Donald De Alwis

Donald De Alwis

Speaker | University of Maryland at College Park

Silver Spring, MD |

Donald De Alwis is currently studying towards dual degrees in Environmental Science and Public Health Science at the University of Maryland, College Park. He specializes in environmental health, and enjoys exploring the interface between humans and the environment. He hopes to continue researching the human-environment nexus after his bachelor’s degree through a graduate or professional degree program.

Session Name: CCREF Supported Research Results: Air Emissions, Soluble Salts, Wetland Restoration

Session Time: Wednesday, January 29, 4:15 to 5:45 PM

Presentation Title: Differently-Aged Organic Matter Amendments Change Reduced Iron in Soils of Restored Wetlands

Presentation Description: Organic matter amendments are frequently added to restored wetlands in order to improve soil and accelerate vegetation development. In theory, compost and other organic amendments will promote the development of hydric soil indicators, including the presence of ferrous iron. In microcosm studies, however, we found that ferrous iron production decreases relative to controls upon addition of certain low energy, highly cured materials, such as LeafGro (a composted yard waste product) and wood mulch. As a follow up study, we investigated the ferrous iron production generated from the addition of two different types of compost – Bloom™(a class A biosolid generated by DC Water) and cow manure, at three different curing times. Using a simulated wetland microcosm study with ferrous iron and biogas measurements conducted on a time course, we discovered that longer curing times generally resulted in decreased ferrous iron production. Conversely, shorter curing times generated more iron production, perhaps because there were more low-molecular weight substrates for microbial growth. So, is there a catch? Compost at shorter curing times also produced more methane – a potent greenhouse gas. Therefore, these findings imply that there is a tradeoff between stimulating indicators of wetland hydric soils, and contributing to greenhouse gas emissions.

This research was supported by the CCREF Young Investigator scholarship, and is part of a larger study by Brian Scott, a PhD student evaluating the use of OM amendments in wetland restoration.

Co-Authors: Brian Scott, University of Maryland, College Park,
Andy Baldwin, PhD, University of Maryland, College Park,
Stephanie Yarwood, PhD, University of Maryland, College Park,