Identifying the causes of sediment‐associated contamination in the Illinois River (USA) using a whole‐sediment toxicity identification evaluation

Abstract

Whole-sediment toxicity identification evaluation (TIE) techniques were employed on the Illinois River Complex (IRC), USA to identify the sources of sediment toxicity that may have contributed to the decline in benthic invertebrate populations. The TIE focused on three classes of contaminants: ammonia, metals, and organics. Sediment toxicity was assessed using the amphipod Hyalella azteca, and the focus of the TIE was on assessing spatial and temporal patterns of contamination. Past studies suggested that ammonia was the major source of contamination in IRC sediments. However, the present study suggested that polycyclic aromatic hydrocarbons (PAHs) were the primary contributor to sediment toxicity. Phase I testing showed 46% of the site trials (12 of 26) exhibited increased H. azteca survival (p < 0.05) with the addition of powdered coconut charcoal (organic amendment), whereas zeolite (ammonia amendment) and Resin Tech SIR 300 (cationic metals amendment) did not increase H. azteca survival. Phase II testing revealed PAH concentrations were high enough to cause the observed toxicity, confirming phase I results. Spatially, sediment toxicity as well as pore-water ammonia concentrations declined with distance downstream from suspected contaminant sources, indicating a potential dilution or remedial effect. Temporally, pore-water ammonia, metals, and PAH concentrations varied among sampling periods over an annual cycle for some sites near urbanized areas, while remaining temporally consistent at others. The results of the present study provide new information on the sources of toxicity within the IRC, and demonstrate the importance of evaluating spatial and temporal aspects in sediment TIEs. This is particularly important for evaluations in riverine systems in which hydrologic processes can result in large variation in sediment toxicity on temporal and spatial scales.

Toxicity of sediment-associated unresolved complex mixture and its impact on bioavailability of polycyclic aromatic hydrocarbons

“…The CH sediment was spiked with 1 g/g dw of each PAH and various levels of mineral oil (0, 0.01, 0.1 and 0.5% dw) in order to investigate the impact of UCM on bioaccumulation of sediment-associated PAHs to L. variegatus. The three PAHs were spiked as a mixture for these tests and the concentrations of PAHs and mineral oil were selected because they were environmental relevant [16,20]. The spiked sediments were aged at 4 • C for 14 d before conducting the bioaccumulation testing in triplicate following USEPA protocols [22].…”

“…Mehler et al [16] detected 0.15-1.2% UCM-like contaminants (e.g. measured as total organic matter) in sediments collected from the Illinois River, USA and the UCM content in three-fourths of that batch of sediments was greater than 0.6%.…”

“…In addition to its own bioaccumulation potential and toxicity, UCM may also alter the bioavailability and toxicity of other contaminants in sediment [16][17][18][19][20]. Mehler et al [16] noted possible changes in sorptive ability of activated carbon to PAHs during the course of conducting a whole-sediment toxicity identification evaluation test, and speculated that the ineffectiveness of the carbon treatment was caused by the co-existence of sediment-associated UCM, with similar reports found by the U.S. Environmental Protection Agency (USEPA) [17].…”

“…Mehler et al [16] noted possible changes in sorptive ability of activated carbon to PAHs during the course of conducting a whole-sediment toxicity identification evaluation test, and speculated that the ineffectiveness of the carbon treatment was caused by the co-existence of sediment-associated UCM, with similar reports found by the U.S. Environmental Protection Agency (USEPA) [17]. Moreover, UCM was also reported to be persistent in sediment for decades [21] and may act as a sedimentary super-sorbent for PAHs and polychlorinated biphenyls [18][19][20].…”

Chronic Toxicity Thresholds for Sediment-Associated Benzo[a]pyrene in the Midge (Chironomus dilutus)

“…Due to their increased concentrations, PAHs have been shown to be the major contributors to acute toxicity to benthic organisms in some sediments (Mehler et al 2010). Acute bioassays are useful for analyzing the hazards of highly toxic chemicals and contamination at high levels, but do not test key life-stage events, such as moulting and reproduction, during which organisms' susceptibility to toxicants may increase, and thus they do not show the long-term effects of contaminant exposure at low levels.…”