Application rate and plant species affect the ecological safety of sewage sludge as a landscape soil amendment |
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| Institution: | 1. Department of Geology and Environmental Geosciences, College of Charleston, 66 George St., Charleston, SC 29424, USA;2. Y-12 National Security Complex, US Department of Energy, Oak Ridge, TN 37831, USA;3. Department of Earth and Planetary Sciences, the University of Tennessee, Knoxville, TN 37996, USA;4. Center for Environmental Biotechnology, the University of Tennessee, Knoxville, TN 37996, USA;5. Department of Geosciences, Baylor University, One Bear Place #97354, Waco, TX 76798, USA;6. Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD 20688, USA;1. Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia;2. Center for Research in Waste Management, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia;3. Department of Biological Sciences, Faculty of Science, Federal University of Kashere, Gombe State, Nigeria;4. Jeffrey Sachs Center on Sustainable Development, Sunway University, Sunway, Malaysia;5. Faculty of Marine Sciences, Lasbela University of Agriculture, Water and Marine Sciences, Uthal, Balochistan, Pakistan;6. Climate Change and Forestry Program, Forestry and Environment Division, Forest Research Institute, Malaysia |
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| Abstract: | Recycling sludge as a soil amendment has become a viable option for sludge disposal. However, such application can lead to soil pollution because of its enrichment in contaminants, especially heavy metals. To identify an effective means to ensure the ecological safety of sewage sludge landscape utilization, a glasshouse experiment was conducted by mixing sewage sludge at 0%, 15%, 30%, 60%, and 100% (V/V) amendment ratios to landscape soils and planting five common landscape plants (Aphelandra ruellia, Syngonium podophyllum, Schefflera odorata, Alocasia macrorrhiza, and Dianella ensifolia). Sludge amendment significantly improved fertility and moisture retention capacity of soil, but dramatically increased the contents of Cd, Pb, Cu, and Zn. Compared with lateritic red soil (CK), sludge amended-soils increased the relative growth rate of landscape plants and enhanced their nutrient uptake and heavy metals accumulation. A rate of 30% or less of sludge application showed positive growth effects for all five landscape plants, and did not cause potential ecological risks of heavy metals to landscape soils. However, rates of 60% or higher posed very high potential ecological risk in multiple metals, particularly in Cd. Interestingly, S. odorata, A. ruellia and A. macrorrhiza could alleviate the ecological risks of Cd, Cu and Zn, respectively, and these results were confirmed by data of relative changes in heavy metal contents in post-experiment soil. Our results suggest that attention to reducing the environmental risks of heavy metals in sludge utilization as landscape soil-amendments should not only be paid to controlling the application dosage of sludge but also to planting suitable plant species. |
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| Keywords: | Soil quality Pot experiment Landscape Heavy metals Phytoextraction |
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