Fighting against POLLUTION to Save Environment

Autoexhaust lead pollution of roadside ecosystem in Delhi:

J. Ind. Asso. Environ. Mgmt. 19, 21-27, 1992.

D. B. BORALKAR, S. K. TYAGI and S. B. SINGH
Central Pollution Control Board, 'Parivesh Bhawan' , CBD-Cum-office Complex, East Arjun Nagar,
Shahdara DELHI-110 032

Table 2: CATEGORISATION OF INTERSECTIONS BASED ON TRAFFIC DENSITY

*Petrol-driven Vehicles during 6 hr (Table 1)

Ambient Air Quality

The ambient air sampling and analysis for Pb, Suspended Particulate Matter (SPM), SO2 and NO2 was done as per Standard Methods.

Lead in Soil

The soil samples were collected in triplicate from top, bottom and middle portion of the pots of each species from every location. A composite sample was thus made for each species at every location. Precautions were taken to maintain uniformity in all soil sampling. Surface vegetation and debris, if any, were removed before sampling. Soil samples were dried for a minimum of 30 hr. After screening, the soil was pulverized and sieved through an 80-mesh screen. Lead content in the soil samples was determined by conventional atomic absorption Spectrophotometry.

Lead in Plants

Three plant species from six different locations were analysed in triplicate after scrubbing (leaf and shoot) and washing with water (root) for the lead content of the root, shoot and leaf using mixture of sulphuric and nitric acid for digestion. The test samples were processed on Atomic Absorption Spectrophotometer for estimation of lead. The dust deposited on leaves of different plant species was collected separately in pre-weighed beakers using a jet of double glass distilled water. The beaker was dried in 80°C oven for 24 hr, weighed and lead content of the dust in the beaker was determined.

Table 3: TRAFFIC FLOW AND AMBIENT AIR QUALITY AT SELECTED TRAFFIC INTERSECTIONS AND NPL NURSERY

* Petrol-driven Vehicles during 6 hr (Table 1)

Plant Growth

The general growth of the plant species at six different locations was studied using the parameters: total chlorophyll, total biomass, leaf area (using LICOR 3000 Area Meter).

RESULTS AND DISCUSSION

Lead in the Roadside Ambient Air: The concentration of lead in ambient air at 13 traffic intersections was in the range 280 ng/m3 and 1,802 ng/m3 and SO2 and NO2 were mostly less than 100 µg/m3 in Jan. 1984. At the same intersections in June 1984, lead ranged between 170 ng/m3 and 926 ng/m3 while SO2 and NO2 did not exceed 100 µg/m3.

The lead in ambient air at five finally chosen traffic intersections and also at the control site within NPL Nursery was monitored once-a-month for 10 months from July 1984 to June 1985. No measurements could be conducted during November and December, 1984. Air quality monitoring was done for different periods of the time of the day, as follows:

AUTOEXHAUST LEAD

09.00 to 12.00 hr morning peak traffic hours 16.00 to 19.00 hr evening peak traffic hours 12.00 to 16.00 hr mid-day lean traffic hours 09.00 to 19.00 hr 10-hour day time traffic hours

Table 4: AMBIENT AIR LEAD CONTENT AT SIX DIFFERENT LOCATIONS*

* Between July 1984 and June 1985