INFLUENCE OF COUPLING OF SORPTION AND PHOTOSYNTHETIC PROCESSES ON TRACE-ELEMENT CYCLES IN NATURAL-WATERS
INFLUENCE OF COUPLING OF SORPTION AND PHOTOSYNTHETIC PROCESSES ON TRACE-ELEMENT CYCLES IN NATURAL-WATERS
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DOI：
10.1038/340052a0
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发表时间：
1989-07-06
期刊：
影响因子：
64.8
通讯作者：
DAVIS, JA
中科院分区：
文献类型：
--
作者：
FULLER, CC;DAVIS, JA
化学和生物过程在自然水体中微量元素的运输和循环中起着重要作用[1-3]，但它们之间复杂的相互作用往往不被很好地理解。例如，微量元素浓度可能受到矿物表面吸附-解吸反应的控制，其平衡受pH值的强烈影响。由于光合作用活性引起的pH值变化应导致浓度波动，因为吸附-解吸平衡随pH值变化。为了研究这些相互作用，我们研究了pH日循环对砷污染多年生溪流中溶解的砷酸盐的影响。正如预期的那样，观察到砷酸盐浓度的日循环，但令人惊讶的是，砷酸盐循环落后于pH循环几个小时。实验室实验表明，这种滞后是由于缓慢接近吸附平衡造成的。我们的观察结果表明，光合作用和吸附过程的耦合可能对许多微量元素的循环产生重要影响，并强调了在模拟这些过程中理解吸附动力学的重要性。
CHEMICAL and biological processes have important roles in the transport and cycling of trace elements in natural waters1-3, but their complex interactions are often not well understood. Trace-element concentrations may, for example, be controlled by adsorption—desorption reactions at mineral surfaces, with the equilibrium strongly influenced by pH. Variations in pH due to photosynthetic activity should result in concentration fluctuations as the adsorption—desorption equilibrium shifts with pH. To investigate these interactions, we have studied the effect of diurnal cycling of pH on dissolved arsenate in a perennial stream contaminated with arsenic. As expected, a diurnal cycle in arsenate concentration was observed, but surprisingly, the arsenate cycle lags several hours behind the pH cycle. Laboratory experiments show that the lag results from a slow approach to sorption equilibrium. Our observations demonstrate that the coupling of photosynthesis and sorption processes may have an important influence on the cycling of many trace elements and emphasize the importance of understanding sorption kinetics in modelling these processes.