Organocopper complexes during roxarsone degradation in wastewater lagoons
Syam S Andra1, Konstantinos C Makris, Shahida Quazi
1Environmental Geochemistry Laboratory, University of Texas at San Antonio, San Antonio, TX, USA.
Environmental Science and Pollution Research International
|January 26, 2010
Summary
Copper (Cu) in swine wastewater may catalyze the degradation of organoarsenicals like roxarsone under aerobic conditions. This finding suggests copper
Area of Science:
- Environmental Chemistry
- Environmental Microbiology
- Analytical Chemistry
Background:
- Organoarsenical compounds, used in animal feed, are excreted and enter wastewater lagoons.
- Previous studies showed partial transformation of roxarsone to more toxic inorganic arsenic (As(V)) and 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA).
- Unidentified metabolites and potential organometallic complexes were previously inferred.
Purpose of the Study:
- To investigate the role of organometallic (copper, Cu) complexes in roxarsone degradation.
- To examine roxarsone degradation under aerobic conditions in swine wastewater.
- To utilize electrospray ionization mass spectrometry (ES-MS) for complex characterization.
Main Methods:
- Two swine wastewater samples with varying solids and copper concentrations were incubated with roxarsone (500 ppb) aerobically for 16 days.
- Arsenic (As) speciation was analyzed using liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC/ICP-MS).
- Metal-organoarsenical complexes were characterized using electrospray ionization mass spectrometry (ES-MS).
Main Results:
- An organocopper roxarsone metabolite was detected exclusively in wastewater with high Cu concentrations.
- Roxarsone degradation was observed only in the high-Cu wastewater sample under aerobic conditions.
- No degradation or organocopper metabolite was observed in the low-Cu wastewater sample.
Conclusions:
- Copper (Cu) plays a significant role in catalyzing the aerobic degradation of organoarsenicals like roxarsone.
- The presence of particulate Cu on wastewater-suspended particle surfaces is linked to organoarsenical degradation.
- Further research is needed to elucidate the mechanisms and pathways involved in Cu-mediated roxarsone degradation.
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