Toxicity of fuels and dispersants to the Antarctic marine nemertean Antarctonemertes unilineata

This metadata record contains the results from bioassays conducted to show the response of an Antarctic nemertean Antarctonemertes unilineata to contamination from combinations of Special Antarctic Blend (SAB) diesel, Marine Gas Oil (MGO) and Intermediate Fuel Oil (IFO 180), chemically dispersed with fuel dispersants Ardrox 6120, Slickgone LTSW and Slickgone NS. Note that the corresponding PhD thesis chapter refers to the species as Antarctonemertes sp., prior to being named Antarctonemertes unilineata in 2018.

Experiments using SAB, MGO and IFO 180 with the dispersant Ardrox 6120, including fuel only and dispersant only treatments were conducted at Casey station. Experiments involving IFO 180 and the fuel dispersants Slickgone LTSW and Slickgone NS were conducted at the Antarctic Division’s Marine Research Facility quarantine labs. All experimental procedures, including test mix preparation and bioassays were conducted at 0 plus or minus 1 degree C. Water accommodated fractions (WAF; fuel mixed in water) and chemically enhanced water accommodated fractions (CEWAF) were made according to the specifications of Singer, Aurand et al. (2000), Barron and Ka’aihue (2003) and Kotzakoulakis (unpublished at time of writing). Dispersant only mixes were also made using filtered seawater (FSW) and dispersant volumes proportional to those used for CEWAF production. WAF was made using a loading ratio of 1: 25 (v/v) fuel to FSW, CEWAF was prepared using 1:100 (v/v) fuel to FSW ratio, and 1: 20 (v/v) dispersant to fuel ratio. Following the 48 h preparation time, the seawater WAF components of the mix were drained from the bottom of aspirator bottles and serially diluted. WAF treatment concentrations were 100%, 50%, 20% and 10%, CEWAF and dispersant only concentrations were 10%, 5%, 1% and 0.1%. Treatment solutions were replenished every four days to simulate a repeated pulse exposure to contaminants and to replace hydrocarbons lost through evaporation and adsorption and to maintain water quality parameters. WAF, CEWAF and dispersant only test solutions were remade every four days using identical methods.

Tests were done in temperature-controlled cabinets set to 0 plus or minus 1 degree C following a 6 h light to 18 h dark photoperiod. Beakers were left uncovered to allow for the natural evaporation of lighter hydrocarbon components to reflect real fuel spill conditions. Experiments ran for 24 d except for the Ardrox 6120 only experiment, which ran for 16 d due to high mortality in this treatment. Sublethal and lethal endpoints were assessed at 1, 2, 4, 7, 8, 12, 14, 16, 20 and 24 d observations.

Aliquot water samples for analysis of total hydrocarbon content (THC) were taken for initial and final test concentrations, and before and after each four-day water change, to obtain accurate profiles of hydrocarbon loss over the test period. Duplicate samples were taken for every treatment concentration and extracted with dichloromethane, spiked with an internal standard of 1-bromoeicosane and cyclooctane. Samples were analysed using gas chromatography with flame ionization detection (GC-FID) and gas chromatography mass spectrometry (GC-MS). Average THC concentrations for the duration of the experiment were obtained by integrating the measured concentrations to which animals were exposed following the methods of Brown et al. (2016) and Payne et al. (2014).

This data submission includes one file detailing the TPH experiment analyses and one detailing the bioassay tests and results. The thesis that relates to this work is available from: https://epubs.scu.edu.au/theses/533/

本元数据记录包含了生物测定（bioassays）实验的结果，该实验旨在探究南极纽形动物（Antarctic nemertean）单纹南极纽虫（Antarctonemertes unilineata）对混合燃料污染的响应。受试燃料包括南极专用混合柴油（Special Antarctic Blend, SAB）、船用柴油（Marine Gas Oil, MGO）以及中间燃料油（Intermediate Fuel Oil, IFO 180），所有燃料均通过燃料分散剂Ardrox 6120、Slickgone LTSW与Slickgone NS进行化学分散。需注意的是，对应博士学位论文章节中该物种曾被标注为Antarctonemertes sp.，直至2018年才被正式命名为Antarctonemertes unilineata。

使用SAB、MGO、IFO 180搭配分散剂Ardrox 6120的实验（包含仅燃料组与仅分散剂组对照处理）在凯西站（Casey station）开展。涉及IFO 180与分散剂Slickgone LTSW、Slickgone NS的实验，则在澳大利亚南极局海洋研究设施的隔离实验室中进行。所有实验流程（含受试混合液制备与生物测定）均在0±1℃的条件下完成。水容馏分（Water Accommodated Fractions, WAF，即燃料与水混合后的水相组分）与化学强化水容馏分（Chemically Enhanced Water Accommodated Fractions, CEWAF）的制备参照了Singer、Aurand等（2000）、Barron与Ka’aihue（2003）以及Kotzakoulakis（撰写本文时尚未发表）的规范。仅分散剂的混合液同样采用过滤海水（Filtered Seawater, FSW）制备，其分散剂体积与CEWAF制备中的用量比例保持一致。WAF的投料比例为燃料与FSW体积比1:25，CEWAF则采用1:100的燃料与FSW体积比，且分散剂与燃料的体积比为1:20。经48小时制备时长后，从抽滤瓶底部抽取混合液中的WAF组分并进行梯度稀释。WAF处理组的浓度设置为100%、50%、20%与10%；CEWAF与仅分散剂组的浓度则为10%、5%、1%与0.1%。每四天更换一次处理液，以模拟污染物的重复脉冲暴露，补充因蒸发与吸附损失的烃类物质，并维持水质参数稳定。WAF、CEWAF与仅分散剂的受试溶液每四天按照相同方法重新制备。

实验在温度控制柜中开展，设置为0±1℃，光照周期为6小时光照、18小时黑暗。烧杯保持敞口，以使轻质烃类组分自然挥发，还原真实燃油泄漏场景。实验总时长为24天，仅Ardrox 6120单独处理组因该组死亡率过高，仅开展了16天。分别在第1、2、4、7、8、12、14、16、20与24天观测并记录亚致死与致死效应终点。

采集等分水样用于总烃含量（Total Hydrocarbon Content, THC）分析，采样时机涵盖初始与终末受试浓度、每四天换水前后，以获取实验周期内烃类损失的准确变化曲线。每个处理浓度均设置平行样品，采用二氯甲烷萃取，并用内标物1-二十烷溴（1-bromoeicosane）与环辛烷（cyclooctane）进行加标。样品采用气相色谱-火焰离子化检测（Gas Chromatography with Flame Ionization Detection, GC-FID）与气相色谱-质谱联用（Gas Chromatography Mass Spectrometry, GC-MS）进行分析。参照Brown等（2016）与Payne等（2014）的方法，通过积分受试动物暴露期间的实测浓度，得到实验周期内的平均THC浓度。

本数据提交包含两份文件：一份详细记录了总石油烃（Total Petroleum Hydrocarbons, TPH）实验的分析结果，另一份则完整描述了生物测定实验与相关结果。本研究相关的学位论文可通过以下链接获取：https://epubs.scu.edu.au/theses/533/