Reef Catchments Science Partnership, School of the Environment, University of Queensland, Brisbane, QLD 4108, Australia; Australian Rivers Institute, Griffith University, Brisbane, QLD 4111, Australia.
Reef Catchments Science Partnership, School of the Environment, University of Queensland, Brisbane, QLD 4108, Australia; Water Quality and Investigations, Department of Environment, Science and Innovation, Brisbane, Queensland, Australia.
Sci Total Environ. 2024 Nov 15;951:175786. doi: 10.1016/j.scitotenv.2024.175786. Epub 2024 Aug 26.
Environmental offsetting has been developed as a mechanism to facilitate the benefits from economic development while avoiding or minimizing environmental harm. This is achieved by compensating for environmental impacts at one location by generating equivalent environmental improvements elsewhere. However, experience with biodiversity and carbon offsetting indicates it can be difficult to ensure the integrity of offsets. Under recent legislation in the catchments of the Great Barrier Reef (GBR), Australia, it is mandatory for water quality emissions from new or expanded point source development to be offset by reducing pollution elsewhere, frequently through reducing non-point source pollution (NPSP). Therefore, informed by experience with biodiversity and carbon offsetting, we summarised sources of uncertainty in NPSP reduction that would influence water quality offset integrity; estimated the maximum potential demand for water quality offsets from sewage treatment plants, the largest point source emitter of total nitrogen (TN) in the GBR catchments, between 2018 and 2050; and discussed the implications of both on the ability of offsetting to counterbalance the impact of economic development in catchments where nitrogen loads have a large influence on the health of important GBR ecosystems. The catchments surrounding the population centres of Cairns and Mackay had both a potentially high future demand for nitrogen water quality offsets and nitrogen loads with a strong influence on the health of the GBR. Consequently, any low integrity water quality offsets in these catchments could jeopardise progress toward the water quality improvements needed to ensure the continued health of the GBR. Water quality offsetting has numerous strengths as a policy instrument however substantial uncertainties remain related to environmental outcomes. Until further research can reduce these uncertainties, water quality offsets that are implemented near increased point source emissions and have a high certainty of effectiveness may provide a balance between scientific rigour and policy workability.
环境补偿已被开发为一种机制，以促进经济发展的利益，同时避免或最小化环境危害。这是通过在一个地点补偿环境影响，同时在其他地方产生等效的环境改善来实现的。然而，生物多样性和碳补偿的经验表明，确保补偿的完整性可能具有挑战性。在澳大利亚大堡礁（GBR）集水区最近的立法下，新的或扩大的点源开发的水质排放必须通过减少其他地方的污染来补偿，通常是通过减少非点源污染（NPSP）。因此，根据生物多样性和碳补偿的经验，我们总结了影响水质补偿完整性的 NPSP 减少的不确定性来源；估计了从污水处理厂获得最大潜在的水质补偿需求，污水处理厂是 GBR 集水区中总氮（TN）的最大点源排放者，在 2018 年至 2050 年之间；并讨论了这两者对补偿能力的影响，即在氮负荷对大堡礁重要生态系统健康有较大影响的集水区中，经济发展的影响。凯恩斯和麦凯这两个人口中心周围的集水区都有潜在的高未来氮水质补偿需求和氮负荷，对大堡礁的健康有很大影响。因此，这些集水区中任何低完整性的水质补偿都可能危及为确保大堡礁健康持续所需的水质改善的进展。水质补偿作为一种政策工具具有许多优势，然而，与环境结果相关的不确定性仍然很大。在进一步的研究能够降低这些不确定性之前，在增加点源排放附近实施且具有高度有效性确定性的水质补偿可能在科学严谨性和政策可行性之间提供平衡。
