arsenic contamination – Lightsources.org

Blowing in the wind

2022/01/102022/01/13

Monitoring dust from legacy mine tailings to keep communities safe

Queen’s university researchers have studied dust blown from legacy mine tailings at the Giant Mine in Yellowknife, NWT and determined vital information to inform future remediation efforts.

Using the CLS@APS, the researchers were able to determine the chemical form of arsenic in dust particles sourced from the Giant Mine tailings which intermittently blow into nearby communities.

“The synchrotron is really useful for looking at dust because you have this really tiny micron scale beam that you can focus on individual dust particles and get really good data,” said Queen’s researcher Alex Bailey, who conducted the study as part of her Master’s.

Giant Mine is a decommissioned gold mine located 5 km North of Yellowknife that is currently being remediated. The main concern around this site is the existence of toxic-to-humans arsenic trioxide which was formed as a byproduct of ore processing in the 1950s and 60s. Arsenic trioxide had been previously found in local soils and lake sediments, and there was a concern from local residents that arsenic trioxide may be present in dust generated from surface tailings which intermittently blows into the community. It was important for the wellbeing and peace of mind of nearby community members to understand what dust from these tailings might carry.

By analyzing dust-sized material from the surface of the mine tailings and dust captured from a strategic location using detailed mineralogical analysis, synchrotron, and more conventional techniques, the team was able to identify what forms the arsenic would take and its implications for human health.

Read more on the CLS website

Image: Alex Bailey at the APS synchrotron collecting uXRD and uXRF data for sieved tailings dust samples

Shedding light on the causes of arsenic contamination

2020/12/092020/12/21

An international team has used the Canadian Light Source at the University of Saskatchewan to uncover the elusive structure of two arsenic-containing compounds, information that can be used to prevent and predict arsenic contamination.

Arsenic occurs naturally in the environment, and it is present in ore deposits and the waste left behind by mining for gold, uranium, and other metals. The concern with arsenic-containing compounds, like yukonite and arseniosiderite, is that soil sources can find their way into waterways. Understanding how this happens on a structural level can help scientists — and industry — better understand how the two are formed and better protect the surrounding environment from potential arsenic contamination.

Discovered more than 100 years ago, yukonite and arseniosiderite, which are compounds of arsenic, calcium, iron and oxygen, have concealed their structure from scientists thanks to their low crystallinity. While it’s relatively easy to determine the structure of materials that have a high degree of crystallinity, because of the complexity in the way these minerals’ atoms are arranged, usual methods have come up short in painting a clear picture of their structure.

Using a special technique at the CLS called the pair distribution function (PDF), an international team of researchers from Canada, China, the USA, Italy, and Ireland was able to visualize for the first time how atoms are structured in samples of arseniosiderite, which is classified as semi-crystalline, and yukonite, which is considered a nano-crystalline mineral.

Read more on the CLS website

Image: Specimen BM.62813 from the collections of the Natural History Museum, London