Reproduction and survival of Eisenia fetida in a sandy loam soil amended with the nitro-heterocyclic explosives RDX and HMX

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The uptake of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) from soil by the earthworm Eisenia andrei was examined by using the equilibrium partitioning (EqP) theory and a three‐compartment model including soil (S), interstitial water (IW), and earthworms (E). The RDX concentrations were measured using U.S. Environmental Protection Agency (U.S. EPA) Method 8330A and high‐performance liquid chromatography (HPLC). The S‐IW studies were conducted using four natural soils with contrasting physicochemical properties that were hypothesized to affect the bioavailability of RDX. Each soil was amended with nominal RDX concentrations ranging from 1 to 10,000 mg/kg. The HPLC analysis showed that the IW extracted from soil was saturated with RDX at 80 mg/kg or greater soil concentrations. The calculated S‐IW coefficient (Kp) values for RDX ranged from 0.4 to 1.8 ml/g soil, depending on the soil type, and were influenced by the organic matter content. In the IW‐E studies, earthworms were exposed to nonlethal RDX concentrations in aqueous media. The uptake of RDX by the earthworms correlated well (r2 = 0.99) with the dissolved RDX concentrations. For the E‐S studies, earthworms were exposed to RDX‐amended soils used in the S‐IW studies. The bioconcentration factors (BCF; ratios of E‐to‐IW RDX concentrations) were relatively constant (∼5) up to 80 mg/kg soil RDX concentrations, which encompass the RDX saturation limit in the interstitial water of the tested soils. At this concentration range, the RDX uptake from interstitial water was likely dominated by passive diffusion and could be used as an indicator of bioavailability. Other mechanisms may be involved at greater RDX soil concentrations. Environ. Toxicol. Chem. 2010;29:998–1005. © 2009 SETAC

Section: Introductionmentioning

confidence: 99%

Role of soil interstitial water in the accumulation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine in the earthworm Eisenia andrei

Savard

Sarrazin

Dodard

et al. 2010

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“…Nonlabeled RDXwasdissolvedinacetoneandaddedtoeachsoilbatchto prepare target concentrations of 1, 10, 100, 1,000, 3,000, or 10,000 mg/kg. The selection of RDX concentrations in soil was based on published results of the earthworm toxicity tests [6,7]. Acetone solutions of RDX were poured evenly across the soil surface, ensuring that the volume of solution added did not exceed 15% ( v / w )o ft h ed r ys o i lm a s s .T h eg r e a t e s t concentration (10,000 mg/kg) was prepared in several steps using a stock solution of 40 g/L, each time not exceeding 15% of soil weight.…”

Section: Soil Handling and Amendmentsmentioning

confidence: 99%

“…Earthworm exposure to RDX adversely affected reproduction, based on the median effective concentrations (EC50s) of 3.7 and 5.0 mg/kg for cocoon and juvenile production, respectively, but did not affect the survival of adult earthworms at concentrations up to and including 756 mg/kg in a 56-d test [5][6][7][8]. Sublethal effects of RDX in earthworms included neurotoxicity at 0.21 mg/cm 2 in a 14-d filter-paper study [9].…”

Section: Introductionmentioning

confidence: 99%

Accumulation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine by the earthworm Eisenia andrei in a sandy loam soil

Sarrazin

Dodard

Savard

et al. 2009

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The heterocyclic polynitramine hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) is a highly energetic compound found as a soil contaminant at some defense installations. Although RDX is not lethal to soil invertebrates at concentrations up to 10,000 mg/kg, it decreases earthworm cocoon formation and juvenile production at environmentally relevant concentrations found at contaminated sites. Very little is known about the uptake of RDX in earthworms and the potential risks for food‐chain transfer of RDX in the environment. Toxicokinetic studies were conducted to quantify the bioaccumulation factors (BAFs) using adult earthworms (Eisenia andrei) exposed for up to 14 d to sublethal concentrations of nonlabeled RDX or [14C]RDX in a Sassafras sandy loam soil. High‐performance liquid chromatography of acetonitrile extracts of tissue and soil samples indicated that nonlabeled RDX can be accumulated by the earthworm in a concentration‐ and time‐dependent manner. The BAF, expressed as the earthworm tissue to soil concentration ratio, decreased from 6.7 to 0.1 when the nominal soil RDX concentrations were increased from 1 to 10,000 mg/kg. Tissue concentrations were comparable in earthworms exposed to nonlabeled RDX or [14C]RDX. The RDX bioaccumulation also was estimated using the kinetically derived model (BAFK), based on the ratio of the uptake to elimination rate constants. The established BAFK of 3.6 for [14C]RDX uptake was consistent with the results for nonlabeled RDX. Radioactivity also was present in the tissue residues of [14C]RDX‐exposed earthworms following acetonitrile extraction, suggesting the formation of nonextractable [14C]RDX metabolites associated with tissue macromolecules. These findings demonstrated a net accumulation of RDX in the earthworm and the potential for food‐chain transfer of RDX to higher‐trophic‐level receptors.

“…These procedures allowed us to more accurately approximate the exposure conditions for soil biota in the field, compared with tests conducted with freshly amended chemicals or tests conducted following a short equilibration period (e.g., 24 h) [22][23][24][25][26]28]. The range-finding tests were conducted to determine Se concentrations for the definitive toxicity testing.…”

Section: Soil Treatmentsmentioning

confidence: 99%

Selenium toxicity to survival and reproduction of Collembola and Enchytraeids in a sandy loam soil

Kuperman¹,

Checkai²,

Simini³

et al. 2018

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We investigated the toxicity of selenium (Se) to the soil invertebrates Folsomia candida (Collembola) and Enchytraeus crypticus (potworm). Studies were designed to generate ecotoxicological benchmarks for developing ecological soil screening levels (Eco-SSLs) for risk assessments of contaminated soils. For the present studies, we selected Sassafras sandy loam, an aerobic upland soil with soil characteristics (low levels of clay and organic matter, soil pH adjusted from 5.2 to 7.1) that support high relative bioavailability of the anionic Se species that is typically found in aerobic soil. The Se was amended into soil as sodium selenate, subjected to weathering and aging using 21 d of alternating cycles of air-drying/rehydration to 60% of the water-holding capacity of the Sassafras sandy loam soil, under ambient greenhouse conditions. Effective concentrations at 20 and 50% (EC20 and EC50) levels for production of juveniles (reproduction) were 4.7 and 10.9 mg of Se/kg of soil (dry mass basis), respectively, for Collembola, and 4.4 and 6.2 mg/kg, respectively, for the potworms. The data enabled the derivation of toxicity benchmarks, contributing to the development of a soil invertebrate-based Eco-SSL of 4.1 mg/kg for Se. Environ Toxicol Chem 2018;37:846-853. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.