Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan

Atmospheric aerosol samples of PM_2.5 and PM₁₀ were collected at a rural site in Tanzania, East Africa, in 2011 during wet and dry seasons and were analysed for carbonaceous components, levoglucosan, mannosan and water-soluble inorganic ions. The contributions of biomass/biofuel burning to the organic carbon (OC) and particulate matter (PM) mass were estimated to be 46&ndash;52% and 87&ndash;13%, respectively. The mean mass concentrations of PM_2.5 and PM₁₀ were 28 ± 6 μg m⁻³ and 47 ± 8 μg m⁻³ in wet season, and 39 ± 10 μg m⁻³ and 61 ± 19 μg m⁻³ in dry season, respectively. Total carbon (TC) accounted for 16&ndash;19% of the PM_2.5 mass and 13&ndash;15% of the PM₁₀ mass. On average, 86 to 89% of TC in PM_2.5 and 87 to 90% of TC in PM₁₀ was OC, of which 67&ndash;72% and 63% was found to be water-soluble organic carbon (WSOC) in PM_2.5 and PM₁₀, respectively. We found that concentrations of levoglucosan and mannosan (specific organic tracers of pyrolysis of cellulose) well correlated with non-sea-salt potassium (nss-K⁺) (<i>r</i>² = 0.56&ndash;0.75), OC (<i>r</i>² = 0.75&ndash;0.96) and WSOC (<i>r</i>² = 0.52&ndash;0.78). The K⁺ / OC ratios varied from 0.06 to 0.36 in PM_2.5 and from 0.03 to 0.36 in PM₁₀ with slightly higher ratios in dry season. Mean percent ratios of levoglucosan and mannosan to OC were found to be 3&ndash;4% for PM_2.5 and PM₁₀ in both seasons. We found lower levoglucosan / K⁺ ratios and higher K⁺ / EC (elemental carbon) ratios in the biomass-burning aerosols from Tanzania than those reported from other regions. This feature is consistent with the high levels of potassium reported in the soils of Morogoro, Tanzania, suggesting an importance of direct emission of potassium by soil resuspension although K⁺ is present mostly in fine particles. It is also likely that biomass burning of vegetation of Tanzania emits high levels of potassium that may be enriched in plant tissues. The present study demonstrates that emissions from mixed biomass- and biofuel-burning activities largely influence the air quality in Tanzania

Estimation of local and external contributions of biomass burning to PM2.5 in an industrial zone included in a large urban settlement

A total of 85 PM2.5 samples were collected at a site located in a large industrial zone (Porto Marghera, Venice, Italy) during a 1-year-long sampling campaign. Samples were analyzed to determine water-soluble inorganic ions, elemental and organic carbon, and levoglucosan, and results were processed to investigate the seasonal patterns, the relationship between the analyzed species, and the most probable sources by using a set of tools, including (i) conditional probability function (CPF), (ii) conditional bivariate probability function (CBPF), (iii) concentration weighted trajectory (CWT), and (iv) potential source contribution function (PSCF) analyses. Furthermore, the importance of biomass combustions to PM2.5 was also estimated. Average PM2.5 concentrations ranged between 54 and 16 μg m−3 in the cold and warm period, respectively. The mean value of total ions was 11 μg m−3 (range 1–46 μg m−3): The most abundant ion was nitrate with a share of 44 % followed by sulfate (29 %), ammonium (14 %), potassium (4 %), and chloride (4 %). Levoglucosan accounted for 1.2 % of the PM2.5 mass, and its concentration ranged from few ng m−3 in warm periods to 2.66 μg m−3 during winter. Average concentrations of levoglucosan during the cold period were higher than those found in other European urban sites. This result may indicate a great influence of biomass combustions on particulate matter pollution. Elemental and organic carbon (EC, OC) showed similar behavior, with the highest contributions during cold periods and lower during summer. The ratios between biomass burning indicators (K+, Cl−, NO3−, SO42−, levoglucosan, EC, and OC) were used as proxy for the biomass burning estimation, and the contribution to the OC and PM2.5 was also calculated by using the levoglucosan (LG)/OC and LG/PM2.5 ratios and was estimated to be 29 and 18 %, respectively

Molecular composition of dicarboxylic acids, ketocarboxylic acids, alpha-dicarbonyls and fatty acids in atmospheric aerosols from Tanzania, East Africa during wet and dry seasons

Atmospheric aerosol samples of PM2.5 and PM10 were collected during the wet and dry seasons in 2011 from a rural site in Tanzania and analysed for water-soluble dicarboxylic acids, ketocarboxylic acids, alpha-dicarbonyls, and fatty acids using a gas chromatography/flame ionization detector (GC/FID) and GC/mass spectrometry. Here we report the molecular composition and sources of diacids and related compounds for wet and dry seasons. Oxalic acid (C-2) was found as the most abundant diacid species followed by succinic and/or malonic acids whereas glyoxylic acid and glyoxal were the dominant ketoacid and alpha-dicarbonyl, respectively in both seasons in PM2.5 and PM10. Mean concentration of C-2 in PM2.5 (121 +/- 47 ng m(-3)) was lower in wet season than dry season (258 +/- 69 ng m(-3)). Similarly, PM10 samples showed lower concentration of C-2 (169 +/- 42 ng m(-3)) in wet season than dry season (292 +/- 165 ng m(-3)). Relative abundances of C-2 in total diacids were 65% and 67% in PM2.5 and 65% and 64% in PM10 in the wet and dry seasons, respectively. Total concentrations of diacids (289-362 ng m(-3)), ketoacids (37.8-53.7 ng m(-3)), and alpha-dicarbonyls (5.7-7.8 ng m(-3)) in Tanzania are higher than those reported at a rural background site in Nylsvley (South Africa) but comparable or lower than those reported from sites in Asia and Europe. Diacids and ketoacids were found to be present mainly in PM2.5 in both seasons (total alpha-dicarbonyls in the dry season), suggesting a production of organic acids from pyrogenic sources and photochemical oxidations. Averaged contributions of total diacids to aerosol total carbon were 1.4% in PM2.5 and 2.1% in PM10 during wet season and 3.3% in PM2.5 and 3.9% in PM10 during dry season whereas those to water-soluble organic carbon were 2.2% and 4.7% in PM2.5 during wet season and 3.1% and 5.8% in PM10 during dry season. The higher ratios in dry season suggest an enhanced photochemical oxidation of organic precursors probably via heterogeneous reactions on aerosols under strong solar radiation. Strong positive correlations were found among diacids and related compounds as well as good relations to source tracers in both seasons, suggesting a mixed source from natural biogenic emissions, biomass burning, biofuel combustion, and photochemical production

IPA-Open access -Distributed under Creative Commons Attribution License 2.0 Working in Noise Environment: An Investigation of Hearing Quality of Drivers in Morogoro Municipality, Tanzania

ABSTRACT The present study has been carried out to assess the hearing quality of commuter bus and taxi drivers in the fast growing Municipality of Morogoro, Tanzania. The study utilized a structured questionnaire and was carried out among 160 drivers randomly selected in August and September 2010. The questionnaire included questions regarding the self-assessment of the drivers about their hearing ability, past and present exposure to loud sound and the use of noise protective gears. The questionnaire was filled up by the respondents at a close supervision and the data were analysed using simple descriptive statistics. The results show that most divers aged below 35 years and have been exposed to the traffic noise environment for 2 to 5 years. Nearly 4% of the respondents felt that their hearing ability was below average and complained of regular tinnitus. The results also show that only 17.5% used noise protective gears and that too, not often. Reasons for non-usage of protective gears (earplugs, earmuffs and canal caps) included awareness (24.4%), non-availability (50%), personal dislike (8.1%) and headache caused by its use (17.5%). Large percent (82.5% of the drivers did not use any method to reduce exposure to noise, while remaining used fingers or hands at time of loud noise to avoid noise exposure. The self-assessment of hearing by the commuter bus and taxi drivers in Morogoro Municipality suggests that most of the drives have normal hearing. However, this study suggests a systematic study with audiometry of these population groups be carried out in future

Teaching practice experience for undergraduate student teachers: A case study of the Department of Education at Sokoine University of Agriculture, Tanzania

Journal of Education and Practice 2016, Vol.7(14)Education is the key to development; however, it is impossible to think the quality of education without having academically qualified and professional responsible teachers. The main objective of this study was to examine the perspectives of undergraduate student teachers toward teaching practice experience as a tool of learning to teach. A qualitative research methods approach using semi - structure questionnaires was carried out to 351 second and third year undergraduate student teachers in the department of education of the Faculty of Science at Sokoine University of Agriculture. The findings indicate that the student teachers perceived teaching practice as an important tool of learning to teach because it promoted the development of teaching experience and prepared them for the real world of work. The results also revealed that teaching practice is sufficiently emphasised and lack of financial support and the mismatch of the teaching practice period with local secondary school calendar were the main challenges. The study recommends provision of adequate fund on time, close supervision, building strong university partnership with the local secondary schools need interventions if not be improved and given its due attention