Fate of glyphosate and its degradation products AMPA, glycine and sarcosine in an agricultural soil: Implications for environmental risk assessment.

Glyphosate can be biodegraded via the aminomethylphosponic acid (AMPA) and the sarcosine/glycine pathway leading to the formation of three intermediate products AMPA, sarcosine or glycine. The fate of the three intermediate compounds of glyphosate biodegradation including nature of non-extractable residues (NERs; harmless biogenic [NERsbiogenic] versus hazardous xenobiotic [NERsxenobiotic]) in soils has not been investigated yet. This information is crucial for an assessment of environmental risks related to the speciation of glyphosate-derived NERs which may stem from glyphosate intermediates. Therefore, we incubated 13C- and 15N-labeled glyphosate (2-13C,15N-glyphosate) and its degradation product AMPA (13C,15N-AMPA), sarcosine (13C3,15N-sarcosine) or glycine (13C2,15N-glycine) in an agricultural soil separately for a period of 75 days. 13C2-glycine and 13C3-sarcosine mineralized rapidly compared to 2-13C-glyphosate and 13C-AMPA. The mineralization of 13C-AMPA was lowest among all four compounds due to its persistent nature. Only 0.5% of the initially added 2-13C,15N-glyphosate and still about 30% of the initially added 13C,15N-AMPA was extracted from soil after 75 days. The NERs formed from 13C,15N-AMPA were mostly NERsxenobiotic as compared to other three compounds for which significant amounts of NERsbiogenic were determined. We noticed 2-13C,15N-glyphosate was biodegraded via two biodegradation pathways simultaneously; however, the sarcosine/glycine pathway with the formation of harmless NERsbiogenic presumably dominated.

Microcosm test for pesticide fate assessment in planted water filters: 13C,15N-labeled glyphosate as an example.

Planted filters are often used to remove pesticides from runoff water. However, the detailed fate of pesticides in the planted filters still remains elusive. This hampers an accurate assessment of environmental risks of the pesticides related to their fate and thereby development of proper mitigation strategies. In addition, a test system for the chemical fate analysis including plants and in particular for planted filters is not well established yet. Therefore, we developed a microcosm test to simulate the fate of pesticide in planted filters, and applied 2-13C,15N-glyphosate as a model pesticide. The fate of 2-13C,15N-glyphosate in the planted microcosms over 31 day-incubation period was balanced and compared with that in the unplanted microcosms. The mass balance of 2-13C,15N-glyphosate turnover included 13C mineralization, degradation products, and the 13C and 15N incorporation into the rhizosphere microbial biomass and plants. We observed high removal of glyphosate (> 88%) from the water mainly due to adsorption on gravel in both microcosms. More glyphosate was degraded in the planted microcosms with 4.1% of 13C being mineralized, 1.5% of 13C and 3.8% of 15N being incorporated into microbial biomass. In the unplanted microcosms, 1.1% of 13C from 2-13C,15N-glyphosate was mineralized, and only 0.2% of 13C and 0.1% of 15N were assimilated into microbial biomass. The total recovery of 13C and 15N was 81% and 85% in planted microcosms, and 91% and 93% in unplanted counterparts, respectively. The microcosm test was thus proven to be feasible for mass balance assessments of the fate of non-volatile chemicals in planted filters. The results of such studies could help better manage and design planted filters for pesticide removal.

Sex Differences in Traditional School Bullying Perpetration and Victimization among Adolescents: A Chain-Mediating Effect.

The study explored sex differences in traditional school bullying perpetration and victimization among Chinese adolescents and the effects of Machiavellianism and school climate. Data were collected from 727 adolescents (M = 16.8 years, SD = 0.9) who completed the Olweus Bully/Victim Questionnaire, Kiddie Machiavellian Scale, and School Climate Perception Questionnaire. Results showed: (1) boys were more likely to bully others and be bullied; (2) both Machiavellianism and school climate partially mediated sex differences in school bullying perpetration and victimization; (3) the chain-mediating effect of Machiavellianism and school climate on sex differences in bullying perpetration and victimization was significant. These results provide insight into the sex differences in Chinese traditional school bullying perpetration and victimization. The implications are interpreted and discussed.

Superabsorbent polymer as a supplement substrate of constructed wetland to retain pesticides from agricultural runoff.

Surface water runoff can export pesticides from agricultural fields into adjacent aquatic ecosystems, where they may pose adverse effects to organisms. Constructed wetlands (CWs) are widely used to treat agricultural runoff contaminated by pesticides, but the removal of hydrophilic pesticides is usually low. In this study, we suggest superabsorbent polymer (SAP), a cross-linked hydrophilic polymer, as a supplement to substrates of CWs and tested the hypothesis that SAP results in an enhanced removal of hydrophilic pesticides. Therefore, batch experiments were conducted to study the retention capacity of water-saturated SAP (w-SAP) for several hydrophilic pesticides. Retention of the pesticides on w-SAP was related to the ionization state and water solubility of the pesticides. The retention of neutral pesticides, imidacloprid, metalaxyl and propiconazole, was about 20% higher than that measured for anionic pesticides, bentazone, glyphosate and MCPA. The retention of the pesticides by w-SAP mainly resulted from their distribution in the gel-water phase of w-SAP, while less water soluble pesticides might have also been adsorbed on the molecular backbone of SAP. Furthermore, we tested the efficacy of w-SAP for treatment of runoff water contaminated by pesticides in lab-scale horizontal subsurface flow CWs. SAP in CWs improved the removal of the pesticides, including the recalcitrant ones. The removal enhancement was owing to the increase of hydraulic retention time and improvement of biodegradation. The removal of the pesticides in SAP containing CWs was > 93% for MCPA, glyphosate, and propiconazole, 62 - 99% for imidacloprid, 50 - 84% for metalaxyl, and 38 - 73% for bentazone. In the control gravel CWs, the removal was > 98% for glyphosate, generally > 83% for MCPA and propiconazole, 46 - 98% for imidacloprid, 32 - 97% for metalaxyl, and 9 - 96% for bentazone.

Retention and distribution of pesticides in planted filter microcosms designed for treatment of agricultural surface runoff.

Pesticides in agricultural surface water runoff cause a major threat to freshwater systems. Installation of filter systems or constructed wetlands in areas of preferential run-off is a possible measure for pesticides abatement. To develop such systems, combinations of filter materials suitable for retention of both hydrophilic and hydrophobic organic pesticides were tested for pesticide removal in planted microcosms. The retention of six pesticides frequently detected in surface waters (bentazone, MCPA, metalaxyl, propiconazole, pencycuron, and imidacloprid) was evaluated in unplanted and planted pot experiments with novel bed material mixtures consisting of pumice, vermiculite, water super-absorbent polymer (SAP) for retention of ionic and water soluble pesticides, and synthetic hydrophobic wool for adsorption of hydrophobic pesticides. The novel materials were compared to soil with high organic matter content. The highest retention of the pesticides was observed in the soil, with a considerable translocation of pesticides into the plants, and low leaching potential, in particular for the hydrophobic compounds. However, due to the high retention of pesticides in soil, environmental risks related to their long term mobilization cannot be excluded. Mixtures of pumice and vermiculite with SAP resulted in high retention of i) water and ii) both hydrophilic and hydrophobic pesticides but with much lower leaching potential compared to the mineral systems without SAP. Mixtures of such materials may provide near natural treatment options in riparian strips and also for treatment of rainwater runoff without the need for water containment systems.

Effects of the earthworm Metaphire guillelmi on the mineralization, metabolism, and bound-residue formation of tetrabromobisphenol A (TBBPA) in soil.

Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants worldwide. The degradation and fate of this organic pollutant of soils is of great concern and can be strongly affected by geophagous earthworms through ingestion and burrowing activities. Using 14C-tracers, we studied the effects of the geophagous earthworm Metaphire guillelmi on the mineralization, metabolism, and bound-residue formation of TBBPA in a typical Chinese rice paddy soil during 30days of incubation in the laboratory. Earthworms significantly decreased both mineralization (from 3.9±0.3% of the initial amount to 2.6±0.2%) and dissipation (from 90.6±0.6% to 84.1±1.2%) of TBBPA in the soil, and stimulated the generation of O-methylation metabolites (TBBPA methyl ethers; from 1.4±0.4% to 15.4±0.6%). This resulted in a strong decrease in bound-residue formation of TBBPA and its metabolites in the soil (from 80.3±0.4% to 41.8±3.1%). Results from a first-order, two-compartment model that describes the fate of TBBPA in soil indicated that the TBBPA-derived bound residues were mainly attributed to the binding of metabolites to the soil matrix and not to the binding of TBBPA, and that earthworms reduced the kinetic rates of both polar metabolite generation and their bound-residue formation. Our results suggested that the geophagous earthworm Metaphire guillelmi strongly influenced the fate of TBBPA by altering the composition of metabolites and therefore bound-residue formation. The increased persistence of TBBPA and the formation of persistent O-methylation metabolites by M. guillelmi would increase the environmental risk of TBBPA.

Strong multi-functions based on conjugating chondroitin sulfate onto an amine-rich surface will direct the vascular cell fate for cardiovascular implanted devices.

Thrombus, hyperplasia, and inflammation are constant threats and challenges for long-term application of cardiovascular implants. Surface endothelialization has been considered as the preferable strategy to solve these problems because of the physiological functions gained from the regenerated endothelial layers covering the implants. Thus, a surface with strong multi-functions including anti-coagulation, anti-hyperplasia, anti-inflammation, and pro-endothelialization is ideal for cardiovascular implants. Herein, we developed a novel coating by conjugating chondroitin sulfate (CS) onto an amine-rich copolymerized film of polydopamine (PDA) and hexamethylenediamine (HD), with the aim of directing the vascular cell fate. The PDA/HD-CS coating exhibited a remarkable suppression of platelet activation/aggregation and thrombosis under a blood flow of 15 dyn cm-2. Inhibition upon proliferation of vascular smooth muscle cells and attachment of macrophages were also observed on this coating. In addition, the PDA/HD-CS coating was compatible with the vascular endothelial cells, suggesting a strong pro-endothelialized function. Further in vivo tests indicated that contractile smooth muscle cells and M2 macrophages regulated by PDA/HD-CS may be involved in the regeneration of the endothelial layer. In summary, this research may support potential applications for surface modification of cardiovascular implants to achieve improved multi-functions.