Assessing human impacts on the Red River system, Vietnam, to enable sustainable management

越南的红河位于世界第13大人口大国的一个快速发展地区。该地区有2000万居民，包括一个主要的稻米种植区、特大城市河内和一系列产业，这些产业都在近几十年里得到了扩张。向北部湾排放水的河流的红河三角洲(RRD)三角洲地区提供关键的生态系统服务，包括保留和去除地下水(饮用水)的营养物质和污染物，保护海洋资源，碳处理，洪水保护，通过一系列农业堤坝和泥沙输送管理严密的洪水保护，控制脆弱沿海地区的侵蚀和沉积。然而，水电大坝的安装、农业化肥使用量的增加、城市废水的增加以及一系列有毒污染物的使用威胁到这些生态系统服务以及该地区居民的健康和福祉。三角洲地区是一个复杂和高度修改的水文网络，很难使用在温带地区更直接的河流流域上开发的校准来建模。因此，这项建议旨在通过应用更适合于复杂系统的另一种方法--物流分析--来提高建模能力。该项目的重点是填补在了解RRD地区水文、营养、碳和污染物之间关系方面的知识空白，以改进模型校准，利用稳定同位素和有机地球化学技术的组合，这些技术在这一领域很少应用。该项目的第一部分将使用稳定的氧和氢同位素来量化降水-地表水-地下水的相互作用，并估计沿海地区上游咸水入侵的程度。第二个工作包将侧重于了解大坝安装如何改变下游河流的营养物质和碳的固存和清除，以便更好地为水库管理提供信息。第三个工作方案旨在通过使用稳定同位素技术更好地限制三角洲地区的养分循环(包括碳、氮、磷和硅)。这项工作将得到一个博士生项目的支持，该项目使用了最近开发的双氮同位素分析技术(分析硝酸盐中的氮和氧原子)和硅-30的应用，硅-30可以提供关于二氧化硅循环的重要信息，这在稻田地区被证明是重要的。最后的一揽子工作将侧重于提供对该区域有毒污染物的最新评估，因为最近没有进行系统监测。将分析广泛的持久性有机污染物和重金属，重点是该地区的一些问题化学品，如杀虫剂滴滴涕及其衍生物，它在1995年被禁止，但在那之后增加，表明非法使用，以及在越南战争中广泛使用的二恶英除草剂落叶剂“橙剂”。我们将首次测量河流沉积物和悬浮颗粒中的药物残留，以评估这些化合物在整个三角洲的分布和趋势。该项目还将在越南安装“Microtox”分析设施，允许对有毒污染物进行快速筛查，以便为环境监测机构试点使用这项技术。该项目的成果将提高营养物和水文学的MFA模型、碳预算、新出现的污染物(药品)的第一次测量、遗留和持久性污染物的最新测量以及新建立的有毒污染物筛选的国家能力。

The Red River in Vietnam is located in a rapidly developing area of the world's 13th most populous country. The area, which supports 20 million inhabitants, includes a major rice-growing region, the mega-city of Hanoi and a range of industries each of which have expanded in recent decades. The Red River Delta (RRD) delta area of the river which discharges water into the Bay of Tonkin provides crucial ecosystem services including the retention and removal of nutrients and pollutants for groundwater (drinking water) and marine resource protection, carbon processing, flood protection which is heavily managed through a series of agricultural dikes and sediment transport which governs erosion and deposition at the vulnerable coastal zones. However, hydropower dam installation, increasing agricultural fertilizer use, increases in urban wastewater and use of a range of toxic contaminants threaten these ecosystem services and the health and wellbeing of the people who live in this region. The delta region is a complex and highly modified hydrological network which is difficult to model using calibrations developed on more straightforward river basins from temperate regions. Therefore, this proposal aims to improve modelling capabilities through the application of the alternative approach of Materials Flow Analysis which is more suited to complex systems. The project focuses on filling in knowledge gaps in understanding on relationships between hydrology, nutrients, carbon and pollutants in the RRD region for improved model calibration using a combination of stable isotope and organic geochemistry techniques which have rarely been applied in this area. The first part of the project will use stable isotopes of oxygen and hydrogen to quantify precipitation-surface water- groundwater interactions and estimate the extent of saline intrusions upstream from the coastal zone. The second work package will focus on understanding how dam installation alters nutrient and carbon sequestration and removal from the downstream river in order to better inform reservoir management. The third work package will aim to better constrain nutrient cycling in the delta (including carbon, nitrogen, phosphorus and silicon) through the use of stable isotope techniques. The work will be supported by a PhD student project using more recently developed techniques of dual nitrogen isotope analysis (analysing N and O atoms in nitrates) and the application of Silicon-30 which can provide important information on silica cycling, shown to be important in rice paddy areas. The final work package will focus on providing an updated assessment of toxic contaminants from this region because systematic monitoring has not been conducted recently. A broad suite of persistent organic pollutants and heavy metals will be analysed, with a focus on some problem chemicals in this region such as the pesticide DDT and its derivatives which was banned in 1995 but has increased after that time indicating illegal usage, and the dioxin herbicide defoliant "Agent Orange" which was used extensively in the Vietnam War. For the first time we will measure pharmaceutical residues in river sediments and suspended particulates in order to evaluate the distribution and trends of these compounds across the delta. The project will also install facilities for "Microtox" analysis in Vietnam, allowing rapid screening for toxic pollutants in order to pilot the use of this technique for environmental monitoring agencies. The outputs from this project will deliver improved capabilities for MFA modelling of nutrients and hydrology, the carbon budget, the first measures of emerging pollutants (pharmaceuticals), updated measures of legacy and persistent contaminants and a newly establish national capability for toxic pollutant screening.