Fluorescence fingerprint of fulvic and humic acids from varied origins as viewed by single-scan and excitation/emission matrix techniques

Excitation/emission matrix (EEM), single-scan excitation and synchronous fluorescence spectra of a series of FA and HA from distinct environments are presented. The EEM plots show at least four spectral features whose corresponding Ex/Em pairs relate to the alpha', alpha, beta and gamma (or delta) fluorophores previously found in natural waters spectra. The alpha' and alpha peaks, which identify typical humic-like components, are present in all samples, independently of the organic matter (OM) source. In FA, their Ex/Em pairs are approximately 260 nm/460 nm and approximately 310 nm/440 nm, respectively. In HA their excitation and emission maxima are red-shifted, the corresponding Ex/Em pairs being located at approximately 265 nm/525 nm and approximately 360 nm/520 nm, respectively. The appearance of beta and gamma (or delta) peaks is dependent both on the OM origin and on HS aging. The former (Ex/Em approximately 320 nm/430 nm), that has been associated with the incidence of marine humic-like material, is present only in a few marine and estuarine HA. It emerges as a shoulder on the alpha peak and its detection is dependent on a balance between its magnitude and the magnitude and emission maxima location of the alpha peak. The gamma (or delta) peak (Ex/Em approximately 275 nm/315 nm in FA, and approximately 275 nm/330 nm in HA), on the other hand, is better visualized in FA than in HA diagrams. It has typical protein-, mainly tryptophan-like, fluorescence properties and appears with varied significance in a few marine and estuarine samples being hardly detected in samples from exclusively terrestrial environments. It is also shown in this study that with selected lambda(ex), lambda(em) and (delta)(lambda) values, regular emission, excitation and synchronous spectra can, together, provide a good picture of the OM sources and aging for extracted HS.     

Sorption of 17α-ethinyl estradiol, bisphenol A and phenanthrene to different size fractions of soil and sediment

The potential for negative effects caused by endocrine disrupting chemicals (EDCs) release into the environment is a prominent concern and numerous research projects have investigated possible environmental fate and toxicity. However, their sorption behavior by size fractions of soil and sediment has not been systematically represented. The sorption of bisphenol A (BPA), 17α-ethinyl estradiol (EE2) and phenanthrene (Phen) by different size fractions of soil and sediment were investigated. Sorption isotherms of EE2, BPA, and Phen by size fractions of soil (SL) and sediment (ST) were well fitted to the Freundlich model. The positive correlation between EE2, BPA and Phen sorption capacity (log K_d) of size fractions and their organic carbon (OC) content suggests that OC of size fractions in SL and ST should regulate sorption, while the surface area (SA) of size fractions may not account for sorption of EE2, BPA and Phen. Each size fraction of ST had higher sorption capacity (K_d or K_OC) of EE2 and BPA than that of SL due to their difference in the polarity of organic matter (OM) between terrestrial and aquatic sources. Sorption capacity logK_d for size fractions of SL and ST did not follow the order: clay > silt > sand due to the difference in OM abundance and composition between the size fractions. Large particle fractions of ST contributed about 80% to the overall sorption for any EE2, BPA, and Phen. This study was significant to evaluate size fractions of soil and sediment as well as their associated OM affecting EE2 and BPA sorption processes.     

Dissolved organic matter with multi-peak fluorophores in landfill leachate

Dissolved organic matter (DOM) sampled from municipal landfill leachate of different ages with/without anoxic or aerobic treatment, was intensively fractionated via size exclusion chromatography (SEC) and hydrophobic resins, and was studied with fluorescence excitation and emission matrix (EEM). Six fluorophores with multiple EEM peaks (fluorophore A-F) were identified based on the collected EEM spectra and validated by bi-variate analysis, principal component analysis, and parallel factor analysis, as follows (excitation wavelength Ex and emission wavelength Em): (Ex 240, 310, 360 nm, Em 460 nm), (Ex 220, 280 nm, Em 340 nm), (Ex 220, 270 nm, Em 300 nm), (Ex 220, 280 nm, Em 360 nm), (Ex 230, 320 nm, Em 420 nm) and (Ex 220, 310 nm, Em 400 nm). The spectral characteristics of these fluorophores were discussed using fractional EEM and apparent molecular weight (AMW) data obtained via SEC analysis. The triple peak flurophore A was pointed at a hydrophobic acid or hydrophobic neutral compound with a pyrenyl functional group of AMW 2500-3500 Da, which displayed an excitation wavelength at 360 nm and a fluorescence intensity ratio of 6.70(+/-1.79):1.70(+/-0.41):1 (fluorescent intensities of Ex 240:Ex 310:Ex 360 nm at Ex 460 nm). This compound is observed to be refractory in landfilling or in anoxic/aerobic treatments, and is specific to this leachate contamination. This paper revealed that the coupling of SEC and EEM can be useful to track the fluorescent DOM fraction in landfill leachate.     

Biofilm controlled sorption of selected acidic drugs on river sediments characterized by different organic carbon content

The sorption process of selected non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, ketoprofen, diclofenac) on biofilm covered river sediments were investigated in laboratory. In the course of the experiments, the effect of pH of aqueous phase, the effect of TOC (total organic carbon) content of biofilm on the sorption processes were studied. The determination of concentration of drugs was performed by gas chromatography mass spectrometry (GC-MS) both in liquid and solid phases. The pseudo-first-order rate constant of the sorption was found to be 83 min(-1). The effect of pH on the sorption of diclofenac was significantly lower than the obtained values in case of the other three drugs. The calculated K(d) (sorption coefficient) values increased in the sequence of ibuprofen, naproxen, ketoprofen and diclofenac and varied between 0.1-0.4; 0.2-0.7; 0.2-1.2; 0.2-1.4 kg L(-1) respectively, depending on the characteristics of the sediments. The value of K(d)×f(oc) showed a straight line as function of f(oc) (fraction of organic carbon) therefore, instead of the widely distributed normalization process (K(d)/f(oc)), an empirical equation (K(d)=A/f(oc)+B) was suggested for estimation of the K(d) values in case of different TOC content sediments.     

Determination and partitioning behavior of perfluoroalkyl carboxylic acids and perfluorooctanesulfonate in water and sediment from Dianchi Lake, China

Perfluorinated compounds (PFCs) have received much attention on their distribution in various matrices including water bodies, precipitations, sediment and biota in different areas globally, however, little attention has been paid to their occurrence and distribution in urban lakes. In this study, water and sediment samples collected from 26 sites in Dianchi Lake, a plateau urban lake in the southwestern part of China were analyzed via high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for ten analytes involving nine perfluoroalkyl carboxylic acids (PFOAs) and perfluorooctanesulfonate (PFOS). Total levels of PFCs were 30.98 ± 32.19 ng L(-1) in water and 0.95 ± 0.63 ng g(-1) in sediment. In water samples PFOA was the dominant PFC contaminant, with concentrations ranging from 3.41 to 35.44 ng L(-1), while in sediments PFOS was the main PFC contaminant at levels from 0.07-0.83 ng g(-1) dry weight. Field-based sediment water distribution coefficients (K(D)) were calculated and corrected for organic carbon content (K(oc)), which reduced variability among samples. The log K(oc) ranged from 2.54 to 3.57 for C8-C12 perfluorinated carboxylic acids, increasing by 0.1-0.4 log units with each additional CF2 moiety. The log K(oc) of PFOS was 3.35 ± 0.32. Magnitudes and trends in log K(D) or log K(oc) appeared to agree well with previously published laboratory data. Results showed that different PFC composition profiles were observed for samples from the lake water and sediments, indicating the presence of dissimilar characteristics of the PFCs compounds, which is important for PFC fate modeling and risk assessment.     

Investigations on the sorption of a toxaphene model congener, the B7-1450, on marine sediments

Sorption is a natural process that takes place in sediments or soils and changes the mobility and availability of hydrophobic organic compounds, such as toxaphene pesticide in the environment. The sorption of the 2-exo,3-endo,5-exo,8,9,10,10-heptachlorobornane (B7-1450), used as a model compound of the toxaphene heptachlorobornane congeners found in sediments, was investigated for the first time through a series of batch sorption experiments. The losses of B7-1450 due to adsorption onto glass walls and to evaporation occurring during analytical treatment steps were corrected. The study showed that these specific losses ranged from 2% to 3.5% for the glass walls adsorption and can be as high as 15% for the evaporation treatment. The sorption coefficients, K(d) and K(oc), of B7-1450 could be overestimated by >30%, particularly for low-concentration samples, if the losses were not corrected. Loss correction equations were established, validated and applied to determine sorption coefficients for the B7-1450 congener. The K(oc) values for B7-1450 determined over a gradient of concentrations ranged from 3.5x10(4) to 6.5x10(4)mlg(-1), revealing a strong affinity of B7-1450 for marine sediments.     

Interaction of erythromycin ethylsuccinate and acetaminophen with protein fraction of extracellular polymeric substances (EPS) from various bacterial aggregates

Extracellular polymeric substances (EPS) are, along with microbial cells, the main components of the biological sludges used in wastewater treatment and natural biofilms. EPS play a major role in removing pollutants from water by means of sorption. The ability of soluble EPS (S-EPS) and bound EPS (B-EPS) derived from various bacterial aggregates (flocs, granules, biofilms) to bind at pH 7.0?±?0.1 to two pharmaceutical substances, acetaminophen (ACE) and erythromycin ethylsuccinate (ERY), has been investigated using the fluorescence quenching method. Two intense fluorescence peaks, A (Ex/Em range, 200–250/275–380 nm) and B (Ex/Em range, 260–320/275–360 nm), corresponding respectively to the aromatic protein region and soluble microbial by-product-like region, were identified in a three-dimensional excitation-emission matrix of EPS samples. The fluorescence peak, which corresponds to humic-like substances, was also identified though at low intensity. The ability of EPS to bind ACE was found to exceed that for ERY. The aromatic protein fraction of EPS displays a slightly higher affinity for drugs than that shown by the soluble microbial by-product-like fraction. The S-EPS and B-EPS present the same affinity for ACE and ERY. The effective quenching constants (log K) derived from the Stern–Volmer Equation equaled at peak A (with S-EPS): 3.7?±?0.2 to 4.0?±?0.1 for ACE and 2.1?±?0.3 to 2.7?±?0.1 for ERY. With B-EPS, these values were 3.9?±?0.1 to 4.0?±?0.1 for ACE and 2.0?±?0.2 to 2.6?±?0.1 for ERY. Our results suggest that the weaker EPS affinity for ERY than for ACE serves to partially explain why only about 50–80 % of ERY is removed from wastewater at the treatment plant. Moreover, this work demonstrates that EPS from natural river biofilms are able to bind drugs, which in turn may limit the mobility of drugs in natural waters.     

Correlations of nonlinear sorption of organic solutes with soil/sediment physicochemical properties

The estimation of solute sorptive behaviors is essential when direct sorption data are unavailable and will provide a convenient way to assess the fate and the biological activity of organic solutes in soil/sediment environments. In this study, the sorption of 2,4-dichlorophenol (2,4-DCP) on 19 soil/sediment samples and the sorption of 13 organic solutes on one sediment were investigated. All sorption isotherms are nonlinear and can be described satisfactorily by a simple dual-mode model (DMM): q(e)=KpCe+Q0 . bCe/(1+bCe), where Kp (mlg(-1)) is the partition coefficient; Ce (microgml(-1)) is the equilibrium concentration; Q0 (microgg(-1)) is the maximum adsorption capacity; Q0 . b (mlg(-1)) is the Langmuir-type isotherm slope in the low concentration (Henry's law) range and b (mlmicrog(-1)) is a constant related to the affinity of the surface for the solute. Based on these nonlinear sorption isotherms and similar other nonlinear isotherms, it is observed that, for both polar 2,4-DCP and nonpolar phenanthrene, Kp, Q0 and Q0 . b are linearly correlated with soil/sediment organic carbon content (f(oc) in the range of 0.118-53.7%). The results indicate that the nonlinear sorption of organic solutes results primarily from interactions with soil/sediment organic matter. The K*oc K*oc=Kp/f(oc)), Qoc (Qoc=Q0/f(oc)), Loc (Loc=Q0 . b/f(oc)) and b for a given organic solute with different soils/sediments are largely invariant. Furthermore, logK*oc, logb and logLoc for various organic solutes are correlated significantly with the solute logKow or logSw (logKow in the range of 0.9 to 5.13 and logSw in the range of -6.176 to -0.070). A fundamental empirical equation was then established to calculate approximately the nonlinear sorption from soil/sediment f(oc) and solute Sw for a given solute equilibrium concentration.     

Photosensitized degradation of bisphenol A involving reactive oxygen species in the presence of humic substances

The photodegradation of endocrine disrupter bisphenol A (BPA) in the presence of natural humic substances (HS) under simulated solar irradiation was studied. BPA underwent slow direct photolysis in neutral pure water, but rapid photosensitized degradation in four kinds of HS, following pseudo-first-order reaction. Reactive oxygen species (ROS) formed from HS were determined, including OH, (1)O(2) and H(2)O(2). The enhancement of BPA degradation by adding Fe(III) was primarily attributed to the oxidation of OH produced from photo-Fenton-like reaction. And the joint effects of HS and nitrate ions coexisting on BPA degradation appeared to depend on respective concentration levels. The effects of dissolved oxygen suggested that the energy transfer between excited state of SRFA and NOFA likely occurred, while the abstraction of phenolic hydrogen atom to reactive triplet state of NOHA possibly took place. Based on the structural analyses of main intermediates and degradation products of BPA detected by GC-MS, the possible photodegradation pathways were proposed, involving the alky cleavage, alkyl oxidation and OH addition. This study gave a better understanding for the photochemical transformation of BPA induced by ROS generated from natural water composition under sunlight irradiation.     

Influences of preparative methods of humic acids on the sorption of 2,4,6-trichlorophenol

Humic acids (HAs) are a major component of soil organic matter which strongly affects the sorption behavior of organic contaminants in soils. To assess the sorption-desorption characteristics of organic compounds on HAs, the organic adsorbent is usually isolated using an acid-base extraction method followed by air-drying or freeze-drying. In this study, a peat soil from the Yangming mountain area of Taiwan was sampled and repeatedly extracted followed by either air-drying or a non-drying treatment (denoted DHAs and NDHAs, respectively). The sorption of 2,4,6-TCP on HAs was evaluated using the batch method. Kinetic sorption results indicated that DHAs exhibited a two-step first-order sorption behavior, involving a rapid sorption followed by a slow sorption. The slow sorption may be attributed to the diffusion of 2,4,6-TCP through the condensed aromatic domains of HAs. On the contrary, the sorption of 2,4,6-TCP on NDHAs was extremely rapid, and the sorption data did not fit existing kinetic models. Each HA sample exhibited a nonlinear sorption isotherm. Sorption nonlinearity (represented by Freundlich N values) and K(oc) had a positive relationship with aliphaticity for DHAs; however, nonlinearity and K(oc) correlated positively with aromaticity when NDHAs adsorbents were used. We conclude that the air-drying technique may artificially create a more condensed area, which strongly affects the sorption characteristics of HAs. Thus, an incorrect evaluation of the sorption capacity and its relationship with the chemical composition of HAs would arise following use of the air-drying method.     

Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans in suspended sediments, dissolved phase and bottom sediment in the Houston Ship Channel

Spatial distributions of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in the water column and bottom sediments of the Houston Ship Channel in Texas were measured three times over a 1-year period. Total TEQ concentrations in water ranged from 0.01 to 0.25 pg/l for the dissolved phase and from 0.09 to 2.91 pg/l for the suspended phase, while TEQ concentrations in bottom sediments varied from 0.9 to 139.8 ng/kg dry wt. The dissolved concentrations were lower than their respective suspended concentrations, with average dissolved/suspended ratios between 0.11 and 0.59 for individual congeners. More than 89% of the total concentration of 2378-substituted PCDD/PCDFs was attributable to OCDD but 2378-TCDD was the major contributor to total TEQ for the three sampled media. Average logs of organic carbon-normalized suspended sediment-dissolved partitioning coefficients (logK(oc)(obs)) varied between 4.92 and 8.59 l/kg-oc; while in the bottom sediment-dissolved interface, logK(oc)(obs) values ranged from 5.48 to 8.48 l/kg-oc. Observed logK(oc)values varied within a factor of 0.64-1.26 from equilibrium logK(oc) values, suggesting fluxes of PCDD/PCDFs across the interfaces. It was found that in the HSC, on average, the tendency of a compound to move from the particulate phase to the dissolved phase decreases with increasing K(ow).     

Human UDP-glucuronosyltransferase isoforms involved in bisphenol A glucuronidation

Bisphenol A (BPA) is one of a number of potential endocrine disruptors which may affect normal hormonal function. In this study, human UDP-glucuronosyltransferase (UGT) isoforms involved in BPA glucuronidation were studied by kinetic analyses using human liver microsomes and recombinant human UGTs expressed in insect cells (UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9, UGT2B4, UGT2B7, UGT2B15 and UGT2B17). BPA glucuronidation was catalyzed by UGT1A1, UGT1A3, UGT1A9, UGT2B4, UGT2B7 and UGT2B15 as well as by human liver microsomes. Among these UGTs, UGT2B15 showed the highest activity of BPA glucuronidation at low- (1.0 microM) and high- (20 microM) substrate concentrations. Kinetic analyses of BPA glucuronidation were performed by constructing Michaelis-Menten and Eadie-Hofstee plots. The kinetic profile of BPA glucuronidation by pooled human liver microsomes and UGT2B15 was monophasic, the K(m) and V(max) values were 6.39 microM and 4250 pmol min(-1)mg(-1)protein for pooled human liver microsomes, and 8.68 microM and 873 pmol min(-1)mg(-1)protein for UGT2B15, respectively. The K(m) values for BPA glucuronidation by pooled human liver microsomes and UGT2B15 were similar. These findings demonstrate that BPA is mainly glucuronidated by UGT2B15 in human liver microsomes, and suggest that this UGT isoform plays important roles in the detoxification and elimination of BPA.     

Sorption of alkylphenols on Ebro River sediments: comparing isotherms with field observations in river water and sediments

This study reports sorption isotherms of the endocrine disruptors nonylphenol (NP) and octylphenol (OP) in three sediment samples from the Ebro River basin (NE Spain), with organic carbon fractions (f_OC) ranging from 0.0035 to 0.082 g_OC g⁻¹. All isotherms were fitted to the Freundlich model with slightly nonlinear exponents ranging from 0.80 to 0.94. The solubility of the compounds as well as the organic carbon (OC) content had the strongest influences on the sorption behavior of these compounds. Comparison of the laboratory-spiked samples with the native contamination of NP of 45 water and concurrent sediment samples resulted in reasonable matches between both data sets, even though the lowest concentrations in the field were not completely reached in laboratory tests. This good agreement indicates that sorption laboratory data can be extrapolated to environmental levels and therefore the distribution of nonylphenol between sediments and water can be predicted with a precision of one order of magnitude. Furthermore, laboratory experiments with simultaneous loading of NP and OP revealed negligible competition for sorption sites at low concentrations.     

Endocrine disrupter nonylphenol and bisphenol A contamination in Okinawa and Ishigaki Islands, Japan--within coral reefs and adjacent river mouths

Certain chemicals possess the potential to modulate endocrine systems, and thereby interfere with reproduction and developmental processes in the wild. We analyzed endocrine disrupters nonylphenol (NP) and bisphenol A (BPA) levels at various sites in Okinawa and Ishigaki Islands, Japan. River-water samples showed undetectable to low concentrations of NP and BPA at most of the sites investigated. However, an appreciable amount of BPA was detected in sediments at one coral reef site. In addition, significant numbers of river sediment samples showed appreciable amounts of NP and BPA. Most of the sampling sites for this study are located within a distance of 1 km from the coral reefs, which are under influence of river-waters to a variable extent. Therefore, influence of endocrine disrupters may have already begun on adjacent coral reefs. Both endocrine disrupters were positively correlated with human population densities, but not with the contents of red soil generated by farm land reformation. Therefore, it is concluded that NP and BPA pollution is a consequence of human waste discharge, both domestic and industrial, and not by agricultural activities.     

Sulfamethoxazole sorption by sediment fractions in comparison to pyrene and bisphenol A

The environmental behavior of antibiotics has attracted great research attention. However, their sorption mechanisms in soils/sediments are still unknown. Comparison of the sorption properties between the widely-studied hydrophobic organic contaminants (HOCs) and antibiotics may provide valuable insight to antibiotic sorption mechanisms. Thus, in this study batch experiments for pyrene (PYR), bisphenol A (BPA), and sulfamethoxazole (SMX) sorption were conducted on a sediment sample and its separated fractions. Our results showed the high sorption of PYR on black carbon and organic matter. Although high sorption of SMX was observed for both separated organic fractions (humic acids) and inorganic mineral particles, the original sediment particles showed relatively low sorption. Competitive sorption between SMX and dissolved humic acid on mineral particles was observed in this study. This competitive interaction is a unique process for antibiotic sorption in soils/sediments compared with apolar HOCs and may be one of the important factors controlling the antibiotic sorption.     

Determination of the distribution coefficient (log Kd) of oxytetracycline,tylosin A,olaquindox and metronidazole in manure

Olaquindox (log Kow = -2.3) and metronidazole (log Kow = -0.1) both have low tendencies to sorp to particles in manure. This corresponds with the negative log Kow values of these antibiotics. Tylosin (log Kow = 1.63) and oxytetracycline (log Kow = -1.12) sorp relatively strongly to the manure particles and have log Kd values between 1.5 and 2.0. The tendency to bind to manure was ranked after increasing binding as follows: metronidazole < olaquindox < tylosin A and oxytetracycline. This order of ranking is consistent with results of sorption in soil. Our experiments illustrate that for some antibacterial agents estimation of the partitioning coefficients, Kd, cannot be made from Kow and f(oc) alone. Sorption of oxytetracycline to manure is much higher than expected from the negative log Kow value of the compound. It is believed that sorption of oxytetracycline to manure is influenced by ionic binding to divalent metal ions as such Mg2+ and Ca2+ as well as other charged compounds in the matrix. Binding of oxytetracycline to soil is stronger than the binding to manure. This is most likely due to the strong mineral related metal complexes formed between soil, metal ion and oxytetracycline. These complexes are not known to exist in manure. The relatively strong sorption of tylosin A to manure corresponds with data found for soil sorption of tylosin. Tylosin has a log Kow value of 2.5, thus it is not surprising that this drug binds strongly to manure.     

Seasonal and spatial distribution of nonylphenol in Shihwa Lake, Korea

Alkylphenols (APs) have been known as endocrine disruptors and consequently received much environmental concern. This study focused on seasonal variation and spatial distribution of nonylphenol (NP) in various matrixes including dissolved water, particulates, surface sediment, sediment trap and sediment core taken from Shihwa Lake and its adjacent areas. A total of 11 phenolic compounds including nonylphenol, t-octylphenol (t-OP) and bisphenol A (BPA) were measured in February, June and October 2002. NP is the most abundant chemical among the phenolic compounds and its concentrations in dissolved water, particulates and surface sediments from Shihwa Lake were measured as 17.4-1533.1 ng/l, 4.3-831.2 ng/l and 10.4-5054.1 ng/g dw, respectively. NP concentration in dissolved water varied with seasons and generally showed a decreasing order of June > October > February, while the seasonal trend was hardly found in sediment. High levels of NP were measured in surrounding industrial complexes, the concentrations was decreased gradually with distance from the industrial areas. NP in core samples showed an increasing trend toward the core depth. There exists a reasonable correlation between NP in dissolved water and in particulates, whereas the correlation between NP in dissolved water and in sediments is not significant. APs concentrations in Shihwa Lake were comparable to other highly polluted areas of the world and their possible effects on various organisms in the lake are discussed.     

The impacts of bisphenol A (BPA) on abalone (Haliotis diversicolor supertexta) embryonic development

The effects of bisphenol A (BPA) on abalone (Haliotis diversicolor supertexta) embryonic development were investigated by exposing the fertilized eggs to four different concentrations of BPA (0.05, 0.2, 2 and 10 μg mL⁻¹). Toxicity endpoints including the embryo development parameters, the physiological features and the expression profile of several reference genes (prohormone convertase 1, PC1; cyclin B, CB; and cyclin-dependent kinase 1, CDK1) were assessed. The results showed that BPA could markedly reduce embryo hatchability, increase developmental malformation, and suppress the metamorphosis behavior of larvae. The possible toxicological mechanisms hidden behind of these effects (i.e. disturbing the embryogenesis) might result from three aspects: (1) BPA disturbance the cellular ionic homeostasis and osmoregulation of abalone embryos by changing the Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase levels; (2) BPA induced oxidative damage of embryos by significantly alterating the peroxidase (POD) activities and the malondialdehyde (MDA) production; and (3) the RT-PCR analysis further demonstrated that BPA perturbed the cellular endocrine regulation and cell cycle progression by down-regulating the PC1 gene, as well as over-expressing the CB and CDK1 genes. This is the first comprehensive study on the developmental toxicity of BPA to the marine abalone at morphological, physiological and molecular levels. The results in this study also indicated that the embryo tests can contribute to the ecological risk assessment of the endocrine disruptors in marine environment.     

Investigations on the sorption of phenols to dissolved organic matter by a QSAR study

The sorption of various phenols to Aldrich-HA and BSA was investigated by solid phase microextraction (SPME). The Aldrich-HA sorption with log K(DOC)-values between 2 and 3 was determined, whereas the sorption to BSA with log K(DOC)-values between 2 and 6 was much stronger. To enable an estimation of sorption constants a QSAR model was investigated. The linear free energy relationship (LFER) model showed a good correlation between the sorption constants and the log K(OW)-values with correlation coefficients of R = 0.910 and R = 0.878 for Aldrich-HA and BSA, respectively.