Development and Evaluation of Consensus-Based Sediment Quality Guidelines for Freshwater Ecosystems

Abstract

Numerical sediment quality guidelines (SQGs) for freshwater ecosystems have previously been developed using a variety of approaches. Each approach has certain advantages and limitations which influence their application in the sediment quality assessment process. In an effort to focus on the agreement among these various published SQGs, consensus-based SQGs were developed for 28 chemicals of concern in freshwater sediments (i.e., metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and pesticides). For each contaminant of concern, two SQGs were developed from the published SQGs, including a threshold effect concentration (TEC) and a probable effect concentration (PEC). The resultant SQGs for each chemical were evaluated for reliability using matching sediment chemistry and toxicity data from field studies conducted throughout the United States. The results of this evaluation indicated that most of the TECs (i.e., 21 of 28) provide an accurate basis for predicting the absence of sediment toxicity. Similarly, most of the PECs (i.e., 16 of 28) provide an accurate basis for predicting sediment toxicity. Mean PEC quotients were calculated to evaluate the combined effects of multiple contaminants in sediment. Results of the evaluation indicate that the incidence of toxicity is highly correlated to the mean PEC quotient (R(2) = 0.98 for 347 samples). It was concluded that the consensus-based SQGs provide a reliable basis for assessing sediment quality conditions in freshwater ecosystems.

Relative sensitivity of an amphipod Hyalella azteca, a midge Chironomus dilutus, and a unionid mussel Lampsilis siliquoidea to a toxic sediment

“…Mean quotients based on PECs were calculated to provide an overall measure of chemical contamination and to support an evaluation of the combined effects of multiple contaminants in sediments [21]. Individual PEC quotients (PECQs) were calculated for each of 5 metals (SEM concentrations of Cd, Cu, Pb, Ni, and Zn) and 13 PAHs (acenaphthalene, acenaphthylene, anthracene, benzo[a]anthracene, benzo[a]pyrene, chrysene, dibenzo[a,h]anthracene, fluoranthene, fluorene, 2-methylnaphthalene, naphthalene, phenanthrene, and pyrene) in each sediment sample by dividing the dry-weight concentration of the chemical by the PEC for that chemical [29]. To weight the contribution of metals or PAHs equally in the evaluation of sediment chemistry and toxicity, an average PECQ for metals or for total PAHs was calculated for each sample [21].…”

Deposition and accumulation of airborne organic contaminants in Yosemite National Park, California

“…In lake sediment, the legacy pesticides were highest in concentration and closest to sediment-based guidelines for benthic organisms [32]. Among the surface sediment samples (Supplemental Data, Table S10), 63% had DDE concentrations above the threshold effect concentration of 3.2 ng/g, which is the concentration below which harmful effects are unlikely to be observed; however, they were all below the probable effect concentration of 31 ng/g, which is the concentration above which harmful effects for benthic organisms are likely to be observed.…”

Evolutionary toxicology in an omics world

“…Currently, regulatory limits are driven by standard toxicological end points, such as mortality and changes in reproduction (Long, Field, & MacDonald, 1998; Long & MacDonald, 1998; MacDonald, Ingersoll, & Berger, 2000). On the other hand, considering that adaptation to contaminated environments is a result of such changes occurring over multiple generations, it seems that evolution can inform regulation and risk analysis.…”