The end of summer is upon us, and I have had much time to reflect on the work I have done this summer. Sampling days at Jamestown were hot, humid and mosquito friendly but were often immediately followed up with respite in the traditionally and characteristically frigid geochemistry lab. During the last few weeks of July and the beginning of August, a new facet of my research was finally introduced: UV Digestion of organic matter. Simply put, the goal of analysing drinking water at Jamestown was to determine whether colonists ingested debilitating or even lethal doses of arsenic and iron. Levels of iron are extremely high, but if the colonists allowed the water to sit in open air essentially all the iron in the water would be oxidized and fall out of solution as a solid. Arsenic does not behave this way and any arsenic in the water will be directly ingested. But, what if there is more arsenic in the water that we aren’t detecting because it is attached to organic matter? This is the new question I have started to pick apart by a method involving UV Digestion of organic material. In the lab I allow a UV light to pass through the water samples which destroys organic material, therby liberating any arsenic attached to these molcules. I can then re-analyze water samples to see if there is any increase in arsenic concentration, and whether this increase is lethal. I found a doubling of arsenic in one well located between the banks of the James River and the wall of the fort, and a slight increase of arsenic in the swamp surface waters. UV Digestion has been performed on a few samples, but not enough to draw any sort of pattern (let alone conclusion) regarding this new facet of my research.
So, here I am. It is the last week of official summer research for 2012 and what have I accomplished? I managed to gather between 20 and 23 Jamestown groundwater samples each week for nine weeks, that amounts to roughly 200 samples! Half of the samples were analyzed for iron, arsenic and dissolved organic carbon to determine the concentrations of these species and the degree to which dissolved arsenic and iron in the early colonists’ drinking water caused or (at the very least) exacerbated illnesses recorded in historical documents. Only 2 of 119 samples analyzed for arsenic, came back with values exceeding the WHO and EPA drinking water standard of 10 parts-per-billion (ppb) arsenic. And even still, these values were 12.2ppb and 14.5 ppb, certainly prolonged exposure to these levels of inorganic arsenic could cause skin and lung irritation, but the health affects were likely minimal for the early colonists. BUT, prolonged exposure to high levels of organic arsenic can cause nerve injury and stomachaches, and thus, there is work left to be finished. My next step is to run my samples through a UV-Digester which will liberate any organic arsenic attached to organic compounds ( up to 90% of arsenic in waters can be attached to organic compounds), which can be potentially metabolized by the human body.
My first summer blog comes after three weeks of laboratory analyses and hot days spent at Jamestown fort, gathering groundwater samples, bantering with tourists and befriending sunbeaten archaeologists. Roughly 65 groundwater samples have been collected from the settlement and analysed for arsenic, iron and DOC (dissolved organic carbon). Measuring iron is relatively simple but requires a few hours of preparation and then ‘doping’ samples by hand with various reagents to produce a delightful magenta-violet color. Simply put, the more purple the sample becomes, the more iron content. When it comes to measuring arsenic, a large and admittedly intimidating machine called a VARIAN Atomic Absorption Spectrometer, is used, and must be treated gingerly, as discovered when this beast demanded a full day of troubleshooting before it would run smoothly. Once attached to a 50psi Argon tank and the inner quartz cell is heated to 950 degrees Celsius, my groundwater samples are heated and turned into a gas which contains any arsenic in the sample. A beam of light is then sent through the gas; the less light thats passes through, the more arsenic in the sample.
Greetings! My name is Glencora Maccubbin. I am a soon-to-be senior geology major studying water pollution at our nation’s first permanent settlement, Jamestown 1607. Water pollution has become a global issue, causing illness and environmental degradation. The discovery of lethal concentrations of arsenic in Bangladesh drinking water by the World Health Organization allowed researchers to isolate the source of health problems and establish drinking water safety standards Researchers have determined the effects of arsenic on health, while geographic and geologic data have helped scientists determine the sources and migration of contaminants to actively used aquifers. By using the modern data on anthropogenic and geologic sources of arsenic in association with historical records that document disease and death chronologies from the establishment of Jamestown settlement, Virginia, in 1607, traditional explanations for the high mortality rate at Jamestown, such as starvation and apathy will be re-evaluated and my research will determine the extent to which contaminants, specifically arsenic, iron and salts exacerbated illnesses such as typhoid, dysentery and salt poisoning experienced by colonists in the first permanent English settlement in North America. My study will focus on the concentrations of arsenic which are attached to ingestible organic molecules. Past work has underestimated arsenic concentration by measured only dissolved inorganic arsenic, thus we expect to find higher levels in my study.( Samples taken from the 16 test wells in Jamestown in March (and we expect in April) have yielded elevated levels of dissolved organic carbon and thus we predict to find higher levels of arsenic than previous expected. )