Stable isotope dynamics of nitrogen sewage effluent uptake in a semi-arid wetland

Our objectives were to determine (1) how much N is transferred into the food web via plants from a wetland receiving not only inputs of treated sewage effluent, but also containing contaminants such as polychlorinated biphenyls (PCBs), (2) how birds, as consumers, utilize exogenous N and uptake PCBs in relation to the food web of the wetlands, (3) the feasibility of using isotopic analysis in estimating trophic levels in a semi-arid system. Our results demonstrate that there is very high spatial variability in the N isotopic composition of primary producers. Birds had lower variability in delta15N, despite feeding at multiple trophic levels. In very high spatial variability in delta15N of primary producers, it is difficult to use N isotope techniques to define trophic levels relevant to the bioaccumulation of organic pollutants, but it is possible to track the flow of exogenous N through the food web.     

不同水溶肥配方对部分白菜品质及土壤性质的影响

本试验以白菜为试验材料,清水为对照探索了5种水溶肥配方对白菜品质及土壤性质的影响。结果表明,与对照相比,配方4处理的白菜Vc含量最多,配方1次之,分别较对照增加了210%、193%,硝酸盐含量除配方3和配方5外,其他处理均小于432 mg/kg,在安全范围内;5种水溶肥均能在一定程度上改善土壤p H值和电导率,配方1土壤碱解氮和有效磷含量最高,分别为327.8 mg/kg和118.23 mg/kg,参照菜园土壤有效养分丰缺状况的分级标准,土壤氮、磷含量过高,可能会对周边的水环境造成污染。     

武宜运河小流域平原河网地区氮磷污染来源解析

采用源解析法对工业污染源、生活污染源、农业面源(含种植业、养殖业)进行分析,并统计分析了武宜运河全线水质现状。结果表明,农业面源是武宜运河流域总氮、总磷污染的主要来源,且以养殖业为主,生活污染源是太湖流域氨氮污染的主要来源,且以农村生活污水为主;武宜运河水质以氮磷污染为主,总氮污染最为严重。武宜运河核心区研究范围占总研究范围的比例为35%,总氮、氨氮和总磷入河量分别占研究范围内各类污染物总入河量的42.8%,45.0%,34.1%,污染分布重点区域为武进前黄镇、牛塘镇及宜兴和桥镇所辖行政村。研究范围内农业面源污染分布重点区域为武进前黄镇、牛塘镇、宜兴屺亭街道及和桥镇;生活污染源氮磷污染物排放主要来自高新区及牛塘镇的农村生活污水排放,其次是屺亭街道和前黄镇的农村生活污水。     

硫素对水稻根系铁锰胶膜形成及吸收镉的影响

添加外源镉污染水稻土进行池栽试验,施入不同形态及数量的硫肥(单质硫、石膏),研究硫素对水稻根系铁锰胶膜的形成及对水稻吸收镉的影响.结果表明,整个水稻生育期内,土壤溶液Eh范围在-200~100 m V之间;p H在6.9~7.9之间;pe+p H在4~10之间.水稻根表胶膜以Fe膜为主,其质量分数达到5 000~13 000 mg·kg-1,Mn膜的质量分数相对较小,为170~580 mg·kg-1.在孕穗期高硫量处理与低硫量处理的铁胶膜质量分数分别为9 400 mg·kg-1和8 600 mg·kg-1,高硫量处理比低硫量处理可生成更多的铁胶膜;而根表锰胶膜的数量差异主要表现在分蘖期,单质硫和石膏硫处理的锰胶膜质量分数分别为600 mg·kg-1和400 mg·kg-1,达到显著差异水平,单质硫比石膏硫更易促进水稻根表锰胶膜的形成.胶膜对于Fe2+过量吸收有一定阻控作用,对Mn2+作用不显著.水稻根表胶膜吸附Cd的质量分数在分蘖期为78.8~131.1 mg·kg-1,孕穗期16.6~21.1mg·kg-1,成熟期3.0~9.2 mg·kg-1.在分蘖期与孕穗期,高硫量处理比低硫量处理的吸附量高,在成熟期反之.采用ACA方法浸提铁锰胶膜内的Cd测定值并不能真实地表明胶膜实际固定Cd的质量分数.水稻体内各部位Cd的质量分数表现为根茎叶籽粒.一定量的施硫能有效减少水稻各器官中Cd的质量分数.对于根和茎叶,单质硫在成熟期以前效果好于石膏硫;对于籽粒,石膏硫效果更佳.一定量的硫肥,能有效阻碍Cd从水稻根部向茎叶与籽粒的转移.对于茎叶,在孕穗期单质硫和石膏硫的Cd转移系数分别为0.13和0.25,差异显著,单质硫能更好地阻碍Cd的转移;对于籽粒,石膏硫的阻碍效果更好.     

磷酸铵镁沉淀法处理制药废水试验研究

制药废水由于制药原料化学纯度较高,废水中常含高浓度氮、磷污染物,采用磷酸铵镁沉淀法可同时回收两种元素不仅可以有效同时去除两种污染物,而且可以得到附加值较高的磷酸铵镁盐,因此本研究用磷酸铵镁化学沉淀法小试实验处理制药废水,讨论了磷酸铵镁沉淀法pH、晶种、初始浓度对P0^3- 4和NI-14同时去除的影响。试验结果表明：投加镁盐,在pH=9．5的条件下,可去除90％PO^3- 4,同时可去除15％NH4,在Po^-3 4和NH4浓度较低时,投加晶种可使Po;一去除率提高20％,该法渴望为制药废水处理提供创造经济效益的经验。     

巢湖水质与流域农业投入的关联性研究

为探讨巢湖富营养化与流域农业生产投入资源的关联性,选择了化肥剩余、节水灌溉面积、农膜、水土流失治理等可能影响水体富营养化的因子;研究中采用相关分析与逐步回归的方法,同时,提出了一种结合Technique for Order Preferenceby Similarity to Ideal Solution(TOPSIS)法计算化肥剩余量的方法.结果表明,巢湖流域农业生产投入的各种资源中,对巢湖水体富营养化影响较大的是化肥剩余、节水灌溉面积和农膜,并且化肥剩余的影响还存在1 a的滞后期.因此,有必要从提高化肥利用效率、改进灌排水方式并减少农业用水入手,以求节约资源,同时降低农业生产对巢湖水质的影响.     

生物炭和有机肥对华北农田盐碱土N2O排放的影响

基于山东滨州地区冬小麦-夏玉米轮作大田试验,探究了施用生物炭和有机肥对夏玉米季土壤氧化亚氮(N_2O)排放的影响,为盐碱土壤N_2O增汇减排提供理论依据.试验按照不同处理氮、磷、钾含量相同原则,设置对照CK[N:0.2t·(hm~2·a)~(-1),P_2O_5:0.12 t·(hm~2·a)~(-1),K_2O:0.2 t·(hm~2·a)~(-1)]、C1[5 t·(hm~2·a)~(-1)生物炭]、C2[10 t·(hm~2·a)~(-1)生物炭]、C3[20 t·(hm~2·a)~(-1)生物炭]、M1[7.5 t·(hm~2·a)~(-1)有机肥]、M2[10 t·(hm~2·a)~(-1)有机肥]这6个处理.结果表明,施加生物炭和有机肥对土壤N_2O排放影响趋势基本一致,排放高峰均出现在施肥(基肥和追肥)后,累积排放量占整个生育期排放量的近一半;与CK相比,C1、C2分别降低N_2O排放的45.3%、31.6%,而C3、M1、M2分别增加了17.3%、37.4%、27.6%.施加生物炭和有机肥均会对土壤N_2O排放产生影响,施加生物炭可以降低N_2O排放,而施加有机肥则促进了N_2O排放.因此,生物炭对减少农田N_2O排放具有巨大潜力.     

缓控释肥侧深施对稻田氨挥发排放的控制效果

以减少氨挥发损失为目的,以无机化肥分次施用为对照,选用树脂包膜尿素(RCU)、硫包衣尿素(SCU)和掺混控释肥(RBB)3种不同类型缓控释肥料,采用一次性施肥(B)和一基一穗(BF)2种施肥方式,研究了插秧施肥一体化条件下不同类型缓控释肥侧深施及施用方式对稻田田面水氮浓度及氨挥发损失的影响.结果表明,除SCU处理基肥期田面水总氮和铵态氮质量浓度均高于常规分次施肥处理CN,RCU和RBB处理均低于CN处理.不同缓控释肥料稻田氨挥发损失差异较大,损失量占施肥量的3.84%~28.17%.与CN处理相比,不同类型缓控释肥料均有减少稻田氨挥发损失的效应,处理间氨挥发损失量表现为:CN、B-SCUBF-SCU、BF-RBB、BF-RCU、B-RBB、B-RCU.一次性基施下,B-SCU处理的氨挥发总量显著高于B-RCU和B-RBB处理,一基一穗下3种处理间氨挥发总量差异不显著.不同肥料在2种施肥方式下氨挥发损失量差异不显著,但表现不一致.BF-SCU处理的氨挥发损失量低于B-SCU处理,BF-RCU和BF-RBB处理的氨挥发损失量分别高于B-RCU和B-RBB处理.阶段氨挥发损失来看,施用SCU处理的基肥-蘖肥(7.54%)和蘖肥-穗肥阶段(16.04%)的损失较高,RBB处理的基肥-蘖肥阶段氨挥发损失(2.91%)明显增加,而RCU处理的穗肥后阶段(2.75%)是氨挥发损失的集中时期.追施穗肥尿素增加了穗肥后阶段的氨挥发排放损失,穗肥后阶段氨挥发量与田面水铵态氮质量浓度在不同类型肥料间无明显相关关系.     

An innovative wood-chip-framework substrate used as slow-release carbon source to treat high-strength nitrogen wastewater

Removal of nitrogen in wastewater before discharge into receiving water courses is an important consideration in treatment systems. However, nitrogen removal efficiency is usually limited due to the low carbon/nitrogen (C/N) ratio. A common solution is to add external carbon sources, but amount of liquid is difficult to determine. Therefore, a combined wood-chip-framework substrate (with wood, slag and gravel) as a slow-release carbon source was constructed in baffled subsurface-flow constructed wetlands to overcome the problem. Results show that the removal rate of ammonia nitrogen (NH₄⁺-N), total nitrogen (TN) and chemical oxygen demand (COD) could reach 37.5%–85%, 57.4%–86%, 32.4%–78%, respectively, indicating the combined substrate could diffuse sufficient oxygen for the nitrification process (slag and gravel zone) and provide carbon source for denitrification process (wood-chip zone). The nitrification and denitrification were determined according to the location of slag/gravel and wood-chip, respectively. Nitrogen removal was efficient at the steady phase before a shock loading using slag-wood-gravel combined substrate because of nitrification–denitrification process, while nitrogen removal was efficient under a shock loading with wood-slag-gravel combined substrate because of ANAMMOX process. This study provides a new idea for wetland treatment of high-strength nitrogen wastewater.