Abstract
Natural wetlands constitute a major source of methane emission to the atmosphere, accounting for approximately 32 ± 9.4% of the total methane emission. Estimation of methane emission from wetlands at both local and national scale using process-based models would improve our understanding of their contribution to global methane emission. The aim of the study is to estimate the amount of methane emission from the coastal wetlands in north-eastern New South Wales (NSW), Australia, using Landsat ETM+ and to estimate emission with a temperature increase. Supervised wetland classification was performed using the Maximum Likelihood Standard algorithm. The temperature dependent factor was obtained through land surface temperature (LST) estimation algorithms. Measurements of methane fluxes from the wetlands were performed using static chamber techniques and gas chromatography. A process-based methane emission model, which included productivity factor, wetland area, methane flux, precipitation and evaporation ratio, was used to estimate the amount of methane emission from the wetlands. Geographic information system (GIS) provided the framework for analysis. The variability of methane emission from the wetlands was high, with forested wetlands found to produce the highest amount of methane, i.e., 0.0016 ± 0.00009 teragrams (Tg) in the month of June, 2001. This would increase to 0.0022 ± 0.0001 Tg in the month of June with a 1 °C rise in mean annual temperature by the year 2030 in north-eastern NSW, Australia.
Highlights
Wetlands are areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water, the depth of which at low tide does not exceed six meters [1]
This study aims to estimate the amount of methane emission from the coastal wetlands in north-eastern
An estimation of methane emission from wetlands has been carried out using Landsat ETM+
Summary
Wetlands are areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water, the depth of which at low tide does not exceed six meters [1]. Wetlands are important because they are a source of primary productivity; they provide habitats to wildlife; enhance water quality and provide an arena for recreation [2]. There is a need for monitoring wetlands because it allows us to determine whether these ecosystems have changed over time in terms of size, extent and quality. Their reliance on rainfall, surface runoff, groundwater levels and evaporation rates make them, and the ecological services they provide, vulnerable to even small climatic changes. Natural wetlands are a major source of methane (CH4) to the atmosphere, accounting for approximately 32 ± 9.4% to the total methane emission [3,4]. Among the existing greenhouse gases, methane is very important because it contributes approximately 17.7 ± 2.5% to the net greenhouse effect [5,6]
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