Collaborative Research: From Global to Local: Geochemistry of Global Phosphate Ores and Implications for Tracing the Environmental Impacts of Fertilizers Utilization

磷（P）是植物生长和作物生产所必需的主要常量营养素之一，因此其可用性对于可持续农业发展和粮食安全至关重要。每年约有4700万吨磷肥从磷矿中产生并在全世界应用。近几十年来，磷肥的大量使用导致了淡水资源和沿海地区的富营养化和水质恶化。然而，磷酸盐岩和磷肥中的镉、铬和铀等金属含量升高，对土壤和水质构成了不太为人所知但却很大的潜在风险。虽然在一些案例研究中记录了磷肥施用对土壤和水的污染，但尚未对全球磷矿石中金属的存在情况以及检测其对环境影响的能力进行系统评价。这项研究的结果将对全球磷酸盐岩以及美国使用的各种肥料中的金属含量提供重要和关键的信息，对农业地区土壤和水质的长期影响，以及磷肥广泛使用地区农村社区可能面临的风险，该项目将描述全球磷酸盐矿石和相关磷肥的地球化学特征，并评估其中所含金属对环境的影响。该项目的基础是开发新的地球化学方法，以追踪磷酸盐岩的来源和磷肥对环境的影响。这项研究的目的是：（1）生成全球主要磷矿石的系统化学数据集，包括主要和微量元素、稀土元素、锶和铅同位素以及放射性核素（铀、镭）用于评价磷矿石的来源（地质背景、时代、成岩改造），以及地质背景与全球磷矿石中金属赋存状态的关系;（2）评价磷肥和废副产品（石膏）中磷矿石溶解产生的金属的差异结合：（3）评价利用地球化学和同位素变化作为示踪剂来描述磷肥对环境的影响的潜力;（4）通过室内试验和田间试验评价磷肥施用对环境的影响。在北卡罗来纳州的一个农业研究站进行的一项规模调查，在那里，不同比例的磷肥已经施用了几十年。实地研究将包括系统监测土壤、植物、非饱和带、农业径流、实验农业田下的浅层地下水以及广泛农业活动附近的区域地下水。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Phosphorus (P) is one of the primary macronutrients essential for plant growth and crop production, and thus its availability is important for sustainable agriculture development and food security. Approximately 47 million tons of P-fertilizers are annually generated from phosphate rocks and applied worldwide. Intensification of P-fertilizer utilization over the last few decades has caused widespread eutrophication and degradation of the quality of freshwater resources and coastal areas. Yet elevated levels of metals in phosphate rocks and P-fertilizers such as cadmium, chromium, and uranium pose less recognized but significant potential risks to soil and water quality. Although pollution of soils and water from P-fertilizer applications has been documented in a few case studies, no systematic evaluation on the occurrence of metals in global phosphate ores and the ability to detect their impact in the environment have been conducted. The results of this study will have important and critical information on levels of metals in global phosphate rocks as well as in various fertilizers utilized in the U.S., the long-term impact on soil and water quality in agricultural areas, and the possible risks for rural communities in areas of extensive P-fertilizers utilization.The project will characterize the geochemistry of global phosphate ores and associated P-fertilizers, as well assess the environmental impact of the metals they contain. The project is based on developing novel geochemical methods for tracing the origin of the phosphate rocks and the impact of P-fertilizers in the environment. The objectives of the study are to: (1) generate a systematic chemical dataset of major global phosphate ores, including major and trace elements, rare-earth elements, strontium and lead isotopes, and radionuclides (uranium, radium) for evaluating the origin of the phosphate ores (geological setting, age, diagenetic modification), and the relationships between the geological settings and the occurrence of metals in global phosphate ores; (2) evaluate the differential incorporation of metals from dissolution of phosphate rocks in P-fertilizers and waste byproducts (gypsum); (3) evaluate the potential of using the geochemical and isotope variations as tracers to delineate the impact of P-fertilizers in the environment; and (4) evaluate the environmental impact of P-fertilizers application through laboratory experiments and a field-scale investigation in an agricultural research station in North Carolina, where different rates of P-fertilizers have been applied for several decades. The field study will include systematic monitoring of soils, plants, unsaturated zone, agriculture runoff, shallow groundwater underlying experimental agriculture fields, and regional groundwater in vicinity of extensive agricultural activities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.