Assessing the Supply of Mercury from Artisanal and Small-Scale Gold Mining Activities, and its Fluvial Transport and Methylation in Madre De Dios, Peru

EPA Grant Number: FP917827
Title: Assessing the Supply of Mercury from Artisanal and Small-Scale Gold Mining Activities, and its Fluvial Transport and Methylation in Madre De Dios, Peru
Investigators: Martinez, Gerardo
Institution: University of California - Davis
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2015 through August 31, 2018
Project Amount: $88,000
RFA: STAR Graduate Fellowships (2015) RFA Text |  Recipients Lists
Research Category: Academic Fellowships

Objective:

According to the Technical Background Report for the Global Mercury Assessment, artisanal and small-scale gold mining (ASGM) is the largest contributor of mercury (Hg) release into the aquatic environment globally. The proposed project seeks to determine the supply of Hg from ASGM activities, its fluvial transport, and its impact on the indigenous population in the Madre de Dios region in Peru. The research goal will be achieved through three objectives: 1) To quantify the concentrations of Hg species in the sediments, water, and fish in each watershed; 2) To characterize the transport of Hg and its methylation along the watershed; and 3) To assess the impact of ASGM activities in each of the three watersheds by comparing annual Hg concentrations.

Approach:

In order to fully understand the supply and transport of Hg that is released to aquatic environments due to ASGM, I will focus on three distinct tributaries flowing to the Madre de Dios River. Water and sediment samples will be collected every 10 kilometers along the rivers. Water samples will be collected at the surface, and the sediment samples will be collected as grab samples. Water samples will be analyzed for total Hg, for MeHg, and for ancillary parameters such as pH, alkalinity, total suspended solids, dissolved organic carbon, nitrate, and sulfate. Ancillary parameters are necessary to determine potential indicators of Hg transport as well as its methylation. Sediment samples will be analyzed for total Hg, MeHg, carbon content, and nitrogen content. Fish samples will be collected at three locations along the rivers and will be analyzed for total Hg. To quantify the amount of Hg transported along each tributary, I will establish gauging stations to determine the height of the water above a data point. The Peruvian Amazon does not have distinct seasons, but generally the period between June and October is associated with lower amounts of precipitation. Sampling will be done twice during the study period - in January and July - to determine any differences in Hg transport due to the intensity of precipitation.

Expected Results:

This research offers a systematic methodology for assessing the methylation of ionic Hg in three different natural streams in the Amazonian rainforest. It is expected to find that the fate of MeHg in these streams differs due to differences in watershed characteristics and usage. Higher concentrations of total mercury (THg) and methylmercury (MeHg) are expected in all samples closer to ASGM activities. Previous research on mercury contamination in watersheds suggests there will be strong relationships between abiotic MeHg concentrations and fish concentrations but weak and variable relationships between abiotic THg concentrations and fish concentrations. In addition, the results of this research will help the scientific community understand the cycling of Hg species in tropical areas subject to Hg contamination.

Supplemental Keywords:

methylmercury (MeHg), bioaccumulation, gold mining, watersheds, mercury regulation

Progress and Final Reports:

  • 2016
  • 2017
  • Final