Browsing by Author "Nyihirani, Fatuma"
Now showing 1 - 4 of 4
- Results Per Page
- Sort Options
Item Boundary layer perspective assessment of air pollution status in Wuhan city from 2013 to 2017(Springer Nature Switzerland, 2019) Mbululo, Yassin; Qin, Jun; Yuan, Zhengxuan; Nyihirani, Fatuma; Zheng, XiangThis study used daily air pollution data (PM2.5, PM10, SO2, NO2, CO, and O3) from nine monitoring stations inWuhan city to calculate the air quality index (AQI) from 2013 to 2017. Together with this data, L-band sounding data, ground meteorological data, and air mass back trajectories were also used to describe the dynamics of atmospheric boundary layer (ABL) during pollution process. Analysis of the results shows that, even though the city is still polluted, the number of polluted days was decreasing. Ranking the years in terms of pollution status shows that the year 2013 was the most polluted year while the year 2017 was the cleanest year. Average annual limit of PM10, PM2.5, and NO2 during these 5 years were 1.3~1.8, 1.5~2.7, and 1.2~1.5 times higher than the annual average acceptable limit, respectively. The average ratio of PM2.5/ PM10 for 5 years was 0.67 which signifies that a significant portion of PM2.5 accounted for the total mass of PM10. Moreover, the condition of ABL during the pollution process shows the dominance of strong ground inversion and weak to calm winds. These conditions are not favorable for horizontal and vertical mixing of air pollutants and prevent dilution of pollutants with clean air. Mean cluster analysis of air mass back trajectory shows that pollutants of local origin were more important than the trans-boundary movement of air pollutants. This indicates that the observed pollution in Wuhan was more of local originItem Chemical composition and deposition fluxes of water-soluble inorganic ions on dry and wet deposition samples in Wuhan, China(MDPI, 2019) Qin, Jun; Mbululo, Yassin; Yang, Muyi; Yuan, Zhengxuan; Nyihirani, Fatuma; Zheng, XiangMeasurement of PM2.5 concentration, dry and wet deposition of water-soluble inorganic ions (WSII) and their deposition flux was carried out. During sampling, a total number of 31 samples of PM2.5, five wet deposition samples and seven dry deposition samples were collected. The analyses results showed that the average concentration of PM2.5 was 122.95 g/m3 whilst that of WSII was 51.63 g/m3, equivalent to 42% of the total mass of PM2.5. The correlation coefficients between WSII in samples of PM2.5 was significant (r = 0.50 and p-value of 0.0019). Ions of SO2 4 , NO 3 , Cl, and NH+ 4 were dominant in the entire samples (PM2.5, dry and wet depositions), nevertheless, the average concentration of both SO2 4 and Cl were below the China environmental quality standard for surface water. The ratio of dominant anions in wet deposition (SO2 4 /NO 3 ) was 1.59, whilst that for dry deposition (SO2 4 /Cl) was 1.4, indicating that acidity was mainly derived from sulphate. In the case of dominant cations, the dry and wet deposition ratios (Ca2+/NH+ 4 ) were 1.36 and 1.37, respectively, suggesting the alkaline substances were mainly dominated by calcium salts. Days with higher recorded concentrations of PM2.5 were accompanied by dry and warm boundary layer structure, weak low-level wind and strong inversion layer.Item Climate characteristics over southern highlands Tanzania(Scientific Research, 2012) Mbululo, Yassin; Nyihirani, FatumaThis study was conducted to examine the climate characteristic of southern highland Tanzania (Latitude 6°S - 12°S and Longitude 29°E - 38°E). The study findings reveal that rainfall over the region is linked with SST over the Indian Ocean, where warmer (cooler) western Indian Ocean is accompanied by high (low) amount of rainfall over Tanzania. During wet (dry) years, weaker (stronger) equatorial westerlies and anticyclone (cyclonic) anomaly over the southern tropics act to reduce (enhance) the export of equatorial moisture away from East Africa. The wettest (driest) season was found to be 1978/79 (1999/00) which can be classified as the severely wet (moderate drought). Two different modes of rainfall have been identified at time scale of 1.5 and 6 years which have been associated with the quasi biennial oscillation (QBO) and El Nino Southern Oscillation (ENSO), respectively.Item Level, source, and distribution of organochlorine pesticides (OCPs) in agricultural soils of Tanzania(Springer, 2022) Nyihirani, Fatuma; Qu, Chengkai; Yuan, Zhang; Zhang, Yunchao; Mbululo, Yassin; Janneh, Mariama; Qi, ShihuaThis study investigated the level, com- position, and spatial and vertical distribution of the organochlorine pesticides (OCPs) at 0–2 cm and 2–20 cm in the agricultural surface soils from South- eastern to Central-western Tanzania. Although the most abundant OCPs were DDT with a mean concen- tration of 2.29 ng/g, dieldrin (1.57 ng/g), and methox- ychlor (0.79 ng/g), HCH was the most dominant (with detection frequency of 88%). OCP dominance was in the Southern Highlands, which is the most productive agricultural zone. Though there were indicators of recent inputs for some sites, OCP contamination was mainly historical. DDT contamination was dominated by p,p′-DDE and resulted from both technical DDT and dicofol while HCH contamination was dominated by γ-HCH and resulted from both technical HCH and lindane. Based on depth, the OCPs dominated mainly the upper 2 cm, which was associated with soil and environmental factors rather than recent inputs since most of the detected compounds were historical. Nev- ertheless, some sites showed exceptional high abun- dance in the lower soil with more concentration of parent compounds. Therefore, this study recommends the need for further studies on the influence of soil properties on OCPs’ transport in the soil, surface water, and air. Besides, detection of recent inputs at some sites calls for more mapping of the OCPs in the country to strengthen their control and prevention of future risks.