Iron-oxidizing bacteria: an unusual natural phenomenon

Iron-oxidizing bacteria: an unusual natural phenomenon

Iron-oxidizing bacteria produces an orange color and oily sheen in the floodplains of Congaree National Park, South Carolina. Used with permission from Karen Jackson, ©2020, Clemson University

“Someone dumped oil in the creek behind my house!” I had dozens of people call with that exclamation when I was a field inspector for the Florida Department of Environmental Protection’s (FDEP) wetlands compliance program. A significant portion of the job entailed responding to concerns and complaints from citizens regarding damage to wetland areas. In the field, I would come across an oily film along creeks in rural, near-pristine conditions in northern Holmes County and in heavily populated neighborhoods in the tourist hot spots of Destin and Panama City. The first time I saw it, I was taken aback. A shiny, rainbow sheen is something you might expect in an oil-soaked parking lot, not a relatively untouched body of water.

The reaction between iron, native bacteria, and oxygen can produce this orange sheen and filamentous material in streams and groundwater (as it exits the soil). Photo credit: Carrie Stevenson, UF IFAS Extension

Thankfully, an experienced colleague explained the workings of iron-oxidizing bacteria to me, and I was able to allay the fears of all those frantic homeowners. All the places I’ve ever seen evidence of iron bacteria on the water were adjacent to wetlands with some level of iron in the soil. The bacteria essentially “eat” ferrous iron, which is common and able to react with other elements in oxygen-free (anaerobic) environments. Wetlands are classic examples of anaerobic soils, and the mucky conditions of a stream floodplain are ideal for iron bacteria. These are naturally occurring, harmless bacteria that gain energy by breaking down iron available in the soil. In addition to the oily film, side effects of iron-oxidizing bacteria can include a swampy odor, a reddish filament, or red chunks of iron. In large amounts, these byproducts can clog wells if present in pipes. This can be problematic and prevent water flow, but the iron and bacteria are not threats to human health

A colleague with Escambia County recently responded to a homeowner call about bright orange water flowing out of their front yard. While not the typical creek location, environmental conditions were absolutely suited for this phenomenon. Their neighborhood is situated adjacent to a large wetland area, and several of the homes have French drains in the backyards that drain out to the street. During heavier rainfalls, excess groundwater enters those pipes, picks up iron bacteria in the soil, and exits to the surface along the road. The red-stained curbs are evidence that iron is common in the local soil.

When touched, the sheen produced by iron bacteria will fracture. This is an easy way to differentiate it from actual oil. Photo credit: City of Kirkland, Washington

While it’s possible someone could dump oil in a backwoods area (and if you do ever see that, report it to FDEP), it is much more likely that you are seeing the natural aftereffects of iron-oxidizing bacteria. To determine the difference between iron bacteria and actual oil, one simple test is to touch the water and its oily film with a stick. If the sheen fractures into small pieces, it’s iron bacteria. If it oozes back to an intact slick (and smells like petroleum), it could very well be oil.

“They Call Me… Karenia brevis”: the story of red tide

“They Call Me… Karenia brevis”: the story of red tide

At the time of this writing, red tide is still lingering off the Pensacola coast.  By the time this is posted it may or may not be.  I have had a few questions about red tide while this has been occurring here, and some misconceptions about it – so, now is a good time to try and set the story straight.

The dinoflagellate Karenia brevis.
Photo: Smithsonian Marine Station-Ft. Pierce FL

 

Red tide is actually caused by a group of small, single-celled marine plants.  The one responsible for the red tide in the Gulf of Mexico is called Karenia brevisKarenia is a naturally occurring dinoflagellate.  If I were to pull a water sample off of Pensacola Beach right now I would find it there – albeit in small concentrations – say 300-500 cells in a liter of water.  At these concentrations there are no problems.  When we say problems, we mean respiratory problems or fish kills.  See, Karenia is a dinoflagellate that when irritated or disturbed, will release a toxin – brevotoxin.  This toxin is a neurotoxin that is known to kill fish, sea turtles, and marine mammals at high concentrations – greater than 1,000,000 cells / liter.  For humans the issue is more of respiratory and eye irritation.  Though consuming filter feeding shellfish, such as oysters and scallops, during a red tide can cause serious gastrointestinal problems and possibly hospitalization in humans.  This is why the state closes shellfish harvesting when Karenia concentrations reach 5,000 cells / liter.

 

What causes Karenia concentrations to increase from 500 cells to 5,000 cells, or even 1,000,000 cells / liter?

 

The same thing that causes all plants to grow – sunlight and nutrients.

Here is where the first misconception arises.

“Red tides are caused by the increase of nutrients in the ocean due to human activity”.

Not exactly correct.  Red tides have occurred in the Gulf of Mexico since the colonial period, and the colonists certainly did not discharge enough nutrients to spawn a red tide bloom.  No, these blooms occur naturally.  Most form off the coast of southwest Florida.  There the continental shelf extends about 200 miles offshore before reaching the slope to the deep sea.  At this slope there are upwelling currents bringing nutrients from the seafloor to bath these phytoplankton in the warm Florida sun.  This combination, along with some other water chemistry needs, fuel the growth of phytoplankton from a few hundred cells / liter to a few thousand, hundred thousand, or even a million cells / liter – an algal bloom.  At concentrations of 1,000,000 cells or more the water actually changes color to reddish – hence the name “red tide”.

 

However…

Today humans ARE discharging large amounts of organic and inorganic nutrients into local waterways.  These eventually make their way to the Gulf and can enhance a natural bloom from say 10,000 cells / liter to over 1,000,000 – we can make the situation worse.  This typically happens when offshore winds blow the naturally occurring red tides closer to shore to meet our “cocktail of nutrients” and wa-la – an enhanced bloom with enhanced problems.

Dead fish line the beaches of the Florida Panhandle after a coast wide red tide event in October of 2015.
Photo: Randy Robinson

Here in the northern Gulf the conditions to spawn naturally occurring red tides do not typically exist.  What we usually see are the blooms generated in southwest Florida pushed northward but weather patterns.  At the time of this writing, Escambia County is experiencing a red tide offshore at background/very low concentrations (0-10,000 cells/liter).  Though are no reports of fish kills or respiratory issues in humans, but these are happening to our east in Okaloosa, Walton, Bay, and Franklin counties.

 

The state is aware of the not only the red tide situation, but other harmful algal blooms occurring around the state and has a task force to try and address these.  We, of course, can help by reducing the amount of nutrients (fertilizers) we discharge into our local waterways.  This would include not only commercial fertilizers, but any plant and animal waste.

 

References

 

Red Tide Current Status.  2021.  Florida Fish and Wildlife Conservation Commission.  https://myfwc.com/research/redtide/statewide/?utm_content=&utm_medium=email&utm_name=&utm_source=govdelivery&utm_term=campaign.

Preparing an Emergency Safe Drinking Water Supply Before a Storm

Preparing an Emergency Safe Drinking Water Supply Before a Storm

Prepare an emergency drinking water supply for your household before a storm hits. Image: Tyler Jones, UF/IFAS.

Storm season is upon us. During a natural disaster, normal drinking water supplies can quickly become contaminated. To be prepared, collect and store a safe drinking water supply for your household before a storm arrives.

How much water should be stored?

  • Store enough clean water for everyone in the household to use 1 to 1.5 gallons per day for drinking and personal hygiene (small amounts for things like brushing teeth). Increase this amount if there are children, sick people, and/or nursing mothers in the home. If you have pets, store a quart to a gallon per pet per day, depending on its size.
  • Store a minimum 3-day supply of drinking water. If you have the space for it, consider storing up to a two-week supply.
  • For example, a four-person household requiring 1.5 gallons per person per day for 3 days would need to store 18 gallons: 4 people × 1.5 gallons per person × 3 days = 18 gallons. Don’t forget to include additional water for pets!

What containers can be used to store drinking water?

Store drinking water in thoroughly washed food-grade safe containers, which include food-grade plastic, glass containers, and enamel-lined metal containers, all with tight-fitting lids. These materials will not transfer harmful chemicals into the water or food they contain.

More specific examples include containers previously used to store beverages, like 2-liter soft drink bottles, juice bottles or containers made specifically to hold drinking water. Avoid plastic milk jugs if possible because they are difficult to clean. If you are going to purchase a container to store water, make sure it is labeled food-grade or food-safe.

As an extra safety measure, sanitize containers with a solution of 1 teaspoon of non-scented household bleach per quart of water (4 teaspoons per gallon of water). Use bleach that contains 5%–9% sodium hypochlorite. Add the solution to the container, close tightly and shake well, making sure that the bleach solution touches all the internal surfaces. Let the container sit for 30 seconds and pour the solution out. You can let the container air dry before use or rinse it thoroughly with clean water.

Best practices when storing drinking water

  • Store water away from direct sunlight, in a cool dark place if possible. Heat and light can slowly damage plastic containers and can eventually lead to leaks.
  • Make sure caps or lids are tightly secured.
  • Store smaller containers in a freezer. You can use them to help keep food cool in the refrigerator if the power goes out during a storm.
  • Keep water containers away from toxic substances (such as gasoline, kerosene, or pesticides). Vapors from these substances can penetrate plastic.
  • When possible, use water from opened containers in one or two days if they can’t be refrigerated.
  • Although properly stored public-supply water should have an indefinite shelf life, replace every 6-12 months for best taste.

More information on preparing an emergency drinking water supply can be found on the CDC website  and in the EDIS Publication ‘Preparing and Storing an Emergency Safe Drinking Water Supply

Reducing the Impact of Septic Systems Through Advanced Nitrogen Treatment

Reducing the Impact of Septic Systems Through Advanced Nitrogen Treatment

Many of Florida’s historic first magnitude springs are classified as nitrogen impaired. Image credit: UF/IFAS Communications

Septic systems are an effective means of treating wastewater when they are properly designed, constructed and maintained. Conventional systems are designed from a public health perspective and have been widely used since the 1940s to remove pathogens and protect human health. About 30% of Florida’s population relies on septic systems, which treat and dispose household wastewater drained from bathrooms, kitchens and laundry machines.

However, septic systems were not designed to remove nutrients. A conventional system removes only about 30 percent of the nitrogen that flows into it. Even a well-maintained system will become a source of nitrogen (particularly nitrate-nitrogen) to the surrounding soil in the drainfield, and may leach to groundwater. Excess nitrogen in Florida’s waterbodies can be a contributing factor to ecological community degradation and increases in algae.

What alternatives are there to conventional septic systems?

Many enhanced nitrogen removal technologies exist, but only those approved by the Florida Department of Health (FDOH) can be installed. Conventional septic systems are made up of a septic tank and a drainfield (or leachfield). Advanced treatment systems add steps to conventional system processes to improve contaminant removal. Types of advanced nitrogen removal technologies available include:

  • Aerobic Treatment Units  ATUs are made of fiberglass, polyurethane or concrete. Unlike conventional systems, ATUs introduce air into the sewage in the tank using a pump. By aerating waste, the organic matter in the tank is broken down faster than in a conventional system. Effluent from an ATU is discharged into a drainfield for further treatment in the soil, just as with a conventional septic system. ATUs require higher energy input than conventional septic systems to power the aerator, and regular operation and maintenance to sustain performance   ATU example from the US EPA
  • Performance Based Treatment Systems PBTS are specialized systems designed by professional engineers to meet specific levels of contaminant removal based on site and/or situation requirements. There are many proprietary commercial options available. Designs often include an ATU. Like ATUs, PBTS require higher energy input than conventional septic systems to power pumps, and regular maintenance is needed to sustain performance.
  •  In-Ground Nitrogen Removing Biofilters INRB are also referred to as modified drainfields. These systems are passive, which means they require no electric aerators or pumps to treat wastewater, and maintenance requirements are lower than those for ATUs and PBTS. INRBs are nitrogen-reducing media layers placed underneath a conventional drainfield.

Ammonium-nitrogen in wastewater leaving the septic tank moves down through the Drainfield Area soil and an additional oxygen-rich zone (Unsaturated Nitrification Soil) to promote conversion into nitrate-nitrogen. Wastewater then passes through a low-oxygen, carbon-rich zone to promote denitrification (Woodchips/Soil Mix Denitrification Media). Denitrification is a process by which specialized bacteria convert nitrate into nitrogen gas that escapes into the atmosphere. This reduces the amount of nitrogen that can leach into groundwater.

FDOH provides comprehensive information about advanced treatment systems and requirements on their product listing and approval requirement web page.

 Where are advanced treatment systems required?

The short answer is wherever a septic system remediation plan to protect Florida Springs has been put into place. The 2016 Florida Springs and Aquifer Protection Act was passed to protect 30 ‘Outstanding Florida Springs.’ The majority are historic first magnitude springs, springs with flows of more than 100 cubic ft/second. Twenty-four of these springs are identified as nitrogen impaired by the Florida Department of Environmental Protection.

If septic systems contribute more than 20% of the nitrogen load to the impaired spring, a remediation plan takes effect in specific areas (Priority Focus Areas) that are particularly susceptible to nitrogen pollution. Septic system remediation plans require new development to connect to central sewer where available. If this isn’t an option, new construction on lots of less than 1 acre must include advanced nitrogen-removal technology. In the Panhandle, areas around Wakulla Springs and Jackson Blue Springs have remediation plans.

The best source of information about specific remediation plans and whether or not you live in a Priority Focus Area is FDOH. Contact your local County Department of Health Office to find out if you live in a PFA or if you have questions about septic tank requirements, permitting and  approved advanced nitrogen-treatment features for septic systems.

For more information and resources about conventional septic systems and advanced treatment system visit our UF/IFAS Septic Systems website.

Senate Bill 712 Aims to Further Protect Florida’s Water Resources

Senate Bill 712 Aims to Further Protect Florida’s Water Resources

Senate Bill 712 ‘The Clean Waterways Act’ was signed into Florida law on June 30, 2020. The purpose of the bill is to better protect Florida’s water resources and focuses on minimizing the impact of known sources of nutrient pollution. These sources include septic systems, wastewater treatment plants, stormwater runoff as well as fertilizer used in agricultural production.

Senate Bill 712 focuses on protecting Florida’s water resources such as Jackson Blue Springs/Merritt’s Mill Pond, pictured here. Credit: Doug Mayo, UF/IFAS.

What major provisions are included in SB 712?

Primary actions required by SB712 were listed in a news release by Governor Desantis’ staff in June 2020 as:

  • Regulation of septic systems as a source of nutrients and transfer of oversight from the Florida Department of Health (DOH) to the Florida Department of Environmental Protection (DEP).
  • Contingency plans for power outages to minimize discharges of untreated wastewater for all sewage disposal facilities.
  • Provision of financial records from all sanitary sewage disposal facilities so that DEP can ensure funds are being allocated to infrastructure upgrades, repairs, and maintenance that prevent systems from falling into states of disrepair.
  • Detailed documentation of fertilizer use by agricultural operations to ensure compliance with Best Management Practices (BMPs) and aid in evaluation of their effectiveness.
  • Updated stormwater rules and design criteria to improve the performance of stormwater systems statewide to specifically address nutrients.

How does the bill impact septic system regulation?

The transfer of the Onsite Sewage Program (OSP) (commonly known as the septic system program) from DOH to DEP becomes effective on July 1, 2021. So far, DOH and DEP submitted a report to the Governor and Legislature at the end of 2020 with recommendations on how this transfer should take place. They recommend that county DOH employees working in the OSP continue implementing the program as DOH-employees, but that the onsite sewage program office in the State Health Office transfer to DEP and continue working from there. DOH created an OSP Transfer web page where updates and documents related to the transfer are posted.

How does the bill impact agricultural operations?

SB 712 affects all landowners and producers enrolled in the Florida Department of Agriculture and Consumer Services (FDACS) BMP Program. Under this bill:

  • Every two years FDACS will make an onsite implementation verification (IV) visit to land enrolled in the BMP program to ensure that BMPs are properly implemented. These visits will be coordinated between the producer and field staff from FDACS Office of Agriculture and Water Policy (OAWP).
  • During these visits (and as they have done in the past), field staff will review records that producers are required to keep under the BMP program.
  • Field staff will also collect information on nitrogen and phosphorus application. FDACS has created a specific form, the Nutrient Application Record Keeping Form or NARF where producers will record quantities of N and P applied. FDACS field staff will retain a copy of the NARF during the IV visit.

FDACS-OAWP prepared a thorough document with responses to SB 712 Frequently Asked Questions (FAQ’s).  It includes responses to questions about site visits, the NARF and record keeping, why FDACS is collecting nutrient records and what will be done with this information. The fertilizer records collected are not public information, and are protected under the public records exemption (Section 403.067 Florida Statutes). For areas that fall under a Basin Management Action Plan (like the Jackson Blue and Wakulla Springs Basins in the Florida Panhandle), FDACS will combine the nitrogen and phosphorus application data from all enrolled properties (total pounds of N and P applied within the BMAP). It will then send the aggregated nutrient application information to FDEP.

Details of how all aspects of SB 712 will be implemented are still being worked out and we should continue to hear more in the coming months.

Stormwater Ponds 101

Stormwater Ponds 101

Well-maintained stormwater ponds can become attractive amenities that also improve water quality. Photo credit: Carrie Stevenson, UF IFAS Extension

Prior to joining UF IFAS Extension, I spent three years as a compliance and enforcement field inspector with the local Florida Department of Environmental Protection (FDEP) office. It was a crash course in drinking water regulation, wetlands ecology, stormwater engineering, and human psychology. For about half of that time, I worked in the stormwater section with an engineer, certifying the proper construction and specifications of stormwater treatment ponds built for residential and commercial developments. During a construction boom in 2000-2003, my coworkers and I traversed back roads from Perdido Key to Freeport, trying to catch every new project and make sure it was done right. If they weren’t, it also fell to the 3 of us to make sure mistakes were corrected.

Since 1982, Florida Statutes have required that rainfall landing on newly constructed impervious surfaces (rooftops, streets, parking lots, etc.) must be treated before turning into runoff that leaves the property and ends up in local water bodies. The pollutants in stormwater runoff—heavy metals, fertilizer, pesticides, trash, bacteria, and sediment—are the biggest sources of water quality problems for the state, more so even than industrial and agricultural sources.

The most common stormwater ponds have sandy bottoms, grassed berms, and piped inlets with riprap to slow the influx of water. Photo credit, Michelle Diller

Therefore, new developments are required to treat that runoff. This may be accomplished by several means, including regional stormwater ponds. However, the most common are still curbs and gutters, which drain to an often-rectangular hole in the ground with a chain-link fence around it. Ideally, water pools into these dry ponds while raining, reducing flood risk and holding water long enough to allow it to soak into the soil. Most of the ponds in northwest Florida have sandy bottoms that percolate easily. Maintenance is required, however, and when heavier soils, trash, or muck accumulate they must be cleaned out to function properly. Depending on the geology of any given location, the ponds may need sand filters or “chimneys” added to allow water to soak into the native soil.

Admiral Mason Park, adjacent to the Veterans’ Memorial Park along Pensacola Bay, is an example of a regional City stormwater treatment facility that also serves as a park. Photo credit: Visit Pensacola

If an area is naturally low-lying, close to the water table, or has highly organic, water-holding soils, it may be necessary to construct a “wet” stormwater pond. In these, water stands to a level below an overflow device, and can become a water feature for the development. Many residential developers will sell lots around a stormwater pond as “waterfront property” and a well-maintained one really can be a nice amenity. However, at their core, these are stormwater treatment mechanisms. A wet pond functions differently than a dry one and is dependent on healthy stands of shoreline vegetation to take up extra nutrients, metabolize them, and render them into harmless compounds. Many of these ponds have fountains to aerate the water and keep them from becoming stagnant. The City of Pensacola and Escambia County have several great examples of these types of ponds that serve as regional stormwater detention and community amenities. These were constructed in lower-lying areas to handle chronic problems with stormwater in areas that were built up and paved many decades before stormwater rules came into effect. Many other innovative and newer stormwater treatments exist as well, including bioretention, rainwater harvesting, green roofs, and pervious pavement.