Department of Geological Sciences, Brigham Young University, Provo, UT, United States of America.
Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT, United States of America.
PLoS One. 2019 Feb 14;14(2):e0212238. doi: 10.1371/journal.pone.0212238. eCollection 2019.
Lakes worldwide are impacted by eutrophication and harmful algal or cyanobacteria blooms (HABs) due to excessive nutrients, including legacy P released from sediments in shallow lakes. Utah Lake (northern Utah, USA) is a shallow lake with urban development primarily on the east side of the watershed, providing an opportunity to evaluate HABs in relation to a gradient of legacy sediment P. In this study, we investigated sediment composition and P concentrations in sediment, pore water, and the water column in relation to blooms of harmful cyanobacteria species. Sediments on the east side of the lake had P concentrations up to 1710 mg/kg, corresponding to elevated P concentrations in pore water (up to 10.8 mg/L) and overlying water column (up to 1.7 mg/L). Sediment P concentrations were positively correlated with Fe2O3, CaO, and organic matter abundance, and inversely correlated with SiO2, demonstrating the importance of sediment composition for P sorption and mineral precipitation. Although the sediment contained <3% Fe2O3 by weight, approximately half of the sediment P was associated with redox-sensitive Fe oxide/hydroxide minerals that could be released to the water column under reducing conditions. Cyanobacteria cell counts indicate that blooms of Aphanizomenon flos-aquae and Dolichospermum flosaquae species tend to occur on the east side of Utah Lake, corresponding to areas with elevated P concentrations in the sediment, pore water, and water column. Our findings suggest that shallow lake eutrophication may be a function of P in legacy sediments that contribute to observed HABs in specific locations of shallow lakes.
由于营养物质过多，包括来自浅水湖泊沉积物中释放的遗留磷，全球的湖泊都受到富营养化和有害藻类或蓝藻水华（HABs）的影响。犹他湖（美国犹他州北部）是一个浅水湖，城市发展主要集中在流域的东侧，这为评估与遗留沉积物磷梯度有关的 HABs 提供了机会。在这项研究中，我们调查了与有害蓝藻物种水华有关的沉积物组成和沉积物、孔隙水和水柱中的磷浓度。湖东侧的沉积物中磷浓度高达 1710 毫克/千克，相应的孔隙水中磷浓度（高达 10.8 毫克/升）和上覆水柱中磷浓度（高达 1.7 毫克/升）也很高。沉积物中的磷浓度与 Fe2O3、CaO 和有机质丰度呈正相关，与 SiO2 呈负相关，这表明沉积物组成对磷的吸附和矿物沉淀很重要。尽管沉积物的 Fe2O3 重量含量<3%，但大约一半的沉积物磷与氧化还原敏感的铁氧化物/氢氧化物矿物有关，这些矿物在还原条件下可能会释放到水柱中。蓝藻细胞计数表明，鱼腥藻和螺旋鱼腥藻物种的水华往往发生在犹他湖的东侧，这与沉积物、孔隙水和水柱中磷浓度升高的区域相对应。我们的研究结果表明，浅水湖富营养化可能是遗留沉积物中磷的作用，这种作用导致了浅水湖中特定位置出现 HABs。
