Uptake, accumulation, and degradation of dibutyl phthalate by three wetland plants.

The uptake and degradation mechanisms of dibutyl phthalate (DBP) by three wetland plants, namely Lythrum salicaria, Thalia dealbata, and Canna indica, were studied using hydroponics. The results revealed that exposure to DBP at 0.5 mg/L had no significant effect on the growth of L. salicaria and C. indica but inhibited the growth of T. dealbata. After 28 days, DBP concentrations in the roots of L. salicaria, T. dealbata, and C. indica were 8.74, 5.67, and 5.46 mg/kg, respectively, compared to 2.03-3.95 mg/kg in stems and leaves. Mono-n-butyl phthalate concentrations in L. salicaria tissues were significantly higher than those in the other two plants at 23.1, 15.0, and 13.6 mg/kg in roots, stems, and leaves, respectively. The roots of L. salicaria also had the highest concentration of phthalic acid, reaching 2.45 mg/kg. Carboxylesterase, polyphenol oxidase, and superoxide dismutase may be the primary enzymes involved in DBP degradation in wetland plants. The activities of these three enzymes exhibited significant changes in plant tissues. The findings suggest L. salicaria as a potent plant for phytoremediation and use in constructed wetlands for the treatment of DBP-contaminated wastewater.

Response of the common reed (Phragmites australis) to nutrient enrichment depends on the growth stage and degree of enrichment: A mesocosm experiment.

Human-induced nutrient enrichment is a major stressor in aquatic ecosystems that has resulted in the alteration of ecosystem structures and functions. However, to date, relatively few studies have explored the temporal dynamics of reed biomass and morphological and biochemical traits under different nutrient levels, as well as the phenological pattern. Based on a mesocosm experiment, we monitored the aboveground and underground biomass of reed at the different plant growth stages, along with plant height, ramet and leaf number, leaf length and width, and carbohydrate and nutrient contents in different organs. We found that the significantly different ratio of aboveground to underground biomass was only observed at the late flowering stage between the slight enrichment (S-E) and heavy enrichment (H-E) groups. The start of the fast-growth phase of the aboveground part and underground part was delayed in the higher nutrient enrichment groups. The length of the fast-growth phase of the aboveground part was the same in the medium enrichment (M-E) and H-E groups and longer than that in the S-E group. For the underground part, the longest fast-growth phase was found in the S-E group (105 days), followed by the H-E and M-E groups (46 and 41 days, respectively). As the nutrient level increased, both increased and decreased values were observed for the 29 monitored morphological and biochemical traits, and the magnitude changed with the different growth stages. Moreover, different degrees of nutrient enrichment could differentially enhance or weaken the relationships among the groups between total biomass and the integrated morphological trait, between structural carbohydrate (SC) and total nitrogen (TN) contents, between total organic carbon (TOC) and TN, between total phosphorus (TP) contents, between TOC and SC contents. Our findings highlight a crucial contribution of ambient nutrient supply to temporal variation in plant biomass and phenological, morphological and biochemical traits.

Determination of trans-fatty acids in food samples based on the precolumn fluorescence derivatization by high performance liquid chromatography.

Trans-fatty acids are unsaturated fatty acids that are considered to have health risks. 1,3,5,7-Tetramethyl-8-butyrethylenediamine-difluoroboradiaza-s-indacene is a highly sensitive fluorescent labeling reagent for carboxylic acids developed by our lab. In this study, using this precolumn fluorescent derivatization reagent, a rapid and accurate high-performance liquid chromatography with fluorescence detection method was developed for the determination of two trans-fatty acids in food samples. Under the optimized derivative conditions, two trans-fatty acids were tagged with the fluorescent labeling reagent in the presence of 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide at 25°C for 30 min. Then, the baseline separation of trans- and cis-fatty acids and their saturated fatty acid with similar structures was achieved with less interference using a reversed-phased C18 column with isocratic elution in 14 min. With fluorescence detection at λex /λem  = 490 /510 nm, the linear range of the TFAs was 1.0-200 nM with low detection limits in the range of 0.1-0.2 nM (signal-to-noise ratio = 3). In addition, the proposed approach was successfully applied for the detection of trans-fatty acids in food samples, and the recoveries using this method ranged from 96.02 to 109.22% with low relative standard deviations of 1.2-4.3% (n = 6).

Physiological Responses and Phytotoxicities of Lythrum salicaria to Decabromodiphenyl Ether (BDE-209).

Decabromodiphenyl ether (BDE-209), a member of a major group of brominated flame retardants, is detected in aquatic environments at considerable levels and induces physiological and toxic effects on aquatic plants. In this study, the physiological responses induced by and the toxic effects of BDE-209 at different concentrations (0, 0.2, 0.5 and 1.0 mg L-1) in Lythrum salicaria were examined. OJIP transient curves indicated that BDE-209 treatment negatively affected photosystem II (PSII) grouping. Additionally, the results showed that BDE-209 inhibited seedling development and elevated reactive oxygen species (ROS), phosphorylated histone H2AX (γ-H2AX), malondialdehyde (MDA) levels and antioxidative enzyme activities in the roots and shoots of L. salicaria. The results revealed that BDE-209 exposure contributed to ROS accumulation, which was considered as the probable toxicity mechanism. The current results provided an insight into the development of L. salicaria with high BDE-209 tolerance.

Treatment performance and microbial response to dibutyl phthalate contaminated wastewater in vertical flow constructed wetland mesocosms.

Phthalic acid esters (PAEs), especially dibutyl phthalate (DBP) pollution in the environment, have attracted worldwide attention. Four Phragmites australis-based, mesocosm-scale vertical flow constructed wetlands (VFCWs) with different hydraulic loading rates (HLRs) were operated for one year to study the removal efficiency and mechanisms of DBP in the reclaimed water. The average removal efficiencies for DBP were 93.77 ± 3.27%, 94.9 ± 2.60% and 97.0 ± 3.00% in the VFCWs under HLRs of 0.33, 0.22 and 0.11 m/d, respectively. DBP can be accumulated and degraded by wetland plants and its concentration in the roots (0.256-8.45 mg/kg) were higher than in the leaves (0.243-0.482 mg/kg). The concentrations of primary and secondary metabolites mono-n-butyl phthalate (MBP) and phthalic acid (PA) were 0.142-2.35 mg/kg and 0.113-0.545 mg/kg respectively in the plant tissues. The concentrations of DBP were 38.2-271 µg/kg in the substrates. Mass balance for DBP indicates that the estimated plant uptake and substrate adsorption of total DBP is negligible. This suggests that biodegradation and other process are the primary pathways for DBP removal in VFCWs. The results of 16S rDNA and ITS rDNA high-throughput sequencing indicated that both bacterial and fungal community diversity decreased with the exposure of DBP. Janthinobacterium, Flavobacterium and Curvularia genera may be the main participants in the biodegradation of DBP in the CWs.