Depuration Rate Research Articles

Fish guts possess higher priority in assessing ecological risk of microplastics in both fish bodies and aquatic environments

Microplastics (MPs, ＜5mm in size) have rapidly spread across aquatic ecosystems, which urgently needs systematic assessment for their ecological risk. Fish species have frequently been selected as indicator organisms in evaluating MPs contaminants. However, it has been questioned that which organs of fishes should be examined due to tissue-specific results. In this study, we investigated the accumulation and depuration process of MPs in the main organs of zebrafish under different MPs concentrations as well as the presence and absence of food resources. Our results recorded consistently higher MPs accumulation in fish guts among different MPs concentrations, implying fish guts as stable organs representing organisms’ MPs contaminants. Meanwhile, MPs accumulated in fish guts increased significantly with increasing exposure concentrations, highlighting fish guts as sensitive organs in reflecting MPs contamination in aquatic environments. In addition, MPs accumulated in fish guts under non-feeding conditions followed a logistic “S” curve while fluctuated under feeding conditions, suggesting increased ecological MPs risk with the absence of food resources. The depuration rate in fish guts was significantly higher in the feeding group than in the non-feeding group, implying better expelling ability of MPs with the presence of food resources. Our study proposes fish guts as the optimal indicator organs in assessing the ecological risk of MPs contaminants in both fish bodies and aquatic environments, and highlights the importance of sustaining sufficient food resources in aquatic environments to reduce the MPs triggered adverse effects on fish species.

Comparative analysis of the efficiency of different commercial depuration systems and the evaluation of species-specific depuration conditions in bivalve mollusc production

This study assesses and compares the efficiency of three commercial depuration systems for live bivalve mollusc production. Ruditapes philippinarum (Rp), Ruditapes decussatus (Rd), Donax trunculus (Dt), and Venus verrucosa (Vv) were used as research materials to evaluate full open (FO), semi-closed (SC), and closed cycle (CC) systems. Results reveal a logarithmic decrease in Escherichia coli levels during the initial six hours across all species. Rd achieved full depuration after 12 hours in the CC system and 24 hours in the FO system; Vv required 18 hours, while others needed up to 24 hours. At the 4600 MPN/100 g level, the CC system fortified by an ozone generator showed the most efficient depuration with the following results: 18 hours for Rp and Vv, 24 hours for Rd, and 36 hours for Dt. The SC system prolonged depuration times for all species. Species-specific filtration behaviour emerged as a crucial factor during contamination and depuration rates. Statistical analysis highlighted pH, dissolved oxygen, and salinity as key parameters influencing depuration efficiency, with temperature showing lesser significance compared to other variables for effective species-specific system design. This study focuses on identifying the parameters affecting the depuration characteristics of different bivalve species and commercial systems, and predicting the effects of potential changes. The findings are expected not only to enhance scientific understanding in this field but also to contribute to the system designs and adaptation of existing businesses to various conditions.

Fugacity and kinetic models reveal specific-fate of geosmin in air-water-fish microcosm and channel catfish (Ictalurus punctatus)

Geosmin (GSM) is a ubiquitous odorant found in aquatic environments and organisms, with significant impacts on drinking water and aquaculture. However, its transfer from contaminated water to fish tissues is poorly investigated, resulting in limited information on its bioconcentration and environmental behavior. Fugacity and one-compartment models were developed to describe the fate, transformation, and transport of GSM in an air-water-fish system and analyze its uptake, distribution, and elimination kinetics in channel catfish (Ictalurus punctatus). The results showed that the fugacity model calculations indicated that 81.3 % of GSM was found in water for all microcosm. The primary mass transfer processes from water were water-air diffusion process (T21v) and that from water to fish (T2 f), with values of 67.3 and 22.54 μg/h, respectively. The emission rate (E2) and area (A2) in water parameters are most sensitive to GSM concentration, impacting the distribution and variance of contaminant concentration. Kinetic studies in fish revealed that GSM primarily accumulate in the muscle and skin, with the earthy-odor burden of fish contributed by the former, reaching 86.59 %. The uptake rate constant (kup), depuration rate constant (kde), and half-lives (t1/2) fell within the ranges of 0.737–3.534 L/(kg·h), 0.024–0.097 1/h, and 7.1–28.9 h, respectively. Bioaccumulation factors (BAFs) for GSM in fish skin, muscle, and liver tissues were 105.79, 61.71, and 51.22 L/kg, respectively. GSM was effectively depurated by other tissues within 72 h, while 18.16 % remained in skin. The liver demonstrated the most accurate curve (R2=0.97), followed by skin and muscle, with the gill showing the worst simulation. This work offers insights into understanding the fate and mass transfer flux of trace odorants in environmental and biological phases.

Biokinetics of Americium-241 in the euryhaline diamond sturgeon Acipenser gueldenstaedtii following its uptake from water or food

Americium-241 whole body and internal biokinetics were experimentally investigated in the euryhaline diamond sturgeon Acipenser gueldenstaedtii during its uptake from water and food, in fresh (FW) and brackish water (BW; 9 psu). Whole-body uptake rates of 241Am from water and subsequent depuration rates were quantified over 14 and 28 days, respectively, and assimilation efficiency (AE) of 241Am from diet (chironomid) was determined over 28 days. FW reduced the biological half-life of 241Am following aqueous uptake by an order of magnitude. In contrast BW greatly reduced 241Am assimilation efficiency (AE) from diet (chironomid) by several orders of magnitude (from an AE of 8.5% (FW) down to 0.003% (BW)). Hence, salinity per se is indicated as a major environmental variable in determining the radiological exposure of A. gueldenstaedtii to 241Am. During aqueous exposure BW appreciably increased 241Am activity concentrations in most body components, but aqueous or dietary exposure pathway at either salinity did not determine marked differences in how 241Am was distributed among six body components. The highly mineralized skin of A. gueldenstaedtii recurred as a major repository of 241Am in all experimental treatments, as high as 50% among body components, due to its internal transfer from diet, surface adsorption and/or active absorption from water. The indicated prominence of the aqueous, compared to the dietary, exposure pathway for 241Am accumulation by A. gueldenstaedtii suggests its radiological exposure would be enhanced by BW as it leads to its greater long-term retention, due to a much longer biological half-life.

Increased extinction probability and altered physiological characteristics in pirimicarb-tolerant Daphnia magna.

We evaluated the physiological characteristics of chemical-tolerant cladocerans. Over the course of 26 generations (F25), Daphnia magna was continuously exposed to pirimicarb (carbamate) solutions (0, 3.8, 7.5, and 15µg/L) in sub-lethal or lethal levels. The 48h EC50 values (29.2-29.9µg/L) for 7.5 and 15µg/L exposure groups were found to be nearly two times higher than that in the control (17.2µg/L). Subsequently, we investigated whether the extinction probability changed when the chemical-tolerant daphnids were fed two different types of food, Chlorella vulgaris and Synechococcus leopoliensis. Furthermore, we ascertained how chemical tolerance influences respiration and depuration rates. The 48h EC50 value was positively related to the extinction probability when the daphnids were fed S. leopoliensis. Because the measured lipid content of S. leopoliensis was three times lower than that of C. vulgaris, the tolerant daphnids struggled under nutrient-poor conditions. Respiration rates across all pirimicarb treatment groups were higher than those in the control group, suggesting that they may produce large amounts of energy through respiration to maintain the chemical tolerance. Since the pirimicarb depuration rate for 7.5µg/L exposure groups was higher than that in the control, the altered metabolic/excretion rate may be one factor for acquiring chemical tolerance. These altered physiological characteristics are crucial parameters for evaluating the mechanisms of chemical tolerance and associated fitness costs.

Research on the Detection Method of the Threshing Rate of Corn Ears Based on Machine Vision

The threshing rate is one of the important indexes to evaluate the effect of corn threshing. The weighing method is often used to calculate the depuration rate of maize at present. This method is time-consuming and laborious and can only calculate the overall threshing rate but does not give the threshing rate of individual corn ears. Different parameters of corn ears have complex effects on the threshing rate. By analyzing the threshing rate of each corn ear, we can choose the appropriate ear treatment method, optimize the processing equipment and process flow, and improve the threshing performance. This paper presents a method based on machine vision to detect the threshing rate of corn ears. In this method, machine vision was used to measure the parameters of the corncob and the area of the top of residual kernels. The area of the top of all kernels was restored based on the parameters of the corncob. The threshing rate of corn ears was calculated by the ratio of the area of the top of the missing kernel to the area of the top of all kernels after threshing. A bivariate linear regression area model was established to restore the area of the top of all corn kernels based on corncob parameters. The R2 was more significant than 0.98, and the goodness of fit was good. The machine vision inspection results showed that the maximum relative error of length and midsection radius was 7.46% and 5.55%, and the mean relative error was 2.58% and 2.23%. The maximum relative error of the corn ear threshing rate was 7.08%, and the mean relative error was 2.04%. When the residual kernels were concentrated in the midsection, the inspection result of the corn ear threshing rate was better. The maximum relative error was 3.98%, and the mean relative error was 1.07%. This paper provides a new idea and reference for measuring the threshing rate of corn ears.

Differences in Toxicokinetics and Maternal Transfer between Lipophilic and Proteinophilic Halogenated Organic Pollutants in Laying Hens.

In this study, we conducted exposure experiments on egg-laying hens to explore the toxicokinetics and maternal transfer characteristics of lipophilic and proteinophilic halogenated organic pollutants (HOPs). The lipophilic HOPs included polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dechlorane plus (DPs), while the proteinophilic HOPs included perfluorocarboxylic acids (PFCAs). The results revealed that most of lipophilic HOPs exhibit lower depuration rate (k d) than PFCAs. The k d of lipophilic HOPs correlated with the octanol-water partition coefficient (log K OW) values in a V-shaped curve, whereas that of PFCAs correlated with the protein-water partition coefficient (log K PW) values in an inverted V-shaped curve. The depuration rate, rather than the uptake rate, was a leading factor in determining the bioaccumulation potential of HOPs in hens. Although the dominant factors determining the tissue distribution of the two types of compounds were explicit (fats vs phospholipids), chemical-specific tissue distribution was still observed. The egg-maternal concentration ratio was dependent on the exposure status, concentration, and maternal tissue choice. Using a single maternal tissue may not be an appropriate method for assessing chemical maternal transfer potential. PFCAs have a greater maternal transfer potential (>80% of the total body burden) than lipophilic HOPs (approximately 30% for BDE209 and DPs, and less than 10% for the others). Their lipophilic and partly proteinophilic nature makes the toxicokinetics and maternal transfer characteristics of BDE209 and DPs different from those of other lipophilic HOPs. These findings are crucial for enhancing our understanding of the behavior and fate of HOPs in egg-laying hens.

Advanced valorisation for cork wastewater

The cork manufacturing process generates cork boiling wastewater, characterized by high COD and phenolic compounds content. The main aim of this study is the advanced valorization of these spills through a green and efficient process with two main stages. Firstly, most of the organic matter was removed by an optimal design of a precipitation with calcium. The resulting depuration rates were in the ranges 37–53 % for COD and 70–87 % for TPC. Secondly, the precipitates generated were subjected to a biodigestion process with production of methane (up to 234 L CH4·kg VS−1) and fertilizers. In conclusion, good recovery of interesting by-products and a good yield of depuration were achieved with the technology proposed, avoiding the use of toxic reagents and demonstrating the potential of concentrate precipitates from CBWs as substrates for biodigestion.

Uptake from water and depuration of 137Cs and 90Sr by silver Prussian carp (Carassius gibelio)

To follow up field observations in the Chornobyl Exclusion Zone (ChEZ), a series of controlled model aquarium experiments were conducted to determine the uptake and depuration rates of 137Cs and 90Sr in silver Prussian carp (Carassius gibelio) in fresh water, varying in temperature from 5 to 27 °C, with daily feeding rates of 0–1.5 % fish weight day−1.In the present study, the 137Cs uptake rates in muscle tissues directly from water, 0.05–0.09 day−1 at temperatures of 5–27 °C, were significantly lower than previously reported for fish fed under natural conditions in contaminated lakes within the ChEZ. The rate of 90Sr uptake in bone tissues of silver Prussian carp varied from 0.055 day−1 at a water temperature of 5 °C and feeding rates ≤0.15 % fish weight day−1 to 1.5 ± 0.2 day−1 at a temperature of 27 ± 1 °С and at the highest tested feeding rate of 1.5 % day−1.The rate of decrease of 137Cs concentration in muscle tissues was kb = 0.0028 ± 0.0004 day−1 (T1/2 = 248 ± 35 days) at the lowest water temperature tested (5 °С). At water temperatures between 13 and 26 °С and a feeding rate of 0.15 % day−1, the rate increased to kb = 0.0071–0.0092 day−1 (T1/2 = 75–99 days).The rates of decrease of 90Sr activity concentration in bone tissues at water temperatures between 22 and 25 °С and a feeding rate of 0.5 % day−1 were kb=0.004–0.0014 day−1, and the associated biological half-life T1/2 ranged 50–160 days, respectively. The present work supported conclusions related to the main pathways of 137Cs and 90Sr uptake by silver Prussian carp, and demonstrated the usefulness of combining field and laboratory uptake and depuration experiments.

Uptake/depuration kinetics, bioaccumulation potential and metabolic transformation of a complex pharmaceutical mixture in zebrafish (Danio rerio)

Uptake and elimination kinetics, bioconcentration factors (BCFs), and metabolic transformation of 20 different pharmaceutically active compounds (PhACs), covering a wide range of therapeutic categories and physico-chemical properties, were studied using zebrafish (Danio rerio). The fish were exposed to the mixture of the selected PhACs at environmentally relevant concentrations similar to 10 µg L−1. The experiments were performed in semi-static conditions and comprised a 7-day uptake period followed by a 7-day depuration period. Most of the PhACs reached a concentration plateau within the 7-day uptake-phase which was followed by an efficient depuration, with the observed uptake (ku) and depuration rate constants (kd,) ranging between 0.002 and 3.752 L kg−1 h−1, and 0.010 to 0.217 h−1, respectively. The investigated PhACs showed low to moderate BCFs. The highest BCFs of 47.8, 28.6 and 47.6 L kg−1 were determined for sertraline, diazepam and desloratadine, respectively. A high contribution of metabolic products to the total internal concentration was observed for some PhACs such as codeine (69%), sulfamethoxazole (51%) and verapamil (87%), which has to be taken into account when assessing the bioconcentration potential. Moreover, most of the metabolites exhibited significantly longer half-lives in zebrafish than their parent compounds and affected the overall depuration kinetics.

Quantitative differentiation of toxicity contributions and predicted global risk of fipronil and its transformation products to aquatic invertebrates

Biotransformation often alters chemical toxicity, yet its impacts on risk assessment are hardly quantified due to the challenges in acquiring internal exposure-based thresholds for chemicals that are readily metabolizable. Here, we integrated toxic unit and toxicokinetics to quantitatively assess toxicity contributions and potential risk of both parent compound and transformation products (TPs) to aquatic organisms, using fipronil (FIP) as a representative toxicant. In aquatic invertebrates Chironomus dilutus and Hyalella azteca, approximately 90 % of FIP was transformed to fipronil sulfone (SUL). FIP and SUL exhibited similar intrinsic toxicity to these organisms, which was contrary to conventional perception that SUL was more toxic than FIP. However, biotransformation was still important in risk assessment because the TP had 10-fold slower depuration rate than FIP. The amphipod H. azteca was found to be as sensitive to FIPs as the insect C. dilutus, which was previously considered ten times more sensitive based on external thresholds. This discrepancy has led to overlooking the toxicity of FIP to H. azteca in regional risk assessments. Lastly, we predicted the lethal risk of FIPs in global surface water. When using external thresholds for prediction, FIPs in 3.4 % of the water samples were lethally toxic to H. azteca, and the percentage of water samples at risk increased to 14 % when internal thresholds were used and SUF dominated the risk. This study presents an improved method for quantifying aquatic risk of readily metabolized toxicants. Our findings underscore the urgency of considering TPs in water quality assessments, especially for sensitive species that are at risk in the environment.

Bioaccumulation and Depuration Dynamics of Nickel Chloride in Nile Tilapia (Oreochromis niloticus) Exposed to Sub-lethal Concentrations

The current objective of this research is to examine the bioaccumulation and subsequent depuration levels of nickel chloride within vital organs such as the gills, liver, and kidney of Oreochromis niloticus under controlled laboratory conditions. The fish were subjected to exposure under two sub-lethal concentrations, i.e., 1/5th (9.39 ppm) and 1/10th (4.69 ppm), for 28 days of absorption and subsequently transferred to uncontaminated, good aerated water for 28days of elimination (depuration). Following 28 days of exposure to lower sub-lethal and higher sub-lethal nickel chloride concentrations, the sequence of bioaccumulation of nickel chloride in organs was observed as kidney > liver > gills. The depuration trend for higher and lower concentrations was gills> liver > kidney. The kidney exhibited the highest accumulation of Ni. Meanwhile, the Ni depuration in the gills was significantly (p<0.05) more when compared to other routes following exposure to both concentrations. This research assessed nickel chloride's bioaccumulation and depuration dynamics in Oreochromis niloticus, providing insights into its physiological responses to metal exposure. The study concludes that nickel accumulates predominantly in the kidney, with gills exhibiting the highest depuration rates, highlighting the importance of understanding metal uptake and elimination mechanisms in aquatic organisms for effective pollution management.

Assessing viral freshwater hazard using a toxicokinetic model and Dreissena polymorpha

The detection all pathogenic enteric viruses in water is expensive, time-consuming, and limited by numerous technical difficulties. Consequently, using reliable indicators such as F-specific RNA phages (FRNAPH) can be well adapted to assess the risk of viral contamination of fecal origin in surface waters. However, the variability of results inherent to the water matrix makes it difficult to use them routinely and to interpret viral risk. Spatial and temporal variability of surface waters can lead to underestimate this risk, in particular in the case of low loading. The use of bivalve mollusks as accumulating systems appears as a promising alternative, as recently highlighted with the freshwater mussel Dreissena polymorpha, but its capacity to accumulate and depurate FRNAPH needs to be better understood and described. The purpose of this study is to characterise the kinetics of accumulation and elimination of infectious FRNAPH by D. polymorpha in laboratory conditions, formalised by a toxico-kinetic (TK) mechanistic model. Accumulation and depuration experiments were performed at a laboratory scale to determine the relationship between the concentration of infectious FRNAPH in water and the concentration accumulated by D. polymorpha. The mussels accumulated infectious FRNAPH (3–5.4 × 104 PFU/g) in a fast and concentration-dependent way in only 48 h, as already recently demonstrated. The second exposure demonstrated that the kinetics of infectious FRNAPH depuration by D. polymorpha was independent to the exposure dose, with a T90 (time required to depurate 90 % of the accumulated concentration) of approximately 6 days. These results highlight the capacities of D. polymorpha to detect and reflect the viral pollution in an integrative way and over time, which is not possible with point water sampling. Different TK models were fitted based on the concentrations measured in the digestive tissues (DT) of D. polymorpha. The model has been developed to formalise the kinetics of phage accumulation in mussels tissues through the simultaneous estimation of accumulation and depuration rates. This model showed that accumulation depended on the exposure concentration, while depuration did not. Standardized D. polymorpha could be easily transplanted to the environment to predict viral concentrations using the TK model defined in the present study to predict the level of contamination of bodies of water on the basis of the level of phages accumulated by the organisms. It will be also provide a better understanding of the dynamics of the virus in continental waters at different time and spatial scales, and thereby contribute to the protection of freshwater resources.

The distribution and metabolism of hexabromocyclododecane isomers varies in the tissues of Nibea albiflora

Hexabromocyclododecanes (HBCDs), as brominated flame retardants, have increasingly drawn concern due to their detection in various marine organisms in recent years. The present test investigated the selective accumulation, depuration, and bioisomerization of HBCDs in different tissues and organs of Nibea albiflora, as well as the genetic metabolic behavior of HBCDs between parents and offspring. In a semi-static water environment, N. albiflora were exposed to individual HBCD diastereoisomers (α-HBCD, β-HBCD, or γ-HBCD) at a concentration of 0.4 μg/L for bioaccumulation, followed by clean food for depuration. During the exposure period, the highest concentrations of these HBCDs were observed in the intestine and gill of N. albiflora. α-HBCD was detected in all exposure groups, suggesting that both β-HBCD and γ-HBCD could be bioisomerized to α-HBCD in N. albiflora. In addition, there was no bioisomerization of α-HBCD to either β-HBCD or γ-HBCD, and there was no bioisomerization between β-HBCD and γ-HBCD. The half-lives (t1/2) were variable among different diastereoisomers, following an order of α-HBCD > γ-HBCD > β-HBCD. The most rapid depuration rate of HBCDs was discovered in the liver while muscle showed the least. Additionally, prior to spawning, the parent fish were exposed to contaminated feed (silkworms sprayed with 200 μL of a 30 μg/mL HBCD solution) for 6 days. By comparing the HBCDs concentrations in the maternal gonad, fertilized eggs, hatching eggs, larvae, and juveniles, it was determined that the maternal transfer coefficients for HBCDs were approximately 1, indicating dynamic equilibrium of HBCDs throughout the process from maternal tissue to progeny development. Differences in HBCDs pattern between organs observed in the experiment support a proposal of an organ-specific diastereomer accumulation.

Bioaccumulation of Linear Siloxanes in Fish.

The bioaccumulation behavior, including the uptake, internal distribution, depuration, and biotransformation rates, of three widely used linear methyl-siloxanes was investigated in rainbow trout. Dietary uptake efficiencies of octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4), and dodecamethylpentasiloxane (L5) were 15% (3.3% standard error [SE]), 8.6% (1.4% SE), and 15% (1.8% SE), respectively, and for L3 and L4 were well below those of nonmetabolizable reference chemicals with similar octanol-water partition coefficients, suggesting significant intestinal biotransformation of L3 and L4. Somatic biotransformation rate constants were 0.024 (0.003 SE) day-1 for L3 and 0.0045 (0.0053 SE) day-1 for L4 and could not be determined for L5. Lipid-normalized biomagnification factors for L3, L4, and L5 were 0.24 (0.02 SE), 0.24 (0.01 SE), and 0.62 (0.05 SE) kg-lipid kg-lipid-1 , respectively. Bioconcentration factors standardized to a 5% lipid content fish for water in Canadian oligotrophic lakes with a dissolved organic carbon content of 7.1 mg L-1 were 2787 (354 SE) for L3, 2689 (312 SE) for L4, and 1705 (418 SE) L kg-wet weight-1 , respectively, and 3085 (392 SE) for L3, 4227 (490 SE) for L4, and 3831 (938 SE) L kg-wet weight-1 in water with a dissolved organic carbon content of 2.0 mg L-1 . A comparison of 238 bioaccumulation profiles for 166 different chemicals shows that the bioaccumulation profiles for L3, L4, and L5 are vastly different from those of other very hydrophobic compounds found in the environment. Environ Toxicol Chem 2024;43:42-51. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Bioaccumulation of zinc by Portunus pelagicus: Nuclear application techniques that use radiotracer 65Zn to study influence of concentration of Zn in seawater

Zinc (Zn) is an essential trace metal, but also a potential toxicant to aquatic organisms. Zinc is one of the toxicants from various industrial and domestic activities whose waste is directly discharged into water. One of the marine organisms used as an indicator of pollution is the blue swimming crab (Portunus pelagicus). Bioaccumulation studies of Zn in Portunus pelagicus from Jakarta Bay were conducted in a radiotracer laboratory. Laboratory experiments were done to study the uptake and release of 65Zn radioisotope in Portunus pelagicus. The experiments conducted were biota collection, acclimatization, bioaccumulation, and elimination. This study was to determine the relationship between the amount of 65Zn released into the aquatic environment and its effect on Zn bioaccumulation ability and radiation dose received by Portunus pelagicus. Biokinetics parameters, such as concentration factors CF, uptake rate constant ku, elimination rate constant ke, and concentration factor steady state (CFss) were investigated. The results showed that an increase in concentration would decrease the rate of absorption and rate of elimination, and that the concentration factor CF values ​​varied from 7.82 - 60.62 ml.g-1 in Portunus pelagicus. The concentration factor at steady-state Zn was 25.55-59.47 ml.g–1, which is influenced by the concentration after 6 days of exposure. The depuration rate was observed to be high, with a value of retention 34.33 - 78.88 % of 65Zn absorbed by Portunus pelagicus, which was absent 7 days after exposure. Highlights Laboratory experiments lasting 14 days showed that Portunus pelagicus has the ability to accumulate the heavy metal zinc (Zn) from the environment and release it back into the water The highest bioaccumulation kinetics of zinc (Zn) metal in Portunus pelagicus during the 7-day experiment occurred at a contaminant concentration of 0.5 ppm with an absorption constant (ku) value of 0.7838 d-1 and a release constant value (ke) of 0.0892 d-1 Portunus pelagicus concentration factor (CF) has a moderate value and the smallest uptake constant (ku) and elimination constant (ke) value compared to other biota

Bioaccumulation, tissue distributions, and maternal transfer of perfluoroalkyl carboxylates (PFCAs) in laying hens

Laying hens were exposed to feeds spiked with a series of perfluoroalkyl carboxylates (PFCAs) ranging from perfluorobutanoic acid (C4) to perfluorooctadecanoic acid (C18) to investigate their bioaccumulation, tissue distribution, and maternal transfer. We found that PFCAs with longer carbon chains (>8) were more efficiently absorbed in the gastrointestinal tract than those with shorter chains (≤8), and that the rate of depuration varied inversely with the carbon chain length in a U-shaped pattern. Moreover, bioaccumulation potential increased with increasing carbon-chain length, except for C4. Distinct affinities were observed for specific carbon-chain PFCAs across various tissues, evident from their differential accumulation during both uptake and depuration phases. Specifically, C9 showed a higher affinity for serum and liver, C12 was more prevalent in yolk, C14 was notably abundant in the brain, and C18 was predominant in other tissues. Furthermore, the egg-maternal ratio (EMR) increased with increasing carbon-chain length from C7 to C11 and reached a plateau phase for C12 to C18. Our study also confirmed the key role of phospholipids in the tissue distribution and maternal transfer of long-chain PFCAs. This study sheds light on the interaction between PFCAs and biological tissues and reveals the toxicokinetic factors that influence the bioaccumulation of PFCAs. Further research is needed to identify the specific proteins or components that mediate the tissue-specific affinity for different carbon-chain lengths of PFCAs.

Cadmium-109 Internal Kinetics in Diamond Sturgeon Acipenser gueldenstaedtii are Strongly Influenced by Salinity, Exposure Pathway and History.

Cadmium-109 whole-body and internal biokinetics were experimentally investigated in critically endangered diamond sturgeon Acipenser gueldenstaedtii after uptake from water or food, in fresh (FW) and brackish (BW; 9‰) salinities typical of the Caspian Sea. Whole-body rates of uptake of 109Cd from water and subsequent depuration were quantified over 14 and 28days, respectively. Uptake was greater in FW than BW by a factor of 2.4, but depuration rates were similar in both salinities. In contrast, for the dietary (chironomid) exposure pathway 109Cd assimilation efficiencies (AEs) were higher in BW (13%) compared to FW (9.5%). Head (including gills) or digestive tract were major repositories of 109Cd following aqueous and dietary exposures, respectively, including both uptake and depuration phases. The point-of-entry of 109Cd into the body was also a major and persistent determiner of its subsequent internal distribution. For aqueous exposures, the internal distributions of 109Cd changed appreciably during depuration with increased activity concentrations in some body components, which again varied with salinity. Increased salinity appreciably enhanced the percentage distributions and activity concentrations of 109Cd in the liver, kidney and digestive tract, which are typically most pathologically altered by elevated Cd exposure. For dietary exposure, increased salinity also enhanced 109Cd activity concentrations in most body components. The results repeatedly indicate the important role of salinity in the whole-body and internal biokinetics of 109Cd in A. gueldenstaedtii, a representative of both a phylogenetically distinct and most endangered family of fishes.

Environmental assessment of oyster beds in the northern Arabian Gulf Coast of the United Arab Emirates

The United Arab of Emirates (UAE) hosts valuable coastal and marine biodiversity, and oysters are one of the habitants of its marine ecosystem. Oysters play an essential role in the nearshore coasts where they work as an active filter. They filter nutrients, phytoplankton, sediments, heavy metals, and toxins out of the water, which improves the water quality. This is the first study that characterizes oyster bed habitats in the UAE by analyzing water quality parameters, polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs)and heavy metals in water, sediments and oyster samples collected from five locations along the coasts of Sharjah, Ajman, and Umm al Quwain. Oyster bed areas supported a diverse assemblage of benthic life including oysters, scallops, pen shells, hard corals, and macroalgae. Mobile species in these habitats included groupers, emperors, snappers, sea snakes, among others. The phytoplankton assemblages were dominated by diatoms, dinoflagellates, and small cryptophytes. Harmful diatom Pseudonitzschia was found in all locations. No detectable concentrations of PAHs and OCPs were reported in this study, and water quality parameters were within the acceptable levels for the region. On the other hand, water quality index was reported marginal, mostly due to the presence of higher than acceptable concentrations of chromium and mercury in all sites studied. Bioconcentration factors concluded that oysters were able to bioconcentrate metals such as arsenic, cadmium, chromium, and zinc, when compared to water. No detectable concentrations of lead and mercury were reported in oysters, suggesting higher depuration rates for those metals.

Kinetics of uptake and depuration of synthetic pyrethroid insecticides in manila clam (Ruditapes philippinarum).

Synthetic pyrethroid insecticides (SPIs) are frequently detected in water bodies and sediments, and they show high toxicity to aquatic organisms, but their toxicity kinetics remain unknown. In this work, the kinetics of uptake and depuration of three SPIs, fenpropathrin (FP), cypermethrin (CM) and deltamethrin (DM) were evaluated in manila clams (Ruditapes philippinarum) for the first time through a bioconcentration-semi-static test. Clams were exposed to three SPIs of different concentrations (2 ng/mL and 20 ng/mL) for 4 days, followed by a 10-day depuration stage. The results indicated that adult manila clams could absorb SPIs rapidly, and the bioconcentration factor (BCF) values of SPIs were different at high and low concentrations of contaminants. The depuration rate constants (k2) of SPIs in adult manila clams ranged from 0.024 h-1 to 0.037 h-1. The bioaccumulation factors ranged from 319.41 to 574.38. And the half-lives (t1/2) were in the range of 18.49 to 29.22 h. These results showed that manila clams have a high bioconcentration capacity, and SPIs have a high cumulative risk for bivalves. Moreover, after 10 days of elimination, SPIs can still be detected in manila clams at all concentrations, indicating that the complete elimination of SPIs required a longer time.