National Oceanography Centre , European Way, Southampton, SO14 3ZH, U.K.
Bristol Glaciology Centre, University of Bristol , University Road, Bristol, BS8 1SS, U.K.
Environ Sci Technol. 2017 Nov 7;51(21):12518-12527. doi: 10.1021/acs.est.7b03121. Epub 2017 Oct 13.
We report the first in situ high-resolution nitrate time series from two proglacial meltwater rivers draining the Greenland Ice Sheet, using a recently developed submersible analyzer based on lab-on-chip (LOC) technology. The low sample volume (320 μL) required by the LOC analyzer meant that low concentration (few micromolar to submicromolar), highly turbid subglacial meltwater could be filtered and colorimetrically analyzed in situ. Nitrate concentrations in rivers draining Leverett Glacier in southwest Greenland and Kiattuut Sermiat in southern Greenland exhibited a clear diurnal signal and a gradual decline at the commencement of the melt season, displaying trends that would not be discernible using traditional daily manual sampling. Nitrate concentrations varied by 4.4 μM (±0.2 μM) over a 10 day period at Kiattuut Sermiat and 3.0 μM (±0.2 μM) over a 14 day period at Leverett Glacier. Marked changes in nitrate concentrations were observed when discharge began to increase. High-resolution in situ measurements such as these have the potential to significantly advance the understanding of nutrient cycling in remote systems, where the dynamics of nutrient release are complex but are important for downstream biogeochemical cycles.
我们利用最近开发的基于片上实验室 (LOC) 技术的潜水式分析器，报告了来自格陵兰冰原两条冰前融水河流的首个原位高分辨率硝酸盐时间序列。LOC 分析器所需的低样品量（320 μL）意味着可以过滤和现场比色分析低浓度（几个微摩尔到亚微摩尔）、高度混浊的冰下融水。来自格陵兰西南的莱弗利特冰川和南部的基亚特特瑟米亚特冰川的河流中的硝酸盐浓度表现出明显的日变化信号，并在融冰季节开始时逐渐下降，显示出使用传统的每日手动采样无法识别的趋势。在基亚特特瑟米亚特的 10 天期间，硝酸盐浓度变化了 4.4 μM（±0.2 μM），在莱弗利特冰川的 14 天期间变化了 3.0 μM（±0.2 μM）。当流量开始增加时，硝酸盐浓度发生了明显变化。这些高分辨率原位测量有可能大大提高对偏远系统中养分循环的理解，这些系统中的养分释放动态复杂，但对下游生物地球化学循环很重要。
