Chlorophyll measurements from the MesoHux mesocosm experiment held in May 2017

<p>Water samples for chlorophyll extraction were collected from the mesocosms via a 5 L Niskin. Chlorophyll samples were filtered in triplicate through a 25mm Glass Fiber Filter (GFF), and immediately extracted in 6 mL of ethanol for 12-18 hours in the dark at room temperature. After extraction, filters were removed from the sample, and the fluorescence of the sample was read on a Turner AU10. The sample was then acidified with 1 drop of 10% HCL and re-read on the same instrument. The fluorometer was calibrated prior to using with a chlorophyll standard purchased from Sigma.</p> <p>Mesocosm treatments are as follows:<br /> P-limited: N:P added in a 60:1 ratio during the first 3 days of the experiment, no shading<br /> Redfield: N:P added in a 16:1 ratio during the first 3 days of the experiment, no shading<br /> Shaded: N:P added in a 16:1 ratio during the first 3 days of the experiment, top shaded of the mesocosm added on May 20, 2017<br /> Ambient: no nutrients added, no shading<br /> Samples were taken from either 1m, 5m, or from sediment from settling cones. Samples were noted in the Sample Depth (m) column.</p>用于叶绿素提取的水样通过5升尼斯金采水器（Niskin）从中型围隔实验系统（mesocosms）中采集。叶绿素样品通过25毫米玻璃纤维滤膜（GFF）进行三份平行过滤，随后立即置于6毫升乙醇中，于室温暗处萃取12至18小时。萃取完成后取出滤膜，使用Turner AU10型荧光分光光度计测定样品荧光强度；随后向样品中滴加1滴10%盐酸（HCL），使用同一仪器再次测定荧光强度。测试前，使用Sigma公司采购的叶绿素标准品对该荧光光度计进行校准。 中型围隔实验系统的处理组设置如下： 磷限制组：实验前3天按氮磷比60:1添加营养盐，无遮光处理 雷德菲尔德比例组：实验前3天按氮磷比16:1添加营养盐，无遮光处理 遮光组：实验前3天按氮磷比16:1添加营养盐，中型围隔实验系统顶部于2017年5月20日实施遮光 原位对照组：未添加任何营养盐，无遮光处理 样品分别采集自1米、5米水层或沉降锥中的沉积物，样品采集深度（米）将记录于Sample Depth (m)列中。