The transmissive critical zone: understanding the karst hydrology-biogeochemical interface for sustainable management

地球表面(土壤和植物)和下面的岩石相互作用，雨水通过土壤流入岩石。土壤赋予水一种化学特征，有时会导致水质下降。这种信号是通过岩石中的运动来调节的，然后当地下水重新出现时，通过细菌活动在溪流和河流中进行调节。因此，地球外层的功能对人类的关键需求至关重要--我们有多少可用水及其质量；土壤因水排出而发挥的作用有多好。因此，对这些层如何相互作用的研究被称为“临界区”研究。我们的研究项目将这种“临界区”研究应用于当地居民面临重大环境挑战的环境--中国农村，这是一个快速增长的地区，许多人生活在贫困线以下。这是英国和中国的联合研究项目。我们将重点关注其中的两个挑战：水的可获得性和质量，以及临界区的水运动如何影响地表植被。对这项研究至关重要的是，下面的岩石大多是石灰岩。石灰石很容易溶解，水可以非常快地在地下流动。因此，土壤可能会更快地干燥(因为地下可以自由排水)，地表和地下的储水量也很有限。石灰岩在世界范围内分布广泛，尤其是中国，因此对这里的研究与世界各地的许多人都有关系。它为他们提供水和食物--这一现象被称为提供服务的生态系统。在斜坡不太陡峭的地方，土地表面是大量耕种的。这反过来又带来了问题，例如，水质很差，硝酸盐(一种在化肥中发现的化学物质)含量高得危险；清除植被暴露了岩石，限制了土地的利用。对当地居民来说，更大的挑战是气候正在变化。雨水输送到集水区的方式一直在变化，以至于水不像以前那样可用。土地利用变化对形成这些生态系统服务很重要，但气候变化可能是居民将面临的最重大威胁之一；科学必须帮助他们为应对这些威胁做好准备，并取得成功。我们的研究将生成临界区目前如何发挥作用的模型，然后我们可以从这些模型中调查临界区的功能如何适应不同的环境驱动因素。在这个项目之外，有大量的科学模型已经确定了气候可能会如何变化。因此，我们可以利用这一点来运行我们将开发的临界区功能的模型，不仅在土地利用变化下，而且在未来的气候情景下。所有这项研究将有助于理解这个集水临界区对未来威胁最敏感的地方。然而，重要的是，需要使用这种理解的人能够理解它。因此，我们将开展的最后一项活动是“知识交流”--与需要这项研究的人分享我们的研究成果，并根据他们所拥有的知识调整我们的理解。因此，我们最后但并非最不重要的活动是与生活在景观中的人和管理景观的人合作，帮助他们确定他们的活动如何才能造成最小的伤害，并为他们的生态系统服务提供最大程度的保护。因此，我们与中国同事的合作至关重要。我们为项目带来了新的技能(例如，新的水文建模技能)，他们将从中受益。此外，由于整个英国的流域管理做法将有很大不同-中国，他们将学习其他良好的做法，以帮助改善他们的环境和使居民摆脱贫困

The Earth's surface (soil and plants), and the rock underneath interact, linked by rainwater flowing through the soil into the rock. The soil imparts a chemical signature to the water, sometimes bad leading to loss of water quality. This signature is mediated by movement through the rock, and then, when underground water re-emerges, in streams and rivers by bacterial activity. As such, how this outer layer of planet Earth functions is 'critical' to key needs of mankind - how much water we have available and its quality; how well the soil functions as a result of water draining through it. The study of how these layers interact is thus called 'critical zone' research.Our research programme uses such 'critical zone' research in an environment where the local residents face significant environmental challenges - in rural China, an area of rapid growth and where many live under the poverty line. This is a joint research programme between UK and China. We will focus on two of these challenges: water availability and quality, and how movement of water in the critical zone influences surface vegetation. Crucial to this research is that the underlying rock is mostly limestone. Limestone is easily dissolved and water can move very quickly through the subsurface. So soils may dry sooner (as the subsurface beneath is freely-draining) and there is limited water storage on the surface and underground. Limestone is widely distributed world-wide, but particularly in China and so study here is relevant to many world-wide.The people living in the catchment generally live-off-the-land. It provides their water and food - a phenomenon known as the ecosystem providing services. Where the slopes are not too steep, the land surface is heavily-cultivated. This in turn presents problems e.g., the water quality is poor, with dangerously high-level of nitrate (a chemical that is found in fertiliser); clearance of vegetation exposes rock, limiting how land may be used. Further challenging to local residents is that the climate is changing. How rain is delivered to the catchment has been changing such that water is not available as before. Thus there have also been water shortages, and this led to crop failure and so loss of food.Land use change is important in shaping these ecosystem services, but climate change may be one of the most significant threats the residents will face; science must help them prepare for facing these threats with successful outcomes. Our research will generate models of how the critical zone functions currently and from these we can then investigate how the critical zone functioning may adapt to different environmental drivers. There is a large body of scientific modelling outside this project that has identified how the climate may change. Thus, we can draw on this to run the models we will develop of the critical zone functioning, not only under land use change, but also under future climate scenarios.All this research will contribute to understanding where this catchment critical zone is most sensitive to future threats. However, it is important that this understanding reaches the people who need to use it. So the final activity we will undertake comes under the umbrella of 'knowledge exchange' - sharing our findings with those who need this research, and adjusting our understanding based on knowledge they too have. Thus our last, but not least, activity is working with those who live in the landscape and those who manage it, to help them identify how their activities can cause the least harm and offer the most protection to their ecosystem services. Our collaboration with Chinese colleagues is therefore crucial. We bring new skills to the project (e.g. new hydrological modelling skills) that they will benefit from. Additionally as catchment management practices will be quite different across UK-China, they will learn about other good practice to help improve their environment and remove residents from poverty