Nimisha Tripathi

Mine spoil acts as a sink of carbon dioxide in Indian dry tropical environment.

Economically important mining operations have adverse environmental impacts: top soil, subsoil and overburden are relocated; resulting mine spoils constitute an unaesthetic landscape and biologically sterile or compromised habitat, and act as source of pollutants with respect to air dust, heavy metal contamination to soil and water bodies. Where such spoils are revegetated, however, they can act as a significant sink for atmospheric carbon dioxide (CO2) through combined plant succession and soil formation. Revegetation, drainage, reprofiling and proper long term management practices help recapture carbon, improve soil quality and restore the soil organic matter content. A survey along an age gradient of revegetated mine spoils of 19 years in Singrauli, India by the authors showed an accumulation of total C in total plant biomass, mine soil and soil microbial biomass by 44.5, 22.9 and 1.8 t/ha, respectively. There was an increase in total sequestered C by 712% in revegetated mine spoils after 19 years, which can be translated into annual C sequestration potential of 3.64 t Cha(-1) yr(-1). Carbon sequestered in revegetated mine spoil is equivalent to 253.96 tonnes/ha capture of atmospheric carbon dioxide (CO2). This indicates that mine spoil can act as a significant sink for atmospheric CO2. Annual C budget indicated 8.40 t Cha(-1) yr(-1) accumulation in which 2.14 t/ha was allocated to above ground biomass, 0.31 t/ha in belowground biomass, 2.88 t/ha in litter mass and 1.35 t/ha in mine soil. This shows that litter mass allocation is much important in the revegetated site. Decomposition of root and litter mass contributes C storage in the mine soil. Therefore, revegetation of mine soils is an important management option for mitigation of the negative impacts of mining and enhancing carbon sequestration in mine spoils.

Reclamation of Mine-Impacted Land for Ecosystem Recovery: Tripathi/Reclamation of Mine-Impacted Land for Ecosystem Recovery

Mining activities significantly impact the environment; they generate huge quantities of spoil, promote deforestation and the loss of agricultural production, as well as releasing contaminants that result in the loss of valuable soil resources. These negative impacts are now being recognized and this book shows how corrective action can be taken. The introduction of sustainable mining requires mitigation strategies that start during the mine planning stage and extend to after mineral extraction has ceased, and post-closure activities are being executed. Reclamation of Mine-impacted Land for Ecosystem Recovery covers: methods of rejuvenation of mine wasteland including different practices of physical, chemical and ecological engineering methods; benefits of rejuvenation: stabilization of land surfaces; pollution control; aesthetic improvement; general amenity; plant productivity; and carbon sequestration as well as restoring biodiversity and ecosystem function; best management practices and feasible solutions to the impacts of mining which will reduce the pollution load by reducing the discharge rate and the pollutant concentration; reduce erosion and sedimentation problems, and result in improved abandoned mine lands; and ecosystem development. The authors explain how mining impacts on soil properties and how soil carbon reserves/soil fertility can be restored when mining has ceased. Restoration involves a coordinated approach that recognizes the importance of key soil properties to enable re-vegetation to take place rapidly and ecosystems to be established in a low cost and sustainable way. This book’s unique combination of the methods for reclamation technologies with policies and best practice worldwide will provide the background and the guidance needed by scientists, researchers and engineers engaged in land reclamation, as well as by industry managers.

Impact of Savannization on Nitrogen Mineralization in an Indian Tropical Forest

The effects of conversion of an Indian dry tropical forest ecosystem into savanna, on mineral nitrogen (N), net N-mineralization rate and microbial biomass carbon (MBC), nitrogen (MBN) and phosphorus (MBP) in soil were studied for two years. There was a marked seasonal variation in all the above parameters at both (upper, 0-10 cm and lower, 10-20 cm) the soil depths of forest and savanna ecosystems. In forest ecosystems the mean annual values of mineral N, net nitrification rate, net N-mineralization rate, MBC, MBN and MBP at both depths were 17.41 and 13.2 µg g -1 , 18.76 and 10.96 µg g -1 mo -1 , 23.54 and 12.83 µg g -1 mo -1 , 623 and 195µg g -1 , 116 and 29µg g -1 , 16 and 9µg g -1 , respectively; while in savanna ecosystems the values were 20.15 and 15.73 µg g-1, 10.74 and 6.29 µg g-1mo-1, 16.59 and 10.11 µg g -1 mo -1 , 453 and 150µg g -1 , 79 and 21.7µg g -1 , 13 and 6µg g -1 , respectively. The soil microbial biomass was positively related to root biomass and total plant biomass (i.e., above- and below-ground biomass). Interestingly, seasonal soil moisture and temperature are reciprocally related to microbial biomass and mineral N and directly related to nitrification and N-mineralization. The microbial biomass, nitrification and N-mineralization are negatively related to clay content. Savannization caused significant loss of soil mean organic carbon (OC), total N (TN) total mean annual nitrification, N-mineralization, MBC, MBN and MBP by 40, 42, 27, 27, 29 and 7%, respectively at upper soil depth and 18, 21, 42, 29 and 22%, respectively at lower soil depth. The reflectances of soil microbial biomass to OC were 1.22 and 1.06 folds at upper and lower soil depths, respectively. Thus, conversion of dry tropical forests into savanna affects remarkably the soil N transformation; microbial biomass and loss of soil organic C which adds to the environmental pollution.