{"id":301,"date":"2011-01-25T08:21:35","date_gmt":"2011-01-25T12:21:35","guid":{"rendered":"http:\/\/web.colby.edu\/colbyatsea\/?p=301"},"modified":"2011-01-25T12:04:24","modified_gmt":"2011-01-25T16:04:24","slug":"sampling-the-ocean-and-not-the-ship","status":"publish","type":"post","link":"https:\/\/web.colby.edu\/colbyatsea\/2011\/01\/25\/sampling-the-ocean-and-not-the-ship\/","title":{"rendered":"Sampling the Ocean and Not the Ship"},"content":{"rendered":"
\"\"<\/a>

Metal-free Niskin Sampler<\/p><\/div>\n

In my last post I described our workhorse sampler, a rosette holding twelve Niskin bottles.\u00a0\u00a0 This is a great sampler for many analytes like dissolved oxygen, salinity, and major nutrients (nitrate, phosphate, silica, and ammonia) because the sampler is not made of these things.\u00a0 \u00a0However, the rosette and hydrowire are made of iron.\u00a0\u00a0 If you look carefully at the surface water as you deploy the rosette you can see the rust streaming off the hydrowire that connects the rosette to the ship.\u00a0\u00a0 This is can be a real problem if you job is to measure iron.\u00a0\u00a0 It wasn\u2019t until oceanographers like John Martin (Colby class of 1962) developed metal free sampling techniques that collecting uncontaminated samples for metal analysis was possible.<\/p>\n

\"\"<\/a>

Thirty-liter GoFlow Sampler<\/p><\/div>\n

The photo in the upper right shows Ben and Sarah<\/a> recovering a special metal-free Niskin bottle.\u00a0 The spring that holds the ends of the bottle closed is located on the outside of the bottle.\u00a0\u00a0 Also, notice that the bottle is not mounted in a rosette, but is attached to a metal-free Kevlar cable.\u00a0\u00a0 Each bottle is attached to the cable by hand and deployed in a string from the deepest bottle to the shallowest.\u00a0 Once the bottles are in place, the white Teflon messenger is sent down the cable.\u00a0\u00a0 The messenger hits a trigger on the first bottle that closes the bottle caps and releases another messenger.\u00a0 The second messenger triggers the second bottle, and the process continues down the string of bottles until all bottles are closed.\u00a0 It is a slow process, but if done correctly, it is very clean.\u00a0\u00a0 These small bottles are easy to deploy because they are light and can be lifted by one person.\u00a0 Ben also has a thirty-liter version of these bottles that his group uses for collecting a large volume of water from a single depth.\u00a0\u00a0 It takes several people to recover this bottle and today I was given the honor of helping to carry the full bottle to the lab. \u00a0I don\u2019t think they wanted me for my mind!<\/p>\n

\"\"<\/a>Clearly, bottles have size limitations.\u00a0\u00a0 Some measurements, like the analysis of metals adsorbed on particles, require sampling much more seawater than could ever be contained in a bottle.\u00a0\u00a0 The Lam group from WHOI<\/a> uses submersible McClane pumps to collect hundreds to thousands of liters of water for particulate analysis.\u00a0 \u00a0They deploy the pumps on the same metal-free wire to avoid contamination.\u00a0\u00a0 Each pump is an autonomous sampler programmed to turn on and off after being lowered to their sampling depth.\u00a0\u00a0 The pump pulls water through filters where particles are trapped. After recovery, the filters are removed for analysis on the ship or lab.<\/p>\n

\"\"<\/a>

Luke (yellow hat) deploying his surface camera<\/p><\/div>\n

Other samples simply can\u2019t be collected for analysis on the ship.\u00a0\u00a0 Try to collect a photon in a bottle.\u00a0 Luke Logan from Miami and Barney\u2019s group from Bigelow use in situ<\/em> optical sensors to measure the light levels in the surface ocean.\u00a0 Luke\u2019s sensors are designed to float just below the surface and measure the upwelling light being scattered from depth.<\/p>\n

\"\"<\/a>

Optical "Lawn Dart"<\/p><\/div>\n

The Bigelow sensors measure both the upward and downward light flux using sensors mounted on the top and bottom of an \u201coceanographic lawn dart\u201d.\u00a0\u00a0 The dart is allowed to sink behind the ship and measures light levels as it goes.<\/p>\n

Finally, the ship\u2019s crew have their own sampling systems.\u00a0\u00a0 We have started to deploy these \u201csamplers\u201d behind the ship whenever we move between stations.\u00a0\u00a0 Stay tuned for Annie\u2019s post tomorrow for more details on what we collect with this sampling gear.\u00a0 It was delicious!<\/p>\n

More photos and details of other sampling gear used on the ship are posted on\u00a0Rebecca’s blog<\/a>.<\/p>\n

\"\"<\/a>– Whitney<\/p>\n","protected":false},"excerpt":{"rendered":"

In my last post I described our workhorse sampler, a rosette holding twelve Niskin bottles.\u00a0\u00a0 This is a great sampler for many analytes like dissolved oxygen, salinity, and major nutrients (nitrate, phosphate, silica, and ammonia) because the sampler is not … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":184,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[17554,17550,1178,1],"tags":[],"_links":{"self":[{"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/posts\/301"}],"collection":[{"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/users\/184"}],"replies":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/comments?post=301"}],"version-history":[{"count":8,"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/posts\/301\/revisions"}],"predecessor-version":[{"id":321,"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/posts\/301\/revisions\/321"}],"wp:attachment":[{"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/media?parent=301"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/categories?post=301"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/web.colby.edu\/colbyatsea\/wp-json\/wp\/v2\/tags?post=301"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}