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首页> 外文期刊>Biogeosciences >Effects of cyanobacterial-driven pH increases on sediment nutrient fluxes and coupled nitrification-denitrification in a shallow fresh water estuary
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Effects of cyanobacterial-driven pH increases on sediment nutrient fluxes and coupled nitrification-denitrification in a shallow fresh water estuary

机译：蓝藻驱动的pH值升高对浅水淡水河口沉积物养分通量及硝化-反硝化作用的影响

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Summer cyanobacterial blooms caused an elevation in pH (9 to ～10.5) that lasted for weeks in the shallow and tidal-fresh region of the Sassafras River, a tributary of Chesapeake Bay (USA). Elevated pH promoted desorption of sedimentary inorganic phosphorus and facilitated conversion of ammonium (NH _4 ~+) to ammonia (NH _3). In this study, we investigated pH effects on exchangeable NH _4 ~+ desorption, pore water diffusion and the flux rates of NH _4 ~+, soluble reactive phosphorus (SRP) and nitrate (NO _3 ~(-4+) through NH -3 formation from both pore water and adsorbed NH 4 + pools. Progressive penetration of high pH from the overlying water into sediment promoted the mobility of SRP and the release of total ammonium (NH _4 ~+ and NH _3) into the pore water. At elevated pH levels, high sediment-water effluxes of SRP and total ammonium were associated with reduction of nitrification, denitrification and oxygen consumption rates. Alkaline pH and the toxicity of NH _3 may inhibit nitrification in the thin aerobic zone, simultaneously constraining coupled nitrification-denitrification with limited NO _3 ~- supply and high pH penetration into the anaerobic zone. Geochemical feedbacks to pH elevation, such as enhancement of dissolved nutrient effluxes and reduction in N _2 loss via denitrification, may enhance the persistence of cyanobacterial blooms in shallow water ecosystems.
机译：夏季的蓝藻水华使美国切萨皮克湾的支流萨萨弗拉斯河的浅滩和潮鲜区的pH升高（9至〜10.5），持续了数周。 pH升高可促进沉积无机磷的解吸，并促进铵（NH _4〜+）转化为氨（NH _3）。在这项研究中，我们研究了pH对可交换NH _4〜+脱附，孔隙水扩散以及NH _4〜+，可溶性反应磷（SRP）和硝酸盐（NO _3〜（-4+）通过NH -3的通量）的影响。孔隙水和吸附的NH 4 +池同时形成水，高pH从上覆水逐渐渗透到沉积物中，促进了SRP的迁移以及总铵（NH _4〜+和NH _3）向孔隙水中的释放。 pH值，SRP的高沉淀水排泄量和总铵与硝化，反硝化和耗氧率的降低有关，碱性pH和NH _3的毒性可能抑制薄需氧区的硝化作用，同时限制了硝化-硝化的耦合作用。有限的NO _3〜-供应和高pH值进入厌氧区，地球化学对pH升高的反馈，例如增加溶解养分的释放和通过反硝化作用减少N _2的损失，可能会增强浅水生态系统中蓝藻水华的持久性。

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