Neuston net sampling in 2020 for surface microplastic analysis in the western Arctic Ocean

The distribution of microplastic in the open ocean of the Arctic Ocean is largely undocumented. Substantial numbers of studies on microplastics have been reported in the Pacific and Atlantic Oceans, yet very few data are available in the polar oceans. In the present study, we conducted microplastic surveys along the cruise track to fill gaps in the Arctic Ocean.Floating microplastic samples were collected at Stns 1, 2, 3, 4, 29 and 35 using a neuston net with a square mouth opening of 75 cm height and 75 cm width, equipped with a 333 μm mesh opening net with a collecting bottle attached at the cod end. At each station, the net was towed three times for 20 min each along the surface of the starboard side. At the stns 29 and 35, each tow was carried out for 15 min due to a logistical reason. The trawl speed ranged between 1 and 2 knots. A flow meter was installed at the net mouth to estimate the volume of water filtered during each tow. The collected samples were fixed with 5% formalin and stored at room temperature until analysis.Microplastic samples from the neuston net will be subjected to enumeration and identification of plastic types using a microscope and FT-IR. The microplastics will also be weighed for mass calculation. The distribution, density and concentration of microplastic in this study will be compared with the previous reports in the Arctic Ocean.

北冰洋开阔海域中的微塑料（microplastic）分布状况在很大程度上仍未被探明。针对太平洋与大西洋海域的微塑料相关研究已为数不少，但极地海洋中的相关数据却极为匮乏。
本研究依托巡航航线开展微塑料调查，以填补北冰洋海域相关数据空白。
本研究于站位1、2、3、4、29和35处采集漂浮微塑料样本，所用工具为网口规格为75cm×75cm的漂浮生物网（neuston net），该网配备孔径333μm的网衣，且在网兜末端连接集样瓶。每个站位均沿右舷海面进行拖网作业，共拖网3次，每次时长20分钟；但受后勤保障因素影响，站位29和35处的单次拖网时长调整为15分钟。拖网作业速度介于1至2节之间，网口处安装有流量计，用以估算单次拖网过程中过滤的海水体积。采集得到的样本经5%福尔马林固定后，于室温下保存直至后续分析。
本研究将借助显微镜与傅里叶变换红外光谱（FT-IR）对漂浮生物网采集的微塑料样本进行计数与塑料类型鉴定，并通过称重计算其质量。本研究所得微塑料分布、丰度与浓度数据，将与此前北冰洋海域的相关研究报告进行对比分析。