Physicochemical assessment of a waste rock dump in the hidden valley gold mine: a case study for bioremediation in Papua New Guinea

Deforestation, environmental degradation, and pollution from the mining activities are much studied global environmental concerns. The effect of waste rock dumping from mining activity on the forest soil characters and suitability of waste rock dumps for bioremediation is least explored. Such information is necessary for making rehabilitation decisions. In this study, soil physicochemical characteristics and some index polluting elements were assessed in the waste rock dump stations (n = 16) and adjacent natural forest stations (n = 14) in a gold mine situated in the Morobe province of Papua New Guinea. Results indicated that the waste rock dump was poorer in organic C, but rich in available P, exchangeable Ca and Mg contents, and extractable Cu and Mn. Comparison of established diagnostic norms for potential sufficiency and toxicity of nutrient elements with those observed in the study indicated that organic carbon content, exchangeable K, Ca and Mg as well as, extractable Cu content was at an insufficient level in a majority of stations of waste rock dump for arable crops. Besides, the mean Cd content of waste rock dump was 15-times greater than that in forest stations while that of extractable Mn was 400-fold higher. Findings of the study warranted the use of adaptable and hardy forest species instead of arable crops for safe bioremediation of waste rock dump.