The larger of our two boats picked up researchers at the final pick up spot 6:00 am. This early start (particularly for those who were picked up first and loaded equipment) ensured that as much time as possible could be spent on the lake. Afternoon wind often makes sampling impossible, so the hours prior to noon are the most valuable of the day. As luck would have it, the wind was relatively calm, so the boat was able to stay out until early afternoon.
The major achievement for today was the successful collection of a sample of sediment from the bottom of the lake. Water and sediment from approximately 310 meters was taken. This is not quite the lake’s deepest point, but this sample will give us valuable information. Not only is it exciting to have the sample, but it’s wonderful that the team is working well enough to make this possible and the equipment is working well.
After our daily lunch at the Natural Reserve of Atitlan, attention focused on the chemistry lab. Timing is critical for preserving or processing some of the samples. The chemistry group prepared as many of the chemical treatments as possible ahead of time, led by Emily Carlson, a graduate student at UC Davis.
Photos: Today's chemistry team
Teachers and students from local high schools’ inter-school science club visited the chemistry lab in the afternoon to learn how the samples are being processed.
After a discussion of how the lab operates, the high school students helped sort invertebrates collected in the morning. Each student was given a bin that contained some sediment in water with many invertebrates. The invertebrates are key indicators of the state of the lake’s food chain and can tell us how well the ecosystem is functioning. The students used tweezers to remove the invertebrates from their bin so that they could be sorted and analyzed by type.
Photo: Students from Pana's inter-school science club at work
While the chemistry group continued analyzing the chemical properties of the samples that were brought in, and after the high school group left, students from the expedition continued sorting invertebrates until the sun went down. There were many invertebrates in the samples, due to Lago de Atitlan’s warm water.
Photos: Expedition students sorting invertebrates
Although this may seem like tedious work, members of the chemistry group joined us outside to “cross train” and seemed to enjoy themselves.
Photos: Expedition students (from today's chemistry team) sorting invertebrates
Pamela, from the regional water district surrounding Lago de Amatitlan, is participating in this expedition. Lago de Amatitlan is a large lake with serious water quality challenges. While some of Lago de Amatitlan's challenges are similar to those facing Lago de Atitlan, Pamela told me that she is optimistic about Lago de Atitlan because there are still many options available for coping with issues such as waste water treatment.
Photo: Pamela, from the water authority in charge of Lago de Amatitlan, helps with the sorting of invertebrates
Jiri Komarek from South Bohemia University is one of only a few people in the world with such a rich understanding of cyanobacteria. He gave a presentation to students in the evening. Eliska Rejmankova introduced Dr. Komarek by alerting the students that they were being given a very special opportunity to hear one of the “science greats.”
Photo: Dr. Jiri Komarek, South Bohemia University, teaching a seminar on cyanobacteria.
Robert Collison, University of California, Davis
The watershed group spent the last three days working our way around the shores of the lake, taking soil and water samples from the major watershed drainage channels. The area between near Santa Cruz also gave us the opportunity to hike about 5km up and down the steep slopes bordering the lake. The volcanic soils have a very steep angle of repose and some of the slopes would be too vertical to cross without ropes. The less vertical slopes (between 1:1 and 2:1) are hand-tilled to support agricultural crops. Erosion is unavoidable when tilling occurs on slopes like this, although the volcanic material is highly porous and its run-off limited by sub-surface drainage.
We talked with some of the local team members who are familiar with the soil conservation service, who told us it is estimated 70% of the phosphorous reaching the lake is derived from soil erosion. After a frank discussion, we felt that the soil conservation service had a clear vision of the requirements to ameliorate the erosion but were handicapped by funding issues.
One of the other major contributors of phosphorous to the lake is the discharge of phosphorous in waste water. Our local colleagues estimate that this is about 10% of the phosphorous load deposited in the lake. Waste water treatment plants are limited to several of the larger population centers in the Atitlan watershed. The other main sources of treatment are septic tanks connected to disposal wells. The wells are sunk into the underlying volcanic debris (sub-soil) which is highly porous and serves as a giant leach field. Local knowledge indicates that much of this septic-tank derived waste percolates into the lake. It would be useful to determine if the studies have been prepared to indicate the distance waste water flows through the subsoil before the organic, nitrogen, and phosphorous pollutants are removed.
Wellington Garcia, Universidad de San Carlos de Guatemala
I have only had three days with all the participants of this scientific expedition, and I’m impressed by all that I can learn in such a little time. I’m part of the group that is analyzing the chemical properties of the water collected from the lake and from communities in the watershed. I have learned effective ways to use laboratory equipment and I hope soon to obtain information about cianotoxins and maybe in the future I will develop studies of the water quality.
Apenas llevo 3 dias compartiendo con todo los participantes de esta expedicion cientifica, y realmente estoy impresionado de lo que se puede aprender en tan poco tiempo. Soy parte del grupo que esta analizando las propiedades fisicoquimicas del agua que se obtiene tanto del lago como de las comunidades que son parte de la Cuenca. He aprendido maneras mas practicas de utilizar el equipo del laboratorio y espero pronto obtener informacion sobre cianotoxinas y poder desarrollar en el futuro studios que brinden informacion sobre la calidad del agua.