IMC report Sep 29,2017

IMC  Report:  Sep 29, 2017 club meeting

Observation of Mono Lake water                                                                              IMC/ Kyu Been Lee

 

 

 

An overall summary of my experience with Mono Lake water

Over the summer, I took a trip up to Mammoth Lakes and encountered something I've never seen before:  a salty lake!!! The lake is called Mono Lake and the reason for its saltiness is because there is no place for water to leave the lake: mountains flow water down to the lake but since the only way for the water to leave is by evaporation, it is saline. Some fun facts: The lake is covered in brine shrimp, attracting A LOT of bird to the shore line! The lake is also nicknamed as the lake that is "saltier than the sea"! If you've seen my posts about drying lubricant tear drops and baking sodas, then this must seem a bit familiar to you. I also dried some of the Mono Lake water I collected and sure enough, they showed a similar image to the other two substances I tested prior to this observation. The likely reason for this is because water is alkaline and has a pH level of around 10. The other reason is, like stated earlier, the water is extremely salty. The water also creates pillars around the lake called tufa towers. Below is a deeper description of how the towers are formed by the calcium and carbonates.  

Additional information found online

Mono Lake is located in the Mono Basin of Mono County, California. The unique historical geological setting of tectonics and volcanism shaped the basin to be completely enclosed by mountains and hills, creating the internally draining watershed known as Mono Basin. In this basin is Mono Lake, one of the most alkaline, most saline, and oldest lakes in the US. The lake is at least 760,000 years old, about 21 km long, about 13km wide, and has a current average depth of about 17 meters. This peculiar lake has unusually high levels other minerals such as carbonates, chlorides, sulfates, and more. This unusual water chemistry grants the lake a unique ecosystem.

 

Geological Features of Mono Basin

Tufa Towers: One of the most striking, unique features of Mono Lake are the tufa towers. Mono Lake is the only place in the world where these particular tufa structures are visible. These towers are composed of calcium carbonate, which is the same chemical composition that constitutes limestone. The tufa forms underwater and has been exposed and become visible due to the lowering levels of the lake water. When freshwater springs in the alkaline lake emit calcium-containing water, the calcium reacts with the accumulated carbonate in the lake to precipitate into the mineral thinolite, an unusual form of calcium carbonate. Over time the tufa forms underwater in a column around the opening of upwelling calcium water, thus the tufa towers indicate the location of current or previous underwater springs.

 

 

HYDROLOGY

 

Inputs

Streams: 5 freshwater streams provide water to Mono Lake. The water source of the streams is the melting of the winter’s snowpack in the high Sierra Nevada. The input streams are Rush, Parker, Walker, Lee Vining, and Mill Creeks.

 

Groundwater: Mono Lake has a number of underground springs providing freshwater to the lake. These springs are sourced by underground aquifers, which are sourced by underground runoff that ultimately came from precipitation on or along the mountains.

 

Outputs

Evaporation: With no outflow of water by any stream or river, evaporation is the primary and arguably the only mechanism by which water leaves Mono Lake. And in this hot, dry climate the rate of evaporation is quite significant, averaging approximately 45 inches per year.

 

Accumulation of Minerals

Due to the fact that Mono Lake has no outflow and water leaves predominantly by evaporation, over time minerals accumulate in the lake. The reason for this is the 5streams providing water to the lake are also depositing minerals such as salts, borate and potassium. When the water is evaporated, these minerals are left behind, and are thus amassed in the lake.

 

 

ECOSYSTEM

 

Abiotic Components

Climate: The Mono Basin climate is a semi-desert, with hot, arid conditions. The largely wide-open area frequently fosters strong winds. During the summer, daytime temperature average at 28°C and drop to about 9°C at night. In the winter, daytime temperature are about 5°C and drop to about -8°C at night.

 

Water Chemistry: Mono Lake is about 3 times saltier than the ocean with an average salinity measure of 81 grams/liter. The lake contains approximately 280million tons of salt, which are primarily sodium chloride, but also include sodium sulfates and sodium carbonates. This also causes the lake to be 80 times more alkaline than the ocean, with an average pH of 10. Mono Lake water additionally contains unusually high concentrations of borate and potassium. The lake’s water also contains trace amounts of the following elements: strontium, magnesium, calcium, fluoride, arsenic, lithium, iodine, tungsten, uranium, thorium, plutonium, carbon-14, and more.

 

Biotic Components

Algae: The algal community of Mono Lake includes cyanobacteria, phytoplankton, and diatoms, and can be categorized into two main groups: phytoplanktons and benthic algae. The two primary species of phytoplanktonic algae found in Mono Lake are Nitzschia communi and the green coccoid species of the genus Coccomyxa. These species are highly tolerant to conditions of high salinity, allowing them to thrive in Mono Lake’s hypersaline waters (Winkler). Small traces of several other algal species were also found. In terms of benthic algae. While the lake exhibits relatively low diversity of algal species due to the unusual and extreme chemical composition of the water, the dominant algal species in the lake are incredibly prolific and abundant. As with all algae, Mono Lake’s algae are autotrophic, and thus via photosynthesis convert the sun’s energy into chemical energy, and in the process produce the much needed-oxygen. Therefore, algae is the foundation of the entire Mono Lake ecosystem.

 

Alkali Flies: The Mono Lake ecosystem is abundant in salinity-tolerant Ephydra hians, commonly known as alkali flies. These flies have a dark brown to black body ranging from 4-7 millimeters in length. Fascinatingly, these flies can go underwater for up to 15 minutes. They achieve this as tiny hairs on the their bodies form an air bubble around themselves, allowing them to breath for an extended period of time. In this way, female flies enter the lake and lay their eggs on algal mats approximately 3 meters below the water’s surface. After the metamorphosis is complete, the adult alkali fly is fully mature and floats to the surface of the water and spends its remaining 2 weeks of its life on the shore of Mono Lake breeding, and returning to the water to feed upon algae.

 

Brine Shrimp: Mono Lake is home to Artemia Monica, a species of Brine Shrimp that is found nowhere else in the world. In the absence of fish or any other aquatic predators, brine shrimp are tremendously fruitful and abundant. In the summer, there are an estimated 4-6 trillion brine shrimp in the lake. In the winter nearly all of the brine shrimp die off, but the females have laid tiny eggs of dormant, undeveloped embryos known as cysts. These cysts can withstand harsh temperatures. The following spring these cysts hatch as microscopic larva known as nauplii. After 14 molts the larva has become a fully mature brine shrimp, which reach an approximate length of 1 centimeter. The brine shrimp feed primarily upon the phytoplankton in the lake.

 

Birds: Mono Lake, with brine shrimp and alkali flies in abundance and with two safe, isolated islands on the lake, is an ideal bird haven. This peculiar yet productive ecosystem has become a vital pit stop for migratory birds. Over 325 species of bird have been spotted at Mono Lake, and in one individual day there has been counted an approximate 800,000 birds feeding at the lake. Of these numerous birds, arguably the most significant is Larus Californicus, the gray-white bodied, black and white wing tipped California Gull. Mono Lake hosts up to 50,000 California Gulls, which constitutes 95% of the state’s population. Seeking warmer weather in the winter, these gulls come to the islands at Mono Lake to breed, nest, and feed.  Along the journey they stop at Mono Lake to feed upon brine shrimp and molt. The California Gulls, Eared Grebes, and Wilson’s Phalaropes are the lake’s most common, consistent, and abundant avian visitors, but they are by no means the only. Millions of birds of hundreds of species visit the productive ecosystem of Mono Lake to rest, nest, breed and feed.

 

 

WORKS CITED

http://www.indiana.edu/~sierra/papers/2014/Geissler.pdf