Plastics in karst groundwater systems

该项目主要研究塑料污染在岩溶地下水系统中的去向和影响。塑料污染无处不在，是一个严重的全球问题，甚至污染到偏远地区，如深层地下水库。然而，几乎没有关于塑料在地下水系统中的存在和去向的研究，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藏库位于岩溶地带，通常以洞穴网络、沉坑和污染物在地下的快速传输为特征。约14%的地球表面被喀斯特地形覆盖，25%的全球人口完全或部分依赖喀斯特系统的饮用水。白垩岩是一个岩溶系统的例子，在欧洲，我们严重依赖这个系统来饮用饮用水--然而，英国喀斯特地区还没有发表关于微塑料污染的研究。该项目将评估一系列欧洲岩溶系统(从脆弱性较低的岩溶系统到最脆弱的岩溶系统)的微米(1-1000微米)和纳米塑料(1微米)污染。通过采样泉水和其他流出点，该项目将阐明岩溶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、它们的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，以收集各种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MPS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)是否控制在地下水中发现的MPS的丰度和类型？(3)环境背景(如土地利用或MPS的特定来源)如何影响岩溶中的MPS？岩溶地下水系统中MPS的主要来源是什么？(4)岩溶系统的性质是否控制MPS的物理特征、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，这些协议可以成为未来监管监测的灯塔--这还处于地下水污染的早期阶段。这也将是第一次尝试和评估地下水(即1-20微米范围)中的近纳米塑料(NNP)，这是一个需要了解的关键问题，因为MP被降解到较小的尺寸，增强了较小颗粒的运移和潜在的生物利用度，而且许多含水层能够通过基质/孔隙流动过滤掉较大的塑料垃圾。为了应对这些挑战，该项目将应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，这目前是阻碍对不同研究的数据进行适当比较的障碍。将使用和比较一系列分析方法来表征地下水中的MP和NNP污染。傅立叶变换红外线(FTIR)和激光直接红外线(LDIR)技术将用于表征微塑性数量、聚合物和尺寸分布。为了探索检测近纳米塑料的可行性，将流式细胞仪和纳米跟踪分析(NTA)与塑料的选择性染色相结合，可能是进入这一具有挑战性的分析领域的有希望的第一步，该项目将探索这一领域。

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.