Experimental assessment and implications of long-term within-trap mineralization of seston in lake trapping studies
Experimental assessment and implications of long-term within-trap mineralization of seston in lake trapping studies
复制标题
湖泊捕集研究中塞斯顿长期圈内矿化的实验评估和影响
作者：
Radbourne A
沉积物捕获是湖泊研究中被广泛接受的一种分析季节性湖泊事件的技术，可以提供对生态演替以及有机和无机通量的季节动态的洞察。最近，来自圈闭的有机通量测量在估计整个湖泊的碳固存方面尤其重要，作为区域和全球扩大湖泊类型碳收支的基础。然而，收集的沉积物(Seston)的圈闭内矿化或溶解作用尚未得到系统的研究，因此，各种沉积通量(特别是含有机碳的沉积通量)圈闭内损失的可靠校正系数仍然未知。这项实验研究评估了在寒冷(~ 5°C)和低氧环境条件下，旋转木马式(封闭式)沉积物捕集器在深水富营养化湖泊中部署6个月后藻类生物量的损失，这是分层温带湖泊典型的低氧环境条件。结果表明，在180 d以上，有机物(OM)的损失速率保持一致，在部署180 d后，初始OM含量的分数减少了约三分之一(OM分数损失的线性回归=−0.001864t)。这些发现的重要性通过对已公布的陷阱数据的应用得到了证明；在英国的Rostherne Mere，这意味着每年的OM通量被平均低估了18.2%(范围为13.7-23.2%)。这突出了对湖泊沉积物圈闭方法和我们对Seston挖掘学的理解的深远影响，建议将OM的矿化校正系数应用于部署超过1周的圈闭。考虑到损失修正因素，这项研究支持了较长期(即~ 6个月)沉积物捕集器部署的可靠性。
Sediment trapping is a widely accepted technique in lake studies for analyzing seasonal limnological events and can provide insight into ecological succession as well as the seasonal dynamics of organic and inorganic fluxes. More recently, organic flux measurement from traps has been especially important in estimating whole‐lake C sequestration as a basis for regional and global upscaling of C budgets across lake types. However, in‐trap mineralization or dissolution of components of collected sediment (seston) has not been systematically examined, and thus a reliable correction factor for in‐trap losses of various sedimentary fluxes (especially those involving organic carbon) is still unknown. This experimental study assesses the loss of algal biomass representative of a 6‐month carousel‐type (closed) sediment trap deployment in a deep, eutrophic lake under cold (~ 5°C) and anoxic ambient conditions typical of the hypolimnion in stratifying, temperate lakes. Results show a loss of organic matter (OM) at a consistent rate over 180 d, reducing the fraction of initial OM content by approximately a third after 180 d of deployment (linear regression of OM fraction loss = −0.001864t). The significance of these findings is demonstrated by application to published trap data; at Rostherne Mere, UK, which implies that annual OM fluxes are underestimated by 18.2% on average (range 13.7–23.2%). This highlights the far‐reaching implications for lake sediment trap methodology and our understanding of seston taphonomy, suggesting a mineralization correction factor for OM should be applied to traps deployed for longer than 1 week. With loss correction factored in, this study supports the reliability of longer‐term (i.e., ~ 6 months) sediment trap deployment.