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ARS Home » Southeast Area » Fayetteville, Arkansas » Poultry Production and Product Safety Research » Research » Publications at this Location » Publication #158182
Title: PERIPHYTIC CHLOROPHYLL A RESPONSE TO TRICLOSAN EXPOSURE: APPLICATION OF A PASSIVE DIFFUSION PERIPHYTOMETER

Author
item WHITE, KATI - BAEG - UNIV OF ARKANSAS
item HAGGARD, BRIAN
item MATLOCK, MARTY - BAEG - UNIV OF ARKANSAS
item KIM, JIN-WOO - BAEG - UNIV OF ARKANSAS

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2004
Publication Date: 3/1/2005
Citation: White, K.L., Haggard, B.E., Matlock, M.D., Kim, J. 2005. Periphytic chlorophyll a response to triclosan exposure: Application of a passive diffusion periphytometer. Applied Engineering in Agriculture. 21(2):307-311.

Interpretive Summary: In situ assessments of chemical toxicity may be accomplished using the natural periphytic community present in streams when allowed to colonize an artificial substrate. In this field trial, we evaluated the growth-inhibiting effects of Triclosan (TCS) on periphytic algae. The proliferation of TCS in consumer products has resulted in its presence in wastewater influent and subsequently in streams. Triclosan aquatic toxicity to periphyton was assessed using a passive-diffusion periphytometer (or Matlock Periphytometer) at the White River, Northwest Arkansas, USA. The periphytometer was deployed for one week with seven replicates of nine treatments, including: control (deionized H2O), methanol, low (0.05 mg/L) TCS, medium (0.1 mg/L) TCS, high (0.5 mg/L) TCS, nutrients (2 mg PO4-P/L and 20 mg NO3-N/L), low TCS with nutrients, medium TCS with nutrients, and high TCS with nutrients. The Student-Newman-Kuels test (a=0.05) identified three significantly different groups within the treatments. Nutrients and low TCS with nutrients had chlorophyll-a means of 10.9 and 5.8 mg/m2, respectively, which were significantly different from each other and all other treatments. The remaining chlorophyll-a treatment means ranged from 1.8 to 3.5 mg/m2 and were not significantly different from each other. Exponential regression of chlorophyll-a content on nutrient treatments against TCS concentration produced a significant decreasing trend; however, we did not observed any trend in chlorophyll a content on treatments without nutrients. Relatively low stream nutrient concentrations were observed; maximum NO3-N, total N, NH4N-N, TOC, and SRP concentrations were 0.23, 0.603, <0.05, 12.5 and 0.015 mg/L, respectively. This inhibition of growth represents a chronic rather than acute response, suggesting that the mechanism of TCS may be more complex than postulated. Periphytic response to TCS exposure was quantified using this innovative, in situ approach and warrants additional investigation using other chemicals.

Technical Abstract: In situ assessments of chemical toxicity may be accomplished using the natural periphytic community present in streams when allowed to colonize an artificial substrate. In this field trial, we evaluated the growth-inhibiting effects of Triclosan (TCS) on periphytic algae. The proliferation of TCS in consumer products has resulted in its presence in wastewater influent and subsequently in streams. Triclosan aquatic toxicity to periphyton was assessed using a passive-diffusion periphytometer (or Matlock Periphytometer) at the White River, Northwest Arkansas, USA. The periphytometer was deployed for one week with seven replicates of nine treatments, including: control (deionized H2O), methanol, low (0.05 mg/L) TCS, medium (0.1 mg/L) TCS, high (0.5 mg/L) TCS, nutrients (2 mg PO4-P/L and 20 mg NO3-N/L), low TCS with nutrients, medium TCS with nutrients, and high TCS with nutrients. The Student-Newman-Kuels test (a=0.05) identified three significantly different groups within the treatments. Nutrients and low TCS with nutrients had chlorophyll-a means of 10.9 and 5.8 mg/m2, respectively, which were significantly different from each other and all other treatments. The remaining chlorophyll-a treatment means ranged from 1.8 to 3.5 mg/m2 and were not significantly different from each other. Exponential regression of chlorophyll-a content on nutrient treatments against TCS concentration produced a significant decreasing trend; however, we did not observed any trend in chlorophyll a content on treatments without nutrients. Relatively low stream nutrient concentrations were observed; maximum NO3-N, total N, NH4N-N, TOC, and SRP concentrations were 0.23, 0.603, <0.05, 12.5 and 0.015 mg/L, respectively. This inhibition of growth represents a chronic rather than acute response, suggesting that the mechanism of TCS may be more complex than postulated. Periphytic response to TCS exposure was quantified using this innovative, in situ approach and warrants additional investigation using other chemicals.