Stanford Synchrotron Radiation Lightsource

In the 1950’s and 60’s a poisoning occurred in Minamata Japan.  In addition to the people, the local cat population was affected with what was called “Dancing Cat Disease” and shortly thereafter neurological signs and symptoms became more prominent in people.  The sickness became known as Minamata Disease.  Eventually it was shown to be a form of organic mercury poisoning.  During the episode, pregnant women who were minimally or not obviously affected delivered infants who had neurological disorders such as seizures, microcephaly, and cerebral palsy.

The local company that caused the pollution employed a physician who played a role in determining the cause.  He found that cats fed chemical effluent from the factory quickly developed signs similar to those seen in people with Minamata Disease. He preserved samples of brain tissue from one of the cats, and remarkably, these samples still exist. An international team of researchers used sophisticated modern techniques to analyze these samples and determine the chemical form of mercury within the tissue.

While a small amount of copper is essential for living organisms, too much copper contaminating our soils can be toxic and pose a serious problem. Copper has an affinity for organic matter in soils, where it mainly exists in the two redox states Cu(I) and Cu(II). In soils that fluctuate in redox conditions, the mobility of copper through the environment can be hard to predict. Mofette sites, produced by CO₂ degassing usually found in seismically active areas, are good natural laboratories due to their wide range of soil redox conditions and of soil organic matter composition within a small area. Near the sites of CO₂ degassing, the soil is anoxic and organic matter does not decompose well. The soils transition to oxic conditions just a few meters away. A team of researchers studied the behavior of copper in the natural gradient of a mofette site in the Czech Republic.

While scientists recognize that oxygen-free soil stores large amounts of carbon, knowledge about the processes that protect and preserve carbon-rich molecules in these environments is lacking. In oxygen-rich soil, microbes break down organic molecules through aerobic respiration, allowing carbon to escape the ground as carbon dioxide gas.

The practice of storing reclaimed or storm water by refilling an aquifer is called managed aquifer recharge (MAR). Advantages of MAR to regions vulnerable to drought or which have depleted aquifers include water storage for future use, reduced water loss of stored water from evaporation, and stabilization of the aquifers. However, refilling aquifers can change the chemistry, allowing naturally occurring toxins in aquifer sediments to dissolve into the water. Arsenic, a potential poison, is of particular concern, since use of MAR has led to arsenic-contaminated water.

Recent work at SSRL has helped reveal a previously unrecognized wealth of bromine chemistry in the environment, where bromine in seawater has long been thought to exist as inorganic bromide, while bromides in soil were considered so unreactive that they've routinely been used as a hydrological tracer.

The reality bromine chemistry in the environment is much more complex. X-ray absorption spectroscopic (XAS) studies conducted by Leri, et al. at SSRL Beam Lines 2-3 and 4-3, as well as at the ALS and NSLS, reveal a complicated association between bromine and organic carbon in both sea water and soil.

Mercury (Hg) is a naturally occurring element that poses considerable health risks to humans, with high exposure levels resulting in damage to the brain, heart, kidneys, lungs, and immune system. Young children and unborn babies are particularly vulnerable to mercury, which can affect their nervous systems and impair their neurological development. As a result, mercury is one of the most strictly regulated pollutants by the Environmental Protection Agency (EPA), which controls mercury emissions from coal-fired power plants and issues consumption advisory warnings for various types of fish, the primary route of mercury exposure to humans

Rice, the grain that provides more than one-fifth of the world population's calories, can become a health hazard if contaminated with arsenic. Such contamination, a surprisingly widespread occurrence, takes place in areas where soil or irrigation water is tainted by naturally occurring arsenic--including broad swaths of south and southeastern Asia. Studies have suggested that the natural iron coating around the roots of rice plants may serve as an important barrier to arsenic uptake because arsenic in its oxidized form has an affinity for iron. A team of Stanford and SSRL researchers recently sought to learn just how significant a barrier iron provides.

Iron, one of the most abundant metals on Earth’s surface, often dominates the reactivity of rocks, soils and sediments, and is important in many biogeochemical processes.  A great challenge for biogeochemists is to identify the iron species in these natural materials at very small scales and to track changes in the iron species as these materials react with water.

When we think of chlorine, we often relate it to the salt used in food preparation, chloride in the oceans, chlorine gas from swimming pools, and gaseous chlorofluorocarbons that have close links to the depletion of stratospheric ozone. We rarely think of thousands of chlorinated hydrocarbons that exist in the natural systems, several of which are highly toxic to humans (1). The C-Cl bond, common to all organo-Cl compounds, is strong and gives high stability to organo-Cl compounds. For this reason, several organo-Cl compounds have been synthesized and used extensively for years in agricultural and industrial applications.