| Frequent appearance of “water blackening and stink” in city water makes contaminant enrichment to form a black mud in the sediment.Accumulation of pollutants will be released into the overlying water and continues to pollute the water.Although the dredging effect is significant,but the dredging sediment volume is large.The high costs of transportation and processing become the technical bottleneck of sediment dredging.Utilization of water sediment for green plant cultivation and improved soil fertility has a good development prospect.The feasibility of black smelly sediment in plant greening was studied in this paper,which lays the theoretical and practical basis for the final treatment and resource realization of dredging black smelly sediment.Physical and chemical properties of the black smelly sediment dredged were analyzed,then used for planting herbs,flowers.The growth rate of plants,total nitrogen(TN),total phosphorus(TP),available nitrogen(AN),available phosphorus(AP)and other indexes of soil were analyzed.The effect of pollutant removal from black smelly sediment during greening cultivation and promotion of greening plant growth were explored.The main conclusions are as follows:1)Black smelly sediment is more suitable for plant cultivation.The average bulk density of the sediment is 0.64g/ml,which is close to the ideal soil bulk density(0.5g/ml).Gravel: coarse sand: medium sand in the sediment is 3: 4: 12,belonging to the grain gradation Cu9,the sediment gradation is continuous and the particle size is uniform;The average moisture content of sediment is 91%,which is 41% higher than that of common soil and has strong water supply capacity.The black smelly sediment with the pH 7.4-7.7,presenting weakly alkaline,meet requirements of green soil.The content of organic matter(?20g/kg)in sediments is far higher than that of first grade greening,which can promote plant root development and form agglomerate structure to improve soil properties.The average TN content 59.201g/kg and the average AN 0.098g/kg in the sediment were 11.491 times and 6.533 times higher as that of the common soil.The average value of AP 0.554g/kg and TP 0.013g/kg were 1.065 times and 1.181 times higher as that of common soil,nitrogen fertilizer and phosphate fertilizer have the advantages of high storage potential,high utilization rate and good fertilizer efficiency.2)The grass germination rates of planting green plants in black smelly sediment are higher at room temperature(18?-22?)environment for single grass planting was higher than that of mixed cultivation.Black smelly sediment silt is beneficial to Zoysia matrella,Zoysia matrella and Zoysia matrella.When the ratio of muddy water was less than 50%,the germination rate of the flower plant was higher than that of the mixed soil.When the proportion of the muddy water was more than 50%,the germination rate of the mixed soil was higher than that of the muddy water.The growth rate of the whole black smelly sediment cultivation group was the fastest in 30-40 days after germination(the plant height increased by 9.61% daily),reached the rapid growth period at 60-70 days(Plant height average daily growth of 7.04%)and the rapid growth period(5.21% of the plant height increased)was 50-70 days.The height,branch number and appearance of Adonis aestiva cultivated with mixed soils and mud watering with 60% sediment were better than that with other proportions.Adonis aestiva plants cultured with mixed soils is the best.It is suggested that the soil mixing method can make the nitrogen and phosphorus elements in the soil more easily absorbed by plants.3)The results showed that removal efficiency of organic matter with singlespecies planting was better than that of mixed-species cultivation.The average removal rates of organic matter,TN,AN,TP and AP with single-species grasses were 49.91%,52.67%,44.80%,75.95%,50.33%,respectively;those with mixed-species planting were 31.37%,39.27%,36.05%,60.34%,28.07%,respectively.It is proved that the single-species planting has better effect on the pollution removal in the black smelly sediment,the effect of Zoysia matrella(L.)Merr grass on the removal of organic matter(58.20%),TN(64.55%),AN(52.66%)and AP(61.39%)was perfected,Festuca elata Kengex E.Alexeev had good effect on TP(86.58%)removal.TN content in sediment accounted for 60%(C5)mixed soil which was used for planing Adonis aestiva is decreased than the initial value by 7.44%.AN(C5)decreased by 75.21% compared with the initial value and it is the best use of absorption and utilization;The release of P element in black smelly sediment is similar to that of Adonis aestiva development,and the optimal growth rate of Adonis aestiva can be ensured.Black smelly sediment are used to grow Adonis aestiva,the reduction rate(Average 88.55%,56.52%)of TP was lower than that of common soil(92.75%,61.92%),indicating that the removal efficiency of TP and AP was lower than that of common soil during the(Adonis aestiva)planting process.4)The correlation coefficients between growth height of plant different grasses and contents of organic matter,TN,AN,TP and AP in black smelly sediments were-0.882,-0.910,-0.940,0.905 and 0.932,respectively,with significant correlation.The correlation between Festuca elata Kengex E.and TN(R2 = 0.895)and TP(R2 = 0.895)were the highest,and Zoysia matrella L.had the greatest effect on AN(R2 = 0.979)in sediment,and the removal efficiency of AP was better(removal rate 61.39%).The effect of mixed grass(R2 = 0.659)on the organic matter in the sediment was less than that of the single grass,single-species planting is beneficial to the utilization of black stalk.Therefore,the growth status of different grass can be used as the main judgment indicators of the changes of organic matter,TN,AN,TP and AP in black smelly sediments.Planting flower plants in different utilization of black smelly sediment.The B5 g roup with the cultivated soil of regularly watered 60% of the proportion of black smell y muddy water and C5 with cultivated soil of mixing by 60% proportion of black sme lly sediment with ordinary soil organic matter and in the both groups,the significant l evels of organic matter,TN,AP and Adonis aestiva growth are more than 0.05,and th ere was no significant correlation with the growth of TP and AN in soil matrix.The co rrelation coefficients between AN and plant growth height were-0.942 and-0.855 respectively when the total black smelly sediment and 60% mixed with black s melly sediment and ordinary soil,which is high intensity correlation. |
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