Particle size distribution of total suspended sediments in urban stormwater runoff: Effect of land uses, precipitation conditions, and seasonal variations.

Understanding particle size distribution (PSD) of total suspended sediments in urban runoff is essential for pollutant fate and designing effective stormwater treatment measures. However, the PSDs from different land uses under different weather conditions have yet to be sufficiently studied. This research conducted a six-year water sampling program in 15 study sites to analyze the PSD of total suspended sediments in runoff. The results revealed that the median particle size decreased in the order: paved residential, commercial, gravel lane residential, mixed land use, industrial, and roads. Fine particles less than 125 µm are the dominant particles (over 75%) of total suspended sediments in runoff in Calgary, Alberta, Canada. Roads have the largest percentage of particles finer than 32 µm (49%). Gravel lane residential areas have finer particle sizes than paved residential areas. The results of PSD were compared with previous literature to provide more comprehensive information about PSD from different land uses. The impact of rainfall event types can vary depending on land use types. A long antecedent dry period tends to result in the accumulation of fine particles on urban surfaces. High rainfall intensity and long duration can wash off more coarse particles. The PSD in spring exhibits the finest particles, while fall has the largest percentage of coarse particles. Snowmelt particles are finer for the same land use than that during rainfall events because the rainfall-runoff flows are usually larger than the snowmelt flows.

Knocking down of lncRNA SBF2-AS1 inhibits proliferation, invasion and induces apoptosis of colorectal cancer through regulating PTEN.

To illustrate the potential function of lncRNA SBF2-AS1 in the progression of colorectal cancer (CRC) and the molecular mechanism. The relative level of SBF2-AS1 in CRC tissues and cell lines was determined by qRT-PCR. Its level in CRC patients with different tumor stages and tumor sizes was examined. After the knockdown of SBF2-AS1, proliferative, invasive abilities and apoptotic rate of CRC cells were evaluated. The correlation between SBF2-AS1 and PTEN was analyzed in CRC tissues. Furthermore, the subcellular distribution of SBF2-AS1 was assessed. Through RIP and ChIP assay, the interaction between SBF2-AS1 and PTEN was identified. Finally, the involvement of PTEN in SBF2-AS1-mediated CRC progression was analyzed. SBF2-AS1 was upregulated in CRC tissues and cell lines. Its level remained higher in CRC with worse tumor stage and larger tumor size. Knockdown of SBF2-AS1 attenuated proliferative, invasive abilities, but induced apoptotic rate of SW480 and DLD1 cells. A negative correlation was identified between expression levels of SBF2-AS1 and PTEN in CRC tissues. PTEN level was negatively regulated by SBF2-AS1. Subcellular distribution analysis indicated that SBF2-AS1 was mainly expressed in the nucleus. Furthermore, the RIP assay proved the binding of SBF2-AS1 to EZH2 and SUZ12. Knockdown of SBF2-AS1 attenuated the recruitment ability of EZH2 to PTEN. Notably, inhibited proliferation by transfection of sh-SBF2-AS1 1# was partially reversed after co-transfection of sh-PTEN. LncRNA SBF2-AS1 is upregulated in CRC. Knocking down of lncRNA SBF2-AS1 inhibits proliferation, and invasion and induces apoptosis of colorectal cancer by interacting with EZH2 to downregulate PTEN level.

Effects of mixed land use on urban stormwater quality under different rainfall event types.

The joint effect of mixed land uses and rainfall event types was studied using a two-year field monitoring program in four urban catchments in Calgary, Alberta, Canada. Event mean concentration (EMC) and event pollutant load (EPL) were employed to evaluate the total suspended sediment (TSS), nitrogen and phosphorus. The correlation analysis showed that most nitrogen and phosphorus components (except for NO2-/NO3- and TDP) predominantly exist in particulate form in the study areas. The correlation for EPL was notably stronger than EMC, which can be attributed to varying rainfall characteristics. The differences in EMCs and EPLs of TSS, nitrogen and phosphorus across catchments indicated that the complexity and spatial distribution of mixed land use can influence the generation and transportation of pollutants in urban runoff. The impacts of rainfall characteristics on stormwater quality are integrated rather than driven by a single rainfall characteristic. Brief but intense events tended to elevate TSS, nitrogen and phosphorus concentrations, especially in complex land-use catchments. Events with long antecedent dry days and short duration also resulted in increased pollutant concentrations, while events with long duration and low intensity could result in higher EPLs. The effect of mixed land use on water quality can vary depending on rainfall event types. Seasonal variations were found in EMC and EPL of TSS, nitrogen and phosphorus, with higher values in the spring and summer than the fall. Seasonal variations are mainly influenced by rainfall conditions, temperature and anthropogenic activities (e.g. lawn fertilization and de-icing with sands). MLR considering rainfall characteristics is an effective method for predicting stormwater quality within a single catchment. Considering complexity and spatial distribution of mixed land use can improve the accuracy of the harmonized MLR model. This research provided insights into understanding the complexities introduced by mixed land use and rainfall event types in urban stormwater quality.