Impact of climate and anthropogenic stressors on groundwater inputs to inland coastal waters

内陆沿海水域对加拿大具有巨大的娱乐、经济和生态价值，但由于水质恶化，这一价值正在迅速下降。例如，据估计，将五大湖从目前受损的状态恢复过来，仅娱乐和旅游一项就将带来65亿至118亿美元的直接经济效益。除非实施有效的政策和计划，否则水质将继续恶化，因为内陆沿海地区面临越来越多的人类影响，以及气候变化-这可能导致不可逆转的生态和经济后果。为了恢复和保护内陆沿海水质，政策制定者和监管机构迫切要求就包括地下水排放在内的各种污染源的贡献提供指导。虽然研究表明，地下水可能是向沿海水域输送污染物的主要途径，但人们对其对水质恶化的贡献知之甚少。例如，地下水占五大湖流域进入地表水的水量的50%，但地下水投入仍然是长期水质预测和制定有效政策和计划的最大不确定性之一。管理来自地下水的污染物输入极具挑战性，因为在实施土地利用变化或最佳管理做法和观察到沿海水质变化之间往往有很大的时间延迟(长达数十年)。这是因为污染物在含水层中的移动速度通常非常慢。由于这种延迟，旨在管理地下水污染物输入的政策和计划如果不基于强有力的科学理解和长期预测而积极实施，就太晚了，无法防止水质危机(例如，伊利湖和温尼伯湖频繁出现大规模藻类水华，以及随后沿海生态系统的关闭)。

Inland coastal waters are of enormous recreational, economic and ecological value to Canada, yet due to degrading water quality this value is being rapidly diminished. For example, it is estimated that restoring the Great Lakes from their current impaired state will lead to direct economic benefits of USD $6.5-11.8 billion from recreation and tourism alone. Unless effective policy and programs are implemented, water quality will continue to degrade as inland coastal areas are exposed to increasing human impacts, and the climate changes – this could lead to irreversible ecological and economic consequences. To restore and protect inland coastal water quality, policy makers and regulators are urgently requesting guidance on the contribution of various pollution sources including groundwater discharge. While studies have shown that groundwater can be a major pathway for delivering pollutants to coastal waters, its contribution to degrading water quality is poorly understood. For instance, groundwater represents as much as 50% of the water entering surface waters in the Great Lakes Basin, and yet groundwater inputs remain one of the largest uncertainties for long term water quality predictions and in the development of effective policy and programs. Managing pollutant inputs from groundwater is extremely challenging because there is often a large time delay (up to decades) between when land use changes or best management practices are implemented, and when changes in coastal water quality are observed. This is because pollutants often travel very slowly in aquifers. Because of this delay, policy and programs targeted at managing groundwater pollutant inputs will be too late to prevent water quality crises (e.g., frequent massive algal blooms in Lake Erie and Lake Winnipeg, and subsequent shutdown of coastal ecosystems) if they are not proactively implemented based on strong scientific understanding and long term predictions.