Potential inhibitory effect of heavy metals on soil N2O emissions

In the first year, the experiment will be carried out using the Denitrification Incubation system (DENIS system) (details described below). There are 12 chambers in the laboratory system, which allows to include 3 treatments with 4 replicates for each. The impact of each targeted element on soil N2O emission will be tested in an individual experimental batch, with the N2O and other greenhouse gases emission data being continuously collected from the soil chambers for 2 weeks. The length of the each incubation (2 weeks) is determined based on the results of (Bateman and Baggs, 2005), reporting that soil N2O emission is highest after the application of the N fertilizers and is continuously decreasing until circa 10 days when the effect of the added amendment expires. The experimental soil will be collected from the pasture fields at North Wyke, United Kingdom (50.76°N, -3.90°W), where soil was sources for several previous experiments. After homogenizing by sieving using a stainless-steel sieve (2mm), soil cores will be prepared to fit the corers at near field bulk density value. The cores will be placed in the incubation system to be flushed with a He/O2 mixture to remove native N2. They will be later amended with ammonium nitrate (with total N concentration in soil column equivalent to 54 kg N/ha, (National Statistics, 2020)) with (a) no additional trace element (b) adding one of the targeted trace elements in its free ion form (metal salts) (c) adding a NI as comparison. The soil moisture will be maintained at 50% water-filled pore space (Bateman and Baggs, 2005) to simulate the aerobic condition. The concentrations of the added metal salts (CdSO4, CuSO4, ZnSO4, NiSO4) will be refer to standard concentrations of the heavy metal limits in compost.

In year 2, the UK researchers will visitTaiwan to discuss the data, visit the current on-site and laboratory GHG measurement equipment and techniques in Taiwan (National Chung-Hsing University) and visit the livestock and pasture experimental sites in the Taiwan Livestock Research Institute, Hengchun, Pingtung, Taiwan. By the end of year 2 we aim to co-writing and publishing a scientific report, providing data for future estimation of the potential impact of waste management (in both Taiwan and the UK) on GHG missions