Liikanen Anu, Puustinen Markku, Koskiaho Jari, Väisänen Tero, Martikainen Pertti, Hartikainen Helinä
Department of Environmental Sciences, Research and Development Unit of Environmental Health, University of Kuopio, P.O. Box 1627, FIN 70211, Kuopio, Finland.
J Environ Qual. 2004 May-Jun;33(3):1124-32. doi: 10.2134/jeq2004.1124.
Phosphorus in surface runoff water may cause eutrophication of recipient water. This study clarifies the mechanisms of P removal in the wetland of Hovi, Finland, constructed on arable land in 1998. Before the construction, the surface soil (removed in the construction) and subsoil (the current wetland bottom) were analyzed for Al and Fe oxides (Al(ox) and Fe(ox)) reactive in P sorption, and for the distribution of P between various pools as well as for P exchange properties. Retention of P from runoff water within the wetland was studied from 1999 to 2001 in situ and factors affecting the P removal (O2 availability and P concentration in water) were investigated in a laboratory microcosm. The processes taking place in the wetland diminished by 68% the total P load and by 49% the dissolved reactive P load. Desorption-sorption tests indicated that without removal of the surface soil, there would have been a risk of the wetland being a source of P, since the equilibrium P concentration of the soil removed was high compared with the mean P concentration of the inflowing water. The subsoil contained less P and high amounts of reactive oxides, which could bind P. Evidently, the P sorption by Al(ox) played an important role in a first phase removal of P, since the wetland retained P efficiently even under anoxic conditions, where Fe tends to be reduced. Fine-textured, mineral soil on the bottom of the wetland (subsoil of the former arable land) seemed to be very efficient in retaining P from agricultural runoff.
地表径流水中的磷可能会导致受纳水体富营养化。本研究阐明了1998年建于耕地上的芬兰霍维湿地中磷的去除机制。在建设之前，对表层土壤（建设过程中移除）和下层土壤（当前湿地底部）进行了分析，测定了对磷吸附有反应的铝和铁氧化物（Al(ox)和Fe(ox)），以及磷在各个库之间的分布和磷交换特性。1999年至2001年对湿地内径流水中磷的截留进行了原位研究，并在实验室微观世界中研究了影响磷去除的因素（水中的氧气可用性和磷浓度）。湿地中发生的过程使总磷负荷减少了68%，溶解活性磷负荷减少了49%。解吸-吸附试验表明，如果不移除表层土壤，湿地就有成为磷源的风险，因为移除的土壤的平衡磷浓度与流入水的平均磷浓度相比很高。下层土壤含磷量较低，但含有大量可结合磷的活性氧化物。显然，Al(ox)对磷的吸附在磷的第一阶段去除中起了重要作用，因为即使在铁趋于还原的缺氧条件下，湿地也能有效地截留磷。湿地底部质地细密的矿质土壤（原耕地的下层土壤）似乎在截留农业径流中的磷方面非常有效。
