Abstract:
Toxicity tests were performed to investigate the health risk of weathered oil residues left in the salt marsh. The commercial bioassay Microtox was used to detect the “hot spots” of field contamination on salt marsh samples collected on 2011-01-06, 2014-10-23, and 2018-10-30 with the commercial Microtox® apparatus (model 500). Samples were run in triplicates. A subset of samples was carefully weighed to determine the dry weights. EC50 values are reported after moisture normalization.
Suggested Citation:
Huan Chen. 2020. Toxicity of oil-contaminated sediments in Louisiana salt marshes as ascertained with the commercial bioassay Microtox from 2011, 2014, and 2018. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-4hww-fz12
Data Parameters and Units:
Station ID, Sample ID, OilingLevel, Sampling Date (YYYY-MM-DD), Lat (latitude in decimal degrees), Lon (longitude in decimal degrees)), EC50 Concentration (mg/L), Wet sample weight Sw (g), Dry Sample weight Sd (g), Microtox EC50 (mg/L, Moisture corrected), Rep1, Rep2, Rep3, Mean (Average), Standard Deviation, Stand Error, and 95% confidence interval.
RF= Reference Sites; MD=Moderately Oiled Sites, HV=Heavily Oiled Sites, rep= sample replicates
Methods:
The whole sediment from heavily oiled, moderately oiled, and reference sites were assessed as it represents more ecologically relevant matrics compared to solvent extracts of sediments and sediment pore waters. Sediment samples from the seven sites of each oiling category were homogenized to generate one sample. Seven grams of wet sediment was resuspended in 45 ml of diluent to prepare primary dilution. The toxicities were measured in triplicates by commercial Microtox bioassay by following the protocols for the basic solid-phase test (BSPT), according to the standard operating procedure (Environmental, 1998) with the modifications (Campisi et al., 2005; Doe et al., 2005; Casado-Martínez et al., 2006). Light emissions of test concentrations were recorded, and the output data was analyzed using Microtox Omni software version 4.3 (Modern Water, New Castle, DE). The EC50 values and its 95% confidence range were recalculated based on the dry weight.
Provenance and Historical References:
Campisi, T., Abbondanzi, F., Casado-Martinez, C., DelValls, T. A., Guerra, R., & Iacondini, A. (2005). Effect of sediment turbidity and color on light output measurement for Microtox® Basic Solid-Phase Test. Chemosphere, 60(1), 9–15. doi:10.1016/j.chemosphere.2004.12.052
Casado-Martínez, M. (2006). Interlaboratory assessment of marine bioassays to evaluate the environmental quality of coastal sediments in Spain. II. Bioluminescence inhibition test for rapid sediment toxicity assessment. Ciencias Marinas, 32(1B), 129–138. doi:10.7773/cm.v32i12.1031
Doe, K., Jackman, P., Scroggins, R., McLeay, D., & Wohlgeschaffen, G. (2005). Solid-Phase Test for Sediment Toxicity Using the Luminescent Bacterium, Vibrio Fischeri. Small-Scale Freshwater Toxicity Investigations, 107–136. doi:10.1007/1-4020-3120-3_3
Environmental, A. (1998). Microtox® Basic Solid-Phase Test (Basic SPT). Carlsbad, CA, USA.