Abstract
Reduced nitrogen (N) and phosphorus (P) released from sediments in rural areas pose a significant challenge to residential sewage treatment and management. Under different disturbance velocities, simulation experiments were undertaken to investigate the effect of disturbance on the release of N and P from rural ditch sediments into the water at the water-sediment interface. No significant difference in the release characteristics of N and P was found among different disturbance velocities. The release fluxes of TN and NH4+-N in the non-disturbance water body were significantly higher than in the disturbance water body, which suggests that increasing water flow influences the release of TN and NH4+-N from sediment into the water. The release fluxes of TP and PO43--P were significantly lower in non-disturbance than the disturbance water body, which suggested that disturbance increased the release of TP and PO43--P in sediments. For both disturbance and non-disturbance conditions, TN and NH4+-N in the sediment were rapidly released into the water body at 0-10 days, and TP and PO43--P steadily rose in the disturbance water body until stabilizing after 20 days. TN, NH4+-N, TP, and PO43--P concentrations all had a negative correlation with DO, and the correlations between TN and NH4+-N were substantial. The percentages of a certain N or P speciation fraction in sediments did not alter between disturbance and non-disturbance conditions, implying that disturbance had no effect on N or P speciation.
Highlights
The cycle of nitrogen (N) and phosphorus (P) in nature is of critical importance because they are essential nutrient elements in the ecosystem
Total phosphorus (TP, 5.91 g.kg-1) in sediments exceededNesslwera’ss ervealgueanttedsptehcrtereopthimoteosm, aentrdy t(hWearnegsu<sWarue2p0r1e6se).nEteadchassample w the threshold effect concentrations (TN, 2 g·kg-1; total phosphorus (TP), 4.8 g·kgt-he reasvuelrtasgaerevaplrueesse.nTtehdeansitarvoegreangienvaalllutehse.sTehdeimneitnrot sgaemn pinleaslwl tahse sedimen 1) for toxic biological effects, which indicated that N and P fractionated as ion-exchanged form nitrogen (IEF-N), weak have potential ecological risks, and their potential ecologicailon-eaxccihdanexgterdacftoarbmlenfiotrromgennit(rIoEgFe-nN()W, wAeEakF-aNc)id, setxrotrnagctaablklealfionrem nitroge risk assessment is needed for extended discussion
Previous studies have shown that nitrogen and phosphorus release in the water-sediment interface is influenced by many factors, such as temperature, pH, DO, body, suggesting that the disturbance increased the release of TP and PO43--P in sediments
Summary
The cycle of nitrogen (N) and phosphorus (P) in nature is of critical importance because they are essential nutrient elements in the ecosystem. In this study, disturbed simulation experiments were used to explore the release characteristics of N and P in the water-sediment interface and their effect on the different disturbance velocities of N and P concentrations of rural ditch sediment into the water.
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