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The increasing load of organophosphate flame retardants (OPFRs) has generated wide concerns about their potential residues in aquatic environments. The uptake and translocation of fourteen OPFRs by wheat (Triticum aestivum L.) were studied under hydroponic conditions. The results revealed that OPFRs were removed from hydroponic solution by wheat, and the removal processes followed first-order kinetics. After 10 days, the removal efficiencies were in a range of 57.9 ± 3.8%−63.8 ± 5.6%. The potential for translocation of these OPFRs from the roots to foliage was also assessed. OPFRs with relatively higher hydrophobicity were more likely taken up by roots, and OPFRs with lower hydrophobicity were more prone to be translocated. Root concentration factors (RCFs), transpiration stream concentration factors (TSCFs), and foliage/root concentration factors (FRCFs) were calculated. Furthermore, significant correlations were found between RCF, FRCF or TSCF values of OPFRs and log Kow (p

Fluoroquinolones (FQs) have attracted wide concerns due to their pseudo-persistent and universal presence in natural water. Here we exposed zebrafish separately to two FQs (enrofloxacin (ENR) and ofloxacin (OFL)) in different copper (Cu) concentrations for 20 days (d) in a flow-through system, followed by a 11 d depuration period in clean water to investigate compound specific bioaccumulation and tissue distribution. Two FQs could accumulate in zebrafish, and the high concentration was observed in liver. Moreover, the levels of FQs in different treatment groups were higher than the corresponding control fish group. The uptake rates (k1), elimination rates (k2), BCF value, and half-lives (t1/2) of FQs ranged from 0.02 to 3.28 d−1, 0.01 to 0.97 d−1, 0.33 to 109.33, 9.90 to 69.31 d, respectively. With Cu exposure concentration's increasing, k1 values in three tissues (liver, skin and gill) obviously decreased. The exposure concentration affected the BCF value significantly, but didn’t change their relative compositions in liver, gill, skin, and muscle after long time exposure. BCF values of ENR were always a little bit higher than those of OFL in almost all the tissues (liver, skin and gill) in the low Cu concentration treatments, whereas, in the high Cu concentration treatments the bioconcentration factors (BCF) values of ENR were lower than the values of OFL. The exposure of Cu played an important role in the FQs bioconcentration and BCF. These results are meaningful for improved understanding and prediction of the behavior and fate of metallic and antibiotics in aqueous environments.

Fluoroquinolones (FQs) are extensively used in humans and animals, which have aroused wide attention due to the emergence of FQ resistant bacteria and frequent detection in water, sediment and organism. However, little information is available about the bioconcentration and tissue distribution of FQs in fish. In the present study, we investigated the uptake and depuration of eight FQs (balofloxacin (BAL), enoxacin (ENO), enrofloxacin (ENR), fleroxacin (FLE), lomefloxacin (LOM), moxifloxacin (MOX), ofloxacin (OFL), sparfloxacin (SPA)) in common carp under controlled laboratory conditions. The results showed that all target FQs could accumulate in fish tissues, and had a similar tendency over time during the whole uptake and depuration periods. The uptake rate constant (k1), depuration rate constant (k2) and half-lives (t1/2) were in the ranges of 0.007–3.599 L/(kg·d), 0.051–0.283 d−1 and 2.4–10.7 d, respectively. The ranges of bioconcentration factors (BCFs) were 0.24–39.55 L/kg, 0.21–24.97 L/kg and 0.04–1.07 L/kg in liver, kidney and muscle, respectively. BCFs of eight FQs decreased in the order: MOX > ENR > ENO ≈ BAL ≈ FLE ≈ OFL ≈ LOM ≈ SPA, which may be correlated with the substituents at positions 7 and 8 of the basic quinolone nucleus and the metabolic capacity. Besides, BCFs were relative with pH-adjusted distribution coefficient (log D), suggesting that molecular status of ionizable compounds strongly influenced the bioconcentration processes. The present study provides important insights for understanding the bioconcentration and tissues distribution of FQs.

The presence and concentrations of 25 antibiotics in Dalian coastal water of the Bohai Sea were investigated using solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry. Results showed that antibiotics were widely detected in this region with total concentration ranging from 22.6 to 2402.4 ng/L. Enrofloxacin and trimethoprim were 100% detected followed by sulfamethoxazole with a detection rate of 90.9%. No significant correlations were found between antibiotics concentrations and sample parameters such as dissolved organic carbon, salinity, and distance from the coast, suggesting that concentrations and distributions of the antibiotics in this area were source-dependent. Antibiotic concentration in the sample from an offshore cage-culture area was the highest. Based on composition profiles, mariculture was supposed to be an important source of antibiotics. According to the assessment, individual antibiotic posed low to moderate risk, while the antibiotic mixture presented high risk. Enrofloxacin, clarithromycin and sulfamethoxazole, the top three contributors to the mixture risk quotients for each site, need priority control in this area. Besides, levels of enrofloxacin were high enough to exert a selective pressure on bacteria that may lead to an increase in the prevalence of resistance.

The increase in the production and usage plus the toxicity nature of organophosphate flame retardants (OPFRs) has become a concern. However, limited information is available about the bioaccumulation potential of OPFRs in fish. In this study, we determined the 96 h LC50 s, and evaluated the bioaccumulation potential of six most frequently reported OPFRs in gill, kidney, liver, and muscle tissues of common carp (Cyprinus carpio) for 48 d, and a quantitative structure-activity relationship (QSAR) model was developed to predict bioconcentration factors (BCFs) for the remaining 16 OPFRs. The BCFs and half-lives (t1/2) in the tissues ranged from 6.54 (Tris (2-chloroisopropyl) phosphate, (TCPP)) to 528.15 (Tris (2-ethylhexyl) phosphate (TEHP)), and 2.25–5.78 days, respectively. The tissue-specific concentration and BCFs values followed the order of liver > kidney ≥ intestine >> muscle. The proposed QSAR model with a high cross-validated value (Q2 (cum)) of 0.930 and a correlation coefficient of 0.94 was obtained and was able to predict log BCF from parameters related to molar volume and isotropic average static field polarizability. The results show that the model has a high level of accuracy, making the proposed approach a suitable method for predicting the log BCF.

Organophosphate flame retardants (OPFRs) have attracted wide concerns due to their toxicities and ubiquitous occurrence in the environment. In this work, Octanol-air partition coefficient (KOA) for 14 OPFRs including 4 halogenated alkyl-, 5 aryl- and 5 alkyl-OPFRs, were estimated as a function of temperature using a gas chromatographic retention time (GC-RT) method. Their log KOA-GC values and internal energies of phase transfer (ΔOAU/kJmol-1) ranged from 8.03 to 13.0 and from 69.7 to 149, respectively. Substitution pattern and molar volume (VM) were found to be capable of influencing log KOA-GC values of OPFRs. The halogenated alkyl-OPFRs had higher log KOA-GC values than aryl- or alkyl-OPFRs. The bigger the molar volume was, the greater the log KOA-GC values increased. In addition, a predicted model of log KOA-GC versus different relative retention times (RRTs) was developed with a high cross-validated value (Q2(cum)) of 0.951, indicating a good predictive ability and stability. Therefore, the log KOA-GC values of the remaining OPFRs can be predicted by using their RRTs on different GC columns.

PFOS and PFOA are potential persistent organic pollutants that have raised many concerns in recent years. Research focusing on phytotoxicity of PFOS and PFOA to higher plants is necessary for their risk assessments. However, few toxicity data exist for PFOS or PFOA and higher plants. Here we investigated phytotoxicity of PFOS and PFOA to Brassica chinensis root growth in six different Chinese soils varying widely in soil properties using a standardized root length assay. The effective concentrations of added PFOS and PFOA causing 50% inhibition (EC 50 ) ranged from 95 to >200 mg kg −1 for PFOS and from 107 to 246 mg kg −1 for PFOA, respectively, representing more than 2.1- and 2.3-fold variation among the tested soils. Regressions of soil PFOS and PFOA toxicity threshold values (EC x and NOECs) with various soil properties showed that the amount of organic matter was the most significant factor affecting their toxicity to B. chinensis .