USC Dana and David Dornsife College of Letters, Arts & Sciences > Blog

October 31, 2011

Where would California agriculture be without the carbon cycle?

The amount of global carbon outputs have increased with the industrial revolution and rising need for agriculture, brought about by a rapid population growth. Agriculture over the years has become a major contributor to the global carbon cycle, especially as it now accounts for approximately 14% of global land use. It tends to deplete soil carbon because land used for agriculture has a lower net primary productivity than land that is kept in it’s natural state with undisturbed soil and processes.

In order to better understand the ways in which we are emitting carbon and effecting the carbon cycle, one must better understand the cycle itself. Carbon is absorbed by plants during photosynthesis in the form of carbon dioxide, along with sunlight and water. Plants then produce glucose and oxygen. When plants decompose, the carbon is transferred to the soil, where it is stored along with mineral carbon. Additionally, when animals eat plants, the carbon is passed from one to the other. Therefore this carbon can be released into the atmosphere during the respiration of plants and animals, the burning of fossil fuels, or, in the case of farming, when soil is tilled (Soil Science and Management 5th Edition, Plaster).

California’s agriculture tends to differ from that in the rest of the US in that it grows a large amount of perennial crops and specialty crops such as vegetables, nuts and fruits. California’s climate makes it the ideal provider of specialized high value crops to the rest of America, and much of its economy has been built on this industry.  Perennial orchards and vineyards account for roughly a third of agricultural land (Kroodsma and Field). Since California has long hot summers, irrigated soils go through distinctive wet and dry cycles between water applications, which impacts the amount of dissolved organic carbon in soils. For these reasons, it’s evident that the carbon cycle is particularly vital in California industries and agriculture (Kroodsma and Fields).

California has smaller levels of carbon sequestration, most likely largely due to warmer temperatures, irrigation, and a strong lack of conservation tillage. This practice disturbs the soil less, but is not practiced as much in California because there is less of a risk of erosion than in the rest of the US. However, carbon storage in California is improved by the growth of perennial agriculture. It agitates the soil less and decomposes faster than annual plants.

There are practices, both farming and industrial, that can be put into effect in California’s agriculture to reduce carbon emissions. Farmers can implement increased use of conservation tillage to leave soil undisturbed and reduce emissions. They can also return pruning of plants to the soil as mulch. It has been proven that if soil is mulched, rarely tilled and has plants growing, loss of CO2 is decreased. Waste wood from orchards and vineyards can be used in biomass power-plants, both to reduce waste and the burning of fossil fuels. California has already begun decreasing field burnings, as that releases CO2 (Kroodsma and Fields). These practices implemented together would reduce carbon emissions while simultaneously improving crop yields and productivity.

About the authors: Lily Phillips and Ariana Verdu are working towards their bachelor degrees in the USC Dornsife College of Letters, Arts and Sciences.

Emerging Contaminants Affecting Marine Ecosystems: Flushing Meds Isn’t as Harmless as it Seems

New research categorizes pharmaceuticals as emerging contaminants because of the harmful effects being seen in marine ecosystems. Emerging contaminants such as pharmaceuticals, industrial byproducts, and pesticides are entering marine ecosystems and affecting them in a detrimental way. As defined by the EPA, an emerging contaminant is “a chemical or material characterized by a perceived, potential, or real threat to human health or the environment or by a lack of published health standards.. Though their exact effects on marine ecosystems are not known because of minimal monitoring and lack of extensive research, some studies have shown to be toxic to aquatic life. These contaminants generally from agriculture, industry, and households can interfere with hormone systems affecting reproduction and growth in marine organisms. We should be concerned about the presence of these emerging contaminants because it is unknown where exactly they come from, what their full effects are, or the result of their interactions.

The Southern California Coastal Water Research Projecthas done a lot of research including studies of contaminants in wastewater. For example, these contaminants are known disrupters to the endocrine system interfering with reproductive hormones such as estrogen and testosterone in male flatfish. The presence of estrogen in these waters can be due to the cycling of birth control and through urination, can enter water, and thus affect the reproductive systems of aquatic organisms. One study measured the potential effect of emerging contaminants on the Southern California coast by the collection of hornyhead turbot fish. This fish in particular was chosen because it lives in the depth at which wastewater is released. Samples from the fish from various locations were taken and tested for specific emerging contaminants. “These findings indicate that aquatic life is exposed to a wide variety of emerging contaminants, even after 100- to 1000-fold dilutions of wastewater effluent in the ocean.”

The lack of knowledge regarding emerging contaminants is due to the focusing of specified contaminants recognized decades ago. The list of contaminants is growing continuously, so the use of old data could be disastrous. The difficulties associated with assessment of the contaminants have to do with ”the distribution and bioeffects of these contaminants comes from a lack of detailed understanding of chemical and toxicological interactions in a very complex environment.” There are many unknowns when it comes to emerging contaminants, but NOAA suggests that these difficulties should be approached by infrastructure and new research initiatives.

NOAA’s Emerging Marine Contaminants Program is quantifying solutions to the unknown effects of marine ecosystems. They are currently developing methods to measure and characterize distribution of these widely various contaminants in marine ecosystems. They are also trying to assess the toxicity of these contaminants in marine species as well as humans. When the exact effect on these species, and subsequently humans, is determined, then new legislation protecting people and marine ecosystems may be enacted. Without further investigation, marine life will further suffer the consequences of manmade chemical pollutants.

About the authors: Sarah Bethel and Megan Won are working towards their bachelor degrees in the USC Dornsife College of Letters, Arts and Sciences.

October 30, 2011

Overuse and Abuse of Nitrogen Fertilizers in California Agricultural Lands

Without the use of nitrogen fertilizer, California agricultural lands could risk not reaching its optimum yield. As a consequence, food production companies would lose a certain amount of profit and consumer demands could possibly not be reached. Often times as nitrogen passes through plants and soil in a repetitive cycle the loss of nitrogen is greater than the benefit and as a result, the plant growth is no longer as significant. This ultimately puts a limit on crop production rate. However, scientists have come up with farming techniques that have revolutionized agriculture. Nitrogen fertilizer is one of those inventions and is a product of the Haber-Bosch process. This fertilizer has ‘allowed agricultural production to keep pace with world population growth,’ according to the International Fertilizer Industry Association.

Nitrogen fertilizers have many effects on the Nitrogen cycle that can lead to negative anthropogenic effects as well as environmental. There are several disruptions in the natural cycle of Nitrogen that can occur.

First of all, artificial nutrients dumped into soil can result in a loss of its capacity to hold nutrients (Lowe, pg.10). It is estimated that plants have no use for up to 50% of the chemical fertilizers placed on them.

Agricultural regions of the Southwest are composed of mainly shallow, coarse-textured and therefore highly permeable soils and aquifers. It is common for these areas to be vulnerable to nitrate contamination (Harter pg.3).

Nitrates are the most readily formed and available use of Nitrogen, and they are extremely soluble. It is easily carried through the soil with water to be taken up by plants. If the land is irrigated, there is a chance nitrate can move past the plant roots and into the groundwater or other agricultural tile drainage or surface waters (Mosier, pg.13). In major agricultural areas such as the Imperial, Central, Salinas, and other coastal valleys in California, there is groundwater nitrate contamination (Harter pg.3). When nitrate levels exceed those of the EPA’s Maximum Containment level set at 10mg/l, certain health risks occur. One of these being methemoglobinemia (infants especially are vulnerable).

In addition, when converting ammonium into nitrate, nitrite will naturally occur. Nitrite is similar to nitrate in its movement through the soil and possibility of contaminating groundwater (Reid para.7).

Ammonia volatilization also contributes to nitrogen losses.  Ammonia volatilization occurs in areas where the soil is warm, dry, and too much of a nitrogen fertilizer is applied (Buchholz). There is a concern with concentrations becoming toxic. This can happen when too many of these tiny particulates enter a confined area. Ultimately, one of the biggest concerns is reducing air quality (Reid, pg. 11).

Moreover, the effects that Ammonia and nitrate can have on biodiversity can be disastrous. Eutrophication that can lead to algal blooms and a die-off of fish species are a concern from Nitrogen fertilizer use such as ammonia emissions that can deposit on bodies of water and nitrate leached from the soil (Mosier pg.17). Ultimately, the impacts this is having can decrease fish populations resulting in less available resources for people to consume.

Lastly, the process of denitrification can transform the nitrogen fertilizer into nitrous oxide. This is a greenhouse gas, which has approximately three hundred times more impact than carbon dioxide on climate change (Lowe, pg.10). The effects of using these nitrogen fertilizers may not be shown right away as can be seen from eutrophication, but the long-term impacts may be detrimental.

If California continues with overusing and abusing its Nitrogen fertilizer use, it makes itself susceptible to the outcomes seen in China’s croplands. The soil became more acidic so that it was unproductive, and in addition to water contamination, China experienced increases in greenhouse gas emissions. All of these disastrous consequences were negligent monitoring of nitrogen fertilizers.

China’s overuse of nitrogen fertilizers has forced the government to take action against the pollution. One of their solutions is a five-year plan, which calls for a reduction in carbon intensity by implementing new domestic laws that legally require companies to meet emission reduction targets.

Although California may not have a government plan to target the nitrogen pollution, there are other ways in which farmers, themselves can become proactive in reducing the pollution. Some example solutions include securing stored manure in order to prevent runoff or enforcing livestock feed rations that are not above the necessary.

Another solution is to completely phase out chemical fertilizers and instead use organic fertilizers. According to the Third World Network’s report, “Avoiding Nitrogen fertilizer over-use is a “multiple win”: farmers save money, there is less water pollution, smaller greenhouse gas emissions, and a smaller acidification burden on soil and water.”

Image Source:

Harter, Thomas. “Agricultural Impacts on Groundwater Nitrate.” Nitrates in Groundwater. University of California, Davis, July-Aug. 2009. Web. 10 Oct. 2011. <>.


Mosier, Arvin, John K. Syers, and J. R. Freney. Agriculture and the Nitrogen Cycle: Assessing the Impacts of Fertilizer Use on Food Production and the Environment. Washington, D.C.: Island, 2004. Print.

Lowe, Marcy, and Gary Gereffi. “A Value Chain Analysis of Selected California Crops.” Center on Globalization. Duke University, 04 July 2008. Web. 10 Oct. 2011. <>.

Reid, Keith, Kevin McMcKague, and Hugh Simpson. “Environmental Impacts of Nitrogen Use in Agriculture.” Ontario Ministry of Agriculture, Food and Rural Affairs / Ministère De L’Agriculture, De L’Alimentation Et Des Affaires Rurales. Web. 10 Oct. 2011. <>.

Harter, Thomas. “Agricultural Impacts on Groundwater Nitrate.” Nitrates in Groundwater. University of California, Davis, July-Aug. 2009. Web. 10 Oct. 2011. <>.

Buchholz, Killpack. “WQ257 Nitrogen in the Environment: Ammonia Volatilization | University of Missouri Extension.” University of Missouri Extension Home. Department of Agronomy. Web. 10 Oct. 2011. <>.

About the authors: Ticia Lee and Wendy Whitcombe are working towards their bachelor degrees in the USC Environmental Studies Program.

How Do You Treat Your Water?

Filed under: Drinking Water Quality — Tags: , , — dginsbur @ 10:48 pm

As privileged students at USC, we often fail to notice how much water is used in our daily activities and around us, and we take for granted our access to it. For example, for our drinking needs, we have water fountains in every building, and water bottles are sold in vending machines and food stations on campus, allowing us to have access to water within every hundred feet. In addition, water is used in many of the aspects of USC that we could not imagine our campus without. Our lawns, trees, and plants would not be green without being watered regularly, not to mention the various fountains found on campus for aesthetic pleasure.

As Americans, we use a substantial amount of water a month, 3.9 trillion gallons to be exact (AWWA Journal, June 2006). The average American uses 176 gallons of water in one day alone. We could not imagine our lives without water being available with the simple twist of a tap. However, the rest of the world is not as fortunate as we are. In contrast to us, the average family living in Africa only uses 5 gallons of water a day, and about 1 billion people around the world do not even have access to clean drinking water. Many people in third world countries, mostly women and children, walk miles to sources of water that are unclean and will eventually make them sick. However, the problem of water scarcity seems so far away to us because water is so readily available; we expect it to be provided by the government without any thought to where it comes from or how much we are using.

It is easy to think of clean and safe sources of water as a right, because most Americans have almost always had access to it. As shown by the statistics above, we are among the lucky few who have been lucky enough to have access to clean water sources. But it is also easy to fall into the trap of expecting these resources, and treating them as a right. Access to clean and safe water sources is not a right; if it was, we would not have such a large problem of people suffering from the lack thereof even in the United States. Rather, it should be treated as a privilege, and we should instead be humbled by the continuous availability of flowing water. This is imperative to our ability to sustain our water. If everyone assumes that water is ‘there for the taking’, before long we will find ourselves without our most valued resource.

We need to realize that there could easily be a day where water does not automatically flow from the tap, and that we may begin to become an area such as African countries, where water scarcity is a serious and imminent problem. We need to respect the access we currently have to clean and safe water as a privilege and appreciate more what we are currently taking for granted.

Sources: (hyperlink ‘average family living in Africa’) (hyperlink ‘176 gallons of water’)

About the authors: Stephnie John and Neelam Savla are working towards their bachelor degrees in the USC Dornsife College of Letters, Arts and Sciences.

Federal Oversight Not Needed by the Coastal States

A big concern regarding the coastal states of western and eastern United States has been should federal oversight of beach safety be ramped up? Our belief is no. According to the Environmental Protection Agency, the United States already granted $10 million directly to states to improve monitoring technology as well as facilitate beach clean-ups where necessary. We believe the states that border the coastal oceans and the Great Lakes are responsible for keeping those areas clean and safe for recreational use by the public. Using data and modern technology to assess whether the Beach is safe is crucial to determining whether or not the beach should be shut down or not. However, this does come with a heavy financial burden. That is why measures such as the BEACH Act of 2000 and the November 8th FInal Rule, which were put into place to safeguard against FIBs (Fecal Indicator Bacteria) and other bacteria in the water, are so important.

With strict federal measures already in place, the state has the guidelines that it must follow in order to uphold quality beaches and lakes. Because the 1986 Criteria for measuring bacteria had been updated by the EPA, state legislature should follow the amendments explicitly, in order to maintain a safety standard for the public by notifying them of possible health concerns. By informing the public when the ocean water is not safe, the state avoids legal complications from sick people and also better informs the public of the risks associated with going into the ocean on a particular day. Since the new measure have been enacted, the number of beach closures has slowly decreased in correlation with the number of beaches being monitored.

This means that the measures of AB 411 and the BEACH Act of 2000 have been effectively improving the monitoring and clean up of the coastal waters and lakes. With this data, we do not support further federal oversight of the states to maintain cleaner beaches. Although it would be excellent to have cleaner and stricter policy, we believe that it is the state’s job to maintain its own beaches and property for the health and safety of its citizens. Along with the financial support the government provides to improve monitoring and to clean up of the beaches, they also give grants for beach-research and health studies to determine the impacts of harmful bacteria and microorganisms on human health. This research and data will further help the states determine which beaches to shut down or not. This will potentially help save the state millions of dollars per year because it will lead to less beach closures and more money spent by tourists.

Overall, we find that the states and local governments are doing the best they can to provide the public quality access to the recreational waters they use. For, it is in the state’s best interest to keep up and maintain a resource that it makes millions of dollars off of from tourism. With the already strict policies, regulations, and sufficient funding, the states are in an excellent position to take care of and maintain safe and clean beaches for the public to enjoy.

About the authors: Sherwood Egbert and Matt Goldberg are working towards their bachelor degrees in the USC Dornsife Environmental Studies Program.

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