Phytostabilization and Retirement of Mercury from Wet Ecosystems

描述（由申请人提供）：由于环境汞对全球公共卫生构成重大挑战，降低空气、土壤和水中的汞含量是国际优先事项。大气中汞（Hg）的广泛分布使得目前处理汞污染的方法，如挖掘和更换土壤，过于昂贵而不实用，因为通常需要大规模的修复活动。第一阶段SBIR提案旨在开发一种创新的、低成本的方法，利用最近发现的一种超富集汞的植物物种从潮湿的生态系统中提取汞。积累的汞很容易与植物中还原的硫结合，形成HgS，这是一种极其难降解（高度稳定）的化学形式，有效地将汞从其全球循环中退役。这个过程利用硫(S)，这是一种营养必需的微量元素，植物从土壤中自然积累，使积累的汞失去生物活性。由于积累的汞以一种不溶性、非生物可利用的形式被截留，因此储存在工厂中的汞可以留在现场，从而消除了收集和处置的需要，减轻了危险废物填埋场的负担。在第一阶段展示了植物汞的高积累，植物将环境汞转化为汞，以及昆虫摄食研究中评估的生物利用度降低之后，第二阶段的任务将探索增加汞吸收的方法，评估植物从根际到植物的硫物种形成，评估两个实地示范点的汞超积累器的植物提取汞的性能。并在每个地点进行就地生态风险研究，以确认植物将其积累的汞储存为温室气体对生态受体的风险较低。该项目的最终结果将是为一种低成本的太阳能方法奠定基础，这种方法可以去除和稳定大面积土壤和大量水中的汞。

DESCRIPTION (provided by applicant): Because environmental mercury poses significant challenges to global public health, reducing mercury levels in air, soil, and water is an international priority. Widespread distribution of mercury (Hg) by the atmosphere makes current methods of addressing Hg contamination, such as excavation and replacement of soil, too expensive to be practical given the typically large scale of remediation activity required. This Phase I SBIR proposal seeks to develop an innovative, low-cost method of extracting Hg from wet ecosystems using a recently-identified Hg-hyperaccumulating plant species. The accumulated mercury readily binds with reduced sulfur in the plant to form HgS, an extremely refractory (highly stable) chemical form that effectively retires the mercury from its global cycle. This process utilizes sulfur (S), a nutritionally essential trace element that is naturally accumulated by plants from soils to render the accumulated mercury biologically inactive. Because the accumulated mercury is trapped in an insoluble, non-bioavailable form, the mercury stored in the plant may then be allowed to remain on-site, thereby eliminating the need for harvest and disposal, reducing the burden on hazardous waste landfills. Following the Phase I demonstration of high plant accumulation of mercury, in planta conversion of environmental mercury to HgS, and decreased bioavailability as assessed in an insect feeding study, Phase II tasks will explore methods of increasing Hg uptake, assess speciation of sulfur from the rhizosphere through the plant, assess the mercury phytoextraction performance of the Hg- hyperaccumulator at two field demonstration sites, and conduct in situ ecological risk studies at each of these sites to confirm the lower risk to ecological receptors of plants storing its accumulated mercury as HgS. The end result of the project will be to establish the foundation for a low-cost, solar powered method of removing and stabilizing mercury over large areas of soil and large volumes of water. PUBLIC HEALTH RELEVANCE: This NIH Phase I SBIR proposal seeks to retire mercury from the environment by inducing the formation of insoluble mercury sulfide (HgS) in a recently identified Hg-accumulating plant species. If successful, large areas of soil contaminated with mercury can be remediated.