April 16, 2013
Environmental Risk: Sacramento-San Joaquin Delta
Introduction
Commonly referred to as the “Bay Delta”, the 1,100 square-mile region lies on the eastern edge of the Bay Area. It gets its name from the merging of the Sacramento and San Joaquin Rivers, which originate in the northern and central mountains of California. When these freshwater rivers meet the San Francisco Bay, they form the largest, and one of the most productive estuaries on the west coast, which is home to half a million people and 300 species of wildlife.
The Problem
The Sacramento-San Joaquin delta has been modified by humans since the mid-1800s, when the Gold Rush sparked a large migration to the area. Those who were unsuccessful at mining tried their hand at farming and found that the soil in this area was rich in organic matter. These farmers built levees to drain the land and built farms that still exist today. But despite large economic gains, their actions destroyed natural habitats and have caused 29 native animal species to become threatened or endangered.
Over the past several decades, the Delta has become the hub of California’s water distribution system. It provides water to over 20 million Californians and supplies one of the largest farming regions in the world, the San Joaquin Valley. Much of the nation’s domestically grown produce comes from water that flows through the Delta, so there is a large economic incentive to divert this water to the Central Valley (Hanson). This diversion is done by pumping stations, which transport freshwater from the rivers into the state and federal water projects. It also changes flow patterns in the channels, which confuses migratory fish. Other factors such as pollution, competition, and predation from nonnative species also add to the environmental risk. It is no surprise that populations of native fish such as the Delta smelt and Chinook salmon are on the decline.
Scientists have determined that the Delta smelt is an indicator species, whose presence or lack thereof demonstrates the quality of an environment. The Delta smelt was placed on the federal endangered species list in 1993 and its population as well as others continues to decline (Healey). The protection of the Delta smelt by the Endangered Species Act has not come without controversy however, with many questioning how preservation of the species justifies reduced water diversion for those who need it.
Drastic changes in the estuary environment can also lead to the extinction of certain plants and animals. Chemical changes can contaminate the freshwater supply and leave large populations without viable drinking water. Fortunately, actions have been taken to remediate this growing problem.
Analysis
During the Gold Rush, one of the strategies used to extract gold from the river was through the use of mercury. Some of this mercury was spilled into the waterways and would eventually flow into the Delta. Other sources of pollution include agricultural runoff, where 200 million pounds of pesticides are applied to California farms every year. The EPA (2013) also reported that large oil refineries along the San Francisco Bay “release more than one million pounds of toxic chemicals”. Some of these chemicals are washed into the Delta and have gone unregulated for more than 20 years (Wren). Dredging in the estuary for water transportation also increases the turbidity of surface waters by temporarily suspending bottom sediments.
Climate change also plays a role in this problem because it will change the water inflow. Much of the water that flows into the Delta comes from the melting of the snowpack, so warmer temperatures would lead to less spring runoff (California Department of Water Resources). The lack of water coming into the Delta affects the reservoirs that release water for human use and agricultural use, spelling trouble for many Central Valley farmers.
The projected sea level of the San Francisco Bay is also expected to rise with warmer temperatures. Most of the islands in the Delta are surrounded by levees that are only 10 feet in height and constructed mainly of dirt. During storm events, the influx of water from the Bay may be strong enough to break levees and lead to widespread mixing with saltwater (Hanson). These levees can also break in the event of a major earthquake, which is already overdue in California.
Lastly, invasive species threaten the well-being of those native to the area. When a new species is introduced to an area, it will proliferate with lightning speed because there is no competition that will limit its population growth (The Green Gate). Hundreds of aggressive species have found a home in the Delta ecosystem and they are leaving little room for native plants and animals. This further worsens the problem of the endangered species and presents new challenges for the human population.
Exposure Analysis
Nutrient concentrations are significantly correlated with changes in components of the food web over time (Glibert). The ammonia (NH4+) that is discharged from sewage treatment plants affects phytoplankton assemblages. This is directly related to zooplankton, clam abundance, and ultimately the population of various fish species such as the Delta smelt. Phytoplankton constitutes much of the diet of primary consumers and this effect will be felt across the food web. The figure below depicts this correlation, where higher concentrations of ammonia lead to a decrease in the number of Delta smelts.
Changes in salinity and temperature also affects the Delta smelts because it needs suitable conditions for its young to grow. We can see from the graphs below that eggs are the most vulnerable to environmental changes due to their low tolerance of high salinity (Glibert). In a warmer world, fewer eggs will be able to survive because temperatures and salinities will be out of their comfort zones. They may not be able to adapt quickly enough to these changes and will likely face extinction. Other plant and fish species face similar threats.
There are always uncertainties when it comes to predicting how species will respond to changes in habitat quality (Healey). Models try to account for each aspect, but the amount of variables and measurements needed to produce a perfect simulation is near impossible given the large area of the Delta. Instead, researchers tend to gather small sets of data, analyze those results, and apply their findings to the whole population.
Conceptual Model
Bay Delta Conservation Plan (BDCP)
A proposed conservation plan, which would operate over the next 50 years under the Endangered Species Act, intends to both promote local species populations (including the Delta smelt) while simultaneously ensuring the availability of freshwater for decades to come. But a report released by the National Research Council in the spring of 2011 discredited much of what the plan intended, claiming “the independent scientists assembled by the NRC found that the BDCP fell well short of an objective analysis of likely impacts of the Plan,” (National Research Council).
Currently, the BDCP is working to update its plan in light of criticisms it received. A new Environmental Impact Statement has been filed, and documents concerning the project are currently up for public review, available at: baydeltaconservationplan.com
Minh Ngo and Austin Reagan
Works Cited:
Hanson, Charles. “Delta Risk Management Strategy”. Jack R. Benjamin & Associates, Inc. Department of Water Resources. 2006.
California Department of Water Resources. “Progress on Incorporating Climate Change into Management of California’s Water Resources”. July 2006.
National Research Council. “Draft Bay-Delta Conservation Plan: National Research Council Review Validates the Bay Institute’s Concerns.” May 2011.
The Green Gate. “Invasive Species”. Natrual Resources Defense Council. 2001. http://www.nrdc.org/greengate/wildlife/invasivef.asp.
Wren, Ian. “EPA Report Details Toxic Discharges from Big Industry”. San Francisco Baykeeper. 29 Jan 2013. http://baykeeper.org/blog/epa-report-details-toxic-discharges-big-industry.
Healey, M.C. et al., “Conceptual Models and Adaptive Management in Ecological Restoration: The CALFED Bay-Delta Environmental Restoration Program”.
Glibert, Patricia. “Long-term changes in nutrient loading and stoichiometry and their relationships with changes in the food web and dominant pelagic fish species in the San Francisco estuary, California”. Fisheries Science Vol. 18, Iss. 2, (2010).
March 19, 2012
Protective Pesky Pesticides
Insecticides, Biocides, Algicides, Herbicides, Rodenticides–what do all of these have in common? These terms are all part of a larger group of 34,000 pesticides, defined as “a substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.” Pesticide use in both 2006 and 2007 amounted to an estimated 5.2 billion pounds worldwide, with 1.1 billion in the United States alone. However, the use of pesticides is quite controversial and is debated from all ends of the spectrum, including health advocates, environmentalists, politicians, consumers, and the agricultural industry. It comes as no surprise that most of these pesticides are toxic–after all, that is the purpose for which they were created. The following article outlines the pros and cons to pesticide use in hopes of determining whether the risk of using pesticides is worth the benefit.
The benefits of pesticide use are extensive and provide a strong basis for pesticide advocates. First, pesticides provide the United States with huge economic profit–the industry made $12.5 billion dollars in 2007, exporting 40% of domestically created pesticides (US EPA). In addition, pesticides have saved millions of lives, eradicating many disease-carrying insects. Pesticides have also helped the forestry ecosystems by helping trees to resist disease-carrying insects like the gypsy moth. However, the largest benefit of pesticides has to do with increased agricultural yield. Worldwide, “90% of the damage sustained by crops is caused by less than 100 species of weeds, insects, fungi and microbes – all considered pests” (Food Safety Factoidz). With the use of pesticides, crop productivity increases by 20 – 50%, thereby making it possible for consumers to choose from an “abundant supply of fresh, high-quality foods that are affordable and accessible year-round” (Crop Life America). Millions of products rely on agricultural products, and without the proper use of protection, a domino-effect of damage and deficiency could lead to serious losses.
Pesticide use also has its cons that affect crops, pests, and humans all around the world. For one, although pesticides are effective in killing or repelling pests, that effect lasts very shortly as many pest species develop resistance to pesticides rapidly, and the number of resistant species has increased since pesticides were first used in the 1950s. Pesticides are also nonspecific, meaning they affect pests and non-pests wherever they are spread. Also, pesticides are mostly sprayed aerially over a field of crops and only 5% of the pesticides reach their target while the other 95% spreads out to the environment: “the air we breathe, the water we drink, and the food we eat” (“Pros and Cons,” Factoidz). Because of the increased use in pesticides, ground water sources have been contaminated, and have also caused farmers to abandon the use of crop rotations which, in turn, has increased pesticide dependence.Lastly, pesticides have caused the acute poisoning and death of millions of people worldwide, according to the World Health Organization.
Clearly, the use of pesticides have posed a risk on humans and the environment. They have prevented the worldwide spread of disease which, many proponents argue, have saved many lives. The mass production and mass use of pesticides, however, has also threatened the environment with contamination and has threatened human, plant, and animal health through poisoning. The risk has not gone unnoticed and people are aware now that pesticide use must be reduced to minimize risk. One way proposed to reduce pesticide use is through integrated pest management (IPM) which involves mainly cultural, biological, and chemical methods and techniques collectively in farming to control pests. Exposure to pesticides must also be reduced and there are several “how-to methods” people can follow at home to minimize exposure after purchasing organic produce. Pesticides have largely remained a risk but the efforts to reduce their use and better management should be considered in order to minimize their risk to the environment.
Additional Sources:
http://food-safety.factoidz.com/the-pros-and-cons-of-using-pesticides-for-food-production/
http://www.epa.gov/opp00001/pestsales/07pestsales/sales2007.htm#2_1
http://www.epa.gov/opp00001/pestsales/07pestsales/usage2007.htm#3_1
http://www.who.int/bulletin/volumes/86/3/07-041814/en/
http://www2.mcdaniel.edu/Biology/eh01/pesticides/alternatives.html
Sergio Avelar and Caroline Smith are undergraduates in the USC Dana and David Dornsife College of Letters, Arts and Sciences.
CAFOs: Contaminants, Animals, Feces, Odor
Some critics would argue that feedlots are required by society in order to keep up with the growing population and increasing demand for food. Even though this statement is debatable, the real question is whether or not feedlots are worth the environmental risk? Specifically, Concentrated Animal Feeding Operations or CAFOs pose an extremely high risk to the environment with their impact on air, water, and land quality.
Water quality is heavily affected by the discharge and waste that comes from thousands of animals confined on a small farm. Often, companies deal with manure and urine from livestock by channeling it into a lagoon or cesspool. The risk of a tear, leak, or break is highly probable at feedlots. Pollution in the form of nitrates, microbes, pathogens, pharmaceuticals, and many more are flooded into nearby water systems and threaten human health, not only the environment. High levels of nitrates, for instance, can increase spontaneous abortions and increase the risk of blue baby syndrome—a disease that causes infant deaths. Antibiotics are heavily used in CAFOs and when those enter our drinking water, it makes it more difficult for us to effectively combat bacteria that progressively become more genetically resistant. The risks of CAFOs are high as not only water is threatened, but the overall environment’s health is compromised.
Contrary to what one might expect, air quality is also at risk due to the broad impact CAFOs have on the environment. Specifically, many hazardous gases are emitted from CAFOs as biological material biodegrades. Methane, ammonia, and hydrogen sulfide are just a few of the gases that pollute the air. Also, cow burps and flatulence produces about one-quarter of the methane released in the USA each year, further contributing to the contamination of our atmosphere. If there is any hope in reducing the risk associated with CAFOs in order to make them a more viable option for livestock farming, society must address the growing air quality issue associated with them.
Any land used by CAFOs immediately faces threats to its quality. Manure is one of the biggest threats to soil quality, and the process of over-fertilization of land causes nitrogen and phosphorus levels within soil to become imbalanced. With these imbalances, the threat of leaching or runoff into groundwater greatly increases. This runoff contains bacteria found in manure but also contains the chemicals and substances given to livestock. In fact, most feedlot runoff is high in salinity and can leave behind salt deposits, which causes farmers to use even more water which is then exposed livestock waste. CAFOs pose an interconnected problem amongst land, water, and air resources which makes the issue difficult to deal with.
After looking at all of the evidence surrounding CAFOs and their operation, one must answer the question posed at the beginning of this post: are feedlots worth the environmental risk? After characterizing and assessing this issue, CAFOs are too hazardous to the environment; consequently, other farming alternatives and actions must be pursued. One solution is through public awareness and participation, where consumers purchase meat that has been produced exclusively by farms practicing sustainable farming. Other solutions are alternative farming practices and new technology. Specifically, the government should promote pollution reducing efforts by farmers and further regulate dangerous practices that can impact the environment. If society and the government both advocate for change, the environmental impact of CAFOs can be greatly reduced. If this were to occur, the environment would not only benefit but humans would as well.
Connor Schroeder and Albert Perez are undergraduates in the USC Dana and David Dornsife College of Letters, Arts and Sciences.
No Prescription: The Dangers of Pharmaceutical Contaminants
Beginning in earnest with the Clean Water Act of 1972, water quality and pollutant regulation have been of relatively prominent concern in the realm of environmental issues. Some major sources of water pollution — such as runoff from urban, industrial, and agricultural areas, and large oil spills— are extremely visible and have garnered much attention. As of late, however, scientists are realizing that that the Environmental Protection Agency’s regulations are inadequate, as they do not require water testing for at least one type of harmful contaminants: pharmaceuticals. According to a recent investigation by the Associated Press, pharmaceuticals can be found in the drinking water of approximately 41 million Americans. Pharmaceutical contaminants come from both human and animal sources: most medications people ingest are broken down in the body, but the subsequent waste products and excess chemicals that the body does not metabolize are passed through urine. Hormones and antibiotics seem to be the most prevalent and most concerning at the moment, but as with other emerging contaminants, hardly anything is known about the long-term health and ecological impacts of prolonged exposure to these drugs. While some scientists say that trace levels of pharmaceuticals are too small to have any impact on the environment, there are already several examples of these toxins affecting organisms. Before any judgment is made on the severity of the issue, there needs to be more research more regulations on pharmaceutical dumping and water testing.
Pharmaceuticals were first discovered in drinking water in Europe about 10 years ago, when scientists detected levels of clofibric acid in groundwater near a German water treatment plant. Soon after this suspicious detection of this cholesterol-lowering drug in groundwater, scientists across Europe tested groundwater near drinking sources and wastewater treatment facilities, finding chemotherapy drugs, hormones, antibiotics, analgesics, and various other prescription drugs. Steroids and other hormones given to livestock are also a huge concern, as left-over chemicals are eliminated from animals in the same manner as humans: in fact, a recent study conducted by the U.S. Geologic Survey found that “steroids, nonprescription drugs, and insect repellent were the chemical groups most frequently detected” in water supplies tested. Unfortunately, sewage treatment plants are not equipped to remove these chemicals, as they are not classified as dangerous contaminants by the EPA’s water quality regulations.
However, their effects are clearly a cause for concern. One study found that a group of male fish downstream from a feedlot had significantly lower levels of testosterone and were smaller than normal because of their exposure to steroids from the feedlot’s runoff. In another instance, scientists determined that small amounts of antidepressants that made their way into water caused some kinds of freshwater mussels to prematurely release their larvae—not necessarily detrimental to the mussels themselves, but greatly lowering the survival chances of future generations. But harm to aquatic organisms are not the only potential problem. If antibiotics are released into water sources, even in small doses, there is a possibility that pathogens in the water will be able to develop drug-resistant strains. Furthermore, there is the threat that pharmaceutical-contaminated water is being pumped into aquifers as part of artificial groundwater recharge, where chemicals can persist for years. And the problem is worldwide: in countries like India with less wastewater treatment infrastructure, huge amounts of pharmaceuticals are being dumped directly into rivers by chemical production plants.
While the concentration levels of pharmaceuticals are arguably low, the concrete examples of the direct negative impacts that pharmaceutical concentrations as low as one part per billion can have is a call to update regulations and drug disposal practices. As an emerging contaminant with a wide variety of sources, it’s difficult to pinpoint who is responsible for pharmaceutical reduction. A solution will have to start with regulations on wastewater treatment, especially in areas near animal feedlots and large cities, as well as education for the public about reducing pharmaceutical contamination at the source through proper disposal and use of medicine. There has been some evidence that the chlorine used to treat drinking water can react with pharmaceuticals to actually make them more toxic. Several methods of water treatment are being tested for pharmaceutical removal, including reverse osmosis and ozone and UV treatments. Some states are already taking matters into their own hands by passing legislature that requires the proper disposal of pharmaceuticals from sources like hospitals.
Though there may not be a convenient solution and though it will require advanced technology to test and identify sources and treatments, increasing our knowledge of pharmaceuticals as contaminants will be vital in protecting both ourselves and the environment from long-term and irreversible consequences. In order to characterize and solve the problem, we must first be able to understand the environmental risk pharmaceuticals pose.
Sources:
http://toxics.usgs.gov/pubs/FS-027-02/
http://ag.arizona.edu/azwater/awr/july00/feature1.htm
http://www.wcponline.com/column.cfm?T=T&ID=2199
http://www.naturalnews.com/029314_waterways_contamination.html
http://www.msnbc.msn.com/id/23504633/#.T1mTQGCZO_Y
http://www.usatoday.com/news/nation/2008-03-10-drugs-tap-water_N.htm
http://www.enn.com/pollution/article/38022
Britanny Cheng and Kali Staniec are undergraduates in the USC Dana and David Dornsife College of Letters, Arts and Sciences.
DDT: A Silent Killer
In the 1960’s Rachel Carson’s book Silent Spring began to expose the issue of DDT and the possible health threats it had on plants, organisms and humans. As pesticide and herbicide use became popular as a way of creating more productive agricultural land, the widespread use was not only destroying the insects and weeds, but the entire environment was targeted with these strong chemicals. Although we have limited our use of DDT today, it is a chemical that does not naturally deteriorate. It stays in groundwater and the soil and continues to harm plants, animals, and humans. Contrary to popular belief, the weeds and insects that we try to eliminate by using DDT can actually benefit the environment. Certain weeds prevent bad insects from destroying plants or crops and insects such as ants aerate the ground with their tunneling as well as eating other harmful bugs. By using DDT we are not only destroying natural solutions to our problems, but also innocent organisms who cannot escape the treatment. Birds may not be in the area when crops are sprayed with chemicals, but they eat the worms that are in the soil. These worms are contaminated and therefore poison the birds. Some may die, while others may become infertile or their eggs cannot hatch. Just like bird populations, fish populations have decreased because of DDT spraying and the runoff from DDT treated agricultural lands that seeps into streams and rivers close by, therefore poisoning the fish and killing them.
For many years, we thought our actions of using DDT were not significantly affecting the environment. Instead, it turned out that we were not only harming the environment but also humans. But because we live off of the land and the crops that are sprayed by DDT, the poison bio-accumulates in the crops we eat from fields sprayed by pesticides and herbicides. Aerial spraying was also a detrimental practice, which harmed many animals and poisoned humans without their knowledge. Because of our lack of knowledge of the dangers of DDT, to this day most people have DDT in their body. Some people still contain DDT because it is stored in fat and as we metabolize that fat, we release the poison into our body, which can cause severe neurological and liver problems.
This controversial use of DDT has triggered a debate over whether or not using pesticides and herbicides is beneficial enough to continue the practice. The variety of harmful effects that DDT has on not only the environment, but also on humans, is reason enough to limit or even eliminate our use of DDT. DDT poses a risk based on how it negatively affects the survival of various organisms. For example, multiple studies have determined that the bioaccumulation of DDT has compromised the ability of birds to create healthy eggs. Some cows are producing milk that has traces of DDT, and all organisms, including humans, that are exposed to the poisons inevitably pass it on to their offspring.
The scientific risk of DDT is assessed by determining the health threats towards organisms and humans and how severe these threats are to their survival. Even though DDT was used in low concentrations around humans, the contaminant had adverse effects because of its poisonous properties. Based on the number of organisms and people affected negatively by DDT, the risk of using it is not worth the very few benefits associated with it. When studying the acceptable exposure levels, lab tests are not accurate enough to prove that DDT is safe for use because a very specific amount is used in highly artificial conditions which does not accurately replicate a real life exposure situation. Different demographics of people also deal with different levels of exposure and those effects. The concentration of DDT increases as it moves down the food chain, therefore we cannot be too sure of the exact exposure to humans.
After years of debate and scientific research, the widespread use of DDT is not worth the risk towards humans and the environment. The pesticides and herbicides do not benefit the land as much as they harm the land. Even though the actual damage due to DDT came before the risk assessment, it has allowed us to be aware of the dangerous effects and to greatly limit our DDT use.
Sources:
http://articles.latimes.com/2009/jun/12/local/me-palos-verdes-pollution12
http://www.chem.duke.edu/~jds/cruise_chem/pest/pest1.html
http://www.epa.gov/pesticides/factsheets/chemicals/ddt-brief-history-status.htm
http://www.malaria.org/attarannaturemed.html
http://www.usatoday.com/news/opinion/letters/2010-05-03-letters03_ST1_N.htm
Alanna Waldman and Chantal Morgan are undergraduates in the USC Dana and David Dornsife College of Letters, Arts and Sciences.