Cape Evans sea ice physical and biological properties

Fast ice was sampled roughly every second day over a 4-week period (November 2019) at a coastal site just off Cape Evans (McMurdo Sound). Ice cores were collected to determine vertical profiles of temperature, salinity, as well as the chlorophyll-a concentration in the lowermost 10 cm (two times 5-cm sections) of the ice cores. Measurements also included snow thickness, ice thickness and sea-ice freeboard levels. The data were collected as part of AAS 4546 and contribute to a larger NZ-led project, Antarctica New Zealand Event KS043, led by Dr Andrew Martin (Victoria University Wellington).Ice cores were sampled from the same 2m2 area using a Kovacs Mark II ice corer (9 cm internal diameter) powered with an electric drill. Snow thickness was measured with a ruler before sampling, and sea ice thickness and freeboard measurements were taken from the resulting ice core holes. Sea ice temperatures were measured with a Testotherm720 thermometer (accuracy 0.2 °C immediately after ice core retrieval from small holes drilled in the core at 5 – 10 cm intervals. Thereafter we sectioned the core in 0.05 to 0.15 m sections using a stainless steel saw. Ice core sections were placed in Milli-Q water washed polyethylene (PE) containers and melted at 4 °C in the dark within 24 to 36 hours after sampling. Ice bulk salinity was determined on the melted samples with a calibrated conductivity meter. Sub-samples of known volume were subsequently filtered onto Whatman GF/F filters and stored frozen (liquid nitrogen) until extraction with acetone for 24 hours at 4 °C in the dark and determination of the chlorophyll a (Chl a) concentration with a Turner Designs 10AU fluorometer according to Arar and Collins (1997, EPA Method 445.0). Chl a is reported in µg l-1 melted sea ice.

2019年11月，在埃文斯角（Cape Evans）近海的麦克默多湾（McMurdo Sound）沿海站位，于4周的观测周期内大致每两天采集一次固定冰（fast ice）样本。本次研究采集冰芯的目的是测定冰体的温度、盐度垂直剖面，以及冰芯最底层10cm（均分为两段5cm切片）内的叶绿素a浓度。本次测量还涵盖雪层厚度、海冰厚度与海冰干舷高度。
本次采集的数据隶属于AAS 4546项目，同时作为新西兰主导的大型科研项目——南极新西兰事件KS043（Antarctica New Zealand Event KS043）的组成部分，该项目由惠灵顿维多利亚大学的安德鲁·马丁博士牵头实施。
研究人员采用科瓦斯Mark II型冰芯钻（内径9cm）搭配电钻，在同一2平方米的采样区域内采集冰芯样本。采样前先用直尺测量雪层厚度，随后通过钻取冰芯留下的钻孔测定海冰厚度与干舷高度。海冰温度采用Testotherm720型温度计（精度0.2℃）测定，具体操作为在冰芯从钻孔中取出后，于冰芯表面以5-10cm的间隔钻取小孔并立即完成测温。随后使用不锈钢锯将冰芯切割为0.05至0.15m的切片，将冰芯切片置于经Milli-Q超纯水清洗后的聚乙烯（PE）容器中，于采样后24至36小时内，在4℃避光环境下完成融化。
通过经校准的电导仪对融化后的冰样进行冰体整体盐度的测定。取已知体积的子样品，经Whatman GF/F滤膜（Whatman GF/F）过滤后置于液氮中冷冻保存；后续在4℃避光环境下用丙酮萃取24小时，并参照Arar与Collins（1997年，EPA方法445.0）所述方法，使用Turner Designs 10AU型荧光光度计（Turner Designs 10AU）测定叶绿素a（Chl a）浓度。本次报告的叶绿素a浓度单位为µg·l⁻¹（融化海冰样本）。