Anaerobic Degradation of Di-<Emphasis Type="Italic">n</Emphasis>-butyl Phthalate and Di-(2-ethylhexyl) Phthalate in Sludge

No abstract available.     

Uptake and Elimination of 4-Nonylphenol by the Clam <Emphasis Type="Italic">Tapes philippinarum</Emphasis>

The present study is the first dealing with the accumulation and elimination of 4-nonylphenol (NP) by the Manila clam, Tapes philippinarum. Specimens of T. philippinarum were exposed to NP-spiked seawater, and the NP contents in whole soft tissue, gills, digestive gland, and haemolymph were measured. Actual NP concentrations in seawater and microalgae (Isochrysis galbana) used for feeding were also determined, and the algal bioconcentration factor (BCF) value (640 ml/g) was calculated. Volatilisation was the main cause of dissipation of NP from experimental tanks, attaining up to 78% of the NP added. NP accumulated by algae used for feeding was negligible with respect to the total added NP, and we concluded that in our experiments, clams accumulated NP mainly from water and not food intake. Accumulation followed a two-compartment, first-order rate coefficient model, with an uptake rate coefficient of 13.8 ± 0.6 mL g⁻¹h⁻¹(fresh weight [fw]) and an elimination coefficient of 0.0070 ± 0.0005 h⁻¹. Ninety percent of the steady state was reached after 14 days of exposure, and the BCF value at the steady state was 1958 ± 158 mL g⁻¹ fw (1.8 ± 0.2^.10⁵ based on lipid weight). Slightly less than 50% of NP bioaccumulated through water was allocated into the gills, whereas the rest was found in the digestive gland. In the first 8 hours, clams eliminated 51% of the NP accumulated, and only 2% of the NP accumulated was detected in the clams at the end of the elimination phase (day 14). Two-compartment first-order decay model described the elimination of the accumulated NP by considering the clam as two compartments each with a different elimination rate. The sudden elimination of NP in the initial hours can be attributed to the elimination of NP accumulated into the gills and readily available for excretion (k _e = 0.30 ± 0.07 h⁻¹). The slower step of the elimination process should be the mobilisation of NP accumulated in internal organs, which must be carried into the haemolymph for excretion (k _e = 0.0091 ± 0.0002 h⁻¹). Because T. philippinarum has been demonstrated to accumulate NP dissolved in water, high NP levels can be hypothesised in clams from highly contaminated environments. This research was performed according to all national and international guidelines for animal welfare.     

Synthetic Musk Toxicity to Early Life Stages of Zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>)

Synthetic musk substances have been found in a number of environmental samples. Some of these chemicals have been detected in concentrations above 1 g/L in water, which raises concern about possible effects on aquatic life. The toxicity of four synthetic musks, 4-tert-butyl-2,6-dimethyl-3,5-dinitrophenylethanone (musk ketone), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene), 1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthalenyl)ethanone (AHTN, tonalide) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-[g]-2-benzopyrane (HHCB, galaxolide), were studied in zebrafish by the use of two different early life-stage methods. In the first method, specific developmental characteristics during the first 48 hours were studied. In the second method, hatching and survival times were studied on eggs and larvae. The results on heart rate in the first test gave the following LOECs: musk ketone 10 g/L, musk xylene and AHTN 33 g/L, and HHCB showed no effect up to 1000 g/L. In the study of survival time, LOEC for musk ketone was 100 g/L, for musk xylene 33 g/L, and AHTN gave no effect on survival time up to 100 g/L. The LOECs for musk ketone, musk xylene, and AHTN in this study are in the range of what has been measured in sewage effluents and recipients, and consequently these substances may have adverse impact on wild fish.     

Uptake of Urea Nitrogen by <Emphasis Type="Italic">Oocystis borgei</Emphasis> in Prawn <Emphasis Type="Italic">(Litopenaeus vannamei)</Emphasis> Aquaculture Ponds

The goal of this study was to assess the rate of urea nitrogen uptake (ρ) by Oocystis borgei and the relationship between environmental factors and ρ. Light intensity, temperature, pH, salinity, and algal concentration, were used to construct an empirical model. The results showed that light intensity, algal concentration, pH and salinity had significant effects on ρ, and the optimal combination of environmental conditions for ρ was a temperature of 25°C, pH of 7.0, light intensity of 81 µmol m^?2 s^?1, salinity of 15‰, and algal concentration of 4.5?×?10⁸ cell L^?1–5.5?×?10⁸ cell L^?1. The model equation was ρ?=?2?×?10^?5?×?(A^0.363B^0.783C^0.045D^?0.503E)?+?0.0017, with a coefficient of determination (R²) of 0.83. No significant difference in variance was observed between the model-predicted values and the measured values (F?=?0.238, p?>?0.05), which demonstrated the high fitting degree of the simulation equation. This study provided valuable insight into the reduction of urea nitrogen levels in aquaculture water by O. borgei.     

Concentrations of Persistent Organic Pollutants in Masu Salmon, <Emphasis Type="Italic">Oncorhynchus masou</Emphasis>

The levels of persistent organic pollutants (POPs) were analyzed in muscle, liver and gills of masu salmon caught in northern Japan. Liver is known to be a major pool site for POPs but there is not much information regarding accumulation of POPs in gills. The salmon were caught at the end of the feeding migration, and the average gonadosomatic index of masu salmon was 0.51 ± 0.16. The total amount of POPs (μg) accumulated in each organ was calculated in order to compare the accumulation potential of each organ. Even though the liver comprises only 1.8%–2.32% of the whole body mass it accumulated 16% ± 8.6% of the total POPs. Similarly, gills comprise only 1.4%–2.1% of the body mass but accumulated 9.1% ± 3.8% of the total POPs. Conversely, muscle comprises 72%–78% of the body mass and it accumulated 75% ± 12% of the total POPs. These results suggest that the gills, in addition to the liver, are an important site for the pooling of high levels of POPs at the end of the feeding migration.     

Toxicopathic Branchial Lesions in Grass Carp (<Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>) Exposed to Chlorpyrifos

Present investigation aimed to assess the alterations in branchial architecture of Ctenopharyngodon idellus exposed to chlorpyrifos. 96 h LC50 of chlorpyrifos to C. idellus was found to be 7.24 µg/L. Fish were exposed chronically to 2.41 and 1.44 µg/L sublethal concentrations (ecologically relevant concentrations) of chlorpyrifos for 15, 30 and 60 days. The gills of the CPF exposed fish showed partially affected secondary lamellae with shortening and curling, increased inter-lamellar space, sloughed off epithelium, hyperplasia and necrosis of pavement cells. On 60 days exposure, more pronounced degenerative changes, including severe necrosis, hyperplasia and hypertrophy of pavement cells, eroded and uplifted lamellar epithelium were noticed. Ultrastructural alterations include distorted nucleus and mitochondria in pavement cells, marked contraction in cisternae of golgi complex. Particularly in chloride cells, abundant mitochondria with distorted shape and size, dilation in between their cristae and tubular network were observed. The severity of damage was more profound at 60 days exposure. Thus, the observed cytopathological lesions of fish gills can be used as sensitive biomarkers for pesticide contamination.     

Toxic Effects in <Emphasis Type="Italic">Siganus oramin</Emphasis> by Dietary Exposure to 4-<Emphasis Type="Italic">tert</Emphasis>-Octylphenol

The integrated toxicities of 4-tert-octylphenol (t-OP) on Siganus oramin were investigated by dietary administration at doses of 5, 25 and 125 mg/kg body weight over 28 days. Significant increase was observed in the activity of hepatic glutathione S-transferase at 125 mg/kg on both day 14 and 28 in males, and at all doses on day 28 in females, and in hepatosomatic index at 25 mg/kg on day 14 in both sexes. Plasma levels of testosterone and cortisol decreased significantly at all doses on day 28. Histopathologic changes in liver, spleen, intestine and testis deteriorated with increasing doses and duration. The results suggest that S. oramin is sensitive to t-OP, and the above endpoints may be potential biomarkers for evaluating toxicities of environmental pollutants such as t-OP.     

Characterization of Cadmium Uptake and Translocation in a Cadmium-Sensitive Mutant of Rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L. ssp. <Emphasis Type="Italic">japonica</Emphasis>)

To understand the physiological mechanism that confers Cd sensitivity/tolerance, Cd uptake and translocation by Cd-sensitive mutant and wild-type rice seedlings were characterized using radioactive tracer. Time-dependent Cd accumulation during 210 min was 1.8-fold higher in roots of the mutant than of wild-type rice. The kinetics of Cd uptake showed that two processes were involved: a first, fast, probably passive process and a second, slower, possibly physiological process. After 96 h, more Cd was translocated to the shoot of mutant compared with wild-type rice. Low temperature (2°C), carbonyl cyanide m-chlorophenylhydrazone, and dicyclohexylcarbodiimide inhibited Cd accumulation to a greater extent in mutant than wild-type rice, suggesting that metabolism plays a more important role in Cd uptake for the rice mutant. Cd uptake into the symplasm is linked to Ca²⁺ transport, as revealed by the inhibition of Cd accumulation by La and high Ca by equal percentages in both mutant and wild-type rice. Cd uptake and root-to-shoot translocation in the mutant were inhibited more markedly by Zn and Mn than in wild-type rice. This indicates that transport sites other than entry into the root symplasm are also stimulated in the mutant. The results suggest that enhanced absorption into the root and further accumulation in the shoot is one of the mechanisms involved in Cd accumulation and sensitivity, and the difference in Cd uptake and root-to-shoot translocation between mutant and wild-type rice may be mediated partly by energy supply and transporters for Zn and Mn.     

Phosphorus Enhances Cr(VI) Uptake and Accumulation in <Emphasis Type="Italic">Leersia hexandra</Emphasis> Swartz

The effects of P supplementation on chromium(VI) uptake by Leersia hexandra Swartz were studied using pot-culture experiment. P-deficiency and zero-P addition controls were included. The Cr(VI) uptake followed Michaelis–Menten kinetics. Compare with the control, the P-supply decreased the Michaelis constant (Km) by 16.9% and the P-deficiency decreased the maximum uptake velocity (V_max) by 18%, which indicated no inhibition and competition between P and Cr(VI) uptake by L. hexandra. Moreover, there were a synergistic action between P and Cr(VI) suggests that Cr(VI) uptake by the roots of L. hexandra may be an active process. The bioconcentration factor (BCF) and the transport factor (TF′) increased with the increase in P supply. The highest BCF was 3.6-folds higher than the control, indicating that the additional P contribute to a higher ability of L. hexandra transporting Cr from root to the aboveground parts.     

First Evidence of Altered Immune Responses and Resistance to Air Exposure in the Clam <Emphasis Type="Italic">Chamelea gallina</Emphasis> Exposed to Benzo(<Emphasis Type="Italic">a</Emphasis>)pyrene

Effects of benzo(a)pyrene [B(a)P] (at a nominal concentration of 0.5 mg/L) on immune responses of the clam Chamelea gallina were investigated after 1, 7, and 12 days exposure. Total hemocyte count (THC), hemocyte volume, phagocytic activity, lysozyme-like activity in both hemocyte lysate (HL) and cell-free hemolymph (CFH) were measured. As unexpected alterations in hemocyte adhesion capability were observed in short-term hemocyte cultures for phagocytosis assays after a 1-day exposure, an adhesion test (not included in the original experimental setup) was performed after 7 and 12 days of exposure only. The survival-in-air test was carried out to evaluate general stress conditions in B(a)P-exposed clams. No alterations in THC was observed, whereas exposure for 7 and 12 days to B(a)P significantly decreased phagocytic activity and adhesion capability when compared with controls. Significant decreases in lysozyme activity were observed in CFH and HL, with respect to controls. B(a)P was also shown to alter the resistance to air exposure of clams. The LT₅₀ values fell from 9 days in control clams to 7 days in 1-day-exposed animals, and from 6 days in control clams to 5 days in 7-day-exposed bivalves. No significant variations in LT₅₀ values were recorded after 12 days of exposure. Results highlight a relationship between B(a)P exposure and alterations in hemocyte functionality and suggest that the contaminant induced irreversible immunosuppression in C. gallina, by altering phagocytic activity, adhesion capability, and enzymatic activity. Conversely, reduction in resistance to air exposure was reversible, suggesting that impairment of important physiological functions of clams occurred in the first phases of exposure only.     

Bioaccumulation of Dietary Endocrine Disrupting Chemicals (EDCs) by the Polychaete, <Emphasis Type="Italic">Perinereis nuntia</Emphasis>

To investigate the biomagnification factor (BMF) of EDCs by the polychaete, Perinereis nuntia, organisms were exposed to EDCs through their diet. BMF values ranged from 0.001 to 0.028 indicating that EDCs were not biomagnified. Elimination rates were (0.20–0.25 day^?1) and were higher than uptake rate (0.0003–0.003 day^?1) verifying that EDCs were not biomagnified by P. nuntia due to their fast elimination. The calculated half-life of each EDC in this study varies from 2.76 to 3.45 days. Overall, the findings from this study demonstrated that the studied EDCs are not biomagnified in P. nuntia but exposure does occur from the diet.     

Kinetics of Cadmium Uptake and Subcellular Partitioning in the Earthworm <Emphasis Type="Italic">Eisenia fetida</Emphasis> Exposed to Cadmium-Contaminated Soil

To understand the bioaccumulation kinetics of cadmium (Cd) at the subcellular level, toxicokinetics and subcellular fractionation of Cd were determined for the terrestrial earthworm Eisenia fetida exposed to Cd-contaminated red soil. The bioaccumulation factor was 1.74 after exposure to soil containing 1 mg Cd/kg dry weight for 21 days. Four distinct compartments with different Cd-binding affinities were obtained by sequential centrifugations, including the cytosolic fraction (G), the organelles fraction (F), the granular fraction (D), and the tissue, cell membrane, and intact cell fraction (E). Most of the accumulated Cd in the organisms existed as fraction G. Cd bound to the tissue and cell membrane fraction (E) was <8% of total Cd. Only approximately 3% of Cd existed in fraction F, and <1% was found in fraction D. Accumulation and elimination kinetics of Cd in different fractions were accurately described by one-compartment models, and kinetic parameters (uptake rate constant k ₁ and elimination rate constant k ₂ ) were derived. Fractions G and F were responsible for the linear accumulation pattern during 3 weeks of exposure, whereas fractions D and E showed a nonlinear uptake curve, and steady state was achieved after 7 and 14 days of exposure, respectively.     

An Evaluation of Molybdenum Toxicity to the Oligochaete, <Emphasis Type="Italic">Tubifex tubifex</Emphasis>, and Early-Life Stages of Brown Trout, <Emphasis Type="Italic">Salmo trutta</Emphasis>

Limited data are available describing the aquatic toxicity of molybdenum in freshwater environments, making it difficult to assess the aquatic risk to freshwater organisms. In order to increase available information on the aquatic toxicity of molybdenum, a 96-h LC50 test with the oligochaete Tubifex tubifex and an 85-day development test using brown trout, Salmo trutta, were conducted. The T. tubifex test resulted in an LC50 value of 2782 mg/L. No adverse effects were observed on brown trout survival or length in the concentrations tested, however an IC10 value for growth (wet weight) was determined to be 202 mg/L. Whole body fish tissue concentrations for molybdenum increased in all treatment concentrations tested, although bioconcentration factors decreased at greater exposure concentrations, and ranged from 0.13 at an exposure concentration of 20 mg/L to 0.04 at an exposure of 1247 mg/L. A body burden of 26.0 mg/kg was associated with reduced wet weight.     

Nondestructive Scat Sampling in Assessment of Mink (<Emphasis Type="Italic">Mustela vison</Emphasis>) Exposed to Polychlorinated Dibenzofurans (PCDFs)

The mink (Mustela vison) is often utilized as a sentinel species for ecological assessments at sites where contaminants of concern include dioxins and dioxin-like compounds. Utilizing mink scat as a nondestructive tool to determine internal exposure to dioxin-like compounds may allow for rapid, accurate estimates of exposure without the need to capture mink or their prey. To determine the relationships between concentrations of polychlorinated dibenzofurans (PCDFs) in tissues (liver and adipose) and those in scat, mink were fed PCDFs in scat during a controlled laboratory study for 180 days. Mink were fed a control diet, diets with three doses of 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PeCDF) or 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF), and a diet with an environmentally relevant mixture of the two congeners. Concentrations of PCDFs in liver and adipose were measured after 0, 90, and 180 days of exposure. Concentrations of the two PCDF congeners in mink scat were determined after 2, 23, 45, 90, and 180 days of exposure. Concentrations of both PCDF congeners in scat were significantly correlated with those in liver and adipose tissue (r ² = 0.94−0.97, p < 0.01). This indicates that measurements of concentrations of both PCDFs in scat can be used to predict concentrations of PCDFs in liver and adipose. Assimilation and elimination characteristics of 2,3,4,7,8-PeCDF or 2,3,7,8,-TCDF and a mixture of the two congeners by mink could be predicted from concentrations of these congeners in scat. Overall, concentrations of PCDFs in mink scat can be used as a rapid and inexpensive nondestructive method to predict concentrations of PCDFs in mink when certain assumptions are met.