Figure 3 should be here

3.3 Hydrogeological methods for denitriding

Fig. 4 showed the concentration distribution of O2, NO3- and DOC at typical moments of water level fluctuation under different K . When the hydrological connectivity was enhanced, the AR and DN reaction areas were significantly enlarged, which was corroborated by that all the solute plumes increased with the increasing K at any moment during the water level cycle. In Table 5, the corresponding denitriding amounts under different Kwere shown, which quantitatively indicated that the larger  was, the greater the denitriding capacity was. This was because the better hydrological connectivity  could increase the maximum aquifer water storage (Q max) (Table 5). AndM in-NO3 has positive correlation with Q max (e.g., Gu et al., 2012). During the water level cycle, when the K increased from 43.2m/d to 129.6m/d, M in-NO3 increased from 40.90g to 66.75g, the range of reaction (lateral coordinate) increased from x =10m to x =12m, M rem-NO3 increased from 6.34g to 8.46g, the maximum denitriding rate increased from 1.58g/d to 2.57g/d, while N rem-NO3 decreased from 15.5% to 12.7% (Table 5).
By comparing case 13, 14 and 15, the range of each solute plume increased with the increase of i . During the water level regression period, each solute plume did not shrink, but continued expanding (concentration distribution picture was omitted), which indicated that the consumption of solute through chemical reactions was smaller than solute being carried from the river induced by the hydraulic gradient between surface water and groundwater. During the water level cycle, the range of reaction (lateral coordinate) increased from =10m to  =16m,M rem-NO3  increased from 6.34g to 35.89g, the maximum denitriding rate increased from 1.58g/d to 2.18g/d, whileN rem-NO3 reduced from 5.5% to 13.6% (Table 5 ). It could be found that the maximum denitriding rate had no significant change with the change of i , and the influence of i onM in-NO3 , M rem-NO3 and the reaction range were much greater than that of  on them.