What's causing toxicity in sediments? Results of 20 years of toxicity identification and evaluations

Abstract

Sediment toxicity identification and evaluation (TIE) methods have been used for 20 yr to identify the causes of toxicity in sediments around the world. In the present study, the authors summarize and categorize results of 36 peer-reviewed TIE studies (67 sediments) into nonionic organic, cationic, ammonia, and "other" toxicant groups. Results are then further categorized according to whether the study was performed in freshwater or marine sediments and whether the study was performed using whole-sediment or interstitial-water TIE methods. When all studies were grouped, nonionic organic toxicants, either singly or in combination with other toxicants, were implicated in 70% of all studies. When studies were divided into interstitial-water TIE methodology compared with whole-sediment TIE methodology, results indicated that studies performed using interstitial-water TIE methods reported nonionic organic toxicity slightly more often than toxicity from cationic metals (67% compared with 49%). In contrast, studies using whole-sediment TIE methods report nonionic organic chemical toxicity, either singly or in combination with another toxicant, in 90% of all sediments tested. Cationic metals play a much smaller role in whole-sediment TIE studies-fewer than 20% of all sediments had a metals signal. The discrepancy between the 2 methods can be attributed to exposure differences. Contrary to earlier findings, ammonia generally plays only a minor role in sediment toxicity.

Natural stressors in uncontaminated sediments of shallow freshwaters: The prevalence of sulfide, ammonia, and reduced iron

“…However, ΣH 2 S and dissolved Fe(II) displayed an inverse pattern ( p = 0.092, r =–0.23; Figure ), such that high ΣH 2 S (>20 µM) never co‐occurred with high dissolved Fe(II) (>200 µM) in the same porewater sample. We observed ΣH 2 S concentrations higher than 5 µM, the concentration known to be toxic to some plants , in 10 of the 54 porewater samples.…”

“…same porewater sample. We observed SH 2 S concentrations higher than 5 mM, the concentration known to be toxic to some plants [65], in 10 of the 54 porewater samples. Porewater SNH 4 þ concentrations ranged from 0.2 mM to 1170 mM (2.5-16 440 mg N L À1 ), with a mean of 195 mM (2730 mg N L À1 ) and median of 50.6 mM.…”

Sediment toxicity identification evaluation (TIE phases I and II) based on microscale bioassays for diagnosing causes of toxicity in coastal areas affected by domestic sewage

“…The contribution of nonionized ammonia to the toxicity in interstitial water toxicity tests and sediment TIE has been extensively reported . Ho and Burgess recently reviewed sediment TIE studies and found that ammonia contributed to interstitial water toxicity in 31% of the studies analyzed. Ammonia can be naturally found in sediments and, as was discussed earlier, it is usually considered to be a confounding factor in sediment toxicity tests .…”

Resolving the false‐negative issues of the nonpolar organic amendment in whole‐sediment toxicity identification evaluations

“…Ho and Burgess (2013) reviewed 30 marine and freshwater sediment TIEs over a 20-yr time span and found that approximately 90% of studies identified a nonpolar organic as a source of toxicity in sediments, with 70% of evaluations characterizing nonpolar organics as the sole source of toxicity. Ho and Burgess (2013) reviewed 30 marine and freshwater sediment TIEs over a 20-yr time span and found that approximately 90% of studies identified a nonpolar organic as a source of toxicity in sediments, with 70% of evaluations characterizing nonpolar organics as the sole source of toxicity.…”

“…The need for reducing false-negatives when working with nonpolar organics amendments becomes even more apparent when considering the likelihood of a nonpolar organic contributing to the risk in contaminated sediments. Ho and Burgess (2013) reviewed 30 marine and freshwater sediment TIEs over a 20-yr time span and found that approximately 90% of studies identified a nonpolar organic as a source of toxicity in sediments, with 70% of evaluations characterizing nonpolar organics as the sole source of toxicity. Because nonpolar organics are one of the key classes causing toxicity, understanding the limitations and working to improve the use of activated carbon or powdered coconut charcoal are critical.…”