for placement of hives!

It is conceivable that cities collectively could play a role in reversing the trend of declining bee populations. The diversity of flowers and trees in our expanding urban landscapes is greater than in the monocultures of modern farms in many regions. Such diversity of plants on which to feed may help to prevent nutritional deficiencies in the bees. The use of chemicals is also different in the two landscapes. These differences could contribute to healthier colonies in urban areas, at least in some cases. Perhaps cities with their diversity in flowering plants will represent safe havens, or refugia, for numerous scattered populations of bees that will help to preserve the greater gene pool of each bee species that is currently in trouble. What a remarkable accomplishment that would be!

And I predict that the uniquely distinctive flavor of the honey taken from the hives of each city will be a “fast sell” at the local farmers market.

Posted in Dan call, Community on Wednesday, January 2, 2013 9:36 am. Updated: 5:32 pm. | Tags: Health , Local Foods

Monday 10/01/2012
The Dollars and Sense of Greenspace

Most of us need a certain amount of greenspace. The exact amount varies greatly amongst individuals, some requiring just a small backyard flower garden or a bench in a favorite park. Others may feel a need for larger expanses, such as a large municipal forest or even the vastness of a western state wilderness area. These greenspace areas, whether small or large, are highly valued to us on a personal level, possibly due to some need for a connection with nature, or for other more complex reasons that are not so easily deciphered. We prize these places, and wish to see them continue to exist over time.

Cities have the opportunity to provide a variety of greenspace areas for their residents and visitors. Many cities are already doing an admirable job of this, while others have a ways to go. The value of greenspace has been recognized for some time. In fact, Frederick Law Olmsted, a famous early landscape architect who developed many city parks, including New York's Central Park in the mid-1800s, recognized the importance of these areas for city residents. Certain values of greenspace were undoubtedly recognized by others even well before Olmsted's time. As our population has grown and our cities have expanded over the past 150 years, the need for a network of greenspaces, or green infrastructure, has become apparent. This amounts to more than just isolated city parks, even as valuable as they are. Mark Benedict and Edward McMahon in their report "Green Infrastructure: Smart Conservation for the 21st Century" consider this infrastructure to be "the network of open spaces, woodlands, wildlife habitat, parks and other natural areas that sustain clean air, water and natural resources, and enrich our quality of life."

The overall value of green infrastructure is both derived from and bestowed upon the human community, as well as the natural environment that makes up the infrastructure. A city holding dear the concept of green infrastructure as a priority in its planning may have some definite economic advantages working in its favor. A positive feeling develops amongst residents from the aesthetic and recreational values afforded to them by the greenspace. A sense of satisfaction and pride for their community bubbles over in conversations with prospective new residents of the community, as well as to prospective new employers. This contributes to economic growth. Additional economic values that accrue from green infrastructure lie in the money that visitors may spend for food and lodging as they use the areas for activities such as fishing, hiking, jogging, biking, bird-watching, and wildlife photography.

Major monetary benefits to cities also include those derived from ecological services provided by the greenspace. An sCityNetwork.com article in November described the economic benefits of a city forest to Elgin, Ill. This city of 108,000, with approximately 50,000 trees, realized an estimated total benefit from the trees that exceeded $3.4 million in energy savings, stormwater management savings, and air quality improvement. Green areas also provide valuable services in water filtration and purification, as rainwater and melted snow trickle down through the soil and rock to underlying aquifers. New York City administrators, for example, when faced with making a decision regarding their deteriorating drinking water quality in the 1990s, determined that an expenditure of $1 billion to preserve the integrity of a natural watershed in the Catskill Mountains, the aquifer of which supplies drinking water for the city, was more cost-effective and desirable in the long run than building a new filtration plant at a cost of $6-8 billion. The plant would also have had an annual operating cost of about $300 million, according to the Ecological Society of America.

In these ways and more, green infrastructure becomes a sustainable entity. It not only saves money for a city and its residents, but helps to create a more vibrant economy, a more satisfied citizenry, and a healthier natural environment.

Posted in Dan call, Environmental, Water, Public works on Monday, October 1, 2012 9:49 am. Updated: 11:08 am. | Tags: Green Infrastructure , Daniel Call , Green Spaces , Urban Forests , Air Pollution , Water Pollution , Wildlife , Forestry , Green Infrastructure

Wednesday 04/20/2011
Floods and Us

The spring floods are here, and the Mississippi River is again beyond its banks. At the present time, it is 5-plus feet above flood stage in Dubuque, Iowa. Similar scenarios are playing out along some of the tributaries of the Mississippi as heavy snow loads from the northern states have melted.

While spring floods have been naturally recurring events over the millennia (river ecologists view periodic flooding as essential to the ecological health of rivers), the frequency and severity of floods appear to have increased in recent decades. This may be attributable in part to the "whims of nature," but also in part to man's ever-increasing alteration of the landscape.

One such alteration is the drainage of wetlands. Wetlands act like giant sponges, soaking up water and holding it back from streams, and then releasing it gradually rather than as a sudden discharge. They also may allow for more of the water to enter the soil and underlying strata, and thus become a part of the groundwater supply, rather than running off directly as surface water.

Further, due to the greater ratio of surface area to volume for wetland water, more of the water is evaporated into the atmosphere. While these beneficial attributes of wetlands are recognized today, they were less obvious in the past when wetlands were generally viewed in an unfavorable light.

Unfortunately, most of our wetlands have now been drained. Pressure to drain them has been great on many fronts. In the Midwestern heartland, they have been drained to increase the overall acreage for crop production. In cities, they have been drained for the development of residential areas, businesses, shopping malls, airports, parking lots, roads, etc.

The figures associated with wetland loss are staggering. A table in Mitsch and Gosselink's book, Wetlands, that summarizes state-by-state loss, shows that in the "Lower 48" states, more than one-half of the original wetlands that existed around 1780 are now gone. Seven states have lost more than three-fourths of their wetlands. The Upper Midwest with its rich farmland has been particularly hard hit, as have Florida and Louisiana. These losses definitely change the dynamics of water movement during the period of spring melt, or following a heavy downpour.

It is important to keep our remaining wetlands intact to provide at least some flood relief. An ancillary, but very important side benefit, is the habitat provided for a wide variety of plant and animal species that depend on wetlands for their survival. These habitat refugia support a rich and diverse array of life forms. They not only serve to ensure the continued existence of these species, but also may serve the human community for recreational purposes.

Many residents and visitors are attracted to the rich natural world of wetlands. For example, there is a community of dragonfly watchers and photographers, just as there is a community of bird watchers and photographers. Wetlands provide such opportunities, and more, at the same time that they help to control flooding.

Posted in Dan call, Public works on Wednesday, April 20, 2011 10:35 am. Updated: 11:32 am. | Tags: Flooding , Wetland Preservation , Daniel Call , Traffic

Tuesday 02/15/2011
Road Salt Swaps One Serious Threat For Another

Ice in the Northland, much appreciated by ice fishermen and figure skaters, can be treacherous while under foot or tire. Consequently, considerable amounts of energy and dollars are allocated each year by cities to reduce this serious threat to our safety.

Application of rock salt in the form of sodium chloride (i.e., NaCl) is still the major means of melting ice on our streets and highways, and this is the form to which I am referring when I use the word "salt."

And it is big business! In a recent USGS government study, a survey of highway superintendents from the northern tier of states indicated that their application rates of salt generally ranged between 10 and 30 tons per road lane mile. At around $50 per ton to purchase and $150 per ton to apply, cities of varying sizes must set aside thousands to millions of dollars each year just to purchase de-icing salt. The metro area of Minneapolis and St. Paul, Minn., for example, spends around $17.5 million to purchase their annual salt supply of about 350,000 tons.

Application of salt to our streets and highways started in the 1950s, and the amount used has been increasing every year since. This is due to the fact that we have added miles and miles of streets and highways to our cities and suburbs as our urban populations have grown.

What happens to the salt when its job is done? Some of it in the form of dissolved sodium and chloride ions in meltwater makes its way into our storm sewers and feeder streams that lead to larger rivers. Some of it eventually winds up in the Gulf of Mexico, the Great Lakes, or the Atlantic and Pacific Oceans.

However, researchers in Minnesota discovered that a large percentage (about 70 percent) of the salt that was applied in the Twin Cities Metro Area remained in the soil, groundwater, wetlands, or lakes of the Metro Area. They found that their lakes have become increasingly salty (measured as chloride concentration) over the past 22 years, following a trend similar to that for road salt purchases by their state. A linear relationship between annual salt purchases and yearly measurement of chloride concentration was used to predict the salinity of the Metro Area lakes into the future.

If rock salt use increases at the same rate as it has up to now, they forecast a doubling of average lake chloride content in 56 years. The average chloride concentration at that time would be about 180 mg/L, approaching a concentration (230 mg/L) that the U. S. EPA has established as the maximum concentration allowable for the protection of aquatic life on the basis of long-term exposure. It is possible that a doubling may occur sooner than this, since urban population growth has been exponential, rather than linear. Hind-casting, or predicting backward in time, gave a near-zero chloride concentration in the 1950s, corresponding to the time when road salt applications were started.

Should we be concerned about the increasing salinity of our freshwater habitat? The answer seems obvious, if we hope to maintain a healthy level of biodiversity in our wetlands and lakes. Every freshwater species of algae, rooted plant, invertebrate, fish and amphibian has a maximum level of salt that it can tolerate and survive in. Many municipal lakes presently have pulses of chloride that exceed the EPA limit of 230 mg/L. The most sensitive species are likely being affected, and possibly eliminated from these lakes.

The USGS study reported that a few shallow groundwater wells near heavily salted streets and highways had chloride levels that exceeded the so-called secondary maximum contaminant level for human drinking water of 250 mg/L. This concentration is where a noticeable salty taste first occurs.

It is important that we maintain not only safe roadways, but also healthy surface and groundwater. Improved approaches to de-icing our streets and highways need to be developed and implemented. This may involve new strategies for applying salt, such as the timing and amount of salt application. It may involve finding substitutes that will be friendly toward our water resources.

While these new approaches are being experimented with and evaluated, a cutback on the tonnage of rock salt used will slow the rate at which our lakes increase in salinity. Perhaps it will allow for enough time to save our lakes. Simultaneously, this will save on budgets allocated for rock salt purchases. Substantial savings in municipal budgets may be achieved by careful study of salt use to apply it only as needed, and not in excess.

The end result could be a win-win combination for a city's overall budget and for the aquatic environment within its city limits. Our readers would be interested in learning what your city is doing about its use of rock salt, any new alternatives being used to de-ice its streets and highways, and the impacts of any changes on the budget of its Street or Highway Department.

Click here to share your experience.


Posted in Dan call on Tuesday, February 15, 2011 11:49 am. Updated: 3:23 pm. | Tags: Road Salt , Water Quality , Water Pollution

Monday 11/22/2010
The Down Side of High Productivity

We tend to think positively about productivity. When viewing ourselves as individuals, or our national economy, or our cornfields, hayfields or apple orchards, we aim for high productivity. The higher the productivity, the more impressed we are.

There is a part of nature, though, where high productivity has a definite down side. The negative aspects of high productivity show up at times in our aquatic ecosystems - our streams, ponds, lakes, and even our oceans. The problem is caused by too much plant growth (i.e., algae and rooted aquatic plants) due to an excess of nutrients.

The outcome can be disastrous for fish and many other aquatic animals living in the water body. When the large amount of plant life dies, it is decomposed by microbes. The microbes multiply exponentially as they feed on the rich food supply of dead plant life, and in the process, use up the available oxygen that is dissolved in the water. The unfortunate outcomes are the deaths of fish and other animal species that are dependent upon this oxygen. While the process and outcome might not be as easy to envision as poisoning by a slug of toxic chemical that enters a stream in a chemical spill, suffocation due to oxygen depletion likely accounts for more annual fishkills than all of the toxic chemical spills combined.

The problem with oxygen depletion is widespread, and stems from too much nitrogen and phosphorus running off our land and entering our streams. We simply over-fertilize! We seek to achieve maximum yields in our corn and soybean fields, to have lush green lawns, and to have attractive golf courses. Unfortunately, some of the fertilizer that is applied to achieve these goals washes off into our streams, ponds and lakes. Some of it from the Corn Belt states even makes its way to the Gulf of Mexico, creating a "Dead Zone" there.

In the upper Midwest, the deaths generally occur silently during the winter months, often after a thick snow layer has developed on the ice. The ice prevents the normal exchange of gases between the air and water, and the snow reduces light penetration into the water, thereby reducing the amount of photosynthesis that might still be occurring. Photosynthesis produces oxygen, so this source of oxygen production becomes very limited or nonexistent. The whole problem and drama that has occurred becomes evident in the spring when the ice thaws, and dead fish float to the surface.

The problem of excessive nutrients and oxygen depletion is a challenging one to remedy, and will likely take some time. For the most part, think in terms of years rather than a single season. Some steps to take follow. First, we must learn to live with lower application rates of fertilizer. In other words, we should strive for maximum crop yields and attractive lawns with "just the right amount" of fertilizer, but not too much where some washes away each year. This might require a new mindset, with some experimentation and "risk-taking." If we can achieve this "right" level, it will save money for us as individuals, homeowners, farmers, and municipalities.

Secondly, aeration of small water bodies could prevent or reduce the severity of the problem. This step might actually show immediate results. Small windmill-powered aerators may serve to reduce the use of nonrenewable energy here.

Thirdly, if the water body is fairly small and the sources of nutrient inputs are known and limited, sediment dredging will remove nutrients, especially phosphorus, that are stored in the mud.

And fourthly, unmowed buffer strips of native grasses, flowers, and shrubs along the banks of streams, ponds, and lakes will capture the nutrients in runoff so that less will enter the water body.

Water bodies within city limits are tremendous resources for recreation and enjoyment by the public. Efforts to reduce the problem of winter fishkills will likely be very well received. Young and old will appreciate the efforts to have a healthy lake!

Posted in Dan call, Energy, Environmental on Monday, November 22, 2010 3:01 pm. Updated: 3:38 pm. | Tags: Daniel Call , Habitat Restoration , Wind , Wildlife

Saturday 09/18/2010
Restoring Our Urban Streams

Many of the streams that flow through our cities are less than attractive due to years and years of neglect. They may flow brown with soil particles, have an oily sheen on the surface, and be practically devoid of aquatic life forms that we regard as desirable. Fish species that may be present in cleaner stretches of the stream are not to be found, nor are the insect larvae that they prey on.

The good news is that the very same stretches that appear hopelessly lost or dead can be brought back to life, and become a plus for a community. Stretches of stream ecosystems respond readily to changes in flow, shape, structure, and water quality by corresponding changes in the plant and animal communities of the stream. If conditions become unfavorable to them, they will simply die out or leave the area (if they are mobile) in search of more favorable haunts. Once conditions have sufficiently improved, the various species of plants and animals will quickly re-colonize the formerly impaired stretches.

How do favorable changes happen? How does a stretch of stream that has been neglected for years, perhaps decades, become a positive force rather than a negative one for a city? Early on, it is important to recognize that it is the entire watershed upstream of the city that contributes to the water quality of the stretch of stream within the city, and that all stakeholders in the watershed (or at least the vast majority) need to be involved and committed to the idea of stream improvement. Consensus building may be the most challenging of all aspects in a stream improvement project, as it will likely involve several jurisdictions and agencies with different budgets and timetables, as well as private landowners.

Assuming that a green light for stream improvement has been turned on, various action steps may be taken. Upstream, these may include land use change recommendations to reduce soil erosion, and the creation of streambank buffer strips of vegetation (small plants, shrubs and trees) to prevent eroding soil and fertilizer from flowing into the stream. The latter is also good within the city. Within the city limits, efforts to reduce direct stormwater runoff into the stream are important. Residents and businesses can be encouraged to incorporate rain gardens in low-lying areas on their properties, which greatly reduce the rapid runoff of rain water. The use of pervious pavement, rather than the traditional impervious forms, allows runoff water to percolate downward into the underlying soil, thereby reducing the volume of surface runoff from driveways, parking lots, streets, and airports. Specific steps within the stream itself might include creating a course of alternating pools and riffles, replacing bends if the stream has been channelized, placing rock riprap along streambanks in critical locations to reduce bank erosion, and adding structure (e.g., rocks of various sizes, logs, and bank hides) for fish habitat.

Following the action steps, it is important to assess the outcome, and to inform the stakeholders about the progress of the project. Perhaps some changes will need to be made to achieve the overall goals. However, it is likely that positive changes will be evident in very short order. Hopefully, the eventual outcome will be one where fish species that are native to the area and to the particular stream will once again be present, along with native plant life, aquatic insects, and other aquatic animals. This should also help to ensure the safety of the water for human contact. If this outcome is achieved, residents of the city and visitors alike should be favorably impressed with the beauty and condition of this rehabilitated resource.

Many cities in the Midwest have already undertaken projects to improve the appearance and water quality of streams that flow through their city limits. Others may have projects in the planning stage. We are interested in hearing about your completed and proposed projects.

Posted in Dan call, Environmental, Public works on Saturday, September 18, 2010 4:33 pm. Updated: 11:39 am. | Tags: Water Pollution , Water Quality , Soil Erosion , Stormwater , Habitat Restoration , Watershed Management , Wildlife , Traffic

Tuesday 09/07/2010
On the Lookout for Toxic “Algae”

It is usually around this time of year, late summer, when blooms of cyanobacteria (aliases blue-green algae or "pond scum") occur. These ancient simple life-forms are very successful in this season at perpetuating themselves at the expense of their more desirable green algal counterparts. They also are capable of producing some highly toxic chemicals, presumably to protect themselves from being eaten by microscopic aquatic animals. It is this phenomenon of toxin production that causes health concerns, especially for our children and pets.

The State of Washington considers the issue of blue-green algal blooms to be an emerging public health issue. If a lake or pond is suspected of having a "toxic bloom," they monitor the water for microcystins (a mixture of related liver toxins) and anatoxin-a, a neurotoxin. A warning sign is posted at the lake or pond if the level of microcystins is 6 parts per billion parts of water (ppb) or slightly higher, or if the level of anatoxin-a is 1 ppb or slightly higher. A closure sign is posted on the pond or lake if the levels are much higher, until weekly analyses indicate that the potential danger no longer exists.

What do these blooms look like? According to the Wisconsin Department of Health Services, blue-green algae can form thick scum layers or mats, and the surface may look bubbly or frothy. They might take on a variety of colors in addition to blue or green, including white, red or brown; and they might give off a foul odor. In some cases, the bloom might look like thick paint floating on the water.

It is not known exactly what triggers the production of toxins in a bloom, as not all blooms generate toxins. However, due to the fact that these chemicals are highly toxic, all blue-green algal blooms should be avoided. These are known to have caused deaths in dogs and livestock. The greatest danger is if algae are ingested, and digestive acids and enzymes cause a rapid release of toxins from the algal cells. Children should be kept clear of ponds or lakes that are suspected of having a bloom. Since dogs have a great attraction for water on hot summer days, owners should keep their dogs on leash where blooms may be suspected.

In our temperate climate, these blooms fortunately tend to disappear for the year with the onset of cooler fall temperatures. However, they are likely to reappear next summer, and in subsequent summers. Getting rid of these annual blooms is not easy. The Wisconsin DNR states that the process of reducing blue-green algal blooms is a slow one, consisting of a number of action steps. These include the reduction of storm water runoff, soil erosion, and use of phosphorus-based fertilizer and detergents; the repair of leaking septic systems; and the creation of buffer strips of vegetation around water bodies to intercept nutrients and soil particles in runoff water.

Does your community have any problems with toxic "algae?" Your response will be useful in helping to document the occurrence, extent and nature of any such blooms.

Posted in Dan call, Environmental on Tuesday, September 7, 2010 4:03 pm. Updated: 3:43 pm. | Tags: Daniel Call , Water Quality , Public Health , Invasive Species , Health , Wildlife