We explored the roles of phytoplankton production, carbon source, and human activity on carbon accumulation in a eutrophic lake (Rostherne Mere, UK) to understand how changes in nutrient loading, algal community structure and catchment management can influence carbon sequestration in lake sediments. Water samples (dissolved inorganic, organic and particulate carbon) were analysed to investigate contemporary carbon sources. Multiple variables in a 55-cm sediment core, which represents the last ~ 90 years of accumulation, were studied to determine historical production rates of algal communities and carbon sources. Fluctuations in net primary production, inferred from sedimentary diatom abundance and high-performance liquid chromatography (HPLC) pigment methods, were linked to nutrient input from sewage treatment works (STW) in the catchment. Stepped combustion radiocarbon (SCR) measurements established that lake sediment contains between 11% (~ 1929 CE) and 69% (~ 1978 CE) recalcitrant carbon, with changes in carbon character coinciding with peaks in accumulation rate and linked to STW inputs. Catchment disturbance was identified by radiocarbon analysis, and included STW construction in the 1930s, determined using SCR analysis, and recent nearby highway construction, determined by measurements on dissolved organic carbon from the lake and outflow river. The quantity of autochthonous carbon buried was related to diatom biovolume accumulation rate (DBAR) and decreased when diatom accumulation rate and valve size declined, despite an overall increase in net carbon production. HPLC pigment analysis indicated that changes in total C deposition and diatom accumulation were related to proliferation of non-siliceous algae. HPLC results also indicated that dominance of recalcitrant carbon in sediment organic carbon was likely caused by increased deposition rather than preservation factors. The total algal accumulation rate controlled the sediment organic carbon accumulation rate, whereas DBAR was correlated to the proportion of each carbon source buried.

中文翻译：

---

碳的来源和数量影响其在 Rostherne Mere（英国）沉积物中的封存：阶梯燃烧放射性碳分析的新应用

我们探讨了浮游植物生产、碳源和人类活动对富营养化湖泊（英国 Rostherne Mere）碳积累的作用，以了解营养负荷、藻类群落结构和集水区管理的变化如何影响湖泊沉积物中的碳固存。分析水样（溶解的无机碳、有机碳和颗粒碳）以研究当代碳源。研究了代表最近 90 年积累的 55 厘米沉积物核心中的多个变量，以确定藻类群落和碳源的历史生产率。从沉积硅藻丰度和高效液相色谱 (HPLC) 色素方法推断出的净初级产量的波动与集水区污水处理厂 (STW) 的养分输入有关。阶梯式燃烧放射性碳 (SCR) 测量表明，湖泊沉积物中含有 11% (~ 1929 CE) 和 69% (~ 1978 CE) 的顽固碳，碳特征的变化与积累率的峰值一致，并与 STW 输入相关。集水区干扰是通过放射性碳分析确定的，包括 1930 年代的 STW 建设，使用 SCR 分析确定，以及最近附近的高速公路建设，通过对湖泊和流出河流中溶解有机碳的测量确定。尽管净碳产量总体增加，但埋藏的原生碳量与硅藻生物量积累率 (DBAR) 相关，并且随着硅藻积累率和阀门尺寸的下降而减少。HPLC色素分析表明，总碳沉积和硅藻积累的变化与非硅藻的增殖有关。HPLC 结果还表明，沉积物有机碳中顽固碳的主导地位可能是由沉积增加而不是保存因素引起的。藻类总积累率控制沉积物有机碳积累率，而DBAR与埋藏的每个碳源的比例相关。