Plastics in karst groundwater systems

该项目的重点是岩溶地下水系统中塑料污染的命运和影响。塑料污染是普遍存在的，是一个严重的全球性问题，甚至污染了偏远地区，如深层地下水储存。然而，几乎没有关于塑料在地下水系统中的发生和命运的研究，而地下水系统是世界各地的主要饮用水供应。一些最重要的地下水储存是在岩溶地区发现的，其特点往往是存在洞穴网络，下沉孔和污染物的快速地下运输。地球上约14%的陆地表面被喀斯特地形覆盖，全球25%的人口完全或部分依赖喀斯特系统的饮用水。白垩是岩溶系统的一个例子，在欧洲，我们严重依赖于饮用水-但没有发表关于英国岩溶微塑料污染的研究。该项目将评估欧洲一系列岩溶系统（从脆弱性较低的岩溶系统到最脆弱的岩溶系统）的微（1-1000微米）和纳米塑料（<1微米）污染。通过对泉水和其他流出点进行采样，该项目将阐明岩溶作用程度与微塑料污染性质之间的关系，包括塑料的数量和类型、大小范围和形状特征。该项目将包括在英国和克罗地亚/斯洛文尼亚进行广泛的实地考察，以收集不同类型岩溶的代表性样本。研究问题包括：（1）岩溶系统中的MP是否对依赖饮用水和地下水的生态系统构成威胁？(2)岩溶系统的性质（即岩溶作用的程度和类型）是否控制地下水中MP的丰度和类型？(3)岩溶地下水系统中的微污染物如何受到环境背景（如土地利用或微污染物的特定来源）的影响？(4)岩溶系统的性质是否控制了MP的物理特性、类型、大小和形状？该项目的一个重要方面将是开发和使用新的采样和分析协议，这可以成为未来监管监测的灯塔-这是在地下水污染的早期阶段。这也将是第一项尝试和评估地下水中近纳米塑料（NNP）（即1-20微米范围）的研究，这是一个需要了解的关键主题，因为MP降解为较小的尺寸，增强运输和较小颗粒的潜在生物利用度，以及许多含水层能够通过基质/孔隙流动过滤出较大的塑料垃圾。为了应对这些挑战，该项目将采用经过验证的分析方法来分离和检测地下水样本中的微塑料，这是目前阻碍对不同研究数据进行适当比较的障碍。将使用一系列分析方法，并与地下水中的CNOMP和NNP污染进行比较。傅立叶变换红外光谱（FTIR）和激光直接红外光谱（LIGHT-RED）技术将用于分析微塑料数量、聚合物和粒度分布。为了探索检测近纳米塑料的可行性，流式细胞术和纳米跟踪分析（NTA）结合塑料的选择性染色可能是进入这一具有挑战性的分析空间的有希望的第一步，将在项目中进行探索。

This project is focussed on the fate and impact of plastic pollution in karst groundwater systems. Plastic contamination is pervasive and a serious global issue, contaminating even remote locations such as deep underground water stores. However, there has been almost no research undertaken on the occurrence and fate of plastics in groundwater systems which are key drinking water supplies around the world. Some of the most important groundwater stores are found in karstic terrains, often characterised by the presence of cave networks, sink holes and rapid subsurface transport of pollutants. Around 14% of the earths land surface is covered by karst terrains and 25% of the global population completely or partially dependent on drinking water from karst systems. Chalk is an example of a karst system which in Europe we rely on heavily for drinking water - yet there is no published research on microplastic pollution in UK karst. This project will assess micro (1-1000 micron) and nano-plastic (<1 micron) contamination across a range of European karst systems (from karstfied systems with lower vulnerability to the most highly vulnerable karst). Through sampling springs and other outflow points the project will elucidate relationships between the degree of karstification and the nature of microplastic pollution, including the amount and type of plastics, their size ranges and shape characteristics. The project will include extensive fieldwork across the UK, and in Croatia/Slovenia to collect representative samples across the full spectrum of different types of karst. Research questions include: (1)Do MPs in karst systems pose a threat to drinking water and groundwater dependant ecosystems? (2) Does the nature of the karst system (i.e. degree and type of karstification) control the abundance and type of MPs found in groundwater? (3) How are MPs in karst affected by the environmental setting (e.g. landuse or specific sources of MPs) and what are the key sources of MPs in karst groundwater systems? (4) Does the nature of the karst system control the physical characteristics of MPs, type, size and shape?A significant aspect of this project will be the development and use of novel sampling and analytical protocols that can be a beacon for future regulatory monitoring - which is at an early stage for groundwater pollution. This will also be the first study to try and assess near nano-plastics (NNP) in groundwater (i.e. 1-20 microns range), a critical topic to understand, given the degradation of MP to smaller sizes, enhanced transport and potential bioavailability of smaller particles, and the fact that many aquifers are able to filter out larger plastic litter via matrix/pore flow. To address these challenges, the project will apply validated analytical methods to isolate and detect microplastics in groundwater samples, which is currently a barrier precluding proper comparison of data from different studies. A range of analytical methods will be used and compared to characterise MP and NNP contamination in groundwater. Fourier Transform Infra-Red (FTIR), and Laser Direct Infra-Red (LDIR) techniques will be used to characterise microplastic numbers, polymers and size distribution. To explore the feasibility of detection of near nanoplastics, a combination of flow cytometry and nano-tracking analysis (NTA) coupled with selective staining of plastics could be a promising first step into this challenging analytical space that will be explored within the project.