Beautiful Vieques

What is phytoremediation?

What is phytoremediation?

Phytoremediation is removing polluting contaminants from soil and water with plants. 

How does that work? 

The same way that plants absorb water and minerals from the soil through their roots, they can also absorb pollutants into their plant tissues.

Well GREAT!  Now we have contaminated plants!  What does that accomplish?

Depending on the pollutant, the metabolic reactions of the plants can break some of these contaminants down and make them non-toxic.  Some of the contaminants such as heavy metals can't be broken down further.  But storing the heavy metals in the plants concentrates them into a much smaller area compared to when these contaminants are spread throughout the environment in the soil and water.  Concentrating the contaminants makes them much easier to manage and/or destroy.  Sometimes the metals can be extracted from the plant material and reused; this process is called phytomining.

Map of Vieques

Sailing off the coast of Vieques, Puerto Rico

Vieques and Positive Local Solutions

Hello All ~  My name is Kristine and I currently live in a suburb of Detroit, Michigan where I grew up, I lived in South Florida for 15 years in the 80's and 90's where I earned my degree in Botany, got married, had my daughter, and worked on the beach for 5 years monitoring nesting sea turtles.  I love the tropics and the ocean and miss them terribly, although I love being near my siblings and currently have a great job in Michigan. 

I went to Vieques on vacation in November 2010 and fell in love with the place. It was the tropics and was everything South Florida wasn't - charming, undeveloped with beautiful beaches and reefs.  The people in Isabel Segundo were friendly and horses roamed the island freely for the best reasons of all - for the best overall health of the horses and the island - imagine that!  An island that was charming and progressive at the same time!  When I went sailing on a small charter boat I learned quite a bit about Vieques past and their experiences with the Navy Bombing Test Range from the owner and captain of the sailboat.  When I took a couple of graduate classes this past Winter/Spring semester, I decided to investigate further and wrote the two papers I will post below about the potential for phytoremediation solutions on the island ov Vieques.  I also intend to reach out to the Viequenses with this blog and try to get their opinions about using phytoremediation to fully restore the areas that have problems that were left behind.  The following paper is somewhat dry, but it is brief and outlines some of the issues.

CONTAMINATION ON VIEQUES ISLAND, PUERTO RICO

AND

POTENTIAL PHYTOREMEDIATION RESOLUTIONS

Kristine Hahn

Global Field Master’s Program

Miami University

Biology in the Age of Technology

Spring 2012

Abstract

            The Puerto Rican island of Vieques has complex contamination problems after serving as a bomb testing range for the US Navy for sixty years.  The native Vieques islanders complained of higher than normal rates of cancer, and inadequate clean-up by the US Navy.  Analyses performed by different contractors hired by US Federal Agencies failed to produce a conclusive path of exposure or risk to human health.  Moreover, the costs of remediating contamination on a small island are astronomical, while federal funding is very limited.

            This paper explores the potential of using propagated plant material from plants native to the bomb testing areas on Vieques to remove or contain the contamination by different methods of phytoremediation.  The potential advantages and disadvantages for the phytoremediation as a possible solution to the contamination on Vieques are explored.      

Introduction

           Vieques is a small tropical island located seven miles off the northeast coast of Puerto Rico in the eastern Caribbean.  I visited the island for a vacation in November 2010 and fell in love with the place.  Vieques is primarily undeveloped and was like going back in time, as there were no chain restaurants, there was still a charming town square in the village of Isabel Segundo where the natives gathered in the evening, and horses freely roamed the island.  Amazingly, the horses were allowed to roam because it was in the best interests of both the horses and the island.  Eating the fresh green tips of the grass provided the best nutrition for the horses.  Only eating the tips kept the grass healthy as well and prevented erosion, thus protecting the near shore reefs.  I thought it was the best version of paradise – undeveloped and progressive at the same time!  Near the end of my vacation I went sailing on a small charter sailboat.  In between snorkeling some of the most beautiful reefs I had seen since the 1980’s, I spoke with the owner of the sailboat who lived on Vieques, and he told me of a different side of the island.  This conversation prompted me to investigate deeper into the situation on Vieques, and to research potential solutions to some very complex contamination issues.

The US Navy acquired a large portion of the east end of the island in the early 1940s, and divided the east end of the island into two areas.  The very eastern end of the island was called the Atlantic Fleet Weapons Training Facility (AFWTF) and included the Live Impact Area (LIA) where live bomb target practice was held.  More towards the central portion of the island was the Eastern Maneuver Area that included public works facilities and weapons storage.  Approximately 8,000 acres on the western end of Vieques was also acquired by the US Navy and was used for weapons storage, disposal and ground training maneuvers. 

           The native residents of Vieques lived in the central portion of the island, mainly in the small towns of Esperanza and Isabel Segundo. 

           In 2001, the US Navy transferred 8,000 acres in western Vieques to the municipality of Vieques, the Puerto Rican Conservation Trust and the US Department of the Interior.  While the western end of the US Navy property did not have live bomb testing, they did have storage and disposal of munitions in that sector.  In 2002 the National Defense Authorization Act (P.L 107-107) prohibited public access to the Live Impact Area at the very eastern tip of the island “for the public health and safety due to the presence of munitions hazards” (Bearden 2005). 

After many years of exposure to airborne explosive elements, Viequenses (the native islanders) claim to have a higher rate of cancer than Puerto Ricans on the main island (Baver 2006).  In recognition of the public and environmental health and safety concerns, the Agency for Toxic Substances andDisease Registry (ATSDR) of the US Department of Health and Human Services (HHS) had four different public health assessments (PHAs) conducted by at least two different contractors between 2001 and 2003. To investigate possible exposure to chemicals emanating from exploded and unexploded ordnance, each PHA assessed a specific exposure pathway: seafood (e.g., fish, shellfish, and land crabs), drinking water, air, and soil (US Dept. of Health and Human Services 2011).

Soil, sediment, near shore and wildlife sampling of the Live Impact Area (LIA) on eastern Vieques showed levels of bomb constituents including HMX (high melting explosive), TNT (tri-nitro toluene), DNT (2, 4/2, 6-di-nitro toluene) and 1, 3, 5-trinitro benzene (US Dept. of Health & Human Services 2011).  All of these bomb constituents except HMX are known or suspected carcinogens and are substances that can leach into soils and groundwater.  But with one exception, a human exposure pathway could not be identified.  The one exception was a local well that was contaminated.  But the public drinking water has been piped over from the Puerto Rico mainland since 1977, so ATSDR concluded that there was no risk of human exposure to the contamination.  ATSDR bases its actions on the risk of human exposure to contamination.   

In April 2003, the US Navy transferred 14,669 acres of its eastern Vieques holdings to the US Department of the Interior to be managed as a Wildlife Refuge.  This transfer had the requirement that the 900 acres of the Live Impact Area of the former bombing range be managed as a Wilderness Area, which meant no public access.

After six decades of live bomb practice and many years of protest from the Viequenses, the US Navy stopped all their activities and vacated the island on May 1, 2003 (US EPA).  Left behind were the bombed out areas devoid of any vegetation, sites of exploded and unexploded ordnance, along with areas contaminated with bomb-related materials and heavy metals.

Post US Navy Evacuation

            As the western end of Vieques did not experience any live bombing, it was vegetated and appeared normal.  Contamination was suspected due to the storage and disposal of munitions activities in these areas.  The Navy identified 17 sites of contamination in their former property in western Vieques in 2004.  Clean-up activities such as surface removal of munitions and open burn/open detonation by the Navy spurred protests by the Viequenses.  They complained of additional exposure to potential carcinogens of the explosives by the open burn / open detonation activities. 

            Due to political pressure and the confirmation of contamination, the Environmental Protection Agency listed Vieques on the National Priorities List of the nation’s most hazardous waste sites in 2005.  This identified Vieques as a Superfund site that needed more investigation and safeguards to human and environmental health and safety.  The measure may require federal oversight.  While this designation seemed to indicate some urgency for clean-up activities by the Navy, the actions required depend on federal funding (Bearden 2005).  And while the Navy is liable for clean-up in the western Vieques properties, it is not liable for any clean-up activities in eastern Vieques including the Live Impact Area because that land was donated the US Fish & Wildlife Service to be part of a Fish & Wildlife Refuge.  Eastern Vieques is probably the most severely contaminated due to the bomb testing and live fire training activities held there for close to sixty years.  Additionally, eastern Vieques will also be the most difficult to clean up due to its large size.

            In 2005 the Navy estimated that the clean-up of both eastern and western Vieques would be a total of $112.6 million.  This estimate appears low compared to the cost of clean-up of a similar former bomb testing range in Hawaii called Kaho’olawe Island.  In the case of Kaho’olawe Island, the land transfer memorandum of understanding with the State of Hawaii required that 100% of the munitions be cleared from all land and that 25% of the land be clean enough for human residential development.  The total cost of the Kaho’olawe Island clean-up was $400 million.  Unfortunately, the Vieques land transfer does not have any requirements for the level of clean-up to be reached by the Navy (Bearden 2005).

            The ATSDR contracted CH2MHILL in 2006 to develop local background levels of the heavy metals arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, mercury, nickel, vanadium and zinc to compare to the levels of the same heavy metals found in soil samples from the Live Impact Area (LIA) that were collected and analyzed in 2000.  The levels of arsenic, chromium, cobalt, lead, vanadium and zinc from the 2000 LIA soil samples were between 1.7 and 5.6 times higher than the background levels.  But, again, because these samples were located in the LIA where the public was not allowed, ATSDR concluded that there was no risk of human exposure to these high levels of heavy metals, and, therefore, no risk to human health (US Dept. of Health & Human Services 2011).  Many questioned the validity of ATSDR’s conclusions from this data, including Dr. John Wargo, Associate Professor of Forestry and Environmental Studies at Yale.  Dr. Wargo published a list of problems with ATSDR’s 2006 study.  One of his major objections was why ATSDR didn’t conduct any tests of its own?  Why did it use former studies of the Puerto Rican Department of Health, US EPA, USGS and the consulting firms hired by the Navy, since none of these studies had been peer reviewed and remain unpublished (Davis 2007)?

Furthermore, if ATSDR knew there was no risk of exposure to the soil samples in the LIA, then why did they develop the background levels of the metals for comparison?  Moreover, why compare soil sample data that was 6 years apart?  ATSDR recognizes many gaps in their sampling and testing procedures, such as “lack of surface soil data is a major limitation for assessing soil exposure in the islands’ residential areas” and that it cannot address the cumulative or mixture effects of the different exposure levels of the munitions materials (US Dept. of Health & Human Services 2011).  Additional testing by NOAA in 2007 found high levels of heavy metals in sediment and coral samples from the near shore and lagoon water near the LIA.  The Puerto Rican Department of Health randomly sampled 500 Viequenses since 1999 and found that 20% of the participants either had aluminum, lead or mercury in their blood, uranium, cadmium or nickel in their urine or nickel or arsenic in their hair that exceeded the laboratory’s reference range.  Again, ATSDR conceded that these levels could not be explained by cigarette use or hair dyes (US Dept. of Health & Human Services 2011).  Again, when ATSDR reviewed all this data together, they concluded in their 2011 report that there was no exposure at levels that would harm human health.

            Another study that conflicted with ATSDR’s testing was a study by staff at the University of Mayaguez Puerto Rico where they analyzed aquatic and land plants from eastern Vieques near the LIA for heavy metals content and compared them with the same plant species from the Guanica Biosphere Reserve located on the southern shore of Puerto Rico.  Both areas were in the same geo-climatic zone with the plants subject to similar conditions, and therefore naturally comparable (Massol- Deya 2005).  The plant species compared were Calotropis procera, Panicum maximum, Ipomoea violacea, Acacia farnesiana, Sporobolus virginiana, Sporobolus pyramidatus and Syringodium filiforme. These plants are representative of common grasses, flowers, a small tree and a seagrass. The sampling and analysis were performed under standardized protocol of Montgomery et al. (1977) and Thompson (1969).  The results showed that the average lead in the plants from eastern Vieques were significantly higher than the Guanica Forest samples.  Additionally there were higher concentrations of mercury, lead and cadmium. Samples of the seagrass Syringodium filiforme collected in 2001 from eastern Vieques had significantly higher concentrations of lead, copper, nickel and cobalt (Massol-Deya 2005). Typically, the pH of the ocean (8.0 + 0.5) limits the solubility of many heavy metals and therefore limits their uptake by plants.  However, the ATWTF discharge monitoring reports from 1984-1999 reported discharges into the nearshore waters with concentrations of lead up to 5 mg/L with fluctuations in pH.  These discharges could have increased the bioavailability of the metals to allow the uptake of them by the seagrasses.  After the Navy left in 2003, there were no more lead discharges.  Syringodium filiforme samples from 2004 showed lower concentrations of the heavy metals compared to the 2001 samples.  However, the 2004 seagrass samples still had significantly higher concentrations of heavy metals than the plant samples from Guanica.

            While there has been confirmation of the contamination on Vieques, the Navy is not required to any specific level of remediation, nor are they allocating sufficient funds for an adequate clean up. And, regardless of how many times the ATSDR reviews the data; they cannot identify a path of exposure that puts human health at risk.  Furthermore, the Superfund status does not determine the clean-up status of Vieques – only the future land use, the expected risks to human health and the available federal funds affect the clean-up activities (Baver 2006).         

The 2000 census shows that 73% of Viequenses live in poverty as compared to 59% of all Puerto Ricans (US Dept. of Health & Human Services 2011).  The Navy presence and the bomb testing limited the development pressures on Vieques, making it appear uniquely unexploited with the largest Wildlife Refuge in the Caribbean.  One of the best hopes for an improved economy for Viequenses is to sustainably develop their tourism industry.  However, more tourists will lead to an increase in population, along with the need for a more sustainable source of water, especially in light of the recent cycle of increasing hurricanes that could damage the pipeline for drinking water from the mainland. The inability of Viequenses to access their groundwater supply due to the contamination could hinder their economic development (Baver 2006).

Moving Forward  

            Phytoremediation has enormous potential to remediate the explosive and heavy metal contamination on Vieques.  Phytoremediation involves installing specific plants into contaminated areas.  These plants are able to tolerate the contaminants well enough to grow and uptake or absorb the contaminants through their roots and accumulate them in their tissues.  There have been dozens of demonstration and field projects listed on the Department of Defense (DoD) environmental research program webpage ( http://serdp-estcp.org/) that have successfully remediated former bombing ranges with bioremediation and phytoremediation schemes that were practical and affordable.  Tropical areas such as Vieques are good candidates for phytoremediation as the year round growing leads to quick development of the plants and they are able to start uptaking and accumulating contaminants quicker than vegetation in areas that have a winter or a dormant period. 

Phytoremediation has many advantages in the Vieques contamination issues.  Conventional methods of remediation also contribute to environmental degradation and are prohibitively expensive, especially when a large area of land or water is involved (Rajakaruna 2006).  Using fast growing, deep-rooted plant species with high biomass for phytoremediation can also reduce exposure of humans and wildlife to contaminants, and make an environmentally degraded area more attractive.  The aesthetic factor alone reduces the psychological stress the residents feel when a loud, disruptive, traditional remediation project with lots of heavy equipment is taking place.  A phytoremediation project would be much more agreeable in a Wildlife Refuge setting. 

In some instances phytoremediation is more effective than conventional remediation methods. The ground water at many Department of Defense facilities is contaminated with explosives such as TNT and RDX.  These contaminants can persist for long periods in the groundwater and conventional pump and treat methods are not able to completely restore them.  Phytoremediation combined with bioremediation (bacterial degradation) was effective at removing greater than 90% of the RDX from the soil pore water (Babcock 2007).  And the biological processes of the plants and microbes actually degrade explosives and reduce their toxicity.

Additionally the issue of where to dispose of the contaminated soil and sediments on a small island makes conventional remediation methods not practical.  Shipping the waste off the island would be cost prohibitive.  And many question what is solved when soil or sediment is dug up from one area and then stored in a solid waste facility.

Heavy metals do not degrade and are persistent in the environment.  However with phytoremediation, there is the option to recover those metals from the plants with different techniques that usually involve burning of the plant material.  These recovery processes are called phytomining and can help recover some of the costs of remediation (Rajakaruna 2007).

  There are many plants that have been identified and demonstrated their effectiveness at uptaking the same contaminants present on Vieques.  Water hyacinth grows very fast in tropical aquatic environments and was shown to be a good accumulator of most metals in its roots in a constructed wetland in Taiwan (Liao 2004). Aquatic macrophytes such as Eichornia crassipes and Lemna minor were able to significantly decrease the metals concentration at a heavily contaminated sited in Belwadah.  The decrease of the metals was in the range of 25- 67.90% (Rai 2009).  Other fast growing, high biomass species that accumulate metals and can be used in both wetland and upland environments include Salix species also known as willows (Harada 2011) and Typha species commonly known as cattails (Lyubenova 2012). There are also tropical ornamental plants such as Canna generalis, Nerium oleander and Pelargonium species that have all demonstrated the capacity to uptake lead, cadmium and nickel. However, Rajakaruna recommends that it is advisable to use native species that grow near the site.  Contrary to a recent paradigm, inoculating plant roots with specific microbes or even genetic modification has not been more effective in the field than wild plant types with respect to phytoremediation ( Makris 2010).

The best option for phytoremediation on Vieques may be to use the plant species from eastern Vieques that were used in the 2005 study “Trace elements analysis in forage samples from a US Navy bombing range (Vieques, PR)”.  These plant species were practically bred to tolerate and uptake toxic munitions elements after growing and producing seed during 60 years of exposure to bombing. Moreover, the symbiotic functions of the plants with the indigenous microbes have proven to play an important role in the phytoremediation processes (Makris 2010).  Plants that occur naturally on the island are more likely to be adapted to the native microbes.

Propagation of these eastern Vieques plants could be very useful in a phytoremediation scheme for a number of reasons.  First, they occur naturally on the island, so they are well adapted to the native climate and soils.   Also, these plants would blend in with the rest of the island vegetation, so they would not look out of place, nor would there be a high risk of them becoming invasive.  These plants have exhibited the ability to grow well in soils and/or sediments that have high metal concentrations.  Additionally, they are able to solubize the metals at the roots so that they can uptake and hyperaccumulate these metals into their tissues.  Moreover, the long-term exposure to explosives and heavy metals has probably developed the physiological traits at the cellular level necessary for plants to be successful in phytoremediation, such as enhanced uptake by metal transporters in the plant cell’s plasma membranes and the detoxification of metals by chelating them with metal binding proteins or sequestration of the metals into their vacuoles (Yang 2005). Other traits of these plants make them well suited for phytoremediation.  For example, the grasses Panicum maximum, Sporobolus virginiana and Sporobolus pyramidatus have long roots that enhance their ability to reach contaminants located deeper in the soil or in groundwater.  These grasses can grow quickly and produce a lot of biomass to accumulate and store contaminants (Rajakaruna 2006).  The tree Acacia farnesiana also has a large amount of biomass for contaminant storage.  The morning glory vine Ipomoea violacea grows very rapidly and is ornamental as well.

The local phytoremediation solution seems to offer the best hope for Vieques.  These options will be publicized through a web-mediated blog and I will attempt to get feedback on these issues.  In the circumstances, I feel that it is the least we can do for a small island that has sacrificed so much.  It would be a great accomplishment to help restore a paradise lost by putting plants in the ground.

REFERENCES

Babcock Jr, R., S. Trunbull, and S. Schenk. (2007). Bioremediation and Phytoremediation of RDX and HMX in Tropical Soils. Poster presented at the Strategic Environmental Research and Development Program Partners in Environmental Technology Technical Symposium and Workshop, Washington, DC (December 4-6, 2007). Retrieved from: http://www.symposiumarchive.serdp-estcp.org/symposium2008/posters/upload/w163%20-%20babcock.pdf

Baver, S. (2006) Environmental Justice and the clean-up of Vieques.  Centro Journal, Spring XVIII (001), 90-107.  Retrieved from: http://redalyc.uaemex.mx/pdf/377/37718106.pdf

Bearden, D., (Updated 2005) Vieques and Culebra Islands: Analysis of clean-up status and costs.  Congressional Research Service Reports on General National Security Topics for Congress.  Order Code RL32533.   Retreived from:  www.fas.org/sgp/crs/nats

Bert V, Seuntjens P, Dejonghe W, Lacherez S, Thuy HT, Vandecasteele B. (2009). Phytoremediation as a management option for contaminated sediments in tidal marshes, flood control areas and dredged sediment landfill sites. Environ Science Pollution Research International (7)745-64. Retrieved from: http://www.ncbi.nlm.nih.gov/pubmed/19533193

Carrea-Torres, S. N., Pacheco-Londono, L. C., Espinosa-Fuentes, E. A., Rodriguez, L., Souto-Bachiller, F. A., Hernandez-Rivera, S. P. 2012. TNT removal from culture media by three commonly available wild plants growing in the Caribbean. Journal of Environmental Monitoring, 14, 30-33. DOI: 10.1039/C1EM10602C

Davis, J.S., Hayes-Conroy, J. S., Jones, V. M. (2007). Military pollution and natural purity; Seeing nature and knowing contamination in Vieques, PR. GeoJournal, 69, 165-179.  DOI:  10.1007/s10708-007-9095-7

Harada, E., Hokura, A., Nakai, I., Terada, Y., Baba, K., Yazaki, K., …Mizuno, T.(2011).   Assessment of willow (Salix sp.) as a woody heavy metal accumulator: field survey and in vivo X-ray analyses. Metallomics, 3, 1340-1346. DOI: 10.1039/C1MT00102G.

Liao, S., Chang, W. (2004). Heavy metal phytoremediation by water hyacinth at constructed wetlands in Taiwan. Journal of Aquatic Plant Management, 42, 60-68.  Retrieved from: http://www.apms.org/japm/vol42/v42p60.pdf

Lyubenova L., Pongrac, P., Vogel-Mikuš, K., Mezek, G.K., Vavpetič, G., Grlj, N., … Schröder, P. (2012) Localization and quantification of Pb and nutrients in Typha latifolia by micro-PIXE. Metallomics. DOI: 10.1039/C2MT00179A.

Makris, K. C., Sarkar, D., Datta, R. 2010. Coupling indigenous biostimulation and phytoremediation for the restoration of 2,4,6-trinitrotoluene contaminated sites. Journal of Environmental Monitoring, 12, 399-403. DOI:  10.1039/B908162C

Massol-Deya, A., Perez, D., Perez, E., Berrios, M., Diaz, E. (2005) Trace elements analysis in forage samples from a US Navy bombing range (Vieques, PR).  Int. J. Environ. Res. Public Health, 2(2), 263-6.  Retrieved from: http://www.ncbi.nlm.nih.gov/pubmed/16705826

Rai, P. K. 2009. Phytoremediation of heavy metals in a tropical impoundment of industrial region.  Environmental Monitoring & Assessment, 165 (1-4), 529-537.  DOI: 10.1007/s10661-009-0964-2.

Rajakaruna, N., Tompkins, K., Pavicevic, P. (2006) Phytoremediation: An affordable green technology for the clean-up of metal-contaminated soils in Sri Lanka. Cey. J. Sci. (Bio. Sci.) 35 (1): 25-39.  Retrieved from: http://www.biology.sjsu.edu/facultystaff/nrajakaruna/9Rajakaruna%20et%20al2006.pdf

U.S. Dept. of Health and Human Services, Agency for Toxic Substances and Disease Registry, Division of Health Assessment and Consultation Atlanta, Georgia 30333. (2011) An evaluation of environmental, biological and health data from the island of Vieques. 361 pgs. Retrieved from: http://www.atsdr.cdc.gov/hac/pha/vieques/2011_ViequesReport.pdf

U.S. Environmental Protection Agency Region 2 Superfund Vieques Island, Puerto Rico – Sectors.  Retrieved from:  http://www.epa.gov/region2/vieques/sectors.htm

Xiong, J., He, Z., Lui, D., Mahmood, Q., Yang, X. (2008). The role of bacteria in the heavy metals removal and growth of Sedum alfredii Hance in an aqueous medium.  Chemosphere, 70(3), 489-94. Retrieved from: http://www.ncbi.nlm.nih.gov/pubmed/1766233 

Yang, X., Feng, Y., He, Z., Stofella, P.J. (2005). Molecular mechanisms of heavy metal accumulation and phytoremediation. Journal of Trace Elements in Medicine and Biology, 18(4), 339-353. Retrieved from: http://www.sciencedirect.com/science/article/pii/S0946672X05000374