Polychlorinated Naphthalenes across the Great Lakes: Lake Trout and Walleye Concentrations, Trends, and TEQ Assessment2004–2018

Polychlorinated naphthalenes (PCNs)
were measured in lake trout
and walleye over the period 2004–2018, utilizing isotope dilution
techniques with high-resolution gas chromatography/high-resolution
mass spectrometry to assess concentrations and toxic equivalence (TEQ).
An age-trend model was applied to mitigate the effect of a changing
lake trout age structure. Most Great Lakes Fish Monitoring and Surveillance
Program sampling sites demonstrated significant half-life and percent
decreases for lake trout total PCNs and total TEQ over the 2004–2018
period, the exceptions being Lake Erie lake trout and walleye which
illustrated increasing concentrations. Great Lakes total PCN concentrations
ranged between 5701 and 100 pg/g ww, whereas total PCN TEQ concentrations
ranged between 8.89 and 0.13 pg-TEQ/g ww. Based on the average number
of chlorines per naphthalene, we determined that the overall lake
trout and walleye PCN congener distribution has significantly shifted
to a lower-chlorinated composition in the Great Lakes (5.33 to 4.48
Cl/CN) and has resulted in a substantial 59.1% reduction of the overall
total PCN TEQ burden. A prominent PCN concentration trend breakpoint
was observed in Lake Ontario lake trout over the 2012–2016
period likely associated with hazardous waste cleanups, channel dredging,
and spoils disposal in the Detroit River and western-basin of Lake
Erie.

本研究于2004至2018年间，对湖鳟（lake trout）与白斑狗鱼（walleye）体内的多氯萘（Polychlorinated naphthalenes, PCNs）进行了检测，采用同位素稀释技术结合高分辨气相色谱-高分辨质谱（high-resolution gas chromatography/high-resolution mass spectrometry, HRGC/HRMS）进行分析，以定量测定其浓度与毒性当量（toxic equivalence, TEQ）。为抵消湖鳟年龄结构变化带来的影响，本研究引入年龄趋势模型进行校正。在2004至2018年的监测周期内，参与五大湖鱼类监测与监视计划（Great Lakes Fish Monitoring and Surveillance Program）的绝大多数采样点位中，湖鳟体内的总多氯萘与总毒性当量均呈现出显著的半衰期与浓度百分比下降趋势；仅伊利湖的湖鳟与白斑狗鱼种群出现浓度上升的例外情况。五大湖区域鱼类体内的总多氯萘浓度范围为100~5701 pg/g 湿重（wet weight, ww），而总多氯萘毒性当量浓度范围则为0.13~8.89 pg-TEQ/g 湿重（wet weight, ww）。基于每分子萘的平均氯原子数，本研究发现五大湖区域湖鳟与白斑狗鱼体内的多氯萘同系物组成已显著向低氯代组分偏移（氯原子数从5.33降至4.48 Cl/CN），并使得总多氯萘毒性当量总负荷大幅降低59.1%。在2012至2016年间，安大略湖的湖鳟种群中观测到显著的多氯萘浓度趋势拐点，该现象大概率与底特律河及伊利湖西盆地的危险废物清理、河道疏浚以及疏浚物处置活动相关。