GSPCB interim report on Source Apportionment Study observes possible mixture of local sources
PANJIM: In what could shock Vasco residents, Goa State Pollution Control Board’s (GSPCB) interim report on the Source Apportionment Study of the town with regard to pollution caused due to handling of coal at Mormugao Port Trust (MPT), has observed a possible mixture of other local sources leading to pollution and not just the contribution from the port area.
The study undertaken through Indian Institute of Technology (IIT) Bombay also observes that “strength of the source (cargo handling) progressively reduces with distance from the port towards the town”.
GSPCB initiated an air pollution source apportionment study in Vasco from November 2017, with a view to address primarily the issue of Particulate Matter (PM10 and PM2.5) in the ambient, after cargo handling units at MPT – JSW and Adani – were found to be involved in violations through excess handling of coal leading to serious air pollution.
The study had identified seven locations for collection of samples – MPT guest house, NCPOR Vasco, Vasco NAMP site, Baina residential location, Chafran residential colony, SMC hospital and Chicalim VP.
The total cargo handled at Adani and JSW during the sampling period (Feb 2018, April-May 2018) was 40,500 metric tonnes and 40,778 metric tonnes respectively.
“The PM2.5 concentrations are spatially similar throughout the loop locations, but vary with the time of the day. These were about 200 μg/m3 in morning, 150 μg/m3 in the afternoon and 100 μg/m3 in the evening,” the report stated.
“From AERMOD (modeling system) runs, where port activities were considered to be the only sources, it is expected that the concentrations at fish market would be higher than Mangor Hill as fish market is closer to the port. However, the concentrations at fish market were comparable to those at Mangor Hill,” the report stated.
“This indicates that there are possible influences of other local sources,” it stated, adding that a further study (source apportionment based on chemical analysis) is required to comment on such local sources.
The study mentions that while the annual averaged windrose shows that the predominant wind direction is towards the shore from the sea, the seasonal patterns show that during October to December the predominant wind direction is from the shore towards the sea. “As per the AERMOD dispersion isopleths, as expected, the strength of the source progressively reduces with distance from the port towards the Vasco area,” it said.
Explaining further, the report mentions that “if the PM at near source (port) is ~10 μg/m3, then within 1 km towards Vasco it reduces to ~0.5 μg/m3. The PM10 at the berth were measured as 128 μg/m3 to 452 μg/m3. If these were to be selected, then it is expected that the contribution at 1 km would be 6.4 to 23 μg/m3, and at 2 km would be 1.28 to 5 μg/m3”.