Inorganic and organic contaminants in sediments from an urban playa and associated toxicity among Hyalella azteca

Abstract

Playa wetlands are important components of the Southern High Plains (USA) landscape as they are the major aquatic surface feature. Chemical contaminants associated with playas have been documented, particularly for grassland and agricultural watersheds, but not for playas in urban settings. The objectives of this study were to determine concentrations of inorganic and organic contaminants in sediments from an urban playa within the I-20 Wildlife Preserve and Jenna Welch Nature Study Center in Midland, TX, and evaluate toxicity of these sediments to Hyalella azteca. Concentrations of most trace elements were below sediment quality guidelines with exceptions of lead, cadmium, and arsenic. Concentrations of organic contaminants, particularly PAHs, DDT, DDE, and malathion, were above sediment quality guidelines at various locations within the playa. Decreased survival was observed among H. azteca exposed to sediment from a single location when compared those exposed to reference sediments. This location also produced maximum observed concentrations for five of seven trace elements, potentially due to its location at the lowest elevation within the playa. This study documented concentrations of contaminants in sediments of an urban playa associated with past and present land uses in its urban setting, including those from automotive emissions and historical pesticide use.

Keywords:

• playa wetlands
• sediments
• toxicity
• trace metals
• urban
• Hyalella azteca

Acknowledgments

We would like to thank Brad Thornhill for his assistance and guidance during the trace element analysis. We would also like to thank Donn Edwards and Morgan Willming for their assistance and advice in the sediment toxicity tests. We also thank the Department of Natural Resources Management and The Institute of Environmental and Human Health for their support.