Combined gel probes for the in situ determination of dissolved reactive phosphorus in porewaters and characterization of sediment reactivity
Combined gel probes for the in situ determination of dissolved reactive phosphorus in porewaters and characterization of sediment reactivity
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DOI：
10.1021/es8001663
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发表时间：
2008-07-15
影响因子：
11.4
通讯作者：
Worsfold, Paul. J.
中科院分区：
文献类型：
--
作者：
Monbet, Phil;McKelvie, Ian D.;Worsfold, Paul. J.
采用薄膜扩散平衡法（DET）和薄膜扩散梯度法（DGT）原位获得了吉普斯兰湖（澳大利亚东南部）两个泻湖夏季高空间分辨率溶解活性磷（DRP）沉积物孔隙水剖面。虽然在每个湖泊的DRP深度剖面是不同的，突出了DRP的沉积物的氧化还原状态的敏感性，从DET和DGT获得的空间DRP变化表现出惊人的相似性，在每个湖泊的深度。比较从DGT和DET获得的DRP浓度可以评估沉积物的反应性。DGT诱导的沉积物通量（DIFS）的动态数值模型定量反应动力学。沉积物响应时间（TC）相关的沉积物磷再补给DGT引起的孔隙水DRP浓度降低计算。维多利亚湖和惠灵顿湖的Tc值分别为4128 ~ 183 400 s和55 ~ 149 400 s。这些结果表明，沉积物的能力有限，快速补给DRP的孔隙水，特别是在表层沉积物，这是始终具有最高的Tc。还根据DIFS计算了吸附和解吸速率常数，维多利亚湖的数值范围分别为2 x 10（-3）至2 x 10（-2）天（-1）和0.3至21天（-1），惠灵顿湖的数值范围分别为2 x 10（-4）至0.8天（-1）和0.6至1558天（-1）。在维多利亚湖和惠灵顿湖，通过DET从沉积物-水界面的原位DRP梯度估算的扩散通量分别为558和1.2 μ mol m（-2）天（-1）。尽管只有一个单一的测量，这些通量突出了大量的贡献，从沉积物中的水柱在夏季维多利亚湖，这是可能有助于经常性的蓝藻水华。这些以最小的沉积物扰动和高空间分辨率获得的计算通量与使用更传统的定量评估，如扩散通量（来自岩心切片）和底栖室的其他报告值有很大差异（6-180倍）。
Diffusive equilibrium in thin films (DET) and diffusive gradients in thin films (DGT) were applied in situ to obtain high spatial resolution dissolved reactive phosphorus (DRP) sediment porewater profiles in two lagoons of the Gippsland Lakes (SE Australia) during summer. Although the DRP depth profiles were different in each lake, highlighting the sensitivity of DRP to the redox state of the sediment, spatial DRP variations obtained from DET and DGT showed striking similarities with depth in each lake. Comparison of DRP concentrations obtained from DGT and DET allows an assessment of the reactivity of the sediment. A dynamic numerical model of DGT-induced flux in sediments (DIFS) quantified reactivity kinetics. Sediment response time (T-c) related to sedimentary phosphorus resupply resulting from DGT-induced lowering of the porewater DRP concentration was calculated. Values of Tc ranged from 4128 to 183 400 s and from 55 to 149 400 s for Lakes Victoria and Wellington, respectively. These results indicate the limited capacity of the sediment to quickly resupply DRP to the porewater, especially in surface sediment, which was always characterized by the highest Tc. Adsorption and desorption rate constants were also calculated from DIFS with values ranging from 2 x 10(-3) to 2 x 10(-2) day(-1) and from 0.3 to 21 day(-1) for Lake Victoria and from 2 x 10(-4) to 0.8 day(-1) and from 0.6 to 1558 day(-1) for Lake Wellington, respectively. Diffusive fluxes estimated from the in situ DRP gradient at the sediment-water interface by DET were 558 and 1.2 mu mol m(-2) day(-1) in lakes Victoria and Wellington, respectively. Despite only a single measurement, these fluxes highlight a substantial contribution of P from the sediment to the water column in summer for Lake Victoria which is likely to contribute to the recurring blooms of blue-green algae. These calculated fluxes obtained with minimal sediment disturbance and high spatial resolution were substantially different (by a factor of 6-180) from other reported values using more conventional quantitative assessments such as diffusive fluxes (from core slicing) and benthic chambers.