The study on contamination of bottom sediments from the Odra River estuary (SW Baltic Sea) by tributyltin using environmetric methods

We present the first comprehensive study on the occurrence of tributyltin (TBT) in the Odra River estuary (SW Baltic Sea) that encompasses both densely populated and urbanized agglomeration Szczecin city, and sparsely populated biosphere reserves "Natura 2000". Relationship between TBT and physicochemical parameters of bottom sediments such as granulometry total organic carbon (TOC), total nitrogen (TN), acid volatile sulfide (AVS), As, and metals: Ba, Cd, Co, Cr, Cu, Fe, Hg, Ni, Mn, Mo, Pb, Sn, and Zn was investigated in 120 samples collected in 2017 and 2018. The highest TBT concentrations were over 3000 ng g^-1 (dry weight). They were observed in samples collected in the vicinity of the ship maintenance zones of the Szczecin city. Despite the EU ban on its use since 2003, TBT is still present in the environment. Environmetrics analyses such as correlation, cluster, and principal component analysis of obtained results revealed that the main source of sediments contamination by TBT, metalloids, and metals is likely related to the maritime industry: shipyards, ship maintenance as well as ports and marines. TBT is still present in the bottom sediments because of its emission to the environment with dust and paint chips formed during sandblasting cleaning of ship surfaces. The pollutant is further transported with water current to remote localization in the Szczecin Lagoon. Slow water exchange between the Szczecin Lagoon and the Baltic Sea favors accumulation of pollutants in the lagoon sediments. Therefore, it is necessary to implement environmentally friendly methods into ship maintenance and management of the materials from dredged waterways, harbors, and marinas.

The assessment of environmental risk related to the occurrence of pharmaceuticals in bottom sediments of the Odra River estuary (SW Baltic Sea)

The occurrence of 130 pharmaceutically active compounds (PhACs) in sediments collected from 70 sampling sites in the Odra River estuary (SW Baltic Sea) was investigated. The highest concentration levels of the compounds were found in the vicinity of effluent discharge from two main Szczecin wastewater treatment plants: "Pomorzany" and "Zdroje", and nearby the seaport and shipyard. The highest environmental risks (RQ > 1) were observed for pseudoephedrine (RQ = 14.0), clindamycin (RQ = 7.3), nalidixic acid (RQ = 3.8), carbamazepine (RQ = 1.8), fexofenadine (RQ = 1.4), propranolol (RQ = 1.1), and thiabendazole (RQ = 1.1). RQ for each compound varied depending on the sampling sites. High environmental risk was observed in 30 sampling sites for clindamycin, 22 sampling sites for pseudoephedrine, 19 sampling sites for nalidixic acid, 4 sampling sites for carbamazepine, and 3 sampling sites for fexofenadine. The medium environmental risk (0.1 < RQ < 1) was observed for 16 compounds: amisulpride, amitriptyline, amlodipine, atropine, bisoprolol, chlorpromazine, lincomycin, metoprolol, mirtazapine, moclobemide, ofloxacin, oxazepam, tiapride, tolperisone, verapamil, and xylometazoline. Due to the scarcity of toxicological data related to benthic organisms, only an approximate assessment of the environmental risk of PhACs is possible. Nevertheless, the compounds with medium and high risk should be considered as pollutants of high environmental concern whose occurrence in the environment should remain under close scrutiny.

Environmental Risk and Risk of Resistance Selection Due to Antimicrobials' Occurrence in Two Polish Wastewater Treatment Plants and Receiving Surface Water

In this study, a screening of 26 selected antimicrobials using liquid chromatography coupled to a tandem mass spectrometry method in two Polish wastewater treatment plants and their receiving surface waters was provided. The highest average concentrations of metronidazole (7400 ng/L), ciprofloxacin (4300 ng/L), vancomycin (3200 ng/L), and sulfamethoxazole (3000 ng/L) were observed in influent of WWTP2. Ciprofloxacin and sulfamethoxazole were the most dominant antimicrobials in influent and effluent of both WWTPs. In the sludge samples the highest mean concentrations were found for ciprofloxacin (up to 28 μg/g) and norfloxacin (up to 5.3 μg/g). The removal efficiency of tested antimicrobials was found to be more than 50% for both WWTPs. However, the presence of antimicrobials influenced their concentrations in the receiving waters. The highest antimicrobial resistance risk was estimated in influent of WWTPs for azithromycin, ciprofloxacin, clarithromycin, metronidazole, and trimethoprim and in the sludge samples for the following antimicrobials: azithromycin, ciprofloxacin, clarithromycin, norfloxacin, trimethoprim, ofloxacin, and tetracycline. The high environmental risk for exposure to azithromycin, clarithromycin, and sulfamethoxazole to both cyanobacteria and eukaryotic species in effluents and/or receiving water was noted. Following the obtained results, we suggest extending the watch list of the Water Framework Directive for Union-wide monitoring with sulfamethoxazole.

Development and Application of a Novel QuEChERS Method for Monitoring of Tributyltin and Triphenyltin in Bottom Sediments of the Odra River Estuary, North Westernmost Part of Poland

A Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction method combined with Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) for determination of organotin compounds (OTC) has been newly developed. The novel analytical method was validated and the quality of the results was tested by the use of certificate reference material of freshwater sediment BCR 646. The method was applied in determination of OTC concentration in real samples of bottom sediments collected from the Polish part of Odra River Estuary. The samples came from locations with different anthropogenic impact. Additionally, the extraction recovery of OTC and matrix effect on MS signal response was investigated based on those real environmental samples. It was found that organic compounds and anthropogenic contaminations present in bottom sediments may affect extraction efficiency of the organotin compounds (OTC) and change the matrix effect on MS signal response. The highest concentrations of tributyltin were found in bottom sediments collected from locations in vicinity of the Szczecin harbor and shipyards. The presence of triphenyltin above limit of detection (5 ng TPhT/g of sediment) was observed only in two samples and its concentration was several times lower compared to concentration of tributyltin (from 58 ng/g to 5263 ng/g). In spite of the fact that, the application of TBT-based paints on hull of vessel entering EU ports has been banned by European Commission regulation No. 782/2003 since 2008, the OTC compounds are still present in bottom sediment and pose significant threat to the environment. This threat should be taken into account during dredging of waterways and other hydrotechnical works.

Unilateral conditioning of an odor aversion in 6-day-old rat pups

In young rats, several forms of olfactory memory can be functionally localized to one side of the brain by restricting training stimuli to one naris and corresponding olfactory bulb. In the experiment, the analysis of lateralized olfactory learning in 6-day-old rat pups was extended by an evaluation of the consequences of aversive reinforcers in a unilateral olfactory conditioning paradigm. An olfactory aversion was conditioned by delivering a mild footshock to animals in the presence of a novel odor. Olfactory stimulation was confined to one naris and corresponding olfactory bulb by inserting a soft rubber plug into the opposite naris. This lateralization in processing resulted in unilateral memory for the odor aversion that was only expressed when the trained naris was open during an odor preference test. The hypothesis that the hedonic value (or valence) component of conditioning is represented in structures that are unilaterally accessed during training and testing is discussed.

Unilateral conditioning of an odor aversion in 6-day-old rat pups

In young rats, several forms of olfactory memory can be functionally localized to one side of the brain by restricting training stimuli to one naris and corresponding olfactory bulb. In the experiment, the analysis of lateralized olfactory learning in 6-day-old rat pups was extended by an evaluation of the consequences of aversive reinforcers in a unilateral olfactory conditioning paradigm. An olfactory aversion was conditioned by delivering a mild footshock to animals in the presence of a novel odor. Olfactory stimulation was confined to one naris and corresponding olfactory bulb by inserting a soft rubber plug into the opposite naris. This lateralization in processing resulted in unilateral memory for the odor aversion that was only expressed when the trained naris was open during an odor preference test. The hypothesis that the hedonic value (or valence) component of conditioning is represented in structures that are unilaterally accessed during training and testing is discussed.

Developmental change in the access to olfactory memories

Memory for a learned odor preference can be functionally confined to one side of the brain in 6-day-old rat pups by preferentially stimulating a single naris and corresponding olfactory bulb during training. We report here that this form of unilateral learning is present only during the first postnatal week; older pups show bilateral recall of unilateral olfactory experience. The maturation of bilateral learning probably depends on the postnatal growth and development of olfactory commissural fibers, because infantlike unilateral learning and memory is reinstated when these commissural fibers are sectioned before training in older pups. Section of commissural fibers after training also resulted in unilateral preferences. This latter finding indicates that the learned odor preference of older pups tested with the untrained naris open depends on access to unilaterally stored memories on the contralateral side, access provided by the newly developed commissural projections.

Developmental change in the access to olfactory memories

Memory for a learned odor preference can be functionally confined to one side of the brain in 6-day-old rat pups by preferentially stimulating a single naris and corresponding olfactory bulb during training. We report here that this form of unilateral learning is present only during the first postnatal week; older pups show bilateral recall of unilateral olfactory experience. The maturation of bilateral learning probably depends on the postnatal growth and development of olfactory commissural fibers, because infantlike unilateral learning and memory is reinstated when these commissural fibers are sectioned before training in older pups. Section of commissural fibers after training also resulted in unilateral preferences. This latter finding indicates that the learned odor preference of older pups tested with the untrained naris open depends on access to unilaterally stored memories on the contralateral side, access provided by the newly developed commissural projections.

New routes to early memories

Stimulation of one side of the olfactory system during training with odor-milk pairings in neonatal rats results in their ability to recall an odor memory by using the trained but not the untrained side of the brain. In 12-day-old rats, olfactory learning can be recalled by stimulation of either the trained or untrained side. The development of bilateral recall reflects the maturation of olfactory commissural pathways that provide access to the olfactory memory stored on the contralateral side. Furthermore, the commissural pathways need not be present at the time of memory formation but can establish new and specific access to already existing olfactory memories.

Further examination of ontogenetic limitations on conditioned taste aversion

This study was to resolve a discrepancy in the literature as to the capability of infant rats in acquiring conditioned taste aversion. Previous studies had indicated that during the 1st postnatal week, an aversion to saccharin could be conditioned when paired with lithium chloride (LiCl). Analogous conditioning with sucrose did not seem to occur until the end of the 2nd postnatal week, however, even though sucrose is discriminated from water and preferred before then. We observed that 5- and 9-day old pups express conditioned taste aversion to both saccharin and sucrose flavors that previously were paired with illness induced by LiCl. This learning occurred only when several hours separated cannulation and conditioning. A number of other factors that seemed likely to determine this early learning were found to have no effect. Thus it appears that rats can learn taste aversions very early in life, but only under certain circumstances. The results are discussed with reference to Vogt and Rudy's (1984) conclusions on the ontogeny of taste guided behaviors in the rat.

Unilateral olfactory conditioning in 6-day-old rat pups

The potential that early olfactory learning might be laterally organized in the brain was investigated in 6-day-old rats. This hypothesis is based on the finding that the commissural systems that subserve bilateral olfactory communication do not mature until the second week of postnatal life. Pups were trained with pairings of cedar odor and intraoral infusions of milk while one nostril was occluded. Animals expressed a conditioned orientation towards cedar if tested with the trained nostril open. No such conditioning was observed if the untrained nostril was open during testing. Further, when individual pups received cedar odor/milk pairings with one nostril open and orange odor/milk pairings with the other open, they expressed a conditioned preference for orange when tested with the orange-trained nostril open, and a preference for cedar when tested with the cedar-trained nostril open. Classically conditioned oral responses (mouthing) also appeared to be lateralized. However, no such unilateral conditioning occurred with respect to behavioral activation, which is also conditioned in this paradigm. Increases in activity to the odor CS were observed regardless of whether the trained or untrained nostril was open during testing. These results suggest that in developing rodents, olfactory memories may be partly represented in structures that can be unilaterally accessed during training and testing. They provide a starting point for isolation of neural substrates of the olfactory conditioning process.

Ontogenetic comparison of memory for Pavlovian conditioned aversions to temperature, vibration, odor, or brightness

Ontogenetic differences in forgetting of Pavlovian conditioning were tested in four experiments with 550 rats of ages 12, 18, or 60 days postpartum. The experiments had in common the same unconditioned stimulus (US; footshock) and procedures for conditioning and testing, but the conditioned stimulus (CS) differed. The CS was a particular vibrotactile stimulus (Experiment 1), ambient temperature (Experiment 2), odorant (Experiment 3), or brightness (Experiment 4). The intent of this study was to assess, in more comparable circumstances than previously tested, the possibility of substantial differences in infantile amnesia for different sensory modalities. Particular attention was given those modalities that mature early and had not been tested in previous studies of infantile amnesia. The results verified some degree of infantile amnesia for even those sensory modalities used adaptively from birth.

Conditioning of an odor aversion in preweanlings with isolation from home nest as the unconditioned stimulus

Four experiments assessed the acquisition of aversions by preweanling rats to odors experienced during isolation from their home-nest environment. Conditioned aversion occurred for animals given a second novel odor paired with the home-nest environment, depending upon the duration of the odor-isolation pairing. With a brief duration of pairing (two pairings of 3 min each) novel odors became more preferred when paired with isolation or, to a lesser extent, when paired with home. With longer durations of pairing (two pairings of 4 hr each) the odor paired with isolation became absolutely aversive, although the odor paired with home did not become absolutely preferred. With intermediate durations neither aversion nor preference for the odors was substantial. Animals conditioned at ages 9, 16, or 23 days postnatal acquired aversions to odors paired with isolation, but 30-day-old rats did not.

Potentiation and overshadowing in preweanling and adult rats

Four experiments compared the aversion acquired by 18-day-old and 60-day-old rats to a flavor that was either tasted alone or in combination, simultaneously or successively, with another flavor when paired with illness. The purpose was to study temporal variables and theoretical issues pertinent to potentiation and overshadowing while investigating ontogenetic differences in these phenomena. When either the preweanlings or the adults were presented a simultaneous compound flavor (sucrose/coffee) followed by lithium chloride-induced illness, greater sucrose aversions were found than for animals conditioned on sucrose alone--that is, potentiation. Preweanlings demonstrated greater potentiation than did adults, whether the conditioned stimulus-unconditioned stimulus (CS-US) delay was 0 or 1 hr. This potentiation was eliminated by nonreinforced presentations of the alternative CS element. Potentiation was not seen when the two flavors were presented successively as the CS; instead, overshadowing occurred. Tests of configuring by extinction procedures indicated a tendency for these animals to form a configured representation of the simultaneous compound solution. This disposition for configuring tended to be more pronounced for preweanlings than for adults. Ontogenetic differences in response to configuration, CS saliency, and generalization decrement seem consistent with at least one model of potentiation and the ontogenetic differences in potentiation seen in the present experiments.

Familiar contextual odors promote discrimination learning in preweanling but not in older rats

For rats 16- or 28-days-old postnatal, we tested the source of the facilitation in instrumental learning provided by odors from home nest materials. Three experiments confirmed that acquisition of a spatial discrimination (to escape footshock) was facilitated not only by the presence of typical nest odors in the training context, but also by the presence of a non-rat odor (banana) to which the animals had been familiarized for 4 hr/day for 7 days. There was a borderline tendency for a similar facilitation after familiarization to the latter odor for only 10 min. These effects occurred for rats 16 days postnatal but not for those 28 days old. The experiments also confirmed that the prior exposure to non-rat odors did not in itself, in the absence of that odor during learning, affect discriminated escape learning, and that enhanced affinity for a contextual odor is not a sufficient condition for enhancement of learning in its presence. There was some indication that the 16-day-old rat was more likely to select a discriminative odor to guide their choice of spatial locations if a familiar contextual odor was present.

Conditioning of aversion to an odor paired with peripheral shock in the developing rat

Four experiments examined an apparent inability to associate, or severe deficiency in associating, an odor and a footshock during the first 2 weeks of life in the rat, a cue-to-consequence relationship that had formerly seemed age-dependent. With a particular classical conditioning procedure, however, significant conditioning occurred on postnatal Days 6 and 10 with relatively few conditioning trials; the procedure employed an odor explicitly unpaired with footshock (CS-), as well as an odor paired with footshock (CS+) (Experiment I). Experiment II assessed the contribution of a CS- exposure in the conditioning of rats 8, 15, or 50 days of age. For 8-day-olds, exposure to both the CS+ and CS- resulted in conditioned aversion to the CS+ after eight but not one conditioning trials, but neither 1 nor eight trials with only a CS+ produced conditioning. For 15- and 50-day-olds, conditioning to the CS+ odor was significant after one trial with, but not without, a specific CS-; with eight trials, however, conditioning was significant with or without the specific CS-. It was verified with the 50-day-olds in Experiment III that aversion to the CS+ was conditioned with a single trial only if a CS- had been presented, with a slight trend toward superior conditioning if the CS- preceded rather than followed the CS+ during conditioning. Experiment IV tested the hypothesis that exposure to the distinctive CS- odor sensitizes the animal to the specific properties of the CS+ odor. Fifteen and 50-day-old rats were given one conditioning trial with a CS+ odor that was either unaccompanied by a CS- or that was presented with a CS- odor in the same context as the CS+ or in a different context. For both 15- and 50-day-old rats, conditioning to the CS+ occurred only for animals given the CS- in the same context as the CS+, indicating that the hypothesis should be rejected. The results generally indicate rapid and substantial odor-footshock conditioning in rats as young as 6 days of age, with CS- exposure established as perhaps especially significant for conditioning early in life, but important for rats of all ages tested, from infancy to adulthood.

Potentiation of a conditioned taste aversion in preweanling and adult rats

Preweanling (18 days old) and adult rats were made ill with LiCl either 2 min or 1 hr after tasting controlled amounts of either one of two single flavors (saccharin or NaCl) or a compound mixture of the two. Conditioning was assessed with a single test 4 days later relative to explicitly unpaired control conditions. Generally, potentiation of the aversions to either flavor occurred for animals conditioned to the compound. The potentiation effect was decreased or eliminated by nonreinforced exposure to the alternative flavor of the compound. These effects tended to be stronger for the younger rats. Specifically, adult animals did not express potentiation of the saccharin aversion whereas preweanlings expressed potentiated salt aversions. Nonreinforced exposure to the alternative element eliminated the potentiation effect. Conditions conducive to potentiation are discussed in light of investigators who have not observed this effect in similar studies with compound stimuli.