Importance of suspended sediment (SPS) composition and grain size in the bioavailability of SPS-associated pyrene to Daphnia magna

Abstract

Hydrophobic organic compounds (HOCs) tend to associate with suspended sediment (SPS) in aquatic environments; the composition and grain size of SPS will affect the bioavailability of SPS-associated HOCs. However, the bioavailability of HOCs sorbed on SPS with different compositions and grain sizes is not well understood. In this work, passive dosing devices were made to control the freely dissolved concentration of pyrene, a typical HOC, in the exposure systems. The effect of pyrene associated with amorphous organic carbon (AOC), black carbon (BC), and minerals of SPS with grain sizes of 0-50 μm and 50-100 μm on the immobilization and enzymatic activities of Daphnia magna was investigated to quantify the bioavailability of pyrene sorbed on SPS with different grain sizes and compositions. The results showed that the contribution of AOC-, BC-, and mineral-associated pyrene to the total bioavailability of SPS-associated pyrene was approximately 50%-60%, 10%-29%, and 20%-30%, respectively. The bioavailable fraction of pyrene sorbed on the three components of SPS was ordered as AOC (22.4%-67.3%) > minerals (20.1%-46.0%) > BC (9.11%-16.8%), and the bioavailable fraction sorbed on SPS of 50-100 μm grain size was higher than those of 0-50 μm grain size. This is because the SPS grain size will affect the ingestion of SPS and the SPS composition will affect the desorption of SPS-associated pyrene in Daphnia magna. According to the results obtained in this study, a model has been developed to calculate the bioavailability of HOCs to aquatic organisms in natural waters considering both SPS grain size and composition.

Suspended Particulate Matter—A Source or Sink for Chemical Mixtures of Organic Micropollutants in a Small River under Baseflow Conditions?

“…Under dry weather conditions, the influence of sediment remobilization caused by agitation and the associated chemical inputs can be disregarded. Due to low SPM concentrations, it is difficult to capture sufficiently large amounts of SPM in a river under low-flow conditions, and thus, the sediment is commonly sampled and resuspended in the lab to simulate the role of SPM in aquatic toxicity . Despite the physical connection of SPM and the sediment, their chemical and toxicological profiles may differ as well as the bioavailability of particle-bound chemicals …”

“…Due to low SPM concentrations, it is difficult to capture sufficiently large amounts of SPM in a river under lowflow conditions, and thus, the sediment is commonly sampled and resuspended in the lab to simulate the role of SPM in aquatic toxicity. 10 Despite the physical connection of SPM and the sediment, their chemical and toxicological profiles may differ as well as the bioavailability of particle-bound chemicals. 11 Previous studies addressing the distribution between aqueous and particulate phases were limited to small groups of chemicals, particularly hydrophobic chemicals.…”

Evaluation of the Acute Effects and Oxidative Stress Responses of Phenicol Antibiotics and Suspended Particles in Daphnia magna

“…Some researchers have pointed out that the simultaneous exposure of aquatic species to mixtures of contaminants and SP might present unique issues (Chen et al 2012). Once SP enter into complicated aquatic ecosystems, they are able to absorb other pollutants (such as antibiotics, metals, hydrophobic organic compounds, pesticides) and interact with them as carriers, which can alter the ecotoxic effects on aquatic species (Herbrandson et al 2003a; Yang et al 2006; Cloran et al 2010;Zhang X et al 2014Zhang X et al , 2015Chen et al 2015;Rivetti et al 2015;Rasmussen et al 2016;Xia et al 2016b;Sun et al 2020). Besides, the competitive or complementary role of SP in the interaction of mixtures remains uncertain.…”