Guilherme Lotufo | Monterey Institute of International Studies (original) (raw)
Papers by Guilherme Lotufo
Environmental Toxicology and Chemistry, 2002
The toxicity of the explosives 2,4,6-trinitrotoluene (TNT); hexahydro-1,3,5-trinitro-1,3,5-triazi... more The toxicity of the explosives 2,4,6-trinitrotoluene (TNT); hexahydro-1,3,5-trinitro-1,3,5-triazine (royal demolition explosive [RDX]); and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (high-melting explosive [HMX]), was evaluated in spiked sediment with two freshwater invertebrates. The midge Chironomus tentans and the amphipod Hyalella azteca demonstrated significant toxic effects after exposure to TNT and its degradation products, 1,3,5-trinitrobenzene (TNB) and 2,4-diamino-6nitrotoluene (2,4-DANT). Significant reductions in survival of C. tentans exposed to TNT, TNB, and 2,4-DANT were observed at nominal sediment concentrations as low as 200 mg/kg. Hyalella azteca was more sensitive to TNT, TNB, and 2,4-DANT than the midge, where significant reductions in survival were observed at nominal concentrations of 50, 100, and 200 mg/kg, respectively. Survival of the midge and the amphipod was unaffected after exposure to RDX or HMX at the highest concentrations of 1,000 and 400 mg/kg, respectively. Growth of the midge, measured as total weight, was significantly reduced by 2,4-DANT. However, significantly increased growth was observed after exposure to sublethal concentrations of RDX and HMX. Although significant reductions in amphipod survival were observed at high concentrations of TNB, growth was significantly increased at sublethal concentrations. The results of the current investigation suggest that organisms exposed to explosives at contaminated sites may be affected at concentrations less than 25 mg/kg through hormetic growth enhancement and at higher concentrations through increased mortality.
Zoologica Scripta, 1994
Five new species of Cyclopina Claus are described and C. mediterranea Steuer is redescribed from ... more Five new species of Cyclopina Claus are described and C. mediterranea Steuer is redescribed from Brazilian sandy beaches. Cyclopina curoli sp. n. can be very abundant in coarse sandy shows. It is related to C. laurentica Mocholls and C. crassisserosa Herbst with which it shares a similar structure of Leg 5 in the female. Cyclopina dorae sp. n. is most closely related to C. meditarranea Steuer. Cyclopina arenosa sp. n. and Cyclopina yutimaete sp. n. are reminiscent of C. pontica Monchenko, the only other species of Cyclopina that possess a 2-segmented endopod in leg 1. Cyclopina caissara sp. n. is distinguished from all other congeneric species by having a very reduced inner spine in the leg 5 exopod of both male and female. This species shares with C. schneideri Scott and C. schneideri and C. brevifurca Sars the 12–segmented antennule. Taxonomical problems related to C. schneideri and C. brevifurea are discussed. Cyclopina mediterranea Steuer, 1940 is recorded for the first time from the American continent.
Environmental Toxicology and Chemistry, 2006
Few studies have determined the toxicity and bioaccumulation potential of explosive compounds in ... more Few studies have determined the toxicity and bioaccumulation potential of explosive compounds in freshwater fish. In the present study, fathead minnow (Pimephales promelas) were exposed to a range of 2,4,6-trinitrotoluene (TNT) concentrations (0.44-44 mol/L [0.1-10 mg/L] and 4.4-22.0 mol/L [1.0-5.0 mg/L] in 4-and 10-d experiments, respectively). Median lethal concentrations of 11.93 mol/L (2.7 mg/L; 95% confidence limit [CL], 10.29-13.83 mol/L) and 9.68 mol/L (2.20 mg/L; 95% CL, 9.17-10.22 mol/L) were calculated in the 4-and 10-d experiments, respectively, and median lethal body residue of 101.0 mol/kg (95% CL, 86.0-118.7 mol/kg) was calculated in 4-d experiments.
Aquatic Toxicology, 1998
Most polycyclic aromatic hydrocarbons (PAHs) entering aquatic systems reside in sediments and in ... more Most polycyclic aromatic hydrocarbons (PAHs) entering aquatic systems reside in sediments and in the storage lipids of the benthic biota. Massive amounts of PAHs reach estuarine systems and threaten their ecosystems. Copepods abound in the estuarine benthos, where they are an important component of food webs. The accumulation of sediment-associated [ 14 C]fluoranthene was examined in adult females of two species of sediment-dwelling copepods, Schizopera knabeni and Coullana sp., collected from a Louisiana salt marsh. Accumulation was measured throughout a short-(24 h) and a long-term (10-day) exposure to concentrations in the sediment ranging from 0 to 1652 nmol (g dry wt.) − 1 . Fluoranthene apparent steady state body residue was reached very rapidly (B12 h) at all concentrations for both species. Lipid and organic-carbon-normalized bioaccumulation factors (BSAFs) calculated at day 1 were 0.57-0.80 for S. knabeni and 0.35-0.71 for Coullana sp. Fluoranthene body burden in female Coullana sp. changed dramatically during their reproductive cycle. A significant fraction of the fluoranthene residue was stored in the lipid-rich maturing eggs which were extruded into paired egg sacs. For S. knabeni, fluoranthene depuration occurred at similar rates in sediment and water (half life approximately 4.8 h), while it was faster in sediment than in water for Coullana sp. (half lives =4.2 and 7.4 h). Fluoranthene was biotransformed to polar compounds in both species. Metabolites accounted for approximately 12% of the 14 C activity in the tissues following a 96-h sediment exposure in both species. Given that fluoranthene was taken up from spiked sediment very efficiently and reached steady-state levels in the tissues very rapidly, PAH-contaminated sediments may pose a risk for benthic copepods and their predators.
Environmental Toxicology and Chemistry, 1996
Acute and sublethal toxicities of sediment-spiked pyrene and phenanthrene to Limnodrilus hoffmeis... more Acute and sublethal toxicities of sediment-spiked pyrene and phenanthrene to Limnodrilus hoffmeisteri Cleparéde were investigated. Phenanthrene was acutely toxic at high sediment concentrations (10-d median lethal concentration of 297.5 g g Ϫ1 ; 252.2-348.3, 95% confidence interval [CI]). Pyrene was not acutely toxic, even at concentrations as high as 841 g g Ϫ1 . A significant impact of pyrene and phenanthrene on the feeding activity of L. hoffmeisteri was demonstrated through daily collection of egested fecal material during 5-and 10-d experiments. A short (5-d) exposure detected toxic effects more efficiently than a 10-d exposure, yielding IC25 values (estimated concentration causing a 25% reduction of measured endpoint in relation to the control[s]) of 58.9 g g Ϫ1 (32.1-89.4, 95% CI) for pyrene and 28.4 g g Ϫ1 (10.0-41.3, 95% CI) for phenanthrene. Effects on burrowing behavior and reproduction were assessed in a 28-d sediment exposure. Low burrowing avoidance (Ͻ25%) was detected in high phenanthrene concentrations (143-612 g g Ϫ1 ) but was not detected with pyrene. Offspring production was significantly reduced in dosed sediments yielding IC25 values of 59.1 g g Ϫ1 (38.3-112.5, 95% CI) for pyrene and 40.5 g g Ϫ1 (12.1-165.5, 95% CI) for phenanthrene. Decreases in egestion rates in the presence of nonpolar contaminants should be quantified when investigating the effects of bioturbation by deposit feeders on the flux of contaminants from sediment into the water column.
Chemosphere, 2003
Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener... more Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR 50 value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR 50 values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC 50 values ranged from 1757 lg l À1 for naphthalene after 10 d exposure to 79.1 lg l À1 for pyrene after 28 d exposure, and the EC 50 ranged from 1587 lg l À1 for naphthalene after 10 d exposure to 38.2 lg l À1 for pyrene after 28 d exposure. The LR 50 values for all congeners at all lengths of exposure were essentially constant and averaged 7:5 AE 2:6 lmol g À1 , while the ER 50 for immobility averaged 2:6 AE 0:6 lmol g À1 . The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound. Published by Elsevier Science Ltd.
Environmental Toxicology and Chemistry, 2000
The influence of exposure source, worm density, and sex on the bioaccumulation and toxicity of 14... more The influence of exposure source, worm density, and sex on the bioaccumulation and toxicity of 14C-labeled DDT was evaluated for Neanthes arenaceodentata. Emergent juvenile worms were exposed to DDT-spiked sediment (SED), DDT-spiked supplemental food (TetraMarin; TM), or a combination of both (SEDTM) in 28-d toxicity experiments. The DDT concentrations in the sediment and in the food were equal on an organic carbon basis. Higher body residues were attained under the TM exposure compared to SED, indicating the importance of nonsedimentary organic matter as a source for contaminant uptake. The DDT was more bioavailable when associated with TetraMarin compared to sediment, indicating that factors other than sorption to organic carbon can influence contaminant bioavailability. Body residues as high as 0.5 mol/g wet weight were not associated with decreased survival, suggesting general narcosis as the mode of lethal toxicity of DDT to N. arenaceodentata. Most of the body burden was DDT unmetabolized compound (∼70%). Reduced growth, observed under all exposures, was significant at lower concentrations when worms were fed DDT-spiked food (TM and SEDTM). Neanthes arenaceodentata may have detected the presence of DDT in the TetraMarin and decreased their feeding rate, at the cost of reduced growth. The influence of worm density on DDT toxicity and bioaccumulation was examined by exposing one or five worms per beaker (74 and 370 worms/m2, respectively) to spiked sediment. Although higher body residues were attained under low density, worms exposed in groups of five were significantly more sensitive to the effects of DDT on growth. Sex also had a large influence on DDT uptake kinetics. In sediment exposures (SED) to a trace concentration, the uptake clearance rate (mgoc/g lipids/h) was two times more efficient and the elimination rate was five times faster in mature males than in mature females.
Environmental Toxicology and Chemistry, 2001
The amphipods Hyalella azteca and Diporeia spp. were exposed to sediments dosed with dichlorodiph... more The amphipods Hyalella azteca and Diporeia spp. were exposed to sediments dosed with dichlorodiphenyltrichloroethane (DDT), and the toxicity and toxicokinetics were determined. The toxicity was evaluated with the equilibrium partitioning (EqP) and critical body residue approaches. The DDT in the sediments degraded during the equilibration period prior to organism exposure. Thus, the toxicity using EqP pore-water toxic units (TUs) was evaluated for DDT and its degradation product, dichlorodiphenyldichloroethane (DDD), as the ratio of the predicted interstitial water concentration divided by the water-only LC50 values. The sum of TUs (⌺TU) was assumed to best represent the toxicity of the mixture. For H. azteca, the 10-d LC50 was 0.98 and 0.33 ⌺TU for two experiments. For Diporeia spp., no toxicity was found in the first experiment with up to 3 ⌺TU predicted in the interstitial water. However, in the second experiment, the 28-d LC50 was 0.67 ⌺TU. These data suggest that the EqP approach approximately predicts the toxicity for the combination of DDT and DDD in sediment, provided a toxic unit approach is employed. The critical body residue approach also used TUs because DDT is biotransformed by H. azteca and because of the dual exposure to DDT and DDD. Because biotransformation was only determined in the second experiment, the critical body residue approach could only be evaluated for that case. The TUs were calculated as the ratio of the concentration in the live amphipods divided by the respective LR50 (residue concentration required to produce 50% mortality) values. The LR50 was 1.1 ⌺TU for H. azteca for the 10-d exposure and 0.53 for Diporeia spp. after a 28-d exposure. Thus, this approach was also quite successful in predicting the toxicity. The accumulation and loss rates for H. azteca were much greater than for Diporeia spp. Thus, 10-d exposures represent steady-state conditions for H. azteca, while even at 28-d, the Diporeia spp. are not at steady state.
Environmental Toxicology and Chemistry, 2005
The lethal toxicity of the explosive compounds 14 C-labeled 2,4,6-trinitrotoluene (TNT) and nonra... more The lethal toxicity of the explosive compounds 14 C-labeled 2,4,6-trinitrotoluene (TNT) and nonradiolabeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to the estuarine amphipod Eohaustorius estuarius was investigated in 10-d spiked sediment exposures. The 10-d median lethal concentration (LC50) was determined using the sum molar initial concentration of TNT, aminodinitrotoluenes (ADNTs), and diaminonitrotoluenes (DANTs), as determined by high-performance liquid chromatography (HPLC), and collectively referred to as HPLC-TNT*. Despite expectations of higher toxicity in sandy sediment (Yaquina Bay [YB], OR, USA) compared to relatively fine-grained sediment (San Diego Bay [SDB], CA, USA), LC50 values were similar: 159 and 125 mol/kg, for YB and SDB sediments, respectively. When expressed as the sum of TNT and all its degradation products ( 14 C-TNT*), LC50s were approximately two times the corresponding LC50s determined by HPLC. The HPLC-TNT* fraction likely corresponds to the most bioavailable and toxic transformation products. The concentrations of 14 C-TNT* in tissues were substantially higher than those for HPLC-TNT*, suggesting that compounds other than TNT and its major aminated transformation products were prevalent. Critical body residues were similar for exposures to SDB (11.7 mol/kg) and YB sediments (39.4 mol/kg), despite marked differences in the nature of compounds available for uptake in the exposure media. The critical body residues for E. estuarius are lower than those reported for other aquatic invertebrates (83-172 mol/kg). Unlike observations for TNT, RDX was only loosely associated with SDB sediment, with near complete recovery of the parent compound by chemical analysis. Exposure to RDX did not result in significant mortality even at the highest measured sediment concentration of 10,800 mol/kg dry weight, nor tissue concentrations as high as 96 mol/kg wet weight. The lack of RDX lethal effects in this study is consistent with results reported for other invertebrate species.
Chemosphere, 2005
Little is currently known regarding the toxicokinetics of TNT in fish. In the present study, the ... more Little is currently known regarding the toxicokinetics of TNT in fish. In the present study, the bioconcentration and distribution of trinitrotoluene (TNT) and TNT biotransformation products was investigated in juvenile channel catfish by exposing catfish to 14C-labeled TNT in water. Uptake experiments showed relatively fast rates (k(u)=10.1 ml g(-1) h(-1)) for TNT from the water; however, bioconcentration factors for TNT were low (0.79 ml g(-1)) due to rapid biotransformation and potential elimination of TNT. Accumulation of extractable radioactivity (TNT and all extractable biotransformation products) was much greater (BCF=10.5 ml g(-1)) than that for parent compound. TNT (parent compound) bioconcentrated to the greatest extent in the gills of the fish, while total radioactivity bioconcentrated to the greatest extent in the viscera. Residual portions of the fish that contained muscle and skin had lower concentrations of TNT than the whole fish, indicating that ingestion of fish fillets would result in decreased exposure to human consumers. Although the bioconcentration potential of TNT is very low, future research needs to be conducted to identify the biotransformation products that make up most of the radioactivity in exposed fish and evaluate their potential to promote toxicity.
Marine Ecology-progress Series, 1997
The lethal and sublethal toxlclty of phendnthrene (a polycyclic aromatic hydrocarbon, PAH) to 2 s... more The lethal and sublethal toxlclty of phendnthrene (a polycyclic aromatic hydrocarbon, PAH) to 2 species of meiobenthic estuarine harpacticoid copepods (Schfzopera knabeni dnd Nitocra lacustrfs) was ~nvestlgated Individuals of different life stages ( n a u p l~u s copepodite, adult male and female) were exposed to sediment-associated phenanthrene In separate 10 d bioassays Overall A' lacustns (10 d LCj, values ranglng from 43 to 105 pg g ' d~y wt) was more sensitive than S knabeni (10 d LCSD values ranging from 84 to 349 pg g ' dry \vt) Signlflcant differences In life-stage-speclfic sensitivity wele observed for S knabeni, with the nauplll belng most seniltive tolloived by copepodltes and adults, adult males and females \Yere equally sensltlve For N Iacustris females wele significantly more sensltlve than all other stages no s i g n~f~c a n t d~tferences \yere evldent among the other stages Phenanthrene effects on offspring productlon were invest~gated In the adult 10 d b~oassay Significant decreases in offspring productlon occurred at sublethal concentratlons for S knabenl (as low as 22 1-19 g.' d r y wt) but d t concentratlons In the same lange as the 10 d LC5,values for A' ldcustr~s In addition phenanthrene slgnlficantly prolonged embryonic and larval development and decreased e g g hatching success for both species Our results suggest that PAHs have a negative effect on the reprod u c t~o n of melobenthic copepods at sublethal concentrations mostly due to a decrease In brood prod u c t~o n rate and impalrlnent of hatchlng Overall, deleterious effects were manifested in the same range of concentratlons for both species but deflnite specles-spec~flc differences In the pattern of responses were evident KEY WORDS Sedlment tox~city Copepod , Life h~story Meiobenthos Phenanthrene 0 Inter-Research 1997
Environmental Toxicology and Chemistry, 2002
The toxicity of the explosives 2,4,6-trinitrotoluene (TNT); hexahydro-1,3,5-trinitro-1,3,5-triazi... more The toxicity of the explosives 2,4,6-trinitrotoluene (TNT); hexahydro-1,3,5-trinitro-1,3,5-triazine (royal demolition explosive [RDX]); and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (high-melting explosive [HMX]), was evaluated in spiked sediment with two freshwater invertebrates. The midge Chironomus tentans and the amphipod Hyalella azteca demonstrated significant toxic effects after exposure to TNT and its degradation products, 1,3,5-trinitrobenzene (TNB) and 2,4-diamino-6nitrotoluene (2,4-DANT). Significant reductions in survival of C. tentans exposed to TNT, TNB, and 2,4-DANT were observed at nominal sediment concentrations as low as 200 mg/kg. Hyalella azteca was more sensitive to TNT, TNB, and 2,4-DANT than the midge, where significant reductions in survival were observed at nominal concentrations of 50, 100, and 200 mg/kg, respectively. Survival of the midge and the amphipod was unaffected after exposure to RDX or HMX at the highest concentrations of 1,000 and 400 mg/kg, respectively. Growth of the midge, measured as total weight, was significantly reduced by 2,4-DANT. However, significantly increased growth was observed after exposure to sublethal concentrations of RDX and HMX. Although significant reductions in amphipod survival were observed at high concentrations of TNB, growth was significantly increased at sublethal concentrations. The results of the current investigation suggest that organisms exposed to explosives at contaminated sites may be affected at concentrations less than 25 mg/kg through hormetic growth enhancement and at higher concentrations through increased mortality.
Zoologica Scripta, 1994
Five new species of Cyclopina Claus are described and C. mediterranea Steuer is redescribed from ... more Five new species of Cyclopina Claus are described and C. mediterranea Steuer is redescribed from Brazilian sandy beaches. Cyclopina curoli sp. n. can be very abundant in coarse sandy shows. It is related to C. laurentica Mocholls and C. crassisserosa Herbst with which it shares a similar structure of Leg 5 in the female. Cyclopina dorae sp. n. is most closely related to C. meditarranea Steuer. Cyclopina arenosa sp. n. and Cyclopina yutimaete sp. n. are reminiscent of C. pontica Monchenko, the only other species of Cyclopina that possess a 2-segmented endopod in leg 1. Cyclopina caissara sp. n. is distinguished from all other congeneric species by having a very reduced inner spine in the leg 5 exopod of both male and female. This species shares with C. schneideri Scott and C. schneideri and C. brevifurca Sars the 12–segmented antennule. Taxonomical problems related to C. schneideri and C. brevifurea are discussed. Cyclopina mediterranea Steuer, 1940 is recorded for the first time from the American continent.
Environmental Toxicology and Chemistry, 2006
Few studies have determined the toxicity and bioaccumulation potential of explosive compounds in ... more Few studies have determined the toxicity and bioaccumulation potential of explosive compounds in freshwater fish. In the present study, fathead minnow (Pimephales promelas) were exposed to a range of 2,4,6-trinitrotoluene (TNT) concentrations (0.44-44 mol/L [0.1-10 mg/L] and 4.4-22.0 mol/L [1.0-5.0 mg/L] in 4-and 10-d experiments, respectively). Median lethal concentrations of 11.93 mol/L (2.7 mg/L; 95% confidence limit [CL], 10.29-13.83 mol/L) and 9.68 mol/L (2.20 mg/L; 95% CL, 9.17-10.22 mol/L) were calculated in the 4-and 10-d experiments, respectively, and median lethal body residue of 101.0 mol/kg (95% CL, 86.0-118.7 mol/kg) was calculated in 4-d experiments.
Aquatic Toxicology, 1998
Most polycyclic aromatic hydrocarbons (PAHs) entering aquatic systems reside in sediments and in ... more Most polycyclic aromatic hydrocarbons (PAHs) entering aquatic systems reside in sediments and in the storage lipids of the benthic biota. Massive amounts of PAHs reach estuarine systems and threaten their ecosystems. Copepods abound in the estuarine benthos, where they are an important component of food webs. The accumulation of sediment-associated [ 14 C]fluoranthene was examined in adult females of two species of sediment-dwelling copepods, Schizopera knabeni and Coullana sp., collected from a Louisiana salt marsh. Accumulation was measured throughout a short-(24 h) and a long-term (10-day) exposure to concentrations in the sediment ranging from 0 to 1652 nmol (g dry wt.) − 1 . Fluoranthene apparent steady state body residue was reached very rapidly (B12 h) at all concentrations for both species. Lipid and organic-carbon-normalized bioaccumulation factors (BSAFs) calculated at day 1 were 0.57-0.80 for S. knabeni and 0.35-0.71 for Coullana sp. Fluoranthene body burden in female Coullana sp. changed dramatically during their reproductive cycle. A significant fraction of the fluoranthene residue was stored in the lipid-rich maturing eggs which were extruded into paired egg sacs. For S. knabeni, fluoranthene depuration occurred at similar rates in sediment and water (half life approximately 4.8 h), while it was faster in sediment than in water for Coullana sp. (half lives =4.2 and 7.4 h). Fluoranthene was biotransformed to polar compounds in both species. Metabolites accounted for approximately 12% of the 14 C activity in the tissues following a 96-h sediment exposure in both species. Given that fluoranthene was taken up from spiked sediment very efficiently and reached steady-state levels in the tissues very rapidly, PAH-contaminated sediments may pose a risk for benthic copepods and their predators.
Environmental Toxicology and Chemistry, 1996
Acute and sublethal toxicities of sediment-spiked pyrene and phenanthrene to Limnodrilus hoffmeis... more Acute and sublethal toxicities of sediment-spiked pyrene and phenanthrene to Limnodrilus hoffmeisteri Cleparéde were investigated. Phenanthrene was acutely toxic at high sediment concentrations (10-d median lethal concentration of 297.5 g g Ϫ1 ; 252.2-348.3, 95% confidence interval [CI]). Pyrene was not acutely toxic, even at concentrations as high as 841 g g Ϫ1 . A significant impact of pyrene and phenanthrene on the feeding activity of L. hoffmeisteri was demonstrated through daily collection of egested fecal material during 5-and 10-d experiments. A short (5-d) exposure detected toxic effects more efficiently than a 10-d exposure, yielding IC25 values (estimated concentration causing a 25% reduction of measured endpoint in relation to the control[s]) of 58.9 g g Ϫ1 (32.1-89.4, 95% CI) for pyrene and 28.4 g g Ϫ1 (10.0-41.3, 95% CI) for phenanthrene. Effects on burrowing behavior and reproduction were assessed in a 28-d sediment exposure. Low burrowing avoidance (Ͻ25%) was detected in high phenanthrene concentrations (143-612 g g Ϫ1 ) but was not detected with pyrene. Offspring production was significantly reduced in dosed sediments yielding IC25 values of 59.1 g g Ϫ1 (38.3-112.5, 95% CI) for pyrene and 40.5 g g Ϫ1 (12.1-165.5, 95% CI) for phenanthrene. Decreases in egestion rates in the presence of nonpolar contaminants should be quantified when investigating the effects of bioturbation by deposit feeders on the flux of contaminants from sediment into the water column.
Chemosphere, 2003
Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener... more Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR 50 value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR 50 values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC 50 values ranged from 1757 lg l À1 for naphthalene after 10 d exposure to 79.1 lg l À1 for pyrene after 28 d exposure, and the EC 50 ranged from 1587 lg l À1 for naphthalene after 10 d exposure to 38.2 lg l À1 for pyrene after 28 d exposure. The LR 50 values for all congeners at all lengths of exposure were essentially constant and averaged 7:5 AE 2:6 lmol g À1 , while the ER 50 for immobility averaged 2:6 AE 0:6 lmol g À1 . The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound. Published by Elsevier Science Ltd.
Environmental Toxicology and Chemistry, 2000
The influence of exposure source, worm density, and sex on the bioaccumulation and toxicity of 14... more The influence of exposure source, worm density, and sex on the bioaccumulation and toxicity of 14C-labeled DDT was evaluated for Neanthes arenaceodentata. Emergent juvenile worms were exposed to DDT-spiked sediment (SED), DDT-spiked supplemental food (TetraMarin; TM), or a combination of both (SEDTM) in 28-d toxicity experiments. The DDT concentrations in the sediment and in the food were equal on an organic carbon basis. Higher body residues were attained under the TM exposure compared to SED, indicating the importance of nonsedimentary organic matter as a source for contaminant uptake. The DDT was more bioavailable when associated with TetraMarin compared to sediment, indicating that factors other than sorption to organic carbon can influence contaminant bioavailability. Body residues as high as 0.5 mol/g wet weight were not associated with decreased survival, suggesting general narcosis as the mode of lethal toxicity of DDT to N. arenaceodentata. Most of the body burden was DDT unmetabolized compound (∼70%). Reduced growth, observed under all exposures, was significant at lower concentrations when worms were fed DDT-spiked food (TM and SEDTM). Neanthes arenaceodentata may have detected the presence of DDT in the TetraMarin and decreased their feeding rate, at the cost of reduced growth. The influence of worm density on DDT toxicity and bioaccumulation was examined by exposing one or five worms per beaker (74 and 370 worms/m2, respectively) to spiked sediment. Although higher body residues were attained under low density, worms exposed in groups of five were significantly more sensitive to the effects of DDT on growth. Sex also had a large influence on DDT uptake kinetics. In sediment exposures (SED) to a trace concentration, the uptake clearance rate (mgoc/g lipids/h) was two times more efficient and the elimination rate was five times faster in mature males than in mature females.
Environmental Toxicology and Chemistry, 2001
The amphipods Hyalella azteca and Diporeia spp. were exposed to sediments dosed with dichlorodiph... more The amphipods Hyalella azteca and Diporeia spp. were exposed to sediments dosed with dichlorodiphenyltrichloroethane (DDT), and the toxicity and toxicokinetics were determined. The toxicity was evaluated with the equilibrium partitioning (EqP) and critical body residue approaches. The DDT in the sediments degraded during the equilibration period prior to organism exposure. Thus, the toxicity using EqP pore-water toxic units (TUs) was evaluated for DDT and its degradation product, dichlorodiphenyldichloroethane (DDD), as the ratio of the predicted interstitial water concentration divided by the water-only LC50 values. The sum of TUs (⌺TU) was assumed to best represent the toxicity of the mixture. For H. azteca, the 10-d LC50 was 0.98 and 0.33 ⌺TU for two experiments. For Diporeia spp., no toxicity was found in the first experiment with up to 3 ⌺TU predicted in the interstitial water. However, in the second experiment, the 28-d LC50 was 0.67 ⌺TU. These data suggest that the EqP approach approximately predicts the toxicity for the combination of DDT and DDD in sediment, provided a toxic unit approach is employed. The critical body residue approach also used TUs because DDT is biotransformed by H. azteca and because of the dual exposure to DDT and DDD. Because biotransformation was only determined in the second experiment, the critical body residue approach could only be evaluated for that case. The TUs were calculated as the ratio of the concentration in the live amphipods divided by the respective LR50 (residue concentration required to produce 50% mortality) values. The LR50 was 1.1 ⌺TU for H. azteca for the 10-d exposure and 0.53 for Diporeia spp. after a 28-d exposure. Thus, this approach was also quite successful in predicting the toxicity. The accumulation and loss rates for H. azteca were much greater than for Diporeia spp. Thus, 10-d exposures represent steady-state conditions for H. azteca, while even at 28-d, the Diporeia spp. are not at steady state.
Environmental Toxicology and Chemistry, 2005
The lethal toxicity of the explosive compounds 14 C-labeled 2,4,6-trinitrotoluene (TNT) and nonra... more The lethal toxicity of the explosive compounds 14 C-labeled 2,4,6-trinitrotoluene (TNT) and nonradiolabeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to the estuarine amphipod Eohaustorius estuarius was investigated in 10-d spiked sediment exposures. The 10-d median lethal concentration (LC50) was determined using the sum molar initial concentration of TNT, aminodinitrotoluenes (ADNTs), and diaminonitrotoluenes (DANTs), as determined by high-performance liquid chromatography (HPLC), and collectively referred to as HPLC-TNT*. Despite expectations of higher toxicity in sandy sediment (Yaquina Bay [YB], OR, USA) compared to relatively fine-grained sediment (San Diego Bay [SDB], CA, USA), LC50 values were similar: 159 and 125 mol/kg, for YB and SDB sediments, respectively. When expressed as the sum of TNT and all its degradation products ( 14 C-TNT*), LC50s were approximately two times the corresponding LC50s determined by HPLC. The HPLC-TNT* fraction likely corresponds to the most bioavailable and toxic transformation products. The concentrations of 14 C-TNT* in tissues were substantially higher than those for HPLC-TNT*, suggesting that compounds other than TNT and its major aminated transformation products were prevalent. Critical body residues were similar for exposures to SDB (11.7 mol/kg) and YB sediments (39.4 mol/kg), despite marked differences in the nature of compounds available for uptake in the exposure media. The critical body residues for E. estuarius are lower than those reported for other aquatic invertebrates (83-172 mol/kg). Unlike observations for TNT, RDX was only loosely associated with SDB sediment, with near complete recovery of the parent compound by chemical analysis. Exposure to RDX did not result in significant mortality even at the highest measured sediment concentration of 10,800 mol/kg dry weight, nor tissue concentrations as high as 96 mol/kg wet weight. The lack of RDX lethal effects in this study is consistent with results reported for other invertebrate species.
Chemosphere, 2005
Little is currently known regarding the toxicokinetics of TNT in fish. In the present study, the ... more Little is currently known regarding the toxicokinetics of TNT in fish. In the present study, the bioconcentration and distribution of trinitrotoluene (TNT) and TNT biotransformation products was investigated in juvenile channel catfish by exposing catfish to 14C-labeled TNT in water. Uptake experiments showed relatively fast rates (k(u)=10.1 ml g(-1) h(-1)) for TNT from the water; however, bioconcentration factors for TNT were low (0.79 ml g(-1)) due to rapid biotransformation and potential elimination of TNT. Accumulation of extractable radioactivity (TNT and all extractable biotransformation products) was much greater (BCF=10.5 ml g(-1)) than that for parent compound. TNT (parent compound) bioconcentrated to the greatest extent in the gills of the fish, while total radioactivity bioconcentrated to the greatest extent in the viscera. Residual portions of the fish that contained muscle and skin had lower concentrations of TNT than the whole fish, indicating that ingestion of fish fillets would result in decreased exposure to human consumers. Although the bioconcentration potential of TNT is very low, future research needs to be conducted to identify the biotransformation products that make up most of the radioactivity in exposed fish and evaluate their potential to promote toxicity.
Marine Ecology-progress Series, 1997
The lethal and sublethal toxlclty of phendnthrene (a polycyclic aromatic hydrocarbon, PAH) to 2 s... more The lethal and sublethal toxlclty of phendnthrene (a polycyclic aromatic hydrocarbon, PAH) to 2 species of meiobenthic estuarine harpacticoid copepods (Schfzopera knabeni dnd Nitocra lacustrfs) was ~nvestlgated Individuals of different life stages ( n a u p l~u s copepodite, adult male and female) were exposed to sediment-associated phenanthrene In separate 10 d bioassays Overall A' lacustns (10 d LCj, values ranglng from 43 to 105 pg g ' d~y wt) was more sensitive than S knabeni (10 d LCSD values ranging from 84 to 349 pg g ' dry \vt) Signlflcant differences In life-stage-speclfic sensitivity wele observed for S knabeni, with the nauplll belng most seniltive tolloived by copepodltes and adults, adult males and females \Yere equally sensltlve For N Iacustris females wele significantly more sensltlve than all other stages no s i g n~f~c a n t d~tferences \yere evldent among the other stages Phenanthrene effects on offspring productlon were invest~gated In the adult 10 d b~oassay Significant decreases in offspring productlon occurred at sublethal concentratlons for S knabenl (as low as 22 1-19 g.' d r y wt) but d t concentratlons In the same lange as the 10 d LC5,values for A' ldcustr~s In addition phenanthrene slgnlficantly prolonged embryonic and larval development and decreased e g g hatching success for both species Our results suggest that PAHs have a negative effect on the reprod u c t~o n of melobenthic copepods at sublethal concentrations mostly due to a decrease In brood prod u c t~o n rate and impalrlnent of hatchlng Overall, deleterious effects were manifested in the same range of concentratlons for both species but deflnite specles-spec~flc differences In the pattern of responses were evident KEY WORDS Sedlment tox~city Copepod , Life h~story Meiobenthos Phenanthrene 0 Inter-Research 1997