Road Trip: 2. The Selenga Delta

The three days we spent in the Selenga Delta were pretty jam-packed, covering a large distance, sampling all of the sites shown below.

Selenga Delta Sites

Selenga Delta Sites (White diamond, sample sites; Red triangle, base camp; Blue arrow head, lake core). Image from Google Earth.

Landsat 5 image of the Selenga River Delta acquired on August 23, 2010. This image clearly shows the tributaries of the delta, meandering channels on the alluvial plain and sediment-laden waters on the delta front. Landsat GeoCover image by the United States Geological Survey.

Landsat 5 image of the Selenga River Delta acquired on August 23, 2010. This image clearly shows the tributaries of the delta, meandering channels on the alluvial plain and sediment-laden waters on the delta front. Landsat GeoCover image by the United States Geological Survey.

The reality of sampling the Selenga Delta became apparent rather quickly. Our high aspirations to sample some of the more remote, inner locations in the delta were soon trumped given the time limitations we had and the absence of a small boat complete with engine. The currents in even some of the smallest channels was quite fast and with such high grasses and Phragmites bordering all channels, it was quite hard to orientate oneself.

Ginnie, rowing upstream in a headwind. Selenga Delta.

Ginnie, rowing upstream in a headwind. Selenga Delta.

For starters, just trying to locate any lakes from maps or satellite imagery, given the ephemeral nature of a Delta, was hard enough. Not to mention dragging all our coring equipment and boat across head high Phragmites fields!

A tired Ginnie after arriving one of the Delta Lakes, after dragging the boat a fair way to reach it.

A tired Ginnie after arriving one of the Delta Lakes, after dragging the boat a fair way to reach it.

Nevertheless, we were very pleased with the different sites that we were able to sample and given the different locations we looked at, feel confident we captured a lot of the delta’s main characteristics. Here are some pics of the different sites we visited. As you can see, the vegetation shows some quite dramatic changes:

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Needless to say, apart from the hard work…some very fun moments were had. Despite all the mosquitoes that plagued us at night! To find out about more of our adventures, heading upstream of the Selenga River, stay tuned…

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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!

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.

Experiment – Day 7

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The time has come to collect our mesocoms which have been left suspended under the ice, in a water depth of 3 m in Lake Baikal. After a bout of continuous heavy snowfall on Saturday we decided to make our way to Neutrino to clear some of the snow cover, and ensure the diatoms would have enough light inorder to make the experiment a success. This turned out to be fortuitous as the snow cover was very deep, and therefore took us some time to clear the area.

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Our Russian colleagues even suggested that we break up the ice as this would make it easier in 3 days time to collect the bags again. After an hour of hard work, we had a clear ice hole to check that all our bags were still suspended from the ice and with a few tweaks (hanging the rope over a wooden frame) we were all set to leave them again, knowing that we would (hopefully) have an easier job to remove them on Wednesday.

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Wednesday soon came around. Luckily the weather today was much warmer than the day before, which had reached c. -30oC overnight. This was good news as we would be collecting the bags and we did not want them to freeze before we were able to transport them back to the lab kunk at Base Camp.

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After succesfully retrieving all 15 sample bags, we headed back to camp to begin our filtering procedures. This entailed a very long evening, operating the filtration units. Through our observations, the nutrient enriched mesocosm water samples took considerably longer to filter. This is as expected, and should imply the experiments have worked. We’ll know more once we start analysing our samples back in the UK. Anyway, back to filtering….