دراسة نوعية لغبار الشوارع في بعض مناطق مدينة كربلاء واستخدام النباتات كمراقب حيوي

Qualitative study of streets dust in some districts of Kerbala city and using plants as a Biomonitor

     The study was carried out during the first half of 2014 , in the north west of Karbala city within the third section of the city . the study aimed to assess the street dust quality and its effect in increasing the air pollution by dust and heavy metals . samples were taken from main streets moderately in traffic intensity and from secondary streets will low traffic intensity . The study included separation of street dust particles by using soil sieve determine some chemical properties . These parameters were pH , EC, salinity and some heavy metals in both the street and fall dust as well as the suspended particles and in four plant species grown in the middle of the streets namely Albizia lebbeck , Eucalyptus spp, Conocarpus lancifolius, Dodonaea viscosa .The morphological and qualitatively structure of the streets dust particles were identified using polarized microscope technique, during winter and summer . These plants were tested in order to determine the best species in terms of pollutants retention and accumulation to be used as a biomonitor for pollution.

     Results of mechanical analysis revealed that , there are two categories of dangerous size (25-53micron with 14.66 gr and less than 25 micron with 2.49 gr ) which able to penetrate the respiratory system . The pH value was 7.2 with 6288 μs/cm and salinity of 3.48 ppt ) respectively . Photo results using polarized microscope showed that street dust consisted of three main contents –light and heavy minerals (where the quartz was dominant), organic matter included plants residues, manufactured substance such as glass and plastic whereas ,results of atomic absorption spectrophotometer appeared 11 metals in the street dust (As 0.048 , Pb 1.444 , Co 0.655 , Cu 1.023 , Cr 0.647 , Se 1.408 , Cd 0.044 , Fe 205.955 , Mn 4.643 , Zn 1.998 , Al 0.006) ppm . It is worth mentioning that these levels are less than most of national and international studies .

       The average fall dust quantities ranged between 29.94 and 65.59 g/month during winter and summer which were more than those of international limits . This increment was attributed to the building activity in this area and to the street dust as well as to activity of vehicle and to the adjacent to the desert area . It is also attributed to the climatic factors such as wind speed . temperature and humidity . The average concentrations of heavy metals in the fall dust were 0.052 for As , 0.546 for Pb , 0.443 for Co , 0.534 for Cu , 0.767 for Cr , 1.320 for Se , 0.063 for Cd , 184.711 for Fe , 2.315 for Mn , 1.840 for Zn , 0.003 for Al .

     Suspended particles concentrations were measured using suspended particles collector, analysis and calculation revealed that their concentration ranged 435.61-2605.80 gμ /m³ during winter and summer respectively and these results were more than Iraqi and international limits. Concentration of heavy metals were (As 1.096 , Pb 1.071, Co 12.318, Cu 3.153, Cr 0.766, Se 47.085, Cd 1.567, Fe 531.433, Mn 10.191, Zn 57.768, Al 0.518) in the suspended which were more than the limits mentioned by WHO except the Cr which was within the limits . Results showed the roles of climatic factors in increasing or decreasing the concentrations of suspended dust particles and heavy metals through the positive and negative correlation between them .Workshop, means of transport and accumulation street dust were considered important sources for creation and disturbance of these particles in the atmospheric air .

       Results also revealed the ability of some plants in the studies area to decrease the percentage of pollution by dust and heavy metals through determination . The quantity of the dust fall on he leaves , which were chemically digested for heavy metals determination .The plants species were in the following order : C. lancifolius > D. viscosa > E. spp > A. lebbeck, whereas in terms of uptake and accumulation of most heavy metals were in the following order : A. lebbeck > C. lancifolius > D. viscosa > E. spp. Through data analysis it is appeared that all heavy metals present in the street dust , fall dust and suspended particles in these plants were in high concentrations , therefore , they could be used as a biomonitor for pollution .