Mining of gravel and sand for construction purposes is big business and gravel pit lakes have become increasingly common all over the world. In Denmark, hundreds of gravel pit lakes have been created during the past decades. We investigated the chemical and biological status of 33–52 gravel pit lakes and compared the results with data from similar-sized natural Danish lakes. The area of the lakes ranged from 0.2 to 13 ha and their age from 0.5 to 26 years. Generally, the gravel pit lakes were clear with low nutrient concentrations, the median concentrations of total phosphorus and total nitrogen being 0.023 mg/l and 0.30 mg/l compared with 0.115 mg/l and 1.29 mg/l, respectively, in natural lakes. Correspondingly, median chlorophyll a was 5 μg/l in the gravel pit lakes and 36 μg/l in the natural lakes. Submerged macrophytes were found in all gravel pit lakes, with particularly high cover in the shallow ones. Most gravel pit lakes were deeper than the natural lakes, which may restrict the area potentially to be covered by submerged macrophytes, with implications also for the biological quality of the lakes. Fish were found in most of the gravel pit lakes, roach (Rutilus rutilus), perch (Perca fluviatilis) and rudd (Scardinius erythrophalmus) being the most frequently observed species. Fish stocking was common and included also non-native species such as carp (Cyprinus carpio) and rainbow trout (Oncorchynchus mykiss). Compared with the natural lakes, fish species richness and catch per gillnet were overall lower in the gravel pit lakes. Groundwater-fed gravel pit lakes add importantly to the number of high-quality lakes in Denmark and with an optimised design and by avoiding negative side effects, they can be positive for both nature and society.

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丹麦的砾石坑湖：化学和生物状态

用于建筑目的的砾石和沙子的开采是一项艰巨的任务，而砾石坑湖在世界各地已变得越来越普遍。在过去的几十年中，在丹麦已经建立了数百个砾石坑湖。我们调查了33-52个砾石坑湖的化学和生物状况，并将结果与​​相似大小的天然丹麦湖的数据进行了比较。湖泊面积从0.2到13 公顷不等，年龄从0.5到26 岁不等。通常，砾石坑湖清澈，养分浓度低，总磷和总氮的中位数浓度分别为0.023  mg / l和0.30  mg / l ，而天然湖泊中分别为0.115  mg / l和1.29  mg / l。相应地，叶绿素a的中位数为5 在砾石坑湖中 微克/升，在天然湖中微克/升为36微克/升。在所有砾石坑湖中都发现了淹没的大型植物，其中浅层湖的盖度特别高。大多数砾石坑湖都比天然湖深，这可能限制了可能被淹没的大型植物覆盖的区域，这也对湖泊的生物质量产生了影响。在大多数砾石坑湖中都发现了鱼类，其中最常见的物种是蟑螂（Rutilus rut​​ilus），鲈鱼（Perca fluviatilis）和陆生（Scardinius erythrophalmus）。鱼类放养很普遍，还包括非本地物种，例如鲤鱼（鲤）和虹鳟鱼（Oncorchynchus mykiss）。）。与天然湖泊相比，砾石坑湖泊的鱼类物种丰富度和每刺网捕获量总体较低。地下水喂养的砾石坑湖对丹麦高质量湖泊的数量起到了重要作用，并且经过优化设计并避免了不利的副作用，它们对自然和社会都具有积极意义。