RESUMEN
Methane (CH4) is the second most abundant greenhouse gas after CO2, which plays the most important role in global and regional climate change. To explore the long-term spatiotemporal variations of near-surface CH4, datasets were extracted from Greenhouse gases Observing SATellite (GOSAT), and the Copernicus Atmospheric Monitoring Service (CAMS) reanalyzed datasets from June 2009 to September 2020 over South, East, and Southeast Asia. The accuracy of near-surface CH4 from GOSAT and CAMS was verified against surface observatory stations available in the study region to confirm both dataset applicability and results showed significant correlations. Temporal plots revealed continuous inflation in the near-surface CH4 with a significant seasonal and monthly variation in the study region. To explore the factors affecting near-surface CH4 distribution, near-surface CH4 relationship with anthropogenic emission, NDVI data, wind speed, temperature, precipitation, soil moisture, and relative humidity were investigated. The results showed a significant contribution of anthropogenic emissions with near-surface CH4. Regression and correlation analysis showed a significant positive correlation between NDVI data and near-surface CH4 from GOSAT and CAMS, while a significant negative correlation was found between wind and near-surface CH4. In the case of temperature, soil moisture, and near-surface CH4 from GOSAT and CAMS over high CH4 regions of the study area showed a significant positive correlation. However significant negative correlations were found between precipitation and relative humidity with GOSAT and CAMS datasets over high CH4 regions in South, East, and Southeast Asia. Moreover, these climatic factors showed no significant correlation within the low near-surface CH4 areas in our study region. Our study results showed that anthropogenic emissions, NDVI data, wind speed, temperature, precipitation, soil moisture, and humidity could significantly affect the near-surface CH4 over South, East, and Southeast Asia.
RESUMEN
Chemical quality and extent of pollution in effluent-contaminated irrigation water collected from two sectors (X and Y) of peri-urban southern regions of Khyber Pakhtunkhwa, Pakistan, were investigated. Various physico-chemical parameters like pH, EC, TS, TSS, TDS, TH, cations (Na1+, K1+, Li1+, Ca2+, Mg2+), anions (Cl1-, F1-, HCO31-, NO31-, SO42-), and heavy metals (Cr, Fe, Cu, Zn, Pb, Cd) were determined. The data indicated wide ranges of variation in all the parameters. Concentration of physico-chemical properties such as EC, TS, TSS, TH, Li1+, Ca2+, Mg2+, and HCO31- and heavy metals (Cr, Fe, Cu, and Cd) exceeded WHO permissible limits. The distribution of heavy metals in two sampling areas followed the increasing order as Fe > Cr > Cd > Cu > Pb > Zn. The Piper diagram showed that water in the region was of alkaline type. Strong positive correlations were observed among most of the parameters; however, pH was negatively correlated with most of the parameters. According to principle component analysis, parameters causing variations in water quality were mainly EC, TDS, TS, TSS, TH, Na1+, K1+, Ca2+, Mg2+, F1-, NO31-, SO42-, Cr, Fe, Cu, and Zn. Linear regression analysis revealed that heavy metals like Cr, Fe, and Cu concentrations were strongly correlated having an R 2 value of 0.92 at P ≤ 0.001 with pH. Overall, the results suggested that irrigation water of the area was not fit for irrigation purposes and might cause serious threats for safe, healthy food and feed production. Proper monitoring of water of the said area should be carried out, and quality of irrigation water should be checked from time to time.