What questions do you have about climate change? Are you interested in only very recent change (last 50-100 years or so), or do you want information from earlier periods?

I know that you can collect modern rainwater (or snow) to analyze oxygen isotopes, and then compare isotopic changes over time. This might be interesting in an area affected by monsoons. But, I don't know if you're interested in water, or just sediments. Here's a citation for starters: Sengupta & Sarkar, 2006, Stable isotope evidence of dual (Arabian Sea and Bay of Bengal) vapour sources in monsoonal precipitation over north India.

I am involved in a project for collection of surface sediment samples from wide geographic area, the samples will be analyzed for major, trace and rare earth elements to generate surface geochemical map, I want to know how this geochemical data can be linked with recent climate change studies.

It depends on time interval which You want to analyse. What does it mean "surface sediment" on time scale? If You have time series of ca 100 years long, You can correlate instrumental (hydrometeorological) and geochemical data. I have such experience. But if You think to consider wide geographic distribution, it is necessary to correlare geochemical composition of sediments with local climatic parameters. Then You need to average mention parameters for chosed time interval for each locality. I suppose it is solving problem, like in pollen analysis.

Study of geochemistry of the sediments indicates the environmental conditions during deposition of sediments as well as the geology of the catchment area. Minerals identified within the sediments are either authigenic or allogenic in nature. Allochthonous minerals include feldspars, zeolites and clay minerals derived from the weathering of the catchment rocks (gives information about erosion and weathering-related with high rainfall or dry condition). Clay minerals (smectite, illite, chlorite, etc.) are promising minerals for the study of climate change because, its direct relation with the climatic parameters such as precipitation and temperature, its stability during and after deposition.

Some peoples are also working on the organic geochemistry part of the sediments; one aspect is that, they analyze to get the isotopic value of C and O in the sediments, which links with precipitation and evaporation in the area.

But ultimately you have to link other records with your geochemical data to get more clear information about climate change.

Please contact Antonio Martínez Cortizas. I am sure that him can help you with this interesting question

If you which to make a comparison of current pollutants to prior pollutants, then

the bottoms of ponds and lakes are a good place to collect samples. The materials that settle out of the water collect in layers on the bottoms of ponds and lakes.

Look for quiet areas where the inflow, and out flow of water do not disturb the

previously deposited layers. You will want to take deep enough samples to

go far enough back in time to get well past the period of human influence so that you can establish a base line of what is naturally deposited in the lake bed you are sampling. The material I observed in layers that were deposited on the Ocean Floor

around 70 million years ago had a deposition rate between 4.5 and 5.5 mm per

each year ( 4 to 5 year to 1 inch of deposition ). The arial deposition rate

in Lawns is approximately 25 years to the inch. Lake bottoms should be

somewhere between these two extremes.

In caves with streams, I have observed similar deposition rates to the

Ocean floors ( 5 to 7 years to the Inch ), in Horizontal Limestone caves

in mountainous areas ( Fort Stanton Cave, Lincoln County, New Mexico, USA ).

As a side bar, type Into Your search engine: Snowy River, Fort Stanton Cave,

it has the worlds longest continuous single calcite formation, currently over 8

kilometers long... look for images, or click on images in a GOOGLE search of that

topic.

I take it by surface sediments you mean recent annual to interdedadal times at the scale of climate variability other than trend. If so then given climate change is a global phenomena at these temporal scales with little delayed effects from northern hemisphere emissions to the Southern Hemisphere, then spatial gradient analysis is useless. However if you wish to determine the source of anthropogenic impacts on the aquatic biology assemblage or productivity then a spatial analysis will identify the major sources and ere relative influence across the globe

Regards Barry

In looking at past climate changes. The Permian extinction event, there was

an 80 meter drop in sea level elevations, ocean acidification, the Limestone of the

Guadaloupe Mountains ( then a reef ) was converted from Calcium Carbonate to

Calcium Sulfate ( Gypsum ).

The reef was sustained by the micro organisms that utilized the Hydrogen Sulfide Gas that came up from the Earth under the reef as a nutrient source, but at the End

Guadaloupian Era, the 80 meter drop in ocean levels and the death of the reef

and the acidification of the reef caused by the Hydrogen sulfide gas converting the

stagnant water in the reef to a dilute sulfuric acid, led to reef acidification and the

acid ( sulfuric acid ) dissolved parts of the reef making some spectacular caves

and canyons in the limestone, and also producing Gypsum Flats in Texas and New Mexico.

The reef itself is now tilted with the west end at a plus 8,000 foot elevation, and the

East end ( 400 miles away ) is at a minus 12,000 foot elevation. This is roughly a

1.25 % axial gradient running along the axis of the reef of a feature that was

know to have formed horizontally in a shallow marine environment near sea level,

in the Permian.

The Point of all this is that to study climate change in the present, you need to compare it to climate change in the prior geologic Time periods for the purpose of

comparison and contrast.

A comparison would be ocean acidification and death of reefs.

Contrast is that the Permian had an 80 meter drop in ocean elevation,

and 10,000 to 8,000 years ago we had a 120 meter rise in ocean elevations,

that turned the British Peninsula into the British Isles, and connected the Arctic

Ocean with the Pacific Ocean.

That change in ocean elevations is continuing today as Ice sheets melt faster

than new ice sheets form.

Google the following: Lechugilla Cave, Chandiler Ball Room and look at the

Gypsum crystals coming from the walls of the Limestone cave.

Also look at Snowy River, Fort Stanton Cave Images. Google Images works best.

I read recently that a cave formation from the Fort Stanton Cave Study Project

was used to check the O 18 for a 45,000 year period and it was compared to the

one in China ( Hulu ? ) and the climate changes were almost exactly opposite.

Take a look at Fort Stanton Cave, Snowy River for a white calcite formation

that is several Kilometers long.

Article History and evaluation of national-scale geochemical data se...