Impacts of Excessive Nutrient Loads In the Mississippi River

Impacts of Excessive Nutrient Loads In the Mississippi River


The Mississippi River originates from Lake Itasca in Minnesota, flowing south through thirty-one states into the Gulf of Mexico. The River flows for 2,350 miles, making it the second longest river compared to the Missouri River (Mississippi River Facts, 2017). Today the river is a vital source of water to communities and farmers for agriculture. As it flows, many nutrients from runoff and erosion are carried downstream into the Gulf creating the hypoxic zone(See Appendix A for a photo of the hypoxic zone). Several studies are being performed to reduce the nutrients, size, and to restore the habitat for the affected aquatic life. With further research on hypoxia in the Gulf, one day it can be applied to unhealthier areas and hopefully lessen the damage caused by human activity.

1.1. Definition and causes of hypoxia

When bodies of water like wetlands and oceans have a low oxygen concentration of less than 2 pm, it becomes hypoxic (About Hypoxia, 2018). Fertilizers, decomposing vegetation, and sewage are some factors that contribute to the Dead Zone. These factors produce phosphorus, nitrogen, and sometimes sulfur that can be difficult to remove. As they flow downstream, the concentration becomes greater before emptying into the Mississippi River Basin. Ecosystems are disrupted and eventually die if the issue persists.

This creates the perfect environment for an algal bloom to form on the surface on the water. They absorb oxygen from the water while receiving sunlight from above. Algal blooms eventually die and decompose, consuming the little oxygen that may be left and killing the few aquatic species can survive in low oxygen environments, making it completely uninhabitable. Stratification is another factor plaguing the Gulf of Mexico (Hypoxia 101, 2017). The temperature of the freshwater flowing from the Mississippi River is warmer than the saltwater in the Gulf of Mexico. When they meet, two layers are formed like oil-in-water, preventing the freshwater from mixing with the dense, seawater. Oxygen levels in the Gulf are low and with the freshwater remaining on top fish can avoid the area, but small species like crab and shrimp die due to lack of oxygen.

1.2. History

Signs of hypoxia first appeared in the Gulf of Mexico in 1972, but consistent documentation began in 1987 to track the movement and spread of the nutrients loads. Over the past 25 years information, studies, and teams have come together to lessen the impact on the ecosystem. One organization, in particular, Mississippi River/Gulf of Mexico Watershed Nutrient Task Force, was developed in Fall 1997 to alleviate nutrient pollution; reduce the size of the zone; restore habitats; and understand the causal effects of eutrophication (Hypoxia 101, 2017). They created the 2001 Action Plan to develop research on the hypoxia in the Gulf, and 5-years after that a new assessment is written to track the progress of reducing the loads.

1.3. Eutrophication-Driven Deoxygenating

In the last ten years, open ocean researchers have put many efforts in the study of deoxygenating. Their research has revealed that there are some zones in the oceans which have no oxygen while others have low dissolved oxygen. The ancient human activities back in the nineteenth century have led to the emergence of regions of low dissolved oxygen. The changes in oxygen are essential in the enhancement of the ecosystem. In the coastal areas, deoxygenation leads to alteration of sediments. The condition of low dissolved oxygen has gained more significant among researchers since it has adverse negative effects in the ecosystem. In the coastal ocean, deoxygenation leads to conditions of low dissolved oxygen or no oxygen which have an undesired impact on aquatic and aerobic organisms. These conditions lead to mortality, reduced growth, loss of secondary reproduction, reduced biodiversity, and death of fisheries.  In 1970, there were several sites of hypoxia in North America. Coastal hypoxia became more prevalent in this region as well of in Japan and Europe in the 1990s. In South America, Australia and Europe cases of hypoxia were reported in the 2000s.

Eutrophication is the increase in carbon accumulation and primary production rate. This condition leased to decrease in hypoxia in coastal waters and consequently leading to consumption of microbial oxygen. There is a close relationship between the global distribution and development of regions of low dissolved oxygen and the development of watershed. There is also an association between the coupling of phosphorus and nitrogen and the production of carbon. For instance, closely related to the Mississippi river’s hypoxic zone is nitrate loads.

The dynamics of oxygen have close integration with the chemistry of silica, phosphorus, carbon, nitrogen, sulfide and trace metals in sediments and water. The composition of chemically related to decreasing in hypoxia depends on the amount of time that oxygen has been exposed. On a seasonal basis, highly productive surface waters lead to over 100% saturation levels of oxygen. Deoxygenation has no impact on the organic carbon that is contained in sediments and surface waters though they are the leading causes of reducing concentrations of oxygen.

The presence of long-lasting severe hypoxic events has led to a decrease or shift in benthic organisms. There is a suit of sediments that is harbored in the residues and can be seen as indicators of chemical or biological alterations in the water column — the high content of organic carbon results from anoxic conditions where there is immense preservation of organic matter. Early Holocene is characterized by high organic carbons contained in laminated sediments. The increase in surface water nutrients in Mississippi River plume led to an increase in biogenic silica accumulation. Atchafalaya River and Mississippi River have influenced the accumulation of sediments which show an increase in the percentages of silica, carbon, and nitrogen.

Human activities have contributed to changes in the world’s climate. It is said that these changes will remain constant even if greenhouse gases are kept under control. This is because there are lagging effects that may have implications for centuries to come. The leading causes of these changes include shifts in patterns of wind, altered hydrological cycles, and increased temperatures. High temperature may lead to increased density of coastal and estuarine water and lowered water salinity. Regional winds patterns may also be influenced by high temperature which changes the mixing and circulation of the wind. It is now confident that there will be a continued increase in the global reports of hypoxia while the quality of coastal waters will be decreasing in the number of nutrient loads due to changes in climate.

According to the evidence of change is seen in the Skagerrak, the Dutch Warden Sea, and the Baltic Sea. Mississippi and Atchafalaya are the major rivers that debouch into the continental shelf that is relatively closed; hence the nutrient load has increased resulting in biological effects on the coastal regions.

The primary sources for freshwater, in the continental shelf contributing to more than 43% are the rives Mississippi and the Atchafalaya. More than a third of the Mississippi water of the remaining section is charged in the Mississippi River system. The recent and rapid changes in the concentration, as well as the rations of the end-member nutrients, have affected the coastal ecosystems in several ways. One of the collective effects is influencing an increase in the rate of phytoplankton production rates. This increase in the nutrient concentrations and loading of phosphates and nitrates have lent to a decrease in the amount of silicate leading to alterations of the nutrient concentrations, causing the corresponding reduction in the nutrient concentration in the nutrient composition in the adjacent continental shelf. The level of silica usually reduces the growth of diatoms in the water. Diatoms are all groups of algae microorganisms that grow in water. As a result of the reduced silicate and increased nutrient load, the diatoms production in the gulf has dramatically improved. Also, increased nitrogen and phosphorous concentration have lent to rapid growth in the plague population.

Diatoms are one of the commonly used indicators for the changes in the environmental conditions within the river system. However, identifying the deposition rates and amounts is usually a challenge. The accumulation of the silicate and the high biologically bound silica have lent to alteration of the stoichiometric nutrient balance in the entire continental shelf.


2.1. Ocean Acidification

With nutrient pollution affecting the ecosystem water, quality in the Gulf of Mexico will continue to decrease over time. Acidification will intensify in the future if hypoxic levels rise with no conservation efforts being implemented. Anthropogenic carbon dioxide is gasses emitted into the air due to human activity. When the CO2 fails to be recycled back into the atmosphere, acidification on metazoans causes at least three biological effects: (1) direct effects of altered carbonate chemistry on external shell dissolution in calcifiers, (2) pathological effects of an modified acid-base status on biomineralization and physiological processes and (3) impacts of an altered acid-base status on species’ energy budgets (Melzner, Thomsen, Koeve, & al, 2012). Shells and exoskeletons on invertebrates become thin while exposed to the acidic water. Some of their physiological process of respiration becomes altered while hypercalcification causes behavioral disturbances. Metabolism in the metazoans decrease, and energy reserves are used to maintain homeostasis. Future calculations show that acidification will not be possible for the next 100 years based on the current CO2 values. Upcoming research on hypoxic coastal areas should focus more on upwelling events, seasonal changes, temperature, and species responses to O2.

2.2. Phytoplankton growth

Phytoplankton is a type of algae that require sunlight and nutrients to grow. Although small, they are a source of food as well for many sea creatures like jellyfish, whales, and shrimp. They were used in this study to see if nitrogen (N), phosphorus (P), or a combination of both would place growth limiters on the population. Both N and P are essential nutrients to phytoplankton growth, but the management of the amount they receive will control overgrowth. One hundred fifty-eight bioassays were collected over eight months, excluding the winter months (Turner & Rabalais, 2013). The phytoplankton was placed in 10mL test tubes and given concentrations of inorganic N, inorganic P or both, and was extended 2 to 3 days past the peak biomass accumulation to a total of 5 to 10 days. The salinity range was higher, between 0 and 36, compared to past experiments with a salinity between 17 and 29. The results showed that light limitation occurred where salinity was <20. Phytoplankton growth becomes mostly N- or NP-limited where salinity is >20, and (3) an N and P synergism exists most strongly where salinity is >30 (Turner & Rabalais, 2013). Therefore, reducing the loads in the will decrease eutrophic waters and lessen the potential of hypoxia.

2.3. Effects on Fish and Fisheries

There has been the commendable publication of the formation of the broad zone of low dissolved oxygen on the coast of Louisiana. It has been proven to be difficult to establish the impact if the establishment of this zone of hypoxia on fisheries and fish. The negative impact of low levels of dissolved oxygen and the positive consequences of bottom-up fueling commonly referred to as the nutrient loading dual effects significant in the quantification of the impact of hypoxia in fisheries and fishes. The determination of the net impact of these zones on fish and fisheries as well as a focused effort in the separation of the positive and negative impacts has become a subject of focus by the researcher. The study used a model of the ecosystem that assumes a holistic focus by simulating the interaction of species while keeping a check on the spatial distribution adjustments as well as the changes in biomass.

There are three biological impacts on the fishing which include aggregation, growth, and mortality due to the presence of hypoxia. The presence of dead zones affects catch efforts patterns and as well provides bioeconomic system feedback. Spatial sorting leads to an ecological disturbance which contaminates the areas which would have been used as a control in a framework of natural experiments. The research revealed that there is a negative correlation between total landings and average shrimp. Likewise, there is also a negative connection between landings and hypoxic severity. Going forward, there is a weak negative relationship between shrimp size and severity of dead zones with growth overfishing being a primary mediating effect since it varies with ecological disturbances and recruitment success.

The primary increase in production in the coastal area of the Gulf of Mexico is associated with the nutrient-rich water that is brought by the waters of the Mississippi River. When the nutrients in the water decompose, followed by the summer stratification leads to conditions of hypoxia. This phenomenon started in the early years of the 1970s. These ‘dead zone’ lead to reduced growth and feeding rates., avoidance behavior, alterations in activity levels and mortality of shellfish and fish. Predator-prey relationships are some of the indirect impacts of low levels of dissolved oxygen. For instance, fish may be affected by the behavior of the organisms that they feed on due to the effects of hypoxia. The impact of the change in changes in the prey on fish may be positive or negative. The effect of such alterations on the prey on fisheries may be a bit complicated as the catch results in my either increase or decrease. On the one hand, hypoxia may increase the concentration of prey hence making it easier to catch more while still, it may kill the pray making the concentration of fish low in the coastal area.

The efforts of nutrient reduction in the coastal areas of the Gulf of Mexico cannot be achieved without incorporating the nutrient enrichment effects on phytoplankton in an inclusive model that focuses on the effects of zones of low dissolved oxygen and suggestions that may reduce such impacts.

The results of the study indicated that hypoxia might favor the landing of some fisheries such as the squid and the crab. The crab landing is directly affected by the effects of the zones of low dissolved oxygen while the arrival of squid is due to indirect influence. There are some species which experience higher positive effects in the presence of nutrient-enriched water while they are not mostly affected by hypoxia such as the Atlantic croaker. It was also proven that there is no single model of nutrient removal can remove all nutrients from the waters of the Gulf of Mexico. The red snapper was proven to be affected by both conditions of high nutrients as well as hypoxia. Additionally, jellyfish showed a positive increase in biomass in the presence of hypoxia, and hence it uses such zones as the hiding place from predators. The study concluded that hypoxia does not necessarily have negative effects on overall fisheries biomass or landing, but it has some positive impact on some species.

Temperature changes in the marine environment that are brought about by variations in climate, leading to various ecological shocks which hinder the efforts of extraction of renewable resources and non-extractive services flow. Other factors that may cause such alterations to include, El Ninos, acidification of ocean waters, availability of dead zones in the ocean waters which are brought about by technological disasters such as oil spills and nutrient pollution.

There are more than apparent effects of dead zones on fisheries that most people think. There are substantial costs that are associated with the efforts of nutrient pollution control and well there are numerous related spatial dynamic complications. Nevertheless, the mere understanding of the effects of such regions of low oxygen on fisheries is a big step in reduction efforts. The research revealed that hypoxia affects the growth and mortality of fisheries leading to reduced harvests.

Various challenges face the fisheries in the Mexico Gulf which in the past 10 years had a landing that ranged between metrics tons of 30, 000 to 70, 000 which translate to not less than $355 million in value. The primary challenge that the shrimp has faced is that of the negative impacts of dead zones alongside others which include the rising cost of fuels, imports competition and increased cost due to environmental regulations. The research concluded that there is a negative relationship between the total landing and the severity of hypoxia which was one of the most striking features that the researchers noted. They also revealed that hypoxia varies throughout the year, but there has been a notable general increase over the previous years. The research did not prove any negative correlation between the average shrimp size landed but instead there was a statistically insignificant positive correlation between the two.  The evidence found suggests that is fishers could fish intensively at the beginning of the season their catch would be significantly good since then there are fewer zones of hypoxia which reduces the amount of fish they can catch at a time. In terms of class sizes, there is a negative correlation between the class size landings and the severity of the zones of low dissolved oxygen.

2.4. Economic loss

The excess nutrient load in the river has an economic impact on the affected countries including the United States and Mexico. The poor water quality leads to loss of revenue as the river is a tourist center. The growth of the algae leads to death, and other pollutants lead to the destruction of fish and other aquatic animals. As a result, the level of fishing activities decreases leading to loss of income and livelihood especially to those who depend mostly on fishing as a source of livelihood. As a nation, the amount of funds that have to be used in cleaning water increases hence costing the country more.

2.5. A decrease in property loss

Elevated nutrient levels lead to a reduction in the level of property value for the properties which are near the river. This is due to increased water clarity, a decrease in the dissolved concentration of oxygen which makes the nearby homes less valuable because the environment becomes pathetic. According to study on the effect of water clay and or direct water quality metrics using hedonic analysis on property value, which was conducted on Mid Atlantic, Midwest and South East regions, the study shows that the clear and quality water leads to an increase in property prices of the neighboring properties while less clear water due to diatoms and other pollutants leads to a decrease in the capital of the adjacent areas.

2.6. Adverse health effects

Nutrient load also leads to human health effects. Algae blooms cause a variety of a considerable number of diseases to human beings and animals through direct contact with skin. This mostly occurs during drinking water and recreation. Consumption of contaminated fish also leads to adverse health effects, which accounts for the increased rate of food poisoning especially in the areas along River Mississippi. This health effect depends on the season, and the cost can rise to more than $ 130,000 especially on algal blooms.

2.7. Climate Change

There have been many stressors, from climate change to oil spills, that have a significant impact on the ecosystem. Climate change is one big influence on an aquatic species’ physiological processes, like reproduction and feeding patterns. It is apparent that hypoxic zones are intensified in the warmer months. Therefore, future prediction of temperature increases will give an idea on how to better manage the zones. Oxygen solubility continues to decrease during the summer months, while stratification is enhanced by the surface water heating, preventing the surface water from mixing with the underlying seawater. Aquatic species like crab and fish have increased demand for metabolic oxygen to maintain tolerance in the environment, but the desire to keep becomes impossible when algal blooms continue to grow and deplete the remaining oxygen.

Significant evidence shows that climate change is occurring, and rising temperatures extend the duration of the dead zones. Several factors contribute to the noxious environment; Rising sea levels, prolonged summer seasons, and precipitation intensity. With the climate steadily rising, it is predicted that the temperature of the dead zones will increase by 2°C by the end of the century (Altieri & Gedan, 2014). As the understanding of climate change affects becomes refined, models can be developed to manage the dead zones better and possibly decrease the anthropogenic impacts on the ecosystem.

2.8. Ecosystem Status

The Gulf of Mexico is one of the United States biggest economic producers with fishery and tourism bringing most of the revenue. But with the Gulf becoming hypoxic, there has been a decrease in the number of aquatic species and their habitat. This is due to anthropogenic impacts and increasing population growth in the Gulf over the past 50 years (Karnauskas, Scjirripa, Kelble, Cool, & Craig, 2013). Human health can be impacted as well for those who are dependent on the ecosystem. Potential indicators should be put in place to evaluate the status of the ecosystem while slowing down any possible damage.

2.9. Changes in human impact

Nitrogen and phosphorus are some of the primary pollutants that flow into the Gulf of Mexico, contributing to the hypoxia plaguing the ecosystem. The purpose of the study was to evaluate two ways to apply conservation policies on agricultural land use. The USDA Conservation Effects Assessment Project (CEAP) was developed to assess nutrient pollution and how it is being delivered to the Gulf of Mexico. Most of the pollutants being deposited into the river come from cultivated croplands producing corn and soybean crops. Two models were used, Agricultural Policy/Environmental eXtender (APEX) and Soil and Water Assessment Tool (SWAT), to simulate flow, sediment, and nutrients deposition (White, Santhi, Arnold, & al, 2014). APEX models small watersheds or fields while SWAT was used to model large basins, but parameterization is limited.

The results from this study proved that conservation models put in place by the CEAP on agricultural croplands reduced nutrient loads in the Gulf by 20% compared to no conversation practices. Simulation results showed that cultivated lands are a major source of pollution in the Gulf. Upper Mississippi, Ohio, and Lower Mississippi river regions were the top contributors of pollution, with 87% of Nitrogen and 90% of Phosphorus predicted to reach the Gulf (White, Santhi, Arnold, & al, 2014). This evidence expresses the importance of cropland conservation to provide better water quality.



At the end of 1972, The Clean Water Act was signed by Nixon into law which made the availability of clean water a fundamental human right. The idea was to make the water of the nation swimmable and fishable at the same time. It is one of the essential environmental law to have ever been passed. Prior to this law, waste from all processing plants and households was channeled into rivers making two-thirds of the United States waters unsafe for fishing and swimming. Water pollution by agricultural activities is evident at the entry of Mississippi into the Gulf of Mexico. This gulf has the largest zone of low dissolved oxygen in Mexico and the United States of America. It comes second in the world ranking.

Increased rates of pollution have been contributed by the change in land use form perennials to the farming of row crops. For a long time and before the 1990s, there was a prairie grass cover which emerged after glaciations. It covered more than 69 million ha of the land of the United States of America. Then the water was clean and solid was highly fertile. Increase in demand for food after the World war I led to the emergence of mechanized farming which cleared the grass cover and replaced it with annual crops. The use of fertilizer in the cornfields became the starting point for water pollution. It increased the concentrations of nitrate and nitrous oxide in the surface water which got transported by the Mississippi River to the Gulf of Mexico. More recently, increased demand for corn has increased the number of cornfields in more than five states.

The loss of grass cover was a big mistake for the nation, and it should be revisited. They played a significant role in the conservation of water and promotion of organic matter in the soil. They also served to reduce soil erosion, retention of carbon dioxide from the atmosphere and they trapped nutrients too. The leading cause of hypoxia has been revealed to be nutrients associated with the production of row crops. The most substantial proportion of nitrogen in the gulf comes from agricultural activities.

There have been efforts to reduce levels of low dissolved oxygen in the Gulf of Mexico. A group of activist citizens once went to court to force the (USEPA) to make efforts to eradicate the Gulf’s hypoxia. The Hypoxia Task Force formed in the year 1970 conducted a study to reveal the leading causes of hypoxia and came up with ways of minimizing its effects. USEPA also made efforts to reduce P and N loadings in the waters of the nation when it commissioned its regional officers to critical steps in the fight. There was a reduction of the amount of N delivered at the Gulf between the year 1997 and 2007, but since then there has been a significant increase.

Significant investments have been made in research related to perennial-based bioenergy. There are three related research centers in the United States of American for the conduction of the proposed research. They should come up with suggests for biofuel systems that produce bio-oil from perennial grass. They should also come up with models of that link land use with the loading of N into the Gulf of Mexico. Additionally, they should even come up with water and soil assessment models. Finally, they should come up with recommendations on how to return perennial grass into the agricultural system.


4.1. Changes in Bacterial and Eukaryotic Communities During Sewage Decomposition in Mississippi River Water

Among the best methods of sewage, contamination control is the microbial decay processes which reduce the environmental effects that may be harmful to human and other living organisms. A combination of eukaryotic and bacterial communities from ambient water and sewage is significant in the process of decomposition. Nevertheless, there limited knowledge of how the populations of bacteria and eukaryotic change during the process of decomposition. This article used the Illumina sequencing model to examine decay in the upper Mississippi River surrounding sewage. River water was mixed with treated sewage water which was kept for seven days in ambient conditions. Microbial community changes were assessed under two different conditions: shaded versus sunlight exposure, absence versus presence of microbiota from the natural river. In the first 65 sequences, there was higher diversity in sewage than in water river. At 185 series, the variety in river water became more elevated than that in sewage water. There was a significant change in bacterial and eukaryotes community composition. The community variations ware highly influenced by the availability of natural river microbiota.

Mainly human fecal microbiome and sewage infrastructure could be used to describe the primary sewage effluent when the sequence distribution was at 165. Sewage impacted water as well as first sewage water contains campylobacteria and hence it was not surprising for them in be seen in abundance in the sequence. Since sewage and open waters are associated with waterfowl and birds, hence the distribution of sequences may not have been influenced by human sources only. Beta, Alpha and Gamma Bacteroidetes, Actinobacteria and Proteobacteria were the representatives of the communities of bacteria in the waters of Mississippi River. These results concurred with another finding of earlier research conducted on the Mississippi River and the other freshwater rivers. Rapid reduction in campylobacteria characterized the decomposition of the affluence of primary sewage in the Mississippi River.  There also other related consequences of sewage such as Clostridiales and Bacteroidales. The riverine community had increased sequence over time with the most increased being Alteromonagales and Sphingobacteriales. In the presence of nitrogen-rich water, Sphingobacteriales increased in abundance. These results were also in line with the finding of a previous study. The study revealed that communities in natural rivers can always recover even after being subjected to water pollution.

Their association between the eukaryotic community and sewage effluent is little known. The study concurs with other reviews that there are detectable bacterivorous ciliates in freshwater.  Human feces or gut is associated with a few communities of eukaryotes. They include Saccharomyces, yeast Candida, and Blastocysts. The presence of a significant number of protists is a prove that raw sewage contains human gastrointestinal microorganisms and also living things from rainwater that enter the wastewater. There was a dramatic change in the community of eukaryotes that occurred when river water was mixed with sewage effluent. There was an increase in numbers to levels that were not discernible in the sewage effluent alone. River water combined with effluent bring about better results as the variations in the bacterial and eukaryotic communities are more visible. The presence of sunlight a well as natural river microbiota influences the differences in the communities. In conclusion, the researchers suggested that alterations in community diversity are linked to eukaryotic and bacterial groups which show that their reactions at 165 and 185 are useful in the description of the decomposition of fecal pollution in river waters.

4.2. Agricultural Conservation Practices

Significant steps have been made in the implementation of water quality improvement and conservation practices. Nevertheless, it has been a significant challenge to do so in complex river systems. This article focused on the efforts of the SPARROW and whether their conservation measures have had any significant impacts on the reduction of nutrient loads in rivers. The model used regulators for factors such as environmental processes, multiple sources, and hydrologic variability. The research revealed that there was a negative correlation between spatial conservation pattern and the number of nitrogen loads in rivers. There was also a weak negative correlation between conservation and phosphorous. The research concluded that conservation efforts had played a significant role in the possible reduction of Phosphorous and nitrogen loadings in rivers and streams of the Upper regions of the famous Mississippi Basins.

The erosion and structural control efforts that have been instituted in the Mississippi River have proven to be effective in the reduction of peak flows and runoff, increasing the water holding capacity of soil and infiltration of water. Nitrate and ammonia which are the most reactive types of nitrogen are very mobile and available in all agricultural solid that contain elements of nitrogen. Higher hydraulic storage is obtained when larger water quantities are routed to the conservation in the conservation process. In the regions where water conservations efforts have been taken, there are fewer instances of water-rich nutrients that the places where such efforts are ignored. Biogeochemical and subsurface hydrological conditions are necessary since they enhance the effectiveness of water conservation efforts that are made to prevent the entry of nitrogen into rivers and streams. These conditions make it easier for nitrogen removal through denitrification.

Several factors can be used to explain the phenomenon of the weak negative correlation between phosphorus loads and conservation efforts. First and foremost, there are long time lags associated with particulate phosphorous which makes it respond very slowly to reduction efforts. Secondly, it takes decades to remove phosphorous from sediments, and hence such facts hinder consecration efforts. Consequently, it may take longer than necessary to remove phosphorous from rivers as compared to nitrogen.

Nevertheless, there are some practices of erosion control, and especially the reduced tillage and no-till have been proven to be responsible for increased levels of dissolved phosphorus in streams. These practices hinder the efforts of the reduction of phosphorous loads in streams through conservation efforts. Additionally, reduced tillage also leads to soil macropores development which connects o systems of tile drainage that facilitate the movement of dissolved phosphorous into rivers. Manures and fertilizers which are rich in phosphorous also increase the chances of having dissolved phosphorous which is transported by runoff to the rivers and streams.

The research concluded that most of the methods that are used to control erosion have a significant effect on the number of phosphorous loads in rivers. The article reveals that these practices increase the chances of soluble phosphorous in water. Consequently, erosion eradication methods limit conservation effectiveness and it is for that reason that there is a weak negative correlation between the reduction of phosphorous loads and the efforts made towards water quality conservation.  In conclusion, the efforts made toward the preservation of river and stream water quality have a significant impact on the reduction of nitrogen loads in water as compared to the effect they have on the reduction of nitrogen load.


Hypoxia will remain an issue if excess nutrient loads continue to flow in the Gulf of Mexico. Management practices must be enforced along the Mississippi River in agricultural croplands to decrease the impact on the ecosystem. There are already early signs of the habitats disappearing, which also has an economic impact on the fisheries that depend on the native fish and shrimp to survive. Creating alternative methods to decrease nutrient will be both times consuming and demanding a substantial amount of resources, but beneficial in preventing the spread of the hypoxic zone.


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