Road Trip: 1. The Southern Basin

The “Road Trip”component of the August expedition set off from Irkutsk, following the edge of the lake in an anti-clockwise direction. The Road Trip had several aims. The principal aim was to sample major streams and tributaries for stable isotope, pigment and chemical analyses.

Solzan River

Solzan River

Khara-Murin River

Khara-Murin River

Sampling equipment

Sampling equipment

Sampling strategies at each site included collecting up to 1L of river water, from as close to the central flow as possible, using a self-modified water sampler (with weight and float). This was to measure DOC, nutrients, TP, silicon concentrations (DSi) and its isotopic composition (δ30SiDSi). At each site we also collected a GPS location, measured pH, temperature and conductivity (in situ).

At certain base camps, large volumes of water were also filtered in order to obtain river diatoms, with the hope to be able to analyse their isotopic composition and compare this with the signature of diatoms from Lake Baikal itself.

Sampling the shore of Lake Baikal, Baikalsk

Sampling the shore of Lake Baikal, Baikalsk

As well as sampling the rivers, we also sampled a few locations in Lake Baikal itself, especially where rivers entered the lake, and close to pollution hotspots such as the Baikal Pulp and Paper Mill.

Camp along the Snezhnaya River, close to Vydrino

Camp along the Snezhnaya River, close to Vydrino

We were not always lucky with the weather, unfortunately. Which slowed us down when it came to all our filtering and analyses. But given the time constraints that we had, we had to plough on…to the next site and camp!

Fixing the generator

Fixing the generator

So on we went, despite obstacles thrown in our way. Including breaking down on our way to the Selenga Delta. Luckily our Russian colleagues were a dab hand at mechanics and were able to temporarily fix the Tabletka until reaching the town Babushkin where Sasha and Pasha (despite it being a public holiday) were able to sweet talk some local engineers to manufacture a new part for the engine. Phew…on we went!

As we approached the Selenga Delta, the weather cleared giving us a great view of the vast landscape. We were able to check out a few satellite lakes as we went, to see their suitability for Renberg coring, which will allow us to place recent pollution impacts of the region into a longer-term perspective.

Finally arriving at our Selenga Delta Base Camp, we could admire the fantastic sunset and prepare plans for the next day…

Pasha carrying wood, at the Selenga Delta Base Camp

Pasha carrying wood, at the Selenga Delta Base Camp

To find out more about our Selenga Delta adventures, stay tuned!

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Our first pigment analyses

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After all the long days of filtering water samples in our lab kunk back in March, the samples have been stored within a freezer ready for pigment analyses to begin. Filtration was carried out on the collected lake-water samples, to concentrate phytoplankton cells on a Whatman GF/F filter. All these samples have been run through the pigment analyser (High-Performance-Liquid-Chromatography system), to provide us with data on the algal community composition. This analysis can be performed as all phytoplankton groups produce pigments (chlorophylls and carotenoids) to enable cell photosynthesis, and some of these pigments can be used as important biomarkers for algal species presence and absence. The detection of these pigments provides information on the entire species assemblage within the samples, and not just a single group. This is an important aspect of the research, as phytoplankton respond very quickly to any changes within their environment, and provide excellent indicators of nutrient enrichment and climate change through species assemblage changes. Pigment records from across Lake Baikal, extending over natural timescales, will then enable the impact of recent nutrient loading on the ecosystem to be assessed.

To find out more about the application of algal biomarkers within this research, click HERE.

HPLC system: Agilent 1200 series

HPLC system: Agilent 1200 series

Before the samples are analysed on this HPLC system, sample preparation is carried out under special conditions, to enable the separation and detection of individual pigments. A mixture of organic solvents is used to extract the pigments from the cells, consisting of acetone, methanol and water. This sample preparation has to be carried out under dim light conditions, to avoid unnecessary photochemical degradation of pigments, which reduces their chemical stability. They are then stored for at least 12 hours within a freezer in the dark, to ensure pigment extraction from all the algal groups. This is important as algal species have different cell walls, and species with heavily silicified walls (such as large diatoms) require more time to fully extract their pigment composition. These samples are further filtered and HPLC-grade acetone is added as part of the final extraction step. Samples are then dried within the glass vials under nitrogen gas before analysis on the HPLC Agilent 1200 series.

Samples are placed in the autosampler within HPLC

Samples are placed in the auto-sampler tray within HPLC

Once dried, injection solvent is added and the glass vials are placed within the auto-sampler tray before being injected into the HPLC. As each sample is injected into the system, a diode-array detector then analyses the pigments. This produces a pigment chromatogram, which displays the pigment composition within the samples and individual pigments can be identified from their peak retention times and spectra.

Interpretation of these pigment chromatograms is now underway, and fortunately all the manual filtering of litres and litres of water paid off…as well as provoking some arm wrestling from all the bicep exercising…

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…Shortly our first pigment analyses on the sediment cores collected from the March 2013 field trip will be carried out, so more on this to follow soon…

Analysing our first water samples

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Part of the research that we are conducting is to analyse the silicon concentration and isotopc composition of lake waters. As we are interested in productivity, it is very important to understand silicon cycling through the year (e.g. winter versus summer conditions). This allows us to constrain down core interpretations. To find out more on why silicon is so important and what organisms use it in Lake Baikal, click here.

P1050563Having collected and filtered all water samples in the field, we are now ready to analyse the silicon concentration of the samples. This is conducted at the Brtish Geological Survey, UK. Concentration of trace metals are also given at the same time which is of great interest when looking at pollution stressors on the lake.

The next step is to measure the isotopc composition of the lake waters (δ30SDSi). In order to do this there are a number of purification steps that must be conducted, with samples being passed through a pre-cleaned resin to remove all cations (e.g. Na+, Ca2+) from the waters. This process takes rather a long time as the liquid must pass through the resin at a slow rate to ensure that there is full Si recovery of the sample.

The acid cleaning stage of the resin.

The acid cleaning stage of the resin.

However, this can only be done once the resin has been acid cleaned. Results from the ICP-MS are used at this stage in order to load onto the resin an exact volume of sample to ensure that the concentrations of all samples are high enough to precisely measure their isotopc composition.

Cationic resin preparation of samples and standards for MC-ICP_MS analyses

Cationic resin cleaning step of samples and standards for MC-ICP_MS analyses

Once samples are fully prepared they are measured once more on the ICP-MS to ensure that there is fully silicon recovery and to know the final concentration of the samples. This is important so that we know the volume of sample we need to analyse on the Multi-Collector Intercoupled Mass Spectrometer (MC-ICP-MS) and match concentrations of Si in bracketing standards.

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A lot of the action happens under the bonnet of the Multi Collector! Samples are injected into a plasma which ionises it, as the sample passes through the magnet the different masses of silicon (28, 29, 30)are separated and collected in three detectors. Based on the ratio between 30/28 we are able to understand the degree of biological uptake by diatoms that has taken place.

Ice Skating on Lake Baikal

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Walking the 1 km home over the ice, after dinner, to our kunks we bumped into Rashid. He was just loading his ice skates into the back of one of the vans and wanted to know if anyone wanted to join him for a sunset ice skate on the lake. This was naturally a tough call to make as we had at least another 10 L of lake water back in the lab kunk that needed filtering that night.

DSC02781However, when he mentioned it would only be for 30 minutes or so, until the sun had set, we could not refuse! In we jumped and drove up the coastline for 10 minutes until we reached a patch of ice where the wind had blown away all of the snow. Clear ice was all that could be seen. We parked up, argued over the pair of ice skates that would fit our feet best and hit the ice. It was breathtaking! It was fascinating to see all of the ice fractures under our feet in the sunset and feel the undulations of it as we glided over. Even the ice cracking sounds, that we are now quite accustomed to, did not impede our enjoyment.

Thanks Rashid. An amazing 30 minutes, never to be forgotten.