Author: Sobeida Figueroa | December 2014
Intensive agricultural practices generate a myriad of polluting agents. My research addresses ways of mitigating transboundary pollution associated with agricultural practices in the U.S. I will begin with a general approach as I introduce public health concerns and environmental issues arising from transboundary pollution. As my paper progresses, I will narrow my scope and give specific examples on ways this pollution can be mitigated.
In response to human population growth and urbanization we have intensified agricultural practices to meet the growing food demand. The implications of intensive farming often result in environmental degradation and an overall reduction in quality of life. I expect my research will help make considerable progress in mitigating agricultural pollution.
My approach synthesizes information recorded from multiple case studies and scientific research projects. The variables I am closely inspecting are water-polluting agents from agricultural sources and their ecological effects, particularly in the Gulf of Mexico.
Agricultural pollution-mitigating techniques are possible in part by natural ecological services and technological advances. The mitigating techniques discussed in my research can be implemented in similar fertile river/delta regions across the globe.
Keywords: antimicrobial pollution, antimicrobial resistance, buffer strips, concentrated animal feeding operations (CAFOs), conservation agriculture, eutrophication, fertilizers, groundwater, hypoxia, leaching, manure, mitigation, nutrient management, nutrient pollution, runoff, sewage sludge, surface water, synthetic hormones.
The birth of agriculture sparked a major shift in human history and our relationship with our environment at large. A majority of our early ancestors, once nomadic people who regularly migrated to hunt and forage for food, adopted land cultivation as a more stable, regular, and predictable food source. Since then agriculture has been modified according to the technology available and values of the time. Today agricultural practices in the U.S. have changed drastically in a relatively short period of time with the introduction of new machinery, biotechnological advances, and the incorporation of chemical pesticides and fertilizers.
As a result of human population growth and the recent shift from agrarian to urban lifestyle we have intensified agricultural practices to meet increasing food demands. The implications of intensive farming often result in environmental degradation and an overall reduction in quality of life for people and other life forms alike. For my report I will evaluate several scientific journals and research projects to address transboundary water pollution from agricultural sources in the U.S. and examine the pollutants’ respective effects on environmental systems, with emphasis on aquatic ecosystems, and public health. I will conclude my report with innovative techniques using both natural services and new technology to mitigate and potentially remediate transboundary water pollution issues from agricultural operations.
2.1) Pharmaceutical Pollution:
Modern day agricultural practices generate a myriad of polluting agents. The journal article “Antimicrobial Residues in Animal Waste and Water Resources” addresses the issues arising from animal feeding operations and their implications on nearby water resources. Animal manure is typically applied onto crop fields as a source of organic fertilizer to increase crop yields. But when “applied in too large amounts than can be utilized by crops and retained by the soil, manure constituents may be transported to surface water and ground water through runoff and infiltration.” (Campagnolo, 2002).
In 1998 a launched investigation in Iowa and Ohio evaluated water quality proximal to animal feeding operations and identified pollutants in animal waste storage lagoons. “Studies detected a multitude of antimicrobial agents including Tetracycline, Macrolides, β-Lactam, Sulfonamides and Fluoroquinolones” (Campagnolo, 2002). It is not uncommon to administer therapeutic doses of antibiotics to livestock in order to prevent illness. However, livestock are continuously exposed to antimicrobials in feeding operations to increase feed efficiency and consequently accelerate the animal’s growth rate. Research also found that “an estimated 75% of antimicrobial agents are excreted back into the environment.” (Campagnolo, 2002).
My query concerns the implications of these agents in terrestrial and aquatic environments and in the context of public health. Though it is unclear the effects of these agents in environmental and aquatic organisms, evidence suggests that, “the interaction between bacterial organisms and antimicrobial agents in the environment may contribute to the development of antimicrobial-resistant pathogens in the human food chain.” (Campagnolo, 2002). This implies that the over-application of antimicrobial treatment to livestock threatens our ability to treat common infectious diseases, potentially posing a major public health crisis.
To corroborate the results from the previous journal and to further explore the issues associated with antimicrobial pollution I will discuss another relevant journal article. “Environmental Antimicrobial Contamination from Terracumulation” evaluates the risks associated with terracumulation of antimicrobials in environmental systems and human health. The article also examines the effects of antimicrobial agents introduced to aquatic systems over recent decades via aquacultural practices. “Terracumulation is the concentration of pollutants in soils from land application of contaminated biosolids generated by agricultural practices” (Stephen, 2003). Biosolids are nutrient-rich recycled organic matter from manure, commonly known as “sewage sludge.”
Terracumulation from antimicrobials serve as a reservoir for antimicrobial-resistant pathogens in surface and ground water. Antimicrobial-resistance threatens the effectiveness of human drug therapy. The same principles apply to livestock who are frequently administered with antibiotics. People are furthermore susceptible to antimicrobial-resistance if they consume animal products, which have been treated with antibiotics. “Bacteria populations in the environment intrinsically resistant to antimicrobials may induce genes coded for resistance that are subsequently transferred to other members of the microbial community.” (Stephen, 2003). This demonstrates a classic example of natural selection in the bacteria kingdom.
Antimicrobial treatment is not exclusive to agriculture. Aquaculture, the breeding, rearing, and harvesting of plants and animals in marine environments, also administers therapeutic doses of antimicrobial agents to prevent infectious diseases from infecting their stocks and to accelerate weight gain. However, unmonitored doses of antimicrobials may lead to the proliferation of antimicrobial resistant bacteria in aquatic systems, only exacerbating the effects of antimicrobial pollution in the environment.
Another pharmaceutical polluting agent generated from agricultural sources are synthetic hormones. The article “Estrogens and Synthetic Androgens in Manure” examined synthetic hormones in animal manure by measuring their concentrations and evaluating potential environmental risks. In this research manure pit and lagoon effluent samples were collected weekly after land application. The results “detected a variety of synthetic androgens and estrogens commonly used to supplement daily grains in beef cattle.” (Khan, 2012). Synthetic hormones were also detected in lagoon water used for crop irrigation.
The extensive applications of synthetic hormones in modern agricultural practices have prompted major research on their immediate effects on wildlife and public health. “Androgenic and estrogenic hormones are likely to cause endocrine disruption in wildlife. The potential endocrine disrupting effects of 17 β-estradiol, such as vitellogenin production and feminization of male fish have been well documented.” (Khan, 2012). Endocrine disruptors generate adverse reproductive, developmental, neurological, and immune effects in both humans and wildlife.
The article also discusses ways in which hormones, in suitable conditions, dissolve in terrestrial environments. “Animal or human material wastes can profoundly influence the kinetics and pathways of hormone dissipation under conditions that reasonably simulate commercial application rates of these materials.” (Khan, 2012). However, the study does not evaluate whether or not synthetic hormones are able to dissipate in aquatic environments. In addition, scientists remain unaware of any potential long-term effects of synthetic hormone exposure to wildlife and public health. More research is required to formulate a definitive conclusion over this matter.
2.2) Alleviating Antimicrobial Pollution:
The article “Residues of Pharmaceutical Products in Recycled Organic Manure” offers sensitive insights for a potential solution to degrading pharmaceuticals in the environment. As mentioned previously sewage sludge generated from livestock is useful for nourishment circulation in farmlands in the form of recycled organic manures (ROM). Research in this article revealed that a number of pharmaceuticals in the form of antibiotics were detected in recycled organic manures. It was also found that “the concentration of pharmaceuticals and fermentation levels of recycled organic manures had a considerable positive correlation.” (Motoyama, 2011).
The samples, although collected in China and Japan, indicate the prevalence of antibiotic application in modern agriculture. “It is well known that portions of various pharmaceuticals reaching processing plants through livestock excrement ﬂow remain in the sewage treatment water even after complete treatment process” and “as much as 30–90% of antibiotics are excreted via swine and cattle feces.” (Motoyama, 2011). When researchers collected ROM samples containing pharmaceuticals they found that most of these agents responded to the fermentation process and could potentially be degraded in aerobic conditions.
Furthermore, “residue levels of the pharmaceutical products in the ROMs relate to the fermentation levels.” (Motoyama, 2011). This means that residues with a higher concentration of pharmaceuticals consume more oxygen than the residues with a lesser concentration. Additional analysis is required to determine the transport mechanisms of pharmaceutical agents in agricultural lands and the surrounding environment.
3.1) Nutrient Pollution:
Pharmaceuticals are only a single form of pollution generated by modern agricultural practices. Nutrient pollution is another major type of agricultural pollution severely effecting aquatic ecosystems today. According to “Understanding Concentrated Animal Feeding Operations,” a report published by the CDC, “the increasing trend of concentrated animal feeding operations (CAFOs) has resulted in an excess production of animal manure.” (Hribar, 2010). The manure surplus has consequently generated nutrient pollution as well as excrement storage concerns.
Many farming organizations in the U.S. store excess manure in pits beneath CAFOs, treatment lagoons or holding ponds on farm grounds. Storage units are not entirely infallible. Units are susceptible to overflow during extreme weather events or may leak due to structural impairments, which can affect surface and groundwater quality. Therefore, “the Clean Water Act of 1972, section 502 identified feedlots as point sources for pollution.” (Hribar, 2010). Animal sewage is laden with nutrients like nitrogen and phosphorous which can be leached into groundwater and contaminate nearby surface water via runoff. The extensive nutrient load in raw animal sewage can have detrimental effects on aquatic ecosystems, which I will later examine in further detail.
A proposed solution for nutrient pollution is a feasible nutrient management program. Programs are implemented to treat or process animal waste in a way that maintains nutrient levels at appropriate quantities. However the CDC report states, “though sewage treatment plants are required for human waste, no such treatment facility exists for livestock waste.” (Hribar, 2010). Considering the magnitude of livestock manure generated by CAFOs I think it is crucial for public health and environmental organizations to play a more active role in order to mitigate the detrimental impacts industrial farms impose on communities and their environment.
The emerging issue of nutrient pollution is being closely studied and monitored by scientists. EPA researchers are conducting studies and evaluating the sources of nutrient pollution. The newsletter article, “Nutrients: How much is too much?” analyzes the different ways ecosystems respond to nutrient pollution and identifies key indicators of nutrient pollution. Researchers are also evaluating the costs and benefits associated with nutrient management and developing ways to sustainably control the issue. This project allows scientist to create spatial distribution maps of sources and concentrations of nitrogen in the U.S.
According to “EPA ecologist Jana Compton, the estimated average annual U.S. nitrogen input to the environment is three times the level before the turn of the 20th century. That’s upwards of 25,000,000 metric tons.” (EPA, 2014). The staggering numbers over the given time frame suggests that nutrient pollution is predominately caused by anthropogenic sources. “Research has found more than 100,000 miles of waterways, close to 2.5 million acres of lakes, reservoirs and ponds, and more than 800 square miles of bays and estuaries in the U.S. have poor water quality due to nutrient pollution.” (EPA, 2014). Given the extent of nutrient pollution, there is clearly an urgent need for action to mitigate the issue.
“Research will help policy makers establish water quality standards in accordance with the Clean Water Act.” (EPA, 2014). Scientists must also identify which watersheds carry the highest concentrations of nitrogen in order to develop strategies, ultimately reducing nutrient levels reaching rivers and streams. I expect insights form this research project will prompt states to develop nutrient specifications and protection plans for their watersheds.
To further discuss the issues related to excess nitrogen and nutrient pollution in water resources, I have incorporated a supplementary news article, “What is causing our reactive nitrogen problem?” from EPA. I will begin discussing the content of this article by briefly describing the nitrogen cycle. Nitrogen is the most abundant inert gas comprising our atmosphere by nearly 80%. However plants cannot uptake nitrogen in this form. Special bacteria in the soil fix inert nitrogen gas so that plants may utilize it to grow. Another form of bacteria returns the fixed nitrogen to the atmosphere in the form of inert gas once plants die.
Though the fertilizer industry has improved productivity in farms, nitrogen loss to the environment from agricultural sources is a major issue. “Nitrogen based fertilizer not absorbed by plants can runoff and degrade nearby water resources.” (Harrison, 2013). Researchers estimate the amount of nitrogen in an environment and determine its ultimate fate. Special distribution maps distinguish naturally occurring nitrogen from human-made nitrogen sources. “These maps indicate that the regions with the highest nitrogen concentrations are located in the Midwest, Mid-Atlantic and Central California regions.” (Harrison, 2013).
Humans have undoubtedly disrupted the natural nitrogen cycle. Agricultural practices today embrace synthetic fertilizers and over apply manure onto farmlands leading to excessive nitrogen inputs. “We’ve also found that other anthropogenic sources, such as biological nitrogen fixation by soybeans and alfalfa or livestock manure, can contribute a large portion of nitrogen to different parts of the country.” (Harrison, 2013). Results from this research should persuade policy makers to develop nutrient reduction programs, as it is necessary in order to maintain suitable water quality standards and protect valuable ecosystem services while fostering a healthy environment.
3.2) Nutrient Management:
Before describing a few nutrient management strategies I want to make a notice that some methods may not be easily adopted. In “Nutrient Pollution: The Sources and Solutions” EPA researchers propose several nutrient management strategies. Some methods discussed on EPA’s webpage include cover crops, conservation tillage, livestock waste management, and drain water management. In managing nutrients it is essential to “apply fertilizers in the proper amount, at the right time of year and with the right method to significantly reduce the amount of fertilizer reaching water bodies.” (EPA, 2014). One of the incentives to nutrient management is that farmers save on fertilizer expenses.
The cover crops method is a fairly simple and inexpensive approach that recycles excess nitrogen and reduces soil erosion. Planting certain grasses and grains in agricultural fields inhibits nutrients from entering nearby water bodies. Another relatively simple nutrient management strategy is the livestock waste management approach. It “keeps animals and their waste out of streams, rivers and lakes…keeping nitrogen and phosphorus out of the water and restoring stream banks.” (EPA, 2014). These are perhaps the most feasible techniques any grower on any budget can adopt.
Another method is conservation tillage. As the name implies, conservation tillage entails a reduction in the tilling of topsoil which in turn, reduces erosion and runoff by enhancing soil compaction. It also allows soils to generate higher organic content, reducing the need for fertilizers. Farmers save time and money on unnecessary labor. Lastly, drainage water management techniques prevent water degradation in local lakes and streams by reducing nutrient loads that drain from agricultural fields.
However, the cost benefit analysis for some of these strategies may deter certain growers from adopting them. For example, conservation tillage sometimes requires new expensive machinery and a greater necessity for herbicides to control weeds. Installing a drainage water management system requires new infrastructure that controls the water table in agricultural fields. Though this system contains nutrients in the fields, resulting in greater crop yields, farmers may not see the benefits of their investment for some time. It is important to select the most efficient and cost effective nutrient management strategy.
4) The Cause and Effects of Hypoxia:
Hypoxia is a state that occurs when there is an absence or depletion of oxygen. “Hypoxic waters have dissolved oxygen concentrations of less than 2-3 ppm.”(EPA, 2008). Many factors contribute to its development including excess nutrients, mainly nitrogen and phosphorus. Excess amounts of these nutrients cause eutrophic conditions in aquatic environments which promote harmful algal blooms. “As dead algae decompose, oxygen is consumed in the process, resulting in low levels of oxygen in the water.” (EPA, 2008). Paradoxically, overly fertile waters may result in dead zone formations. Dead zones are devastating to marine ecosystems and fishing communities relying on them.
Hypoxia is a naturally occurring process usually found in deep ocean basins. However, with the increase of anthropogenic nutrient inputs, hypoxia is becoming more prevalent in shallow coastal marine environments and already threatened estuaries. Nutrient pollution can come from many sources though the agricultural sector is by far the greatest contributor in the U.S. This is due to the over application of fertilizers, and animal manure onto crop fields. Erosion of soils laden with nutrients is also a major factor stemming from agricultural sources.
The Gulf of Mexico hypoxic zone forms every summer as a result of water nutrient enrichment from agriculture delivered by the Mississippi River. “It is the largest hypoxic zone in the world and was first documented in 1972.” (EPA, 2008). Nutrient-rich freshwater from the Mississippi River remains suspended above the water column due to the density gradient principle. Though the freshwater is laden with nutrients it is still less dense than the surrounding saline waters of the Gulf of Mexico. Mississippi freshwater is also warmer in the summer than the deep Gulf waters, further stratifying the water column. “This stratification prevents the mixing of oxygen-rich surface water with oxygen-poor water on the bottom of the Gulf. Without mixing, oxygen in the bottom water is limited and the hypoxic condition remains.” (EPA, 2008).
As mentioned earlier in the section, hypoxia is directly associated with dead zone formations causing mass fish kills, depleting fisheries and upsetting ecosystems. Perhaps the most devastating impact of dead zones is the possibility for marine ecosystems never rebounding. If they happen to do so, they may be altered forever. The more mobile species usually survive a hypoxic episode by simply moving to more oxygen-rich waters. However the less mobile animals like crabs and starfish and even the totally immobile creatures like mussels cannot easily move to more oxygenated waters and are likely killed by the event. “Hypoxia also affects the ability of young fish or shellfish to find the food and habitat necessary to become adults. As a result, fish and shellfish stocks may be reduced or become less stable because fewer young reach adulthood.” (EPA, 2008). Hypoxia also affects species that prey on fish and other marine creatures as a primary food source. These species, like marine birds, may have to relocate entirely to find the necessary food to survive.
Reducing the hypoxic zone in the Gulf of Mexico is the primary focus for the Mississippi River – Gulf of Mexico Watershed Nutrient Task Force. Their efforts along with state government cooperation and aid have already shrunken the extent of the dead zone since 2011.
5) Transboundary Water Pollution Mitigation and Remediation:
To end my research I want to concentrate on ways to mitigate transboundary water pollution and perhaps even remediate some of its effects. Sustainable agriculture is key to neutralizing conventional agricultural pollution while protecting the environment, and public health, fostering wholesome communities and conserving biodiversity. Conservation buffers are a form of sustainable agriculture in that they “remove up to 50 percent or more of nutrients and pesticides. They eliminate up to 60 percent or more of certain pathogens and remove up to 75 percent or more of sediment.” (USDA, 2005). Buffers are strips of land in permanent vegetation intended to mitigate the movement of pollutants that would otherwise make their way to local water bodies.
Buffers come in numerous designs and serve multiple purposes. Different types of buffers “include: riparian buffers, filter strips, grassed waterways, shelterbelts, windbreaks, living snow fences, contour grass strips, cross-wind trap strips, shallow water areas for wildlife, field borders, alley cropping, herbaceous wind barriers, and vegetative barriers.” (USDA, 2005). Conservation buffers delay runoff and enhance infiltration within the buffer zone. Buffers also intercept heavy metals and help trap snow to reduce soil erosion in windy areas. Further more, they protect livestock and local wildlife from harsh weather conditions and nearby buildings from wind damage.
Conservation buffers just seem like a common sense practice especially when considering all the financial incentives offered to farmers for installing them. “Conservation buffers work economically because of financial incentives available through USDA conservation programs, the Conservation Reserve Program (CRP), Environmental Quality Incentives Program (EQIP), Wildlife Habitat Incentives Program (WHIP), Wetlands Reserve Program (WRP), and Conservation Stewardship Program (CSP).” (USDA, 2005). Aside from these programs many state and local governments, and some private organizations offer additional financial incentives for buffer implementation.
Another type of sustainable agriculture, though not be as simple and inexpensive as conservation buffers, is precision farming. Precision farming is a form of land management that entails site-specific information to accurately administer production inputs. “The philosophy behind precision agriculture is that production inputs (seed, fertilizer, chemicals, etc.) should be applied only as needed and where needed for the most economic production.” (Stephen, 2011). It is essential for farmers using this method to understand the relationship between their soil and crop characteristics in relation to the uniqueness of each land segment apportioned for that specific crop. The precision behind this method allows for the optimization of production inputs within a relatively small portion of land.
Typically, traditional farming methods treat entire fields as a single entity, although there is an obvious natural variability within the land. Furthermore, traditional farmers may lack the tools necessary to manage that variability. These growers generally base their production management decisions on the overall average condition of their fields, hoping production inputs would suffice. Farmers may lack the required inputs for greater yields or oppositely, they may over apply production inputs, costing them more and jeopardizing the environment.
Precision farming requires information technologies, like GPS, to apportion fields properly for crops. The grower can then apply production inputs in specific locations and quantities necessary for maximum economic yield. “Precision farming techniques can improve the economic and environmental sustainability of crop production.” (Stephen, 2011). This method is beneficial in that it reduces environmental loading by applying fertilizers and pesticides only where and when they are needed. Another benefit to precision farming is a reduction in pesticide resistance.
Although this farming operation has a lot to offer to producers and the environment, there are some drawbacks that may discourage farmers from implementing this method. For one, it is time intensive to meticulously divide fields, especially if they are extensive. Another downside to this technique is the expensive information technologies required to segment cropland. Additionally, farmers may lack the education necessary to operate information technologies. They may need to hire someone specializing in the field, adding to their expenses.
Taking into consideration the topics discussed in this research, readers should question whether traditional farming practices are still applicable to current times. The American diet has drastically changed as a result of the last “Green” agricultural revolution, the genesis of synthetic fertilizers. What we are now observing are the adverse affects of the over production and application of these fertilizers. Similarly, we face an ethical dilemma stemming from a shift in American values where over production leads to over consumption, while the developing world still struggles to meet food demands. A forth agricultural revolution is in order to revise outdated, inadequate farming methods. Its foundation is sustainability.
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