持续充氧对养殖池塘上覆水—泥水界面—沉积物间隙水中离子垂直分布的影响

为研究底部充氧对养殖系统上覆水—泥水界面—沉积物间隙水中离子垂直分布的影响,在室内条件下构建模拟装置,设充氧组(实验组)和未充氧组(对照组),每组4个平行,利用Peeper技术分别采集各装置中第0、1、4和7天,上覆水—泥水界面—沉积物间隙水整个垂直剖面的原位水样,然后应用微量分光光度法测定样品中的NH_4~+-N、NO_3~-N、NO_2~--N、PO_4~(3-)-P和SO_4~(2-)-S浓度。结果显示:(1)短期充氧对NH_4~+-N在上覆水和沉积物间隙水中的垂直分布特征影响不显著;(2)充氧可使沉积物上覆水和表层沉积物(0~2 cm间隙水中的NO_3~--N浓度大幅升高;(3)硝化作用的中间产物NO_2~--N,由于不能和氧气大量共存,其平均浓度的最大值由未充氧前出现在上层上覆水,逐渐转变为在表层沉积物1 cm深处;(4)充氧促进了沉积物对PO_4~(3-)-P的吸附和固定,显著降低了其在上覆水和表层沉积物(0~2 cm)间隙水中的浓度;(5)充氧通过化学和生物途径氧化了系统中还原性含硫物质,大幅升高了上覆水和表层沉积物(0~2 cm)间隙水中的SO_4~(2-)-S的浓度;(6)主成份分析(PCA)表明,持续充氧1、4和7 d显著改变了上覆水的理化性质,其中第4天和第7天的数据与对照组差异最大,相对于上覆水,充氧对沉积物间隙水的总体影响不显著。研究表明,底部充氧可降低引起池塘富营养化PO_4~(3-)-P的浓度,提高了氧化性离子NO_3~--N、NO_2~--N和SO_4~(2-)-S的浓度,显著改变了上覆水和表层沉积物间隙水的理化性质,是养殖池塘水质调控和环境修复的一种有效方法。

Effect of aeration on vertical distribution of the ions in overlying and interstitial waters of microcosms paved with aquaculture sediment

In order to study the effect of aeration on vertical distribution of the ions in overlying and interstitial waters in aquaculture systems, we constructed 8 plexiglass microcosms paved with aquaculture sediment, including 4 tests with continuous aeration and 4 controls without aeration. Intact overlying and interstitial waters were collected by Peeper (pore water equilibriums) devices on the days of 0, 1, 4 and 7 respectively, before and after initiating the aeration. The ions of NH4+-N, NO3--N, NO2--N, PO43--P and SO42--S were measured by miniaturized photometrical methods using a microplate reader. The result showed that one week aeration didn't significantly change the vertical distribution of NH4+-N in interstitial and overlying waters, but it greatly increased the concentration of NO3--N in overlying and 0–2 cm interstitial waters. The highest average concentration of NO2--N presented in surface layer waters before the aeration, while it peaked in the surface sediment interstitial waters at the depth of 1 cm during the aeration. The aeration promoted the adsorption and immobilization of PO43--P in the sediment, greatly decreased the concentration of PO43--P in overlying and 0–2 cm interstitial waters. The concentration of SO42--S in overlying and 0–2 cm interstitial waters was significantly increased by oxidizing reducible sulfur in biological and chemical path. The physicochemical property of the overlying water on 1 d, 4 d, 7 d was greatly changed, which distanced farthest away from the control group, suited at the bottom of the PCA image. On the contrary, it didn't distinctively chang the property of the sediment interstitial waters, which suited at the left site of the PCA image. In conclusion, aeration conditions can elevate oxidative ions of NO3--N, NO2--N and SO42--S, and reduce the ions of PO43--P which can cause eutrophication. It greatly changes the physicochemical property of the overlying water and surface sediment interstitial waters, which is an applicable method to control aquaculture pond water quality and remediate sediment.