Institute of Soil, Water and Environmental Sciences, The Volcani Center, Agricultural Research Organization, HaMaccabim Road 68, P.O.B 15159, Rishon LeZion 7528809, Israel.
Institute of Soil, Water and Environmental Sciences, The Volcani Center, Agricultural Research Organization, HaMaccabim Road 68, P.O.B 15159, Rishon LeZion 7528809, Israel.
Sci Total Environ. 2017 Jan 1;574:1174-1181. doi: 10.1016/j.scitotenv.2016.09.075. Epub 2016 Oct 14.
Managed aquifer recharge (MAR) events are occasionally carried out with surplus desalinated seawater that has been post-treated with CaCO in infiltration ponds overlying the northern part of the Israeli Coastal Aquifer. This water's chemical characteristics differ from those of any other water recharged to the aquifer and of the natural groundwater. As the MAR events are short (hours to weeks), the sediment under the infiltration ponds will intermittently host desalinated and natural groundwater. As part of comprehensive research on the influence of those events, column experiments were designed to simulate the alternation of the two water types: post-treated desalinated seawater (PTDES) and natural groundwater (GW). Each experiment included three stages: (i) saturation with GW; (ii) inflow of PTDES; (iii) inflow of GW. Three runs were conducted, each with different sediments extracted from the field and representing a different layer below the infiltration pond: (i) sand (<1% CaCO), (ii) sand containing 7% CaCO, and (iii) crushed calcareous sandstone (35% CaCO). The results from all columns showed enrichment of K and Mg (up to 0.4meq/L for 20 pore volumes) when PTDES replaced GW, whereas an opposite trend of Ca depletion (up to 0.5meq/L) was observed only in the columns that contained a high percentage of CaCO. When GW replaced PTDES, depletion of Mg and K was noted. The results indicated that adsorption/desorption of cations are the main processes causing the observed enrichment/depletion. It was concluded that the high concentration of Ca (relative to the total concentration of cations) and the low concentration of Mg in the PTDES relative to natural GW are the factors controlling the main sediment-water interaction. The enrichment of PTDES with Mg may be viewed as an additional post-treatment.
在以色列沿海含水层北部的渗透池上，偶尔会用经过碳酸钙后处理的多余淡化海水进行含水层人工补给（MAR）活动。这种水的化学性质与补给含水层的任何其他水以及天然地下水不同。由于 MAR 事件持续时间短（数小时到数周），渗透池下的沉积物会间歇性地存在淡化海水和天然地下水。作为对这些事件影响的综合研究的一部分，设计了柱实验来模拟这两种水类型的交替：后处理淡化海水（PTDES）和天然地下水（GW）。每个实验包括三个阶段：（i）用 GW 饱和；（ii）流入 PTDES；（iii）流入 GW。进行了三次运行，每次都使用从现场提取的不同沉积物，代表渗透池下的不同层：（i）砂（<1% CaCO），（ii）含 7% CaCO 的砂，和（iii）粉碎的钙质砂岩（35% CaCO）。所有柱子的结果都表明，当 PTDES 取代 GW 时，K 和 Mg 会富集（多达 20 个孔隙体积的 0.4meq/L），而只有在含有高百分比 CaCO 的柱子中才会观察到 Ca 耗尽的相反趋势（多达 0.5meq/L）。当 GW 取代 PTDES 时，Mg 和 K 的消耗会被注意到。结果表明，阳离子的吸附/解吸是导致观察到的富集/耗尽的主要过程。得出的结论是，PTDES 中 Ca 的浓度（相对于阳离子的总浓度）较高，而与天然 GW 相比，Mg 的浓度较低，是控制主要沉积物-水相互作用的因素。PTDES 中 Mg 的富集可以被视为额外的后处理。
