Heavy metal contamination of sediments in mangrove forests of the Persian Gulf

Abstract

Mangroves are sensitive ecosystems with prominent ecological value that have unfortunately lost much of their areas across the world, partly because of pollution. The present study investigated heavy metal contaminations in three mangrove forests of southern Iran. Surface sediments (0-10 cm) were collected from the mangroves in northern Persian Gulf in April 2009. Also, biometric features of trees were measured. Metal concentration ranges were as follows: Al 1795-30240, Fe 6425-51530, Cd 0.6-3.45, Cu 14.1-98.28, Ni 14.1-204.54, Pb 34.15-191.6, V 57.38-825.26 and Zn 44.91306.15 µg g -1 dry weight. Principal component analysis on heavy metal concentration of sediments suggested three sources of pollution, industry, natural mineralogy of soils and oil, and industrial activities were the most important source. There was no significant difference among the three mangrove forests in heavy metal concentrations of sediments indicating that the pollution source was the same. There was little correlation between biometric characteristics of mangrove trees and heavy metal concentrations of sediment suggesting that pollution had no effect on mangrove trees. In conclusion, the overall average concentrations of above metals exceed the primary standard criteria but meet the secondary standard criteria of the Chinese National Standard of Marine Sediment Quality and also United State Environmental Protection Agency (USEPA) Standard.