Impact of Industrial Activities on the Concentration of Lead and Mercury in Soils of Cultivated Lands at Abis and El-Nanda Regions, South Alexandria City, Egypt

摘要

CULTIVATED soils south Alexandria city (Abis and El-Nahada) are subjected to contamination from different sources of industrial activities. These sources are distributed in the south and southwest of the city. The current study was carried out to assess the impact of these industrial activities on Pb and Hg levels in the cultivated soils of El-Nanda and Abis regions. The amounts of DTPA-extractable Pb from soils varied from 0.16 to 11.50 mg kg(-1).Extremely high values of DTPA-Pb are found in soils of sites located near by the Black carbon plant at El-Nanda, self-burning municipal solid waste at Abis and industrial complex of El-Max. On the other hand, the lowest DTPA-Pb levels were measured in soils of sites at distance greater than 3 km south and south west the hot spot sources. The amounts of total Hg in soil samples collected in 1985 varied from 0.30 to 1.75 mg kg-1 and in those collected in 1998 from 0.15 to 1.45 mg kg(-1).The main hot spot sources of Hg in the studied area are oil refining, petro chemicals, cement production, chemical industries of special interest is the chlor-alkal and self burning of municipal solid waste at Abis. Five topographic map sheets at scale 1:50,000 (Alexandria - Abo-Quir - Kafr El-Dawer - King Maruit and Abo El-Matamur) were analyzed using ArcGIS and a Digital Elevation Model (DEM) was produced. Elevation values ranged between 3 below sea level to about 30 meter above sea level. Descriptive variance analysis showed that DTPA-Pb has more variability than total Hg as the variance is much higher.This is attributed to the greater number of soil samples (63) used in DTPA-Pb and organic carbon analysis compared to the number of samples (18) used for total Hg analysis. Geostatistical analysis, in ArcGIS, indicated that the DTPA-Pb and total Hg concentrations was best fitted Gaussian model while organic carbon was best fitted spherical model. The range showed that maximum interpolation of the concentration of Pb and OC at Abis-El-Nanda area were 7580.7-1634 m. The nugget variance of concentration of Pb and OC at Abis-El-Nanda area were 1.37-2231.3m. Ordinary Kriging was used for DTPA-Pb and OC and showed that this variable represent high spatial dependence. On the other hand, Simple Kriging was used for total Fig in soils collected in 1985 and 1998 which showed no spatial dependency. The ordinary and Simple Kriging maps showed that the spatial distribution and interpolation of the concentrations of Pb, Hg and OC and also significant concentrations of these parameters were increased in the soils closer to the hot point source and then were decreased with distance. The challenges of sustainable agriculture development in El-Nanda and Abis depend on compliance and enforcement of environmental regulations in order to control Pb and Hg emission into the atmosphere. High concentration levels of Pb and Hg in the atmosphere can adversely affect the ecosystem and human health.