Screening and quantification of pesticides in wetland water, ice, sediment and soil: Occurrence, transport and risk assessment.

Current researches on pesticides in wetlands are limited in terms of screening and quantification of many types of pesticides. Understanding the spatial and temporal dynamics, distribution patterns, and environmental risks of pesticides in multiple media is important for wetland ecological conservation. In this study, 222 pesticides were determined in multimedia samples collected simultaneously from the Songhua Wetland during four seasons. Concentrations of target pesticides in water, ice, sediment and soil ranged from 94.1 to 7445 ng/L, 62.6-953 ng/L, 0.82-50.2 ng/g dw, and 4.32-146 ng/g dw. Large spatial differences (p < 0.05) in pesticide concentrations in ice were found. However, there were no significant differences in the spatial and temporal distribution of pesticides in water, sediment, and soil (p > 0.05), suggesting that there were no correlation between the spatial and temporal use of pesticides. The dynamic exchange of pesticides between water-ice indicated that most pesticides were more enriched in water. However, there were still some pesticides (Dichlorvos and Biphenyl) that showed a stronger tendency to transfer from water to ice. Sediment-water exchange suggested that sediment is a source of secondary releases of most pesticides in wetland ecology, but is a sink for Biphenyl and Oxadiazon. The correlation between concentration ratios and fugacity fraction supported this finding. Most individual pesticides in wetland water and ice had shown low or moderate ecological risk conducted using risk quotient. The cumulative toxic effects of multiple pesticides had a high potential to pose a threat to wetland aquatic organisms.

Therapeutic effects of mesenchymal stem cell-derived microvesicles on pulmonary arterial hypertension in rats.

AIM: Microvesicles (MVs) are nanoscale membrane fragments released from virtually all cell types upon activation or apoptosis, and may contribute to the beneficial effects of stem cell therapy. In this study, we investigated the therapeutic effects of mesenchymal stem cell (MSC) derived MVs (MSC-MVs) on pulmonary artery hypertension (PAH) in rats. METHODS: MSC-MVs were isolated from rat bone marrow MSCs that were cultured in a serum-free conditioned medium. Transmission electron microscopy (TEM), flow cytometry and nanoparticle tracking analysis (NTA) were used to characterize the MVs. Adult SD rats were injected with monocrotaline (50 mg/kg, sc) to induce PAH. Three weeks later, the rats were intravenously injected with MSCs, MSC-MVs or saline for 2 weeks. At the end of treatments, the hemodynamic parameters and pathological right ventricular and pulmonary arterial remodeling were analyzed in each group. RESULTS: The MSC-MVs showed general morphologic characteristics of MVs and expressed annexin V and CD29 markers under TEM, and their size ranged from 40 to 300 nm. Intravenous injection of MSC-MVs or MSCs significantly ameliorated the mean pulmonary artery pressure (mPAP) and mean right ventricle pressure (mRVP) in PAH rats. Furthermore, intravenous injection of MSC-MVs or MSCs significantly decreased the right ventricle (RV) hypertrophy and pulmonary arteriole area index (AI) and thickness index (TI) in PAH rats. CONCLUSION: Intravenous injection of MSC-MVs or MSCs produces similar beneficial effects for treating PAH, and our results provide a basis for cell-free approach in stem cell therapy.

Multimedia distribution, dynamics, and seasonal variation of PAHs in Songhua wetland: Implications for ice-influenced conditions.

The knowledge of polycyclic aromatic hydrocarbons (PAHs) in wetlands remains limited. There is a research need for the dynamics between interfaces of multimedia when ice is present in this fragile ecosystem. In this study, sediment, open-water, sub-ice water, and ice samples were collected from the Songhua wetland to study the behaviors of PAHs with and without influences from ice. The concentration of all individual PAHs in sub-ice water (370-1100 ng/L) were higher than the open-water collected from non-ice-covered seasons (50-250 ng/L). Enrichment of PAHs in the ice of wetland was found, particularly for high-molecular-weight PAHs (HMW). This could be attributed to the relatively lower polarity of hydrocarbons compounds, making them more likely to remain in the ice layer during freezing. Source assessments reveal common sources for sub-ice water and ice, which differ from those in the open water in non-ice-covered seasons. This difference is primarily attributed to heating activities in the Harbin during winter. The average percentage contributions were 79% for sub-ice water and 36% for ice related to vehicle exhausts and coal combustion. Additionally, wood burning contributed 25% to sub-ice water and 62% to ice. Sediment in the wetland was found to serve as a final deposit particularly for heavier PAHs, especially those with 6 rings. Sediment also has the potential to act as a source for the secondary emission of low-molecular-weight PAHs (LMW) congeners into the water. PAHs in wetland displayed low ecological risk, while HMW PAHs with relative higher ecological risk is recommended to be further monitored.