Interlaboratory variability of amphipod sediment toxicity tests in a cooperative regional monitoring program

Marine sediment toxicity tests are widely applied in monitoring programs, yet relatively little is known about the comparability of data from different laboratories. The need for comparability information is increased in cooperative monitoring programs, where multiple laboratories (often with variable skill levels) perform toxicity tests. An interlaboratory comparison exercise was conducted among seven laboratories in order to document the comparability of sediment toxicity measurements during the Bight'98 regional sediment survey in southern California. Sediments from four stations in Los Angeles and Long Beach Harbors were tested using a 10-day survival test of the amphipod Eohaustorius estuarius. All laboratories successfully performed the sediment test and associated reference toxicant test. Statistically significant differences were found in mean amphipod survival rates among some laboratories for the field-collected sediments, but there was little evidence of a consistent bias among laboratories. Although the reference toxicant test indicated a five-fold variation in test sensitivity among laboratories, these results were not accurate predictors of interlaboratory performance for the sediment tests. The laboratories demonstrated excellent concordance (Kendall's W = 0.91) in ranking the field-collected sediments by toxicity. Agreement on classifying the sediments into categories (nontoxic, moderately toxic, and highly toxic) based upon the percent of survival was best for highly toxic sediments. An analysis of test precision based upon the variance among replicates within a test indicated that the measured survival rate for a sample may vary by up to 12 percentage points from the actual response.     

Using the Sediment Quality Triad to characterize baseline conditions in the Anacostia River, Washington, DC, USA

The Sediment Quality Triad (SQT) consists of complementary measures of sediment chemistry, benthic community structure, and sediment toxicity. We applied the SQT at 20 stations in the tidal portion of the Anacostia River from Bladensburg, MD to Washington, DC to establish a baseline of conditions to evaluate the effects of management actions. Sediment toxicity was assessed using 10-day survival and growth tests with the freshwater amphipod, Hyalella azteca and the midge, Chironomus dilutus. Triplicate grabs were taken at each station for benthic community analysis and the Benthic Index of Biotic Integrity (B-IBI) was used to interpret the data. Only one station, #92, exhibited toxicity related to sediment contamination. Sediments from this station significantly inhibited growth of both test species, had the highest concentrations of contaminants, and had a degraded benthic community, indicated by a B-IBI of less than 3. Additional sediment from this station was tested and sediment toxicity identification evaluation (TIE) procedures tentatively characterized organic compounds as the cause of toxicity. Overall, forty percent of the stations were classified as degraded by the B-IBI. However, qualitative and quantitative comparisons with sediment quality benchmarks indicated no clear relationship between benthic community health and contaminant concentrations. This study provides a baseline for assessing the effectiveness of management actions in the Anacostia River.     

Toxicity of Surficial Sediments from Sydney Harbour and Vicinity, Australia

The toxicological responses of three species to 103 surficial saltwater sediment samples from Sydney Harbour, and coastal lakes and estuaries on the south-east coast of New South Wales, Australia, were tested in a battery of four to six laboratory toxicity tests. This is the first large-scale toxicological study of sediments in Australia, the objective of which is to assess the protective and predictive abilities of North American biological effects-based sediment quality guidelines, recently adopted in Australia. Amphipods were exposed to whole sediments in survival and reburial tests, sea urchin fertilisation and larval development tests were conducted on porewaters, and bacterial bio-luminescence (Microtox) tests were conducted on organic solvent extracts and porewaters. Local indigenous species were used for the amphipod and sea urchin tests (Corophium sp. and Heliocidaris tuberculata, respectively). A wide range of responses, from <25 to 100% of negative controls were observed in all tests. Mean control-adjusted responses ranged from 46 to 96% for all tests. The percentages of highly toxic samples ranged from 11 to 83% in the various tests. The order of test sensitivity was: amphipod survival < Microtox test of porewaters < amphipod reburial < sea urchin larval development < sea urchin fertilisation < Microtox test of solvent extracts. Concordance between toxicity tests in classifying samples as highly toxic or not, ranged from 47 to 79%, indicating some similarities between test results, but not complete equivalence. Combined toxicity test results showed that the incidence of highly toxic responses occurring in the majority of tests (75-100% of tests) was low (5% of samples), but a large percentage of samples had highly toxic results in at least one test (76% of samples). Toxicity was more pervasive in the Sydney region than in coastal lakes and estuaries south of Sydney. The current study demonstrated the utility of indigenous invertebrate species and the Microtox bacterium in a sediment toxicity test battery for Australian saltwater sediments.     

Toxicity of sediment pore water in Puget Sound (Washington, USA): a review of spatial status and temporal trends

Data from toxicity tests of the pore water extracted from Puget Sound sediments were compiled from surveys conducted from 1997 to 2009. Tests were performed on 664 samples collected throughout all of the eight monitoring regions in the Sound, an area encompassing 2,294.1 km². Tests were performed with the gametes of the Pacific purple sea urchin, Strongylocentrotus purpuratus, to measure percent fertilization success as an indicator of relative sediment quality. Data were evaluated to determine the incidence, degree of response, geographic patterns, spatial extent, and temporal changes in toxicity. This is the first survey of this kind and magnitude in Puget Sound. In the initial round of surveys of the eight regions, 40 of 381 samples were toxic for an incidence of 10.5 %. Stations classified as toxic represented an estimated total of 107.1 km², equivalent to 4.7 % of the total area. Percent sea urchin fertilization ranged from >100 % of the nontoxic, negative controls to 0 %. Toxicity was most prevalent and pervasive in the industrialized harbors and lowest in the deep basins. Conditions were intermediate in deep-water passages, urban bays, and rural bays. A second round of testing in four regions and three selected urban bays was completed 5–10 years following the first round. The incidence and spatial extent of toxicity decreased in two of the regions and two of the bays and increased in the other two regions and the third bay; however, only the latter change was statistically significant. Both the incidence and spatial extent of toxicity were lower in the Sound than in most other US estuaries and marine bays.     

A ten year summary of concurrent ambient water column and sediment toxicity tests in the Chesapeake Bay watershed: 1990-1999

The goal of this study was to identify the relative toxicity ofambient areas in the Chesapeake Bay watershed by using a suiteof concurrent water column and sediment toxicity tests at seventy-five ambient stations in 20 Chesapeake Bay rivers from1990 through 1999. Spatial and temporal variability was examinedat selected locations throughout the 10 yr study. Inorganicand organic contaminants were evaluated in ambient water andsediment concurrently with water column and sediment tests toassess possible causes of toxicity although absolute causalitycan not be established. Multivariate statistical analysis wasused to develop a multiple endpoint toxicity index (TOX-INDEX) at each station for both water column and sediment toxicity data. Water column tests from the 10 yr testing period showed that49% of the time, some degree of toxicity was reported. The mosttoxic sites based on water column results were located inurbanized areas such as the Anacostia River, Elizabeth River andthe Middle River. Water quality criteria for copper, lead,mercury, nickel and zinc were exceeded at one or more of thesesites. Water column toxicity was also reported in localizedareas of the South and Chester Rivers. Both spatial and temporalvariability was reported from the suite of water column toxicitytests. Some degree of sediment toxicity was reported from 62% of the tests conducted during the ten year period. The ElizabethRiver and Baltimore Harbor stations were reported as the most toxic areas based on sediment results.Sediment toxicity guidelines were exceeded for one or more of thefollowing metals at these two locations: arsenic, cadmium,chromium, copper, lead, nickel and zinc. At the Elizabeth Riverstations nine of sixteen semi-volatile organics and two of sevenpesticides measured exceeded the ER-M values in 1990. Ambientsediment toxicity tests in the Elizabeth River in 1996 showedreduced toxicity. Various semi-volatile organics exceeded the ER-M values at a number of Baltimore Harbor sites; pyrene anddibenzo(a,h)anthracene were particularly high at one of thestations (Northwest Harbor). Localized sediment toxicity was alsoreported in the Chester, James, Magothy, Rappahannock, andPotomac Rivers but the link with contaminants was not determined.Both spatial and temporal variability was less for sedimenttoxicity data when compared with water column toxicity data. Acomparison of water column and sediment toxicity data for thevarious stations over the 10 yr study showed that approximatelyhalf the time agreement occurred (either both suite of testsshowed toxicity or neither suite of tests showed toxicity).     

Integrative sediment assessment at Atlantic Spanish harbours by means of chemical and ecotoxicological tools

This study refers to the integrative assessment of sediment quality in three harbour areas at the Spanish Atlantic Coast: Vigo (Northwestern Spain), Bilbao and Pasajes (Northern Spain). At each site, two lines of evidence have been considered: chemical analyses (metal, PAH and PCB concentrations in sediments and ammonia concentration in bioassays) and toxicity tests (Microtox®, Corophium sp. marine amphipod and Paracentrotus lividus sea urchin larvae). Chemical and ecotoxicological results have been integrated by means of a tabular matrix and a multivariate factorial analysis (FA). Highly toxic samples have been characterised in Vigo and Pasajes harbours while Bilbao samples present toxicity levels ranging from non-toxic to moderately toxic. High toxicity is associated with high levels of contaminants whereas confounding factors (ammonia, organic matter and mud) have been identified to be the main cause of low to moderate toxicity. Based on the obtained results, it can be concluded that deriving potential toxicity of sediments based on comparison with Sediment Quality Guidelines (SQGs) is in agreement to toxicity results in areas presenting high levels of contaminants. However, at lower levels of toxicity (low to moderate), the mismatch between the potential toxicity (SQG approach) and the toxicity measured by bioassays is greater, as the former only accounts for chemical concentrations, without considering the interaction between contaminants and the effect of confounding factors. Contrarily, the multivariate analysis seems to be a robust tool for the integration and interpretation of different lines of evidence in areas affected by different sources of contamination.     

Disposal of dredged sediments in tropical soils: ecotoxicological effects on earthworms

The upper limit concentrations of metals established by international legislations for dredged sediment disposal and soil quality do not take into consideration the properties of tropical soils (generally submitted to more intense weathering processes) on metal availability and ecotoxicity. Aiming to perform an evaluation on the suitability of these threshold values in tropical regions, the ecotoxicity of metal-contaminated dredged sediment from the Guanabara Bay (Rio de Janeiro, Brazil) was investigated. Acute and avoidance tests with Eisenia andrei were performed with mixtures of dredged sediment with a ferralsol (0.00, 6.66, 13.12, 19.98, and 33.30 %) and a chernosol (0.00, 6.58, 13.16, 19.74, and 32.90 %). Mercury, lead, nickel, chromium, copper, and zinc concentrations were measured in test mixtures and in tissues of surviving earthworms from the acute tests. While ferralsol test mixtures provoked significant earthworm avoidance response at concentrations ≥13.31 %, the chernosol mixtures showed significant avoidance behavior only at the 19.74 % concentration. The acute tests showed higher toxicity in ferralsol mixtures (LC50?=?9.9 %) compared to chernosol mixtures (LC50?=?16.5 %), and biomass increased at the lowest sediment doses in treatments of both test soils. Most probably, the expansive clay minerals present in chernosol contributed to reduce metal availability in chernosol mixtures, and consequently, the ecotoxicity of these treatments. The bioconcentration factors (BCF) for zinc and copper were lower with increasing concentrations of the dredged sediment, indicating the existence of internal regulating processes. Although the BCF for mercury also decreased with the increasing test concentrations, the known no biological function of this metal in the earthworms metabolism lead to suppose that Hg measured was not present in bioaccumulable forms. BCFs estimated for the other metals were generally higher in the highest dredged sediment doses.     

Pesticide concentrations in water and sediment and associated invertebrate toxicity in Del Puerto and Orestimba Creeks, California, 2007�C2008

The California??s San Joaquin River and its tributaries including Orestimba (ORC) and Del Puerto (DPC) Creeks are listed on the 2006 US EPA Clean Water Act §303(d) list for pesticide impairment. From December 2007 through June 2008, water and sediment samples were collected from both creeks in Stanislaus County to determine concentrations of organophosphorus (OP) and pyrethroid insecticides and to identify toxicity to Ceriodaphnia dubia and Hyalella azteca. OPs were detected in almost half (10 of 21) of the water samples, at concentrations from 0.005 to 0.912 ??g L^???1. Diazinon was the most frequently detected OP, followed by chlorpyrifos and dimethoate. Two water samples were toxic to C. dubia; based on median lethal concentrations (LC₅₀), chlorpyrifos was likely the cause of this toxicity. Pyrethroids were detected more frequently in sediment samples (18 detections) than in water samples (three detections). Pyrethroid concentrations in water samples ranged from 0.005 to 0.021 ??g L^???1. These concentrations were well below reported C. dubia LC₅₀s, and toxicity was not observed in laboratory bioassays. Cyfluthrin, bifenthrin, esfenvalerate, and ??-cyhalothrin were detected in sediment samples at concentrations ranging from 1.0 to 74.4 ng g^???1, dry weight. At DPC, all but one sediment sample caused 100% toxicity to H. azteca. Based on estimated toxicity units (TUs), bifenthrin was likely responsible for this toxicity and ??-cyhalothrin also contributed. At ORC, survival of H. azteca was significantly reduced in four of the 11 sediment samples. However, pyrethroids were detected in only two of these samples. Based on TUs, bifenthrin and ??-cyhalothrin likely contributed to the toxicity.     

The response of nematode assemblages to intensive mussel farming in coastal sediments (Southern Brazil)

The impact of mussel farms on the benthic environment was investigated using free-living nematode assemblages as indicators of environmental condition of the Enseada do Brito, a shallow embayment in South Brazil. The studied area is located at the State of Santa Catarina, responsible for 90% of the production of mussel farmed in the country. Samplings were carried out quarterly, from July 2004 to May 2005, below mussel ropes and at control sites located 300 m apart from the longlines. The results suggested that the mussel culture changed ecological functioning of the benthic environment at studied coastal embayment. The intense organic loads due to the biodeposition of the mussel farms, which had been in production for more than 10 years, have turned fine and well-sorted sand bottoms into a muddy deposit with significantly higher total organic content than the control. The number of nematode genera, diversity, dominance and trophic diversity were significantly lower under the mussel farms than at the control sites. The mussel farms biodeposition had also affected the temporal variability of nematode assemblages, which was detected only for samples at the control sites. The low depth and environmental energy, together with the age of the farms, were probably responsible for the observed changes in the nematode assemblages.     

Spatial Extent of Sediment Toxicity in U.S. Estuaries and Marine Bays

Acute, laboratory toxicity tests were performed by the National Oceanic and Atmospheric Administration (NOAA) on 1543 surficial sediment samples collected during 1991 through 1997 throughout 25 estuaries and marine bays. Selected areas were sampled along the Atlantic, Gulf of Mexico, and Pacific coasts. The toxicity of each sample was determined with 10-day amphipod survival tests performed with solid-phase (bulk) sediments. Collectively, the 1543 samples tested through 1997 represented a total area of approximately 7300 km². Toxicity was observed with the amphipod survival tests in samples that represented approximately 6% of the combined area. Using similar tests conducted on samples collected in different, but overlapping, study areas, the U.S. Environmental Protection Agency (EPA) estimated that approximately 7% of the combined estuarine area sampled was toxic. Generally, toxicity was most severe in northeastern and southwestern estuaries and least prevalent in southeastern and northwestern areas. However, considerable portions of the Pacific coast have not been tested with the same methods. In tests of CYP1A enzyme induction (n=464), samples were toxic that represented about 5% of the combined study areas. Toxicity was much more widespread, however, when the results of two sub-lethal tests were analyzed. Significant results occurred in samples that represented approximately 25% and 39% of the study areas in tests of sea urchin fertilization (n=1309) and microbial bioluminescence (n=1215), respectively.     

An interlaboratory comparison of sediment elutriate preparation and toxicity test methods

Elutriate bioassays are among numerous methods that exist for assessing the potential toxicity of sediments in aquatic systems. In this study, interlaboratory results were compared from 96-h Ceriodaphnia dubia and Pimephales promelas static-renewal acute toxicity tests conducted independently by two laboratories using elutriate samples prepared from the same sediment. The goal of the study was to determine if the results from the elutriate tests were comparable between two U.S. Environmental Protection Agency (USEPA) laboratories when different elutriate preparation procedures were employed by each lab. Complete agreement in site characterization was attained in 22 of the 25 samples for both bioassays amongst each lab. Of the 25 samples analyzed, 10 were found to be toxic to at least one of the species tested by either laboratory. The C. dubia elutriate tests conducted by the National Exposure Research Laboratory (NERL) indicated that 7 of the 25 sediment samples were toxic, while 8 sediment samples were characterized as such in testing conducted by USEPA Region 6 (Region 6). The P. promelas elutriate tests conducted by NERL determined 8 samples as toxic, while Region 6 tests displayed toxicity in 5 of the samples. McNemar's test of symmetry for C. dubia (S?=?0.33, p?=?0.5637) and P. promelas (S?=?3.0, p?=?0.0833) tests indicated no significant differences in designating a site toxic between NERL and Region 6 laboratories. Likewise, Cohen's kappa test revealed significant agreement between NERL and Region 6 C. dubia (K?=?0.7148, p?<?0.01) and P. promelas (K?=?0.6939, p?<?0.01) elutriate tests. The authors conclude that differences in interlaboratory elutriate preparation procedures have no bearing on the ability of either the C. dubia or P. promelas bioassay testing methods to detect toxicity while yielding similar results.     

Weighing the evidence of ecological risk from PAHs contamination in the estuarine environment of Salina Cruz Bay, México

Results of bulk-phase chemical measurements, toxicological tests combined with bioaccumulation measures in fishes, were used to evaluate the toxicity of the 16 USEPA priority polycyclic aromatic hydrocarbons from the sediment collected from eight stations of the Ventosa Estuarine System, located close to the main center of processing oil in the Mexican Pacific coast. Levels of the sum of polycyclic aromatic hydrocarbons varied from 22 to 6,850 μg kg^???1 dry weight. Based on sediment quality guidelines, the compounds with high environmental priority were acenaphtylene, acenaphtene, and phenanthrene. Acute toxicity tests with Vibrio fischeri and Daphnia magna as well as chronic toxicity with Panagrellus redivivus were performed. The quantification of hepatic ethoxyresorufin O-deethylase activity was used to assess the induction of the mixed function oxygenase system of brown trout. However, because it is often difficult to blend the results from such very different assays into a unified decision about the potential for impacts, a weight-of-evidence (WOE) approach to sediment quality investigations was followed. These assays provided measurement endpoints that could be used to develop an overall evaluation of the potential for environmental impacts from the oil processing operations. WOE provides a valuable tool for assessing the results of environmental investigations because it provides a framework for considering the strengths and weaknesses of environmental measurements, an approach for addressing uncertainty in the measurements, and documentation of the evaluation and its assumptions.     

Water chemistry influences the toxicity of silver to the green-lipped mussel Perna viridis

The study determined the influence and relative importance of water chemistry parameters (pH, alkalinity, hardness) on the acute toxicity of silver to the green mussel Perna viridis. A preliminary bioassay revealed that 4 mg L^???1 of silver caused 50% mortality (LC₅₀) in 96 h for mussels placed in seawater with pH 8.5, hardness 1,872 mg L^???1, and alkalinity 172 mg L^???1. Mortality of mussels increased with decreasing pH and increasing hardness and alkalinity variables. In contrast the mortality decreased with increasing pH and decreasing hardness and alkalinity values. The water chemistry also affected the concentration of sliver in experimental seawater and bioaccumulation of silver in mussels. The results revealed that the chemical properties of seawater must be considered while conducting toxicity tests with metals like silver. The possible explanations for the influence of water chemistry on silver toxicity to P. viridis are discussed.     

Sedimentation and remobilization of radiocesium in the coastal area of Ibaraki, 70 km south of the Fukushima Dai-ichi Nuclear Power Plant

Sedimentation and remobilization processes of radiocesium were investigated from time-series observations at nine stations in the coastal area of Ibaraki, 70–110 km south of the Fukushima Dai-ichi Nuclear Power Plant (1FNPP). Sediment samples were collected four times between June 2011 and January 2012, and concentrations of radiocesium as well as sediment properties such as grain size and elemental compositions were analyzed. Cumulative inventory of ¹³⁷Cs in sediment (0–10 cm) ranged between 4?×?10³ and 3?×?10⁴ Bq/m² as of January 2012. This amount was generally higher at stations nearer 1FNPP and has remained at the same level since August 2011. From these results, it can be inferred that dissolved radiocesium advected southward from the region adjacent to the 1FNPP and was deposited to the sediment of the study area in the early stage after the accident. The incorporation of radiocesium into sediments was almost irreversible, and higher concentrations of ¹³⁷Cs were obtained from the finer-grained fraction of sediments. In the northern offshore stations, resuspension of the fine-grained sediments formed a high-turbidity layer 10–20 m above the seabed. These results indicate that radiocesium-enriched fine particles were transported from the coast to offshore regions through the bottom high-turbidity layer.     

Physicochemical and ecotoxicological based assessment of bottom sediments from the Luján River basin, Buenos Aires, Argentina

The physicochemical analysis of bottom sediments of the Lujan River was done on samples from 14 sites situated along its course and covered grain size and organic matter, total N and P, sulfides, heavy metals, organochlorine, and pyrethroid pesticides. In addition, acute 10-day whole-sediment laboratory toxicity tests were carried with each sample, using the native amphipod Hyalella curvispina as test organism. In order to correlate both types of results, data were assessed by multivariate analysis, including principal component analysis (PCA). The physicochemical profile of samples resulted similar along the river course, though several anomalous data were registered in the middle course of the river, mainly in samples taken downstream a large industrial complex; with a few exceptions in upper basin sites characterized by the dominance of agricultural activities, the pesticides concentration were consistently below the analytical detection limits. Almost 50 % of the samples induced adverse effects on the amphipod when testing sublethal and lethal end points. The toxicity of the samples in terms of survival rate was extremely high in two sites, in particular in samples taken downstream the Pilar industrial complex. The integration of a selection of physicochemical and toxicological parameters of the sediments by PCA allowed discriminating areas of the river basin according the type and intensity of their particular pollution condition.     

Habitat Conditions and Correlations of Sediment Quality Triad Indicators in Delaware Bay

This paper summarizes sampling results from NOAA's National Status and Trends (NS&T) Program for marine environmental quality in Delaware Bay. A stratified-random design was used to determine the spatial extent of sediment contamination and toxicity in Delaware Bay from offshore stations in the coastal zone, the lower estuary, the upper estuary, the fresh/salt mixing zone, and tidal fresh areas. Sediment samples were taken for chemical analyses of major classes of environmental contaminants, a suite of toxicity bioassays, and benthic macrofaunal community assessment to identify patterns of resident species. The tidal-fresh areas and portions of the mixing zone of the study area were heavily contaminated. Contaminant concentrations were frequently above the 90th percentile of EMAP Virginian Province levels. PAHs in the sediment were higher than previously documented, with a major component of PAHs being pyrogenic in origin. Bioassay results were highly variable. Toxicity and contaminant levels were correlated when aggregated into indices, but were only marginally correlated with benthic community impacts. High and low abundance stations were found in all zones. Most of the tidal fresh stations were dominated by pollution tolerant species. Species diversity and abundance were generally lowest in the fresh/salt mixing zone.     

Evaluation of a bioassays battery for ecotoxicological screening of marine sediments from Ionian Sea (Mediterranea Sea, Southern Italy)

Sediments are an ecologically important component of the aquatic environment and may play a key role in mediating the exchange of contaminants between particulate, dissolved, and biological phases. For a comprehensive assessment of potential sediment toxicity, the use of a single species may not detect toxicant with a specific mode of action. Therefore it is advisable to carry out ecotoxicological tests on a base-set of taxa utilizing test species belonging to different trophic levels. This paper describes the ecotoxicological evaluation of marine sediments from seven sites of Mar Piccolo estuary (Southern, Italy), four of them were located in the first inlet and three in the second inlet of Mar Piccolo estuary. Sediment samples from a site in Taranto Gulf were used as control sediment. Dunaliella tertiolecta, Tigriopus fulvus, Mytilus galloprovincialis, and Corophium insidiosum, were employed to identify the quality of sediments. The integration of biological tests results showed that all sampling sites located in the first inlet of Mar Piccolo were identified as toxic, according to all tests, while the sites of second inlet were found not toxic. The results obtained in this study indicate that the use of a battery of biological tests have important implications for risk assessment in estuarine e coastal waters.     

Preliminary results of laboratory toxicity tests with the mayfly, Isonychia bicolor (Ephemeroptera: Isonychiidae) for development as a standard test organism for evaluating streams in the Appalachian coalfields of Virginia and West Virginia

Selecting the most appropriate test species for sediment and water column assays has been a primary goal for ecotoxicologists. Standard test organisms and established test guidelines exist, but the USEPA-recommended species may not be the most sensitive organisms to anthropogenic inputs. This paper describes preliminary results of toxicity tests with the mayfly, Isonychia bicolor (Ephemeroptera). Results suggested that Isonychia were moderately sensitive to NaCl after 96 h with an average LC₅₀ value of 3.10 g NaCl per liter. This value decreased after 7 days of exposure, resulting in a mean LC₅₀ value of 1.73 g NaCl per liter. When exposed to a coal-mine-processed effluent, Isonychia generated LC₅₀ values that ranged from 13% to 39% effluent. I. bicolor were more sensitive to the coal processing effluent than Ceriodaphnia dubia with conductivity lowest observable effects concentration (LOEC) values for mayfly survivorship that ranged from 1,508 to 4,101 μS/cm, while LOEC values for C. dubia reproduction ranged from 2,132 to 4,240 μS/cm.     

Polycyclic aromatic hydrocarbon concentrations,mutagenicity, and Microtox® acute toxicity testing of Peruvian crude oil and oil-contaminated water and sediment

The oil industry is a major source of contamination in Peru, and wastewater and sediments containing oil include harmful substances that may have acute and chronic effects. This study determined polycyclic aromatic hydrocarbon (PAH) concentrations by GC/MS, mutagenicity using TA98 and TA100 bacterial strains with and without metabolic activation in the Muta-ChromoPlate? test, and Microtox® 5-min EC₅₀ values of Peruvian crude oil, and water and sediment pore water from the vicinity of San José de Saramuro on the Marañón River and Villa Trompeteros on the Corrientes River in Loreto, Peru. The highest total PAH concentration in both areas was found in water (Saramuro?=?210.15 μg/ml, Trompeteros?=?204.66 μg/ml). Total PAH concentrations in water from San José de Saramuro ranged from 9.90 to 210.15 μg/ml (mean?=?66.48 μg/ml), while sediment pore water concentrations ranged from 2.19 to 70.41 μg/ml (mean?=?24.33 μg/ml). All water samples tested from Saramuro and Trompeteros sites, and one out of four sediment pore water samples from Trompeteros, were found to be mutagenic (P?<?0.001). One sediment pore water sample in Saramuro was determined to have a measurable toxicity (Microtox EC₅₀?=?335.1 mg/l), and in Trompeteros, the EC₅₀ in water and sediment pore water ranged from 25.67 to 133.86 mg/l. Peruvian crude oil was mutagenic using the TA98 strain with metabolic activation, and the EC₅₀ was 17.18 mg/l. The two areas sampled had very high PAH concentrations that were most likely associated with oil activities, but did not lead to acute toxic effects. However, since most of the samples were mutagenic, it is thought that there is a greater potential for chronic effects.     

Distribution of polycyclic aromatic hydrocarbons in marine sediments and their potential toxic effects

The presence of polycyclic aromatic hydrocarbons (PAHs) in samples of marine sediments from Paranagua Bay on the southern coast of Brazil was investigated. Paranagua Bay is the location of a major port, one of the busiest in Brazil. The region has a great potential for tourism and port-related industries and activities. Due to its characteristics as a venue for tourism, two major campaigns were planned: one 3 months before the summer (between December and February) and a second after the vacation season. Total concentration of PAHs in sediments ranged from 26.33 to 406.76 ng/g (in both campaigns). The highest values were found in sediments with higher organic carbon content. We found no substantial differences between the two campaigns, and the values are quite similar. Ternary diagrams show that points P5 and P6 were considered polluted, while others were classified as non-polluted. Molecular ratios indicate that the main sources of PAHs are petrogenic and the burning of fossil fuels. Sediment toxicity was assessed by the presence of PAHs in terms of benzo(a)pyrene (BaP) concentration. The toxicity of PAHs mixtures can be characterized more accurately by developing and establishing toxic equivalency factors (TEFs) for PAHs. Considering TEFs, the BaP_eq concentrations vary between 0.264 and 5.922 ng/g (considering both campaigns). Thus, two points are above the maximum level recommended (3 ng/g) by the Netherlands sediment quality guidelines. In fact, sites P5 and P6 apparently are exposed to a greater number of pollution sources, thus reflecting the higher concentration of PAHs compounds in sediments.