Airborne pollen grains of Visakhapatnam: A combined field and air sampling study

Abstract

Field assessments at regular intervals from April 1975 to March 1979 recorded 61 plant species comprising 13 grasses, 20 weeds and 28 trees and shrubs as emitting appreciable amounts of pollen into the atmosphere of Visakhapatnam. The data also showed relative prevalence of these taxa in different zones of the city and their flowering periods. Pollen output in terms of number per anther and per flower was determined for 29 taxa. Air sampling with rod traps of 0·53 cm diameter enabled the identification of 23 different pollen types in the atmosphere with Poaceae accounting for Ca. 37% of the total pollen load.Casuarina contributed to 13% followed by Cyperaceae 6%,Eucalyptus 5·8%,Dodonaea 3·8%, Amaranth-Chenopod andPhoenix each 3·4%,Borassus 2·4% andPeltophorum 2%. Of the total identified pollen, ca 85% belonged to anemophilous taxa. There was no pollen-free day. The total pollen and individual types displayed seasonality quite closely corresponding with the blooming seasons of the source plants. Three pollen peaks, two in the wet period (June–November) and one in the dry period (December–May) were evident. Year to year variations in pollen abundance occurred and urban growth affected pollen frequency pointing to the need for routine monitoring of the atmosphere.