Project ID: 2004GA59B

Title: Reductive Biotransformation of Polychloro-Nitrobenzenes Under Iron-Reducing Conditions

Project Type: Research

Focus Categories: Agriculture, Hydrogeochemistry, Toxic Substances

Keywords: Bioavailability, bioremediation, chlorinated organics, iron reduction, pesticides, reductive dehalogenation, sorption

Start Date: 03/01/2004

End Date: 02/28/2005

Federal Funds: $16,000

Non-Federal Matching Funds: $32,000

Congressional District: 5

Principal Investigator:
Spyros G. Pavlostathis

Abstract

Persistent anthropogenic, hydrophobic organic compounds in the environment pose a chronic threat to the health and safety of humans and wildlife. Despite the fact that chloronitroaromatics are extensively used synthetic compounds in industry and agriculture (e.g., pesticides, fungicides, pharmaceuticals, dyes) and found worldwide in surface and subsurface soils, as well as streambed sediments, studies on their fate and transformation, especially for polychloronitro-substituted compounds, have been rare as compared to either chlorinated or nitroaromatic compounds. To address and explore this paucity of information, the focus of the proposed research is to elucidate the reductive biotransformation of polychloronitrobenzenes (polyCNBs), and their corresponding chloroanilines (CAs). Members of the target compounds are classified as either carcinogenic, potentially carcinogenic, or as methemoglobinemia-causing chemicals. Although a number of selected polyCNBs will be used in the proposed study, the main parent compound will be pentachloronitrobenzene (PCNB). PCNB (C6Cl5NO2), a powerful fungicide commonly used to combat phytopathogenic fungi, is a registered organochlorine fungicide used as a seed dressing or soil treatment to control a wide range of fungi species in crops such as cotton, potatoes, wheat, onions, lettuce, tomatoes, tulips, garlic, and others, as well as on grass, lawn flowers, ornamental crops, shrubs and in gardens (EXTOXNET, 1996; U.S. EPA, 2003). Commercial products of PCNB include impurities such as hexachlorobenzene, pentachlorobenzene (PeCB), and tetrachloronitrobenzene. PCNB is included in U.S. EPA¡¦s toxicity class III and is among the thirty chemicals included in the U.S. EPA¡¦s list of ¡§Waste Minimization Priority Chemicals¡¨.

During 2000 alone, 23,500 pounds of PCNB were used in six participating States (CA, FL, MI, OR, PA, and TX) in nursery and floriculture, whereas, 5,400 pounds were used in 2002 in the production of a single vegetable (fresh snap beans) in five participating States (FL, GA, NY, NC, and TN)(USDA, 2002; USDA, 2003). Although PCNB is used in several States, most of its usage is found in the Southeastern US because of its effectiveness against phytopathogenic fungi associated with crops predominantly found in this region. For example, in 2000, from the total reported PCNB usage of 543,500 lbs of active ingredient, 331,100 lbs (i.e., 61%) were used in seven States in the region (Table 1). In addition, PCNB is extensively used as a fungicide for the prevention and control of certain soil borne diseases on golf courses, sod farms, home lawns and institutional areas where turf is grown. PCNB is also extensively used to prevent the formation of slime in industrial waters. According to the U.S. EPA Toxics Release Inventory, the amount of PCNB released in 2001 was 9,717 pounds, whereas the amount of waste transferred and total waste managed amounted to 487,088 and 666,938 pounds, respectively. In a recently published report on the occurrence of semivolatile organic compounds in streambed sediments of twenty major river basins across the United States, PCNB was detected at a maximum concentration of 180 ƒÝg/kg (Lopes and Furlong, 2001). Therefore, as the above-mentioned, PCNB-related activities are more intense in the Southeastern US, the fate of PCNB and its potential effect is of regional interest. The proposed research is in line with the U.S. Geological Survey=s and the Georgia Water Resources Institute=s mission on groundwater quality protection, subsurface pollutant interactions, in situ treatment systems, and bioremediation.

Progress/Completion Report PDF