Assessing contaminated sediments in the context of multiple stressors

Abstract

Abstract-Sediments have a major role in ecosystem functioning but can also act as physical or chemical stressors. Anthropogenic activities may change the chemical constituency of sediments and the rate, frequency, and extent of sediment transport, deposition, and resuspension. The importance of sediments as stressors will depend on site ecosystem attributes and the magnitude and preponderance of co-occurring stressors. Contaminants are usually of greater ecological consequence in human-modified, depositional environments, where other anthropogenic stressors often co-occur. Risk assessments and restoration strategies should better consider the role of chemical contamination in the context of multiple stressors. There have been numerous advances in the temporal and spatial characterization of stressor exposures and quantification of biological responses. Contaminated sediments causing biological impairment tend to be patchy, whereas more pervasive anthropogenic stressors, such as alterations to habitat and flow, physical disturbance, and nutrient addition, may drive large-scale ecosystem responses. A systematic assessment of relevant ecosystem attributes and reference conditions can assist in understanding the importance of sediments in the context of other stressors. Experimental manipulations then allow for the controlled study of dominant stressors and the establishment of causal links. This approach will result in more effective management of watersheds and waterways. Environ. Toxicol. Chem. 2010;29:262529: -264329: . # 2010

Impact of contaminated-sediment resuspension on phytoplankton in the Biguglia lagoon (Corsica, Mediterranean Sea)

“…However, when disturbed, moved or relocated, sediment-bound contaminants can be remobilized in the water column (Latimer et al, 1999;Saulnier and Mucci, 2000) and thereby become bioavailable to pelagic organisms. Sediment can therefore act as a substantive source of contaminants (Burton and Johnston, 2010;Roberts, 2012), and sediment resuspensions can be viewed as pulsed environmental disturbances (Roberts, 2012). Owing to their shallowness and location at the landesea interface, coastal environments such as lagoons can experience frequent and significant sediment resuspension events.…”

Making ecosystem reality checks the status quo

“…Typically, water and sediment quality assessments are conducted in response to a regulatory directive, rely heavily on chemical benchmarks, and use standardized toxicity and bioaccumulation tests [2]. It is also well recognized, however, that assessing ecosystem and sediment quality that integrates multiple methods into a WoE-based approach can be more accurate and more useful from a resource management perspective.…”

“…Future human activities in areas with high UV radiation may be affected by these results. The increase of organism sensitivity due to UV is just a single example of a wide range of stressors that increase mortality due to toxicants, including temperature, nutrients, siltation, oxygen, competition, predation and parasites [2].…”

Joint toxicity of a pyrethroid insecticide, cypermethrin, and a heavy metal, lead, to the benthic invertebrate Chironomus dilutus

“…Thus, understanding the joint toxicity of these contaminants in aquatic systems is needed for more accurate assessment of ecological risk. However, most studies on joint toxicity have only focused on the combination of organic contaminants or inorganic contaminants [16][17][18].…”