Dong Bin, Han Ruiming, Wang Guoxiang, Cao Xun
Jiangsu Key Laboratory of Environmental Change and Ecological Construction, School of Geographical Science, Nanjing Normal University, Nanjing, P. R. China; School of Resource and Environment, Linyi University, Linyi, P. R. China.
Jiangsu Key Laboratory of Environmental Change and Ecological Construction, School of Geographical Science, Nanjing Normal University, Nanjing, P. R. China.
PLoS One. 2014 Jul 8;9(7):e101825. doi: 10.1371/journal.pone.0101825. eCollection 2014.
This study aimed to elucidate the effects of periphyton on the microprofiles of oxygen (O2), pH, and oxidation-reduction potential around the stems and leaves of a submerged macrophyte Potamogeton malaianus and on the plant growth in the eutrophic shallow Taihu Lake, China. The microprofiles were measured using a motorized microprofiling system equipped with microsensors. The leaf age of the macrophyte and periphyton exerted significant effects on the microprofiles of O2, pH, and oxidation-reduction potential. O2 concentration and pH increased whereas the oxidation-reduction potential decreased with decreasing distance to the stem/leaf surface. The fluctuation amplitudes of O2, pH, and oxidation-reduction potential were the largest in the microprofiles of mature leaves and the lowest in senescent leaves. The periphyton increased the thickness of the broad diffusive boundary layer and fluctuation amplitudes of O2, pH, and oxidation-reduction potential. When the periphyton was removed, the thickness of the broad diffusive boundary layer in the microprofiles of stems, senescent leaves, and mature leaves reduced by 29.0%, 49.72%, and 70.34%, and the O2, pH, and oxidation-reduction potential fluctuation amplitudes also declined accordingly. Our results suggest that a thick periphyton exerted negative effects on the growth of macrophytes by providing extensive shading and creating a barrier that hindered the transport of dissolved substances such as O2, and led to premature decline in macrophytes in the eutrophic Taihu Lake. The consequent implications can help to elucidate the control mechanism of the broad diffusive boundary layer around macrophytes on nutrient cycling in eutrophic waters and to better understand the role of this layer in the Taihu Lake and other similar eutrophic waters.
本研究旨在阐明附着生物对沉水植物苦草茎和叶周围的氧气（O₂）、pH值以及氧化还原电位微剖面的影响，以及对中国富营养化浅水太湖中该植物生长的影响。使用配备微传感器的电动微剖面测量系统测量微剖面。大型植物的叶龄和附着生物对O₂、pH值和氧化还原电位的微剖面有显著影响。随着距茎/叶表面距离的减小，O₂浓度和pH值升高，而氧化还原电位降低。O₂、pH值和氧化还原电位的波动幅度在成熟叶的微剖面中最大，在衰老叶中最小。附着生物增加了宽扩散边界层的厚度以及O₂、pH值和氧化还原电位的波动幅度。去除附着生物后，茎、衰老叶和成熟叶微剖面中的宽扩散边界层厚度分别减少了29.0%、49.72%和70.34%，O₂、pH值和氧化还原电位的波动幅度也相应下降。我们的结果表明，厚厚的附着生物通过提供广泛的遮荫并形成阻碍O₂等溶解物质运输的屏障，对大型植物的生长产生负面影响，并导致富营养化太湖中大型植物过早衰退。由此产生的影响有助于阐明大型植物周围宽扩散边界层对富营养化水体中养分循环的控制机制，并更好地理解该层在太湖及其他类似富营养化水体中的作用。
