Quantifying annual cycles of macronutrient fluxes and net effect of transformations in an estuary: their responses to stochastic storm-driven events

河口不仅仅是代表河流和海洋之间的过渡地带的泥和沼泽区域。它们作为休闲和商业活动的场所，如钓鱼和划船，在我们的经济中起着至关重要的作用。此外，它们还是许多具有重要经济价值的鱼类的重要繁殖地，这些鱼类后来会迁徙到公海。由于世界上大约40%的人口居住在距离海岸100公里的范围内，河口也是最容易受到人类活动影响的地区之一。它们不仅受到河口内发生的活动的影响，而且还标志着河流从内陆大片地区聚集的污染物可以积聚的点。河口的主要污染问题之一是河流携带的磷酸盐和硝酸盐浓度过高。这些污染物的来源多种多样，如肥沃农田的径流和污水处理厂的排放（意外或故意）。不管它们的来源是什么，它们都可能导致严重的问题，比如刺激藻类的过度生长，这会耗尽水中的氧气，导致广泛的鱼类死亡，或者导致有毒藻类的生长（赤潮），导致贝类渔业关闭。虽然人们认识到这个问题已经有一段时间了，环境署和水务公司等机构的监测活动在控制污染方面发挥了重要作用，但我们的认识仍然存在重大差距。特别是，很明显，很大一部分硝酸盐和磷酸盐的通量是由突然的风暴事件输送到河口的，但大多数监测都是在固定时间进行的，这些时间间隔太远，无法捕捉到这些事件。这是我们知识上的一个重大空白，随着气候变化可能导致风暴的强度和频率增加，这一空白将变得更加重要。此外，河流中的磷酸盐和硝酸盐负荷可以采取多种形式——溶解的和颗粒的，有机的和无机的——相对而言，人们对这些不同形式的浓度在整个季节和风暴期间的变化知之甚少。只有我们能够完全了解这些过程，我们才能够采取必要的步骤来确定和控制流入河口的硝酸盐和磷酸盐的污染源。我们的研究旨在通过对一年中从河流和海洋进入克赖斯特彻奇港河口（多塞特）的多种形式的磷酸盐和硝酸盐进行详细监测，来解决我们知识上的这一差距。我们将使用最先进的技术（其中大部分是我们自己开发的），这将使我们能够每隔30分钟监测一次关键参数。因此，我们将能够捕捉到以前的研究和常规监测实践无法捕捉到的突然和短暂风暴的影响。然后，我们将利用我们的研究结果来研究这些突然的风暴事件如何影响河口内磷酸盐和硝酸盐的分布。特别是，我们将研究当沉积物在河口被风暴搅动时会发生什么——它们是将磷酸盐和硝酸盐移走还是添加到系统中？我们还将研究这些突发风暴对河口生物活动的影响。同样，它们是增加还是减少藻类的生长，风暴发生在夏季还是冬季有什么区别？我们研究的各种线索将汇集成一个强大的统计模型，使我们能够更好地了解磷酸盐和硝酸盐从河流，通过河口进入沿海海域的转移，以及风暴在这一过程中所起的作用。然后，我们的研究结果将使政策制定者能够就如何减少硝酸盐和磷酸盐对河口的污染做出更明智的决定。

Estuaries are more than simply areas of mud and marsh that represent the transition zone between rivers and the ocean. They play a vital role in our economy as sites of leisure and commercial activities, such as fishing and boating. In addition, they are important nursery grounds for many species of economically important fish that later migrate to the open sea. As approximately 40% of the world's population live within 100 km of the coast, estuaries are also some of the most vulnerable sites for impact from man's activities. Not only can they suffer from activities occurring within the estuary itself, but they also mark the point where pollutants gathered by rivers from large areas of the interior can accumulate.One of the major pollution concerns in estuaries arises from the excess river borne concentrations of phosphate and nitrate. These can be derived from a variety of sources, such as run off from fertilised fields and discharge (accidental or purposeful) from sewage treatment plants. Regardless of their source, they can cause severe problems, such as stimulating the growth of excess algal growth that can deplete the water in oxygen and causing widespread fish kills, or causing the growth of poisonous algal species (red tides) that cause shell fish fisheries to be closed. Although this problem has been recognised for some time, and monitoring activities by bodies such as the Environment Agency and water companies play an important role in keeping pollution in check, there are still major gaps in our knowledge. In particular, it is apparent that a large proportion of the flux of nitrate and phosphate are delivered to estuaries by sudden storm events, but most monitoring takes place at fixed times that are spaced too far apart to capture these events. This is a major gap in our knowledge that will become more important as the intensity and frequency of storms are likely to increase due to climate change. Additionally, the phosphate and nitrate load of rivers can take many forms - dissolved and particulate, organic and inorganic - and relatively little is known about the concentrations of these different forms varies throughout the seasons and during storm events. Only if we are able to fully understand these processes will we be able to take the necessary steps to identify and control polluting sources of nitrate and phosphate to estuaries.Our research seeks to address this gap in our knowledge by carrying out detailed monitoring of the many forms of phosphate and nitrate that enter Christchurch Harbour estuary (Dorset) from both the rivers and the sea over the course of a year. We will be using state-of-the-art technology (much of it developed by ourselves) that will allow us to monitor they key parameters at intervals of every 30 minutes. Hence, we will be able to capture the effects of sudden and short-lived storms that have eluded previous studies and routine monitoring practices. We will then use the results of our study to examine how these sudden storm events affect the distribution of phosphate and nitrate within the estuary. In particular, we will examine what happens when sediments are stirred up in the estuary by storms - do they remove or add phosphate and nitrate to the system? We will also examine the effects of these sudden storms on the biological activity in the estuary. Again, do they increase or decrease the growth of algae, and what difference is there if the storm happens in the summer or the winter?The various threads of our study will be drawn together into a powerful statistical model that will allow us to better understand the transfer of phosphate and nitrate from rivers, through estuaries and into the coastal seas, and the role that storms play in this process. Our results will then allow policy makers to make more informed decisions about how we can seek to reduce pollution of estuaries by nitrate and phosphate.