Characterization of dissolved organic matter in biochar derived from various macroalgae (Phaeophyta, Rhodophyta, and Chlorophyta): Effects of pyrolysis temperature and extraction solution pH.

Characterization of biochar-derived dissolved organic matter (DOM) can provide deep insight into potential applications of biochar. Herein, biochar from six macroalgae (Phaeophyta-Sargassum fusiforme, Sargassum thunbergii, and Sargassum vachellianum; Rhodophyta-Grateloupia turuturu and Chondria crassicaulis; and Chlorophyta-Ulva pertusa) were subjected to pyrolysis at different temperatures (200 °C-500 °C). The effects of pyrolysis temperature and extraction solution pH on the characteristics of the macroalgal biochar-derived DOM (MBDOM) were investigated via fluorescence excitation-emission matrix spectroscopy with parallel factor (PARAFAC) analysis. Five humic-like substances and one protein-like substance were identified. The distributions of the six PARAFAC components depended on the macroalgae species, pyrolysis temperature, and extraction solution pH. The proportion of the protein-like substance (0 %-46.77 %) was less than that of the humic-like substances (100 %-53.23 %) in a given MBDOM regardless of the extraction solution pH values. Fluorescence spectral indicators show that DOM from macroalgal biochar is more autochthonous and humified than that from the corresponding biomass. Hierarchical cluster analysis and redundancy analysis results further show that the macroalgae species, pyrolysis temperature, and extraction solution pH jointly affect DOM characteristics with varying contribution levels.

A Multiscale Interactive Recurrent Network for Time-Series Forecasting.

Time-series forecasting is a key component in the automation and optimization of intelligent applications. It is not a trivial task, as there are various short-term and/or long-term temporal dependencies. Multiscale modeling has been considered as a promising strategy to solve this problem. However, the existing multiscale models either apply an implicit way to model the temporal dependencies or ignore the interrelationships between multiscale subseries. In this article, we propose a multiscale interactive recurrent network (MiRNN) to jointly capture multiscale patterns. MiRNN employs a deep wavelet decomposition network to decompose the raw time series into multiscale subseries. MiRNN introduces three key strategies (truncation, initialization, and message passing) to model the inherent interrelationships between multiscale subseries, as well as a dual-stage attention mechanism to capture multiscale temporal dependencies. Experiments on four real-world datasets demonstrate that our model achieves promising performance compared with the state-of-the-art methods.

Comparing the sorption of pyrene and its derivatives onto polystyrene microplastics: Insights from experimental and computational studies.

In this study, the sorption behaviors and mechanisms between polystyrene microplastics (micro-PS) and 4-rings polycyclic aromatic hydrocarbons (PAHs) pyrene (Pyr) and its derivatives (S-Pyr), including 1-methylpyrene (P-CH3), 1-hydroxypyrene (P-OH), 1-aminopyrene (P-NH2), 1-pyrenecarboxylic acid (P-COOH) were investigated at neutrality. The results revealed that the sorption rates of micro-PS for S-Pyr were higher than those for parent Pyr. Meanwhile, -CH3 could slightly facilitate the sorption, whereas -OH, P-NH2, and P-COOH intensively inhibit the sorption of S-Pyr onto micro-PS. The sorption capacities of Pyr/S-Pyr increased with decreasing size of micro-PS. Besides, the effects of salinity and temperature on the sorption characteristics of micro-PS for Pyr/S-Pyr depended on their substituents. Combined with experimental and computational methods, it could be concluded that the main sorption mechanisms were possibly hydrophobic interaction, π-π interaction and pore-filling. The observations reported here could improve predictions of environmental behaviors and bioavailability of PAHs and micro-PS.

Spectroscopic characterization of dissolved organic matter from macroalgae Ulva pertusa decomposition and its binding behaviors with Cu(II).

Dissolved organic matter (DOM) from macroalgae is regarded a crucial source of autochthonous DOM in coastal ocean. In the present study, the characteristics of DOM from the macroalgae Ulva pertusa decomposition (U. pertusa-DOM) and its binding behaviors with Cu(II) using multiple spectroscopic techniques and chemometric analyses. The labile U. pertusa-DOM could be consumed and transformed by microorganisms. The absorption spectroscopic descriptors indicate that the hydrophobicity, aromaticity, and molecular weight of the U. pertusa-DOM increase during the 27-day incubation period. Fluorescence excitation-emission matrix spectroscopy combined with parallel factor analysis suggests that the relative abundance of the protein-like component (C1) (96.10-84.96%) sequentially decreases, whereas the humic-like components (C2) (2.16-9.73%) and (C3) (1.75-5.31%) in the U. pertusa-DOM increase with the U. pertusa decomposition. The Cu(II) binding properties of the U. pertusa-DOM are dependent on the decomposition time. The order of the conditional stability constant (logKM) is C2 > C1 > C3. The complexation capacity (f) of C1 is higher than those of C2 and C3 at a specific time. Synchronous fluorescence spectroscopy coupled with two-dimensional correlation spectroscopy reveals that the microbial degradation could accelerate the Cu(II) binding to humic-like fractions in the U. pertusa-DOM. These findings will help us better understand the biogeochemical behaviors of macroalgal DOM and heavy metal in coastal ecosystems.

Mercury and selenium in squids from the Pacific Ocean and Indian Ocean: The distribution and human health implications.

Squids are globally distributed. Hg-contaminated squids may have high risks on humans. With abundant Se (antagonistic effect on Hg), the risks can be reduced. We collected squids around the world (Northwest Pacific Ocean, Southeast Pacific Ocean and Indian Ocean). Concentrations of Hg and Se were region-based and tissue-based. The higher content of Se were, the lower relative Hg levels were. The correlation between Se:Hg and Se was the strongest in the digestive gland. The values of Se:Hg and THQ all confirm that the health risk was lower in samples with higher concentrations of Se. Despite the risk assessment by Se:Hg, BRV and THQ analysis showed no risk when consumed in moderation, the maximum daily intake is provided based on Monte Carlo simulation. In future, when evaluating the risks cause by Hg exposure and providing the recommended daily amount, it may need to concurrent consideration of Se levels.

PAH residue and consumption risk assessment in four commonly consumed wild marine fishes from Zhoushan Archipelago, East China Sea.

The concentration, constitution, distribution, possible sources, and associated consumption risks of polycyclic aromatic hydrocarbons (PAHs) in four marine fishes in the Zhoushan Archipelago were investigated. The concentrations of PAHs in the edible muscle of these four fishes ranged from 34.7 to 108 ng/g wet weight. Four-ring and six-ring PAH congeners constitute the most and least percentages of the total PAHs, respectively. The highest PAH concentrations were found in Mugil cephalus, followed by Sebastiscus marmoratus, Lateolabrax maculatus, and Collichthys lucidus. The highest PAH concentrations were found at the sampling island Liuheng, followed by Gouqi, Qushan, Dongji, and Zhujiajian. PAH concentrations in wet weight were remarkably different among these four fish species but not among different locations. High-molecular-weight congeners predominated the PAH composition pattern in most of the samples. Results showed that the consumption of M. cephalus might have potential carcinogenic risk. This study provided baseline data on PAH concentrations in seafood and consequent human consumption risk.

Influence of water washing treatment on Ulva prolifera-derived biochar properties and sorption characteristics of ofloxacin.

The influences of water washing treatment on the properties of Ulva prolifera-derived biochar (U.P-biochar) and its sorption characteristics of ofloxacin (OFL) were investigated. The results showed that the water washing treatment significantly changed the physiochemical structures of U.P-biochars, and improved the sorption capacity of OFL. The sorption capacity of OFL by U.P-biochar was closely dependent on pyrolysis temperature (200-600 °C) and equilibrium solution pH (3-11). Different sorption mechanisms (e.g. cation exchange, electrostatic attraction, H-bond and cationic-π and π-π interactions) were dominant for specific U.P-biochars under various pH regions (acidic, neutral and alkaline). Moreover, the unwashed and washed U.P-biochars prepared at 200 °C (BC200 and BCW200) showed a higher sorption capacity of OFL at pH = 7. The two-compartment first-order model provided an appropriate description of the sorption kinetics of OFL by BC200 and BCW200 (R2 > 0.98), which revealed that the contribution ratios between the fast and slow sorption compartments (ffast/fslow, 1.55 for BC200 and 1.25 for BCW200) reduced after water washing treatment of U.P-biochar. The values of n for the Freundlich model were less than 1, which demonstrated that the sorption of OFL by BC200 and BCW200 was favourable and nonlinear. Also, the sorption of OFL by BC200 and BCW200 increased with an increase in solution temperature and the sorption process was spontaneous and endothermic. This study provides valuable information for being a primary consideration in the production and application of U.P-biochar.

A Study on Ecotoxicological Effects of Nano-copper Oxide Particles to Portunus trituberculatus.

BACKGROUND: As an important nano-material, nano-copper oxide particles (CuO-ENPs) harbor a vast range of characteristics, including an electronic correlation effect, thermal stability, catalytic activity, sterilization, and other properties. At present, the mechanism of ecotoxicological effects of CuO-ENPs is unclear and has been inconclusive. Therefore, we aimed to explore the ecotoxicological effects of nano-copper oxide particles (CuO-ENPs) on Portunus trituberculatus. OBJECTIVE: The crabs were exposed to seawater containing different concentrations of CuO-ENPs to conduct the acute toxicity test and chronic accumulation test. METHODS: Acute toxicity, metal accumulation, and SOD activity in different tissues were determined. RESULTS: We found that the lethal concentration of 50% 96 h LC50 of CuO-ENPs to Portunus trituberculatus belonged to low toxicity. The accumulation of CuO-ENPs in different tissues from high to low was: gill > haemolymph > muscle > hepatopancreas > heart and stomach, and decreased gradually with time after reaching the maximum. DISCUSSION: Subsequently, it was in a relatively steady state after a certain period and showed an obvious concentration effect. With the increment of exposure time and concentration of CuO-ENPs, the SOD activities in different tissues were quite different. In conclusion, the 96 h LC50 of CuOENPs to Portunus trituberculatus was 49 mg/L, and its toxicity belonged to low toxicity. CONCLUSION: With the increment of exposure time and concentration of CuO-ENPs, the SOD activities in different tissues were quite different, which were increased remarkably in gill and hepatopancreas, but were suppressed at an early stage of exposure in muscle and haemolymph.

Characterization of fluorescent dissolved organic matter from green macroalgae (Ulva prolifera)-derived biochar by excitation-emission matrix combined with parallel factor and self-organizing maps analyses.

This study investigated the effects of various pyrolysis temperatures and extraction salinities on the fluorescence features of DOM from Ulva prolifera-derived biochar under aseptic conditions using fluorescence excitation-emission matrix (EEM) spectroscopy with parallel factor (PARAFAC) analysis and self-organizing maps (SOM). Four humic-like substances and one protein-like substance were identified by the PARAFAC model. The contents and compositions of PARAFAC components depended more on the pyrolysis temperature than on the extraction salinity. A high pyrolysis temperature could enhance the release of humic-like DOM from biochar. Coupling PARAFAC and SOM facilitates the visualization and interpretation of the relationship between the pyrolysis temperature and the fluorescence properties of DOM. These results are valuable for understanding the effects and processes of macroalgal biochar in the possible environmental and industrial applications.

Insight into the heterogeneous adsorption of humic acid fluorescent components on multi-walled carbon nanotubes by excitation-emission matrix and parallel factor analysis.

The heterogeneous adsorption behavior of commercial humic acid (HA) on pristine and functionalized multi-walled carbon nanotubes (MWCNTs) was investigated by fluorescence excitation-emission matrix and parallel factor (EEM- PARAFAC) analysis. The kinetics, isotherms, thermodynamics and mechanisms of adsorption of HA fluorescent components onto MWCNTs were the focus of the present study. Three humic-like fluorescent components were distinguished, including one carboxylic-like fluorophore C1 (λex/λem= (250, 310) nm/428nm), and two phenolic-like fluorophores, C2 (λex/λem= (300, 460) nm/552nm) and C3 (λex/λem= (270, 375) nm/520nm). The Lagergren pseudo-second-order model can be used to describe the adsorption kinetics of the HA fluorescent components. In addition, both the Freundlich and Langmuir models can be suitably employed to describe the adsorption of the HA fluorescent components onto MWCNTs with significantly high correlation coefficients (R2> 0.94, P< 0.05). The dissimilarity in the adsorption affinity (Kd) and nonlinear adsorption degree from the HA fluorescent components to MWCNTs was clearly observed. The adsorption mechanism suggested that the π-π electron donor-acceptor (EDA) interaction played an important role in the interaction between HA fluorescent components and the three MWCNTs. Furthermore, the values of the thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), showed that the adsorption of the HA fluorescent components on MWCNTs was spontaneous and exothermic.

Microbial transformation of intracellular dissolved organic matter from Microcystis aeruginosa and its effect on the binding of pyrene under oxic and anoxic conditions.

The environmental behaviour and the bioavailability of polycyclic aromatic hydrocarbons (PAHs) are strongly affected by dissolved organic matter (DOM) in aquatic environments. In this study, we investigated the dynamics of the bioavailability and character of the intracellular DOM (IDOM) from Microcystis aeruginosa (M. aeruginosa-IDOM) during 10 days oxic and anoxic incubations by spectroscopy. Subsequently, the binding affinity of pyrene with the initial/altered M. aeruginosa-IDOM was estimated by fluorescence quenching method. The incubation results indicated that changes in dissolved organic carbon (DOC) concentration and selected spectral descriptors of the M. aeruginosa-IDOM under oxic condition were different from those of anoxic condition. The microbial transformation of the M. aeruginosa-IDOM resulted in an enhancement of the organic carbon-normalized binding coefficient (K DOC) of pyrene in both oxic and anoxic treatments. Moreover, only for the oxic condition, Pearson correlation analysis demonstrated that aromaticity (specific UV absorbance at 254 nm, SUVA254), humification degree (humification index, HIX) and the percent distribution of humic-like component 2 (%C2) presented significantly positive correlations with the pyrene K DOC, while the percent distribution of protein-like component 1 (%C1) exhibited a negative correlation with the K DOC. However, no significant correlation was observed between any spectral descriptor and the K DOC under anoxic condition. This result suggested that the binding affinity of pyrene may be primarily influenced by the altered M. aeruginosa-IDOM characteristics associated with the biological transformation. Hence, our results provided potential evidence for resolving the inconsistency in the relationships between DOM characteristics and the binding affinities of PAHs.

Insights into the binding interactions of autochthonous dissolved organic matter released from Microcystis aeruginosa with pyrene using spectroscopy.

The autochthonous dissolved organic matter (DOM) released by Microcystis aeruginosa (M. aeruginosa-DOM) during its growth period was characterized by spectroscopy. Furthermore, the relationships between the M. aeruginosa-DOM spectroscopic descriptors and the pyrene binding coefficient (KDOC) values were explored. The results showed that the spectroscopic characteristics of the M. aeruginosa-DOM and the binding properties of pyrene were dynamically changed along with the algae growth. Pearson correlation analysis demonstrated that a higher pyrene KDOC value was observed for the M. aeruginosa-DOM that has a higher humification index (HIX) value, a lower biological index (BIX) value and a lower absorption ratio (E2/E3). The presence of protein-like and long-wavelength-excited humic-like components may impose negative and positive effects on binding of pyrene by the M. aeruginosa-DOM, respectively. Principal component analysis (PCA) further supported that the binding affinity of pyrene may be primarily influenced by the humification degree of the M. aeruginosa-DOM.

Influences of humic acid on the bioavailability of phenanthrene and alkyl phenanthrenes to early life stages of marine medaka (Oryzias melastigma).

The influences of humic acid (HA) on the environmental behavior and bioavailability of parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAHs were investigated and compared using the early life stages of marine medaka (Oryzias melastigma, O. melastigma). It was demonstrated that the binding affinity of parent phenanthrene (PHE) with HA was smaller than that of 3-methyl phenanthrene (3-MP) and 9-ethyl phenanthrene (9-EP). Furthermore, the bioaccumulation of the three PAHs and the levels of lipid peroxidation (LPO) were calculated to study the changes in bioavailability of PAHs in presence of HA. The results indicated that the addition of HA significantly decreased the bioaccumulation and toxicity of PAHs by decreasing free PAHs concentrations. The bioavailable fractions of HA-bound PAHs in bioaccumulation (α) and toxicity (ß) were evaluated, indicating that the HA-bound 3-MP and 9-EP show higher bioavailability in bioaccumulation and lower bioavailability in toxicity relative to those of PHE. The ß/α values were less than 1 for all PAH treatment groups containing HA, suggesting that the fraction of HA-bound PAHs contributing to bioaccumulation was higher than that of HA-bound PAHs inducing toxic effect. In addition, we proposed that the free PAHs generated by desorption from HA in the cell were toxic by showing that the ß/α ratio values are correlated with the log KOW values (p = 0.007 and R(2) = 0.8355). Thus, oil spill risk assessments should consider both alkyl PAHs and the factors that influence the bioavailability and toxicity of PAHs in the natural aquatic environments.

In Situ Investigating of the Interaction of Phenanthrene and Alkyl Phenanthrene with Humic Acid with Laser Induced Nanoseconds Time Resolved Fluorescence Quenching Method.

Investigations both on the binding properties and mechanisms of parent polycyclic aromatic hydrocarbons (PAHs) and alkyl PAHs with humic acid (HA) are crucial to understand the environment behavior and bioavailability of PAHs in aquatic ecosystems. Thus, a novel approach for in situ investigation of the interactions between parent PAHs and alkyl PAHs, exemplified by Phenanthrene (Phe), 9-Ethylphenanthrene (9-EP) and Retene (Ret), and HA was established by using fluorescence quenching method with laser-induced nanosecond time-resolved fluorescence (LITRF). By changing the delay time of 50 ns, the fluorescent interference of HA can be eliminated effectively and the concentrations of free Phe, 9-EP and Ret can be determined directly. The binding characteristics of the dissolved HA and Phe, 9-EP and Ret were described by Freundlich nonlinear isothermal model. The results of the model parameters and the single point binding coefficients KOC of Phe, 9-EP and Ret with HA by LITRF quenching method were consistent with those of the conventional fluorescence quenching method. Nonlinear bindings of Phe, 9-EP and Ret to HA were also observed because of the parameter n values below 1, and the degree of nonlinearity of Phe was lower than 9-EP and Ret duo to the n value of Phe larger than 9-EP and Ret. At a same given equilibrium concentration, the KOC of Phe was lower than 9-EP and Ret, and that of 9-EP was near to Ret. The binding affinity of the three PAHs increased with decreasing the equilibrium concentration. The binding characteristics of PAHs with HA largely depends on their hydrophobicity, substituent groups and its ability to fit into hydrophobic cavities in HA. The fluorescence lifetimes of Phe, 9-EP and Ret in presence of HA were 36.90, 35.34 and 35.13 ns, meanwhile the fluorescence lifetimes of Phe, 9-EP and Ret in absence of HA were 36.36, 35.34 and 35.84 ns. There was no significant difference of three PAHs fluorescence lifetime with or without HA, indicating the quenching mechanism for Phe, 9-EP and Ret with HA were primarily static quenching. The LITRF quenching method could be used to in situ explore the interactions between PAHs and HA, which could be contribute to realize the PAHs risk assessment in real time.