Abstract:
Mineral mining often alters the soil environment and reduces the sustainability of the
surrounding environment. Recovery of soil physical and chemical properties after tin mining on
tropical Belitung Island, Indonesia, has been a painstaking process, even after more than 100
years of reclamation. This study aimed to determine which parameters of soil properties are
responsible for the slow recovery and whether there are other properties that show more rapid
changes. Physical, chemical, and biological properties of the soil were measured at different time
periods after tin mining: soil samples were collected from three areas at 0-, 1-, and 6-years postmining
and from an adjacent natural forest as a reference site. Soil moisture, hydraulic
conductivity, bulk density, particle distribution, mineral content, and soil microbial composition
were measured in the field and analyzed in the laboratory. The soil showed a decrease in
particulate matter and, despite the absence of clay, a significant increase in water holding capacity
and a 0.2% increase in organic carbon after 6 years. Copper, iron, manganese, and zinc in the soil
changed little. Lead and cadmium were present in very small amounts. The soil bacterial
community clearly varied with the age of the land, with actinobacteria predominating in the first
few years after mining, but after 6 years, proteobacteria had established themselves in the mined
area. The degree of land recovery was more clearly described by including the results of the
microbial community analysis in the principal component analysis. This study examined more
clear changes in soil properties on land after tropical tin mining. Soil and bacterial properties can
be used as markers to monitor land restoration progress.
