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The study area, Kuttanad Waters is a part of the Cochin estuarine system on the west coast of India. Kuttanad is well known for its agricultural activity and so the major contribution to the inorganic ions of nitrogen will be from fertilisers applied in agriculture. Based on observed salinity the stations have been divided into three zones. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. The chemical speciation scheme applied here distinguishes three forms of ammoniacal nitrogen species: exchangeable, fixed, and organic ammoniacal nitrogen. No significant trends were observed in the seasonal distribution of total, exchangeable, fixed and organic nitrogen. A significant concentration of exchangeable ammonia was observed in the sediment due to their predominantly reducing environment, which restricts nitrification. High NH4-N concentrations in the pore waters, along with the sedimentary composition leads to a significantly high quantity of fixed NH4-N. The low values for N org is due to high mineralisation or deamination of organic nitrogen 相似文献
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The internal nutrient load from bottom sediment to the water column of a Louisiana Barataria Basin lake (Lake Cataouatche) receiving diverted Mississippi River water was determined. Dissolved reactive phosphorus (DRP), ammonium (NH4-N) and nitrate (NO3-N) flux from sediment to water column were measured. The DRP flux averaged-0.22 mg m-2 d-1 under aerobic water column conditions, as compared with that 3.29 mg m-2 d-1 under anaerobic conditions. The average NH4-N released under anaerobic conditions (1.42 mg m-2 d-1) was significantly greater than rates under aerobic conditions (-0.02 mg m-2 d-1), indicating a strong relationship between nutrient flux and oxygen availability in the water column. The average NO3-N flux was 2.13 mg m-2 d-1 under aerobic conditions as compared with-0.24 mg m-2 d-1 under anaerobic conditions in the sediment-water column. When the water column maintained under anaerobic conditions was switched to aerobic conditions, the DRP, NH4-N, and NO3-N concentrations in overlying water decreased rapidly over a short period of time. The mean annual internal DRP and NH4-N load from the sediment to the overlying water was estimated to be 69.26 and 29.9 tonnes (Mg) yr-1 respectively, which represents a significant portion of the total nutrient load to the Lake. Results demonstrate that the internal flux of nutrients from sediments can contribute a significant portion of the total nutrient load to the water column and should be considered in decisions on impact of nutrient in diverted Mississippi River on water quality of Barataria Basin. 相似文献
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Luxi Zou Huaibo Li Shuo Wang Kaikai Zheng Yan Wang Guocheng Du Ji Li 《Frontiers of Environmental Science & Engineering》2019,13(6):83
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The efficiency of microalgae in removing various pollutants in landfill leachate after pretreatment by free stripping or air stripping was tested by a laboratory batch system. The results showed that Chlorella pyrenoidosa and Scenedesmus sp. had similar removal efficiencies with regard to ammoniacal‐nitrogen, oxidized‐nitrogen, orthophosphate and chemical oxygen demand (COD). The COD removal by algal treatment was better in Junk Bay (JB) leachate than in Gin Drinkers’ Bay (GDB) leachate (14–21% and 0.4–7% respectively). No significant difference (P > 0.05) was found in removing other nutrients including ammoniacal‐nitrogen, oxidized‐nitrogen and orthophosphate between leachate from the two landfills, regardless of the pretreatment used. The removal efficiencies of ammoniacal‐nitrogen and phosphorus were found to be higher in air‐stripped leachate than in free‐stripped one. Removal of ammoniacal‐nitrogen and phosphorus in air‐stripped leachate was 30% and 87% respectively. Poor removal of ammoniacal‐nitrogen was probably due to a deficiency in phosphorus (high N : P ratio) for algal growth in leachate. The two‐stage leachate treatment (ammonia stripping followed by algal purification) resulted in overall reduction of COD (38–51%), ammoniacal‐nitrogen (72–96%) and orthophosphate (79–96%). 相似文献
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Liyun Song Shilin Deng Chunyi Bian Cui Liu Zongcheng Zhan Shuangye Li Jian Li Xing Fan Hong He 《Frontiers of Environmental Science & Engineering》2023,17(8):96
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Hong YAO Shichao ZHANG Xiaobo XUE Jie YANG Kelin HU Xiaohua YU 《Frontiers of Environmental Science & Engineering》2013,7(2):273-280
Increasing shortages of fresh water has led to greater use of treated wastewater for irrigation of crops. This study evaluates the spatial variability of soil properties after irrigation with wastewater and freshwater. Geostatistical techniques were used to identify the variability of soil properties at the different sites. A set of physical and chemical soil properties were measured including total nitrogen (TN), total phosphorus (TP), organic matter (OM) and soil moisture. The TN concentration levels varied from 567 to 700 mg·kg-1, while OC levels ranged from 7.3 to 16.3 mg·kg-1 in wastewater-irrigated zones. The concentration levels of TP were between 371.53 and 402.88 mg·kg-1 for the wastewater-irrigated sites. Wastewater irrigation resulted in higher TN, TP and OM concentrations by 18.4%, 8% and 25%, respectively. The highest TN and OM occurred along the wastewater trunk. It was also observed that nitrogen concentrations correlate with the soil's organic matter. The increase of salinity may be associated with the increase of pH, which might suggest that a reduction of pH will be beneficial for plant growth due to the decrease of salinity. The average concentrations of nitrogen in topsoil were higher than those in subsurface soils in irrigated areas. Such differences of the N profile might be due to variations in organic matter content and microbial populations. Consistent with TN and OM, soil C:N decreased significantly with an increase of depth. This phenomenon possibly reflects a greater degree of breakdown and the older age of humus stored in the deeper soil layers. The analysis of pH levels at different depths for the three sites showed that pH values for wastewater irrigation were slightly lower than the controlled sites at the same depths. 相似文献
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Quanli Man Peilian Zhang Weiqi Huang Qing Zhu Xiaoling He Dongsheng Wei 《Frontiers of Environmental Science & Engineering》2022,16(6):69
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Zhenfeng Han Ying Miao Jing Dong Zhiqiang Shen Yuexi Zhou Shan Liu Chunping Yang 《Frontiers of Environmental Science & Engineering》2019,13(4):52
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An incubation experiment lasting 111 d was carried out to study the effect of the addition of three clay minerals (Na-bentonite, Ca-bentonite, and zeolite) to soil derived from sewage sludge on water-extractable and exchangeable forms of four heavy metals (Zn, Cd, Cu, and Ni), as well as on soil organic matter mineralization, microbial biomass C and the release of inorganic N. The addition of clay minerals led to a significant decrease in water-extractable and exchangeable forms of heavy metals. The extent of decrease ranged from 14 to 75% for the water-extractable heavy metals and from 12 to 42% for the exchangeable form over the incubation time, as compared with untreated soil. The reduction in extractability of heavy metals was greater due to the addition of Na-bentonite and Ca-bentonite than that due to the addition of zeolite. Addition of clay minerals did not affect any of the following microbiological parameters in the soil: microbial biomass C, organic C (Corg) mineralization, and metabolic quotient (qCO2), and release of inorganic N during the first 3 weeks of incubation. However, as the incubation period increased, these parameters were significantly increased by the addition of clay minerals, especially by the addition of Na-bentonite and Ca-bentonite. This result is explained by a strong reduction in extractability of heavy metals after the addition of Na-bentonite and Ca-bentonite. 相似文献
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氨(NH3)挥发是农业生态系统氮肥损失的重要途经,然而,北方干旱半干旱地区水肥耦合马铃薯田土壤NH3挥发规律缺少数据支撑.该研究利用通气法田间原位观测我国西北滴灌水肥一体化和传统沟灌施肥马铃薯田水肥耦合土壤NH3挥发特征,设置滴灌施肥500 kg·hm-2(DDF)、滴灌施肥1000 kg·hm-2(DGF)、滴灌不施肥(DCK)、沟灌施肥500 kg·hm-2(FDF)、沟灌施肥1000 kg·hm-2(FGF)、沟灌不施肥(FCK)6个处理.结果表明,NH3挥发速率峰值出现在施用氮肥后1—2周,不同水肥处理土壤NH3挥发存在显著差异(P<0.01).2018年DDF、DGF、DCK、FDF、FGF、FCK土壤NH3累积挥发量分别为21.50、28.14、7.20、37.06、66.25、11.88 kg·hm-2;2019年,分别为9.42、15.25、7.24、34.73、76.81、8.56 kg·hm-2.2018年和2019年,沟灌FDF处理的NH3挥发损失率分别是滴灌DDF处理的1.76倍和11.89倍;沟灌FGF处理分别是滴灌DGF的2.60倍和8.54倍.滴灌DGF处理NH3挥发强度比滴灌DDF处理分别增加27.03%和52.94%,沟灌FGF处理比沟灌FDF处理分别增加76.04%和118.37%.随施肥量增加,传统沟灌马铃薯田土壤NH3挥发损失率和NH3挥发强度的增量高于滴灌水肥一体化模式.NH3挥发速率与土壤体积含水量、NH4+-N和NO3--N呈极显著相关(P<0.01).和传统沟灌比较,滴灌水肥一体化技术降低马铃薯田土壤NH3挥发损失率,减轻NH3挥发强度,提高马铃薯水肥利用率,减轻环境污染. 相似文献
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Crude-oil-inundated soils were collected from the Agbada oil field in the Niger Delta region of Nigeria 2 months after the recorded incidence of oil spillage. The soils were taken on the second day of reconnaissance from three replicate quadrats, at surface (0-15 cm) and subsurface (15-30 cm) depths, using the grid sampling technique. The total extractable hydrocarbon content (THC) of the polluted soils ranged from 1.24 × 102 to 3.86 × 104 mg/kg at surface and subsurface depths (no overlap in standard errors at a 95% confidence level). Greenhouse trials for possible reclamation were later carried out using 10-100 g of (NH4)2SO4, KH2PO4 and KCl (NPK) fertilizer as nutrient supplements. Nitrogen as NO3-N and potassium were optimally enhanced at 2% (w/w) and 3% (w/w) of the NPK supplementation, respectively. Phosphorus, which was inherently more enhanced in the soils than the other nutrients, maintained the same level of impact after treatment with 20 g of NPK fertilizer. Total organic carbon (%TOC), total organic matter (%TOM), pH, and percentage moisture content all provided evidence of enhanced mineralization in the fertilizer-treated soils. If reclamation of the crude-oil-inundated soils is construed as the return to normal levels of metabolic activities of the soils, then the application of the inorganic fertilizers at such prescribed levels would duly accelerate the remediation process. However, this would be limited to levels of pollution empirically defined by such THC values obtained in this study. 相似文献
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Zhiqiang Chen Lizhi Zhao Ye Ji Qinxue Wen Long Huang 《Frontiers of Environmental Science & Engineering》2019,13(4):54
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Yanfei Wang Xiaona Zheng Guangxue Wu Yuntao Guan 《Frontiers of Environmental Science & Engineering》2023,17(6):74
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长春市土壤微生物生化作用与重金属化学形态关系研究 总被引:2,自引:0,他引:2
研究了长春市土壤微生物的生化作用强度(氨化作用强度、固氮作用强度,纤维素分解强度和土壤基础呼吸)与重金属(Pb、Cd、Cu、Zn和Ni)化学形态的关系。通过科学采样和实验室测试分析了不同功能区土壤中,重金属含量和化学形态与微生物生化作用强度,并使用相关分析、偏相关分析多种数据统计方法进行数据处理。结果表明:各功能区因土地利用方式的差别和土壤中重金属的各种化学形态对土壤微生物生化作用强度有不同的影响。其中氨化作用与交换态Cd、Zn和Ni含量呈显著正相关;固氮作用与土壤重金属各化学形态相关性均不显著;呼吸作用与铁锰氧化物结合态Pd和交换态Cu呈显著正相关;纤维素分解作用强度与交换态Pd含量呈显著负相关。在土壤理化性质等相关变量受控时,重金属化学形态对微生物生化作用强度的影响有较明显的变化。其中与无控制变量相比,在控制变量作用下,纤维素分解作用强度受交换态Pd影响上升了0.0314,表现为交换态Pd抑制纤维素分解作用强度。呼吸作用与交换态Pd的相关系数在无控制因素情况下为-0.1425,在有控制因素情况下为-0.3230,表明交换态Pd促进呼吸作用强度。而有机结合态Ni表现为抑制固氮作用。因此可利用交换态Pd与纤维素分解作用强度、呼吸作用强度的相互关系,有机结合态Ni与固氮作用的相互关系等相结合来评价城市土壤重金属污染状况。文章为评价长春城市土壤重金属污染提供了微生物学指标的理论依据。 相似文献
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Tingwei Gao Kang Xiao Jiao Zhang Wenchao Xue Chunhai Wei Xiaoping Zhang Shuai Liang Xiaomao Wang Xia Huang 《Frontiers of Environmental Science & Engineering》2022,16(4):49
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五指山不同海拔高度的土壤化学性质特征 总被引:4,自引:0,他引:4
根据海南省五指山2003年土壤样品的分析结果,对不同海拔高度下五指山土壤的化学性质特征进行了分析。结果表明,在不同海拔高度下水提pH和盐提pH随采样深度的增加基本呈明显的增大趋势,交换性H 、CEC、全N和有机质随采样深度的增加基本呈明显的下降趋势;而交换性Al3 和交换性酸除在720m、894m处剖面外,其它海拔高度下也基本随采样深度的增加而明显降低。从化学过程较为活跃的表层土壤来看,水提pH、盐提pH、交换性H、交换性Al3 和交换性酸随海拔高度的增加并没有明显的同时增大或减小的分布规律,而CEC、全N和有机质有明显的增加趋势。 相似文献