sub-tidal surface sediment sampling

[Eric Nicholson]

Hello everyone,

I'm a new member - G'day!

I'm not actually a diver, but I'm doing a PhD project in a coastal environment and I thought perhaps some among you could help me solve a sampling problem.

I'd like to buy or construct a device for sucking up sediment from the surface in mangrove wetlands, but only to a depth of about 1-2cm. I also need quite a bit for my analysis of the substrate, so the diameter should be fairly big, but also allow me to get in amongst dense mangrove roots and pneumatophores.

If anyone has any advice or suggestions on how I could go about doing this work, I'd love to hear from you. I'm working in the mangroves just north of Adelaide, South Australia, in case there's a local who can help me. Cheers!

 

[Kayla]

I'm hoping that there is someone that can help you here! I know that I'm not that person, but with as many people that we have here.. and the wide variety of things that they do, I'm thinking that someone might be able to help you!! Good luck with your project!!!

Kayla

 

[Koreanfrogger]

welcome to the board

 

[Jason Ooi]

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[DandyDon]

Howdy and welcome to SB!

Looks like your thread was moved for better coverage.

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:bandit_2: don

 

[scubamanny]

I can help you. I am a diver and archeologist in training. I have experience pulling core samples on land and in the water, but none of the diamiter you need. do you need the material to stay as a complete unit like a core sample of can it be all the material from a desired area removed as a blended bag of material? Are you going to do doing this using scuba? If so, silt-out will be a makor factor. If you are doing it by hand, I am sure you can find a long handled tool to d the job probabl even through the EPA of Cornell Cooperative exention. I will ask around but would suggest that you continue your own research. If all else fails, try contacting a costal national park in Florida. NPS scientist tend to have the best practicle field knowledge out there.

 

[Scubakevdm]

Hello everyone,

I'm a new member - G'day!

I'm not actually a diver, but I'm doing a PhD project in a coastal environment and I thought perhaps some among you could help me solve a sampling problem.

I'd like to buy or construct a device for sucking up sediment from the surface in mangrove wetlands, but only to a depth of about 1-2cm. I also need quite a bit for my analysis of the substrate, so the diameter should be fairly big, but also allow me to get in amongst dense mangrove roots and pneumatophores.

If anyone has any advice or suggestions on how I could go about doing this work, I'd love to hear from you. I'm working in the mangroves just north of Adelaide, South Australia, in case there's a local who can help me. Cheers!

Hey! Welcome to the board! I'm not a very clever fella, and I probably won't be able to help you much with your project. Hell, I'm not even sure exactly what you mean by "sediment from the surface" I saw you talking about sub tidal up there too, so the way I understand what you're trying to do, is that you're trying to skim 1-2 cm of sediment off the bottom. Can you quantify "quite a bit"? Could you maybe skim it off with very fine aquarium nets?

 

[Guba]

Welcome, Eric
I'm on the same page with Scubamanny on this one. What kind of sampling do you need? There are a variety of sampling techniques, but it depends upon what you're trying to lift. As he asked, do you need a core sample? Or will it be more of a detritis sweep that will remove larger areas but along flatter layers?
Core sampling requires a tool that simply punches holes and traps the core within. I'm certain you've seen or used something like that. If you want to suck up wider areas of materials, then a air driven suction device might work IF you have a few feet of depth to work with. If it's just under the surface (such as near shallow mangrove root systems), then you might be down to the ol' spade and bucket" system. Let us know what you need, and we'll try our best to point you in a good direction.
Again, welcome, and good luck!

 

[Eric Nicholson]

Hi Guba,

To give you a better idea of what I'm doing:
I'm analysing modern diatoms at the sediment/water-column interface and I want to collect the adjacent surface sediment that these microscopic organisms are living in. So, I only need the very upper level of sediment (no more than a couple of centimetres). Additionally, I'll be collecting water samples. The idea is to correlate all of these ambient environmental variables (water quality and substrate chemistry) with the modern diatom assemblages. Knowing this, I can later analyse the diatoms throughout a long core and infer past environmental conditions based on the types of diatom assemblages I find at different depths.

In the mangrove environment I'm working in, the high tide level gets to about 2m. Depending on the time of day and the time of year, my sample sites will be either inundated or exposed. When exposed, I can simply scrape the upper surface and easily collect the 500g or so of sediment I need for substrate analysis. However, when the surface is covered in ~2m of water, I need some sort of device to use either from the side of a boat or standing in the shallow water. I want all of the sediment from within the sampled area, but it doesn't have to be a complete unit like with a core sample, as I'll be mixing it up for the analysis anyway.

I don't mind getting in the water and using a hand-held device, but I don't want to lose any sediment as I'm trying to put it into a bag. Thus, spades and trowels are out of the question. A suction device seems to be the best alternative, but I don't know how to go about getting such a thing, or making my own. This is where I need some advice.

So, hopefully you better understand what I'm doing and what I'm after. I look forward to any advice you may have.

Cheers,

Eric