不同施肥模式调控沿湖农田无机氮流失的原位研究——以南四湖过水区粮田为例

为探索山东南四湖沿岸麦玉轮作区玉米季内减少土壤无机氮素淋溶和径流损失的施肥策略,降低其对湖区水质产生的潜在威胁,采用田间原位安装淋溶水采集器和地表水径流池收集水样结合室内分析不同形态氮含量的方法,研究了不同施肥模式下无机氮素淋溶和径流损失特征。结果表明：土壤淋溶水量及地表水径流量与降水呈显著正相关关系,其水量受秸秆类物质还田的影响;硝态氮(NO3--N)与铵态氮(NH4 -N)随地表水径流损失的浓度及总量均明显高于淋溶水,由径流方式损失的氮素占2/3以上,是氮素以水溶液形式流失的主要途径;淋溶和径流均以NO3--N损失为主(径流损失中NO3--N占总量的82.9%-90.8%,淋溶损失中NO3--N占63.5%-72.9%),地表径流水NO3--N浓度对水质有较大影响,但土壤淋溶水NO3--N浓度对地下水污染不构成威胁;农民习惯施肥处理在玉米整个生育期淋溶和径流氮损失最高。在保证玉米产量前提下,降低氮素流失造成湖区的污染,平衡施用氮磷钾肥、施用控释氮肥、有机替代无机和秸秆还田等措施均可在沿南四湖区农田使用。     

浑河上游不同类型农户氮负荷特征

选取浑河上游大伙房水库上游的小流域为研究区域,对农户氮素非点源污染特征进行了分析.根据氮素流动的特点,将农户分为养殖型农户、蔬菜种植户、传统种植户3种类型.氮素污染负荷顺序为:养殖型农户(348 ±76 kg·hm-2·a-1)＞蔬菜种植户(307±127kg·hm-2·a-1)＞传统种植户(213±126 kg·hm-2·a-1).不同农户农田氮损失量的大小顺序为:蔬菜种植户(256±21 kg hm-2·a-1)＞养殖型农户( 188±52 kg·hm-2·a-1)＞传统种植户(168±65 kg·hm-2·a-1).表明,该地区的蔬菜种植户、养殖型农户对水体质量影响较大,是氮素非点源污染重点防治对象.在农户氮排放中,居民生活排放的氮素占28%,农田氮损失占72%,说明农田是主要的氮污染源,但居民生活的氮素污染也不可忽视.该研究范围内最佳氮循环的临界值为395.5 kg hm-2·a-1,此时的总流动量是1883.3 kg·hm-2·a-1,氮素输出是376.7 kg·hm-2·a-1.     

养殖污水直灌对稻田土壤氮、磷积累与垂直迁移的影响

尽管国内外对养殖污水处理已提出了一系列的工艺技术,但因经济原因养殖污水直接灌溉农田在我国农村地区仍较为常见.为了解长期畜禽养殖污水直灌对稻田土壤质量的影响,在浙江省绍兴市柯桥区选择了养殖污水直灌不同年限(0、4、7、13年)的稻田,比较研究了养殖污水直接灌溉对稻田土壤不同深度土层中各形态氮和磷含量的影响,探讨了长期养殖污水灌溉对氮、磷在土壤剖面中垂直迁移的影响.结果表明: 长期养殖污水直接灌溉可显著提高稻田土壤中氮和磷的积累,积累量随灌溉年限的增长而增加,其中磷素的增幅高于氮素.养殖污水灌溉4、7和13年后,土壤表层中全P和全N分别比对照增加了43.6%、95.2%、1484%和7.7%、17.0%、28.4%.土壤氮素的变化为NH₄⁺-N、NO₃^--N>酸解有机氮>非酸解有机氮;土壤有效磷的变化明显大于全磷.长期养殖污水灌溉可促进氮、磷在土壤剖面中的垂直迁移,增加对地下水的污染风险.
     

施肥对太湖地区青紫泥水稻土稻季农田氮磷流失的影响

选取太湖东岸的青紫泥水稻土区,对常规施肥和不施肥条件下水稻季稻田氮、磷的流失进行了观测。结果表明:水稻种植季内田面水和降雨径流水中氮磷的浓度呈现前期高后期低的趋势,初期施肥之后的降雨流失使稻田水中氮磷浓度大幅度降低;整个水稻生长季稻田氮磷的流失总量分别达38.8和0.95kg.hm-2,且主要以田面水径流流失为主;氮素主要以水溶性的铵态氮流失,而磷素则主要为颗粒态流失。不施肥处理中稻田氮、磷流失分别是常规施肥处理的47%和60%;水稻生长初期降雨下的氮径流流失占整个水稻生长期的50%,磷素占33%。降雨事件下的流失是农田非点源污染的主要贡献期,因而应作为控制的关键因子;对于基础肥力高的水稻土可考虑轮流施肥以减少环境的氮、磷流失与水系污染风险。     

太湖地区典型水稻土稻-麦轮作地表径流中磷的变动规律

为了了解来自农田土壤径流磷浓度对太湖水体富营养化的贡献状况,采用田间小区试验的方法,研究了太湖地区安镇爽水型水稻土和常熟囊水型水稻土2000～2002年度磷素流失浓度变化及其原因。结果表明:太湖地区农田水稻土磷素流失的主要形态是颗粒态磷;施磷处理对地表径流磷浓度有显著影响;两种水稻土的径流中磷浓度呈现出随时间而降低的趋势;稻季土壤磷素流失的最大风险时期约在水稻移栽后一个月内,而麦季约在磷肥施用后1～2个月内;对于同期地表径流事件,囊水型水稻土径流中DP和TP浓度均高于爽水型水稻土;土壤类型对地表径流次数有明显的影响,并且随季节表现不同。     

太湖河网地区农村非点源氮负荷——以宜兴市大浦镇为例

采用野外试验与实地调查相结合,利用泥沙流失方程和GIS平台,定量估算了江苏宜兴市大浦镇农村非点源氮排放负荷.结果表明:大浦镇农村非点源氮排放负荷为207.0 t·a-1,其中农田、生活污水、养殖、垃圾和非农田泥沙流失的排放负荷分别为80.6、61.1、49.3、10.5和5.4 t·a-1,分别占39.0%、29.5%、23.8%、5.1%和2.6%;5种排放源中,农田、生活污水和养殖为优先控制因子;方钱、大浦、浦北和浦南4村平均氮排放负荷为80.4、73.0、60.4和52.3kg·hm-2·a-1,远高于其他区域,为优先控制区.     

汉江上游金水河悬浮物及水体碳氮稳定同位素组成特征

金水河位于南水北调中线工程水源地的汉江上游,研究其污染物来源及分布规律对水源地水资源保护尤为重要。研究了不同水文季节金水河中悬浮颗粒物C和N稳定同位素值、水体硝酸盐与铵盐含量及其N稳定同位素特征。结果表明:金水河流域可溶性氮素与悬浮颗粒物的来源具有明显的空间性和季节性差异,并且流域内叶绿素浓度、水体浊度、悬浮物浓度都会对河流碳氮素稳定同位素值造成影响,主要体现在环境因子的变化制约着水体中硝化和反硝化生物对氮素的可利用性。结果显示:1)水体中悬浮颗粒物的碳稳定同位素为-8.03‰-14.57‰,平均值为2.59‰;氮稳定同位素范围为-7.50‰-7.34‰,平均值为:4.33‰,表明悬浮颗粒物的来源主要为外源性土壤有机质与内源性水生植物残体的混合;2)河流水体中铵盐与硝酸盐N-稳定同位素范围分别为-5.86‰-17.20‰,平均值为5.02‰及-1.48‰-15.86‰,平均值为5.75‰;水体可溶性氮素主要来源为大气沉降、河流水生生物以及地表径流所带入的化肥农药等;3)悬浮颗粒物含量不仅随着河流径流量的季节性变化而变化,还随着人为干扰强度的加强而呈递增的趋势,水体悬浮颗粒物含量最高达到(9.883±3.45)mg/L。而NH_4~+及NO_3~-的浓度也呈现出相同的趋势,含量分别为0.07-0.45 mg/L,平均值为0.25 mg/L;0.08-0.44 mg/L,平均值为0.37 mg/L。稳定同位素测定为河流生态系统提供了一个整合时空氮素来源和转移循环过程的综合指标,揭示了环境因子对河流生态系统氮循环的影响过程与机制。     

从水环境角度探析农田氮素流失及控制对策

综述了国内外关于农田氮素流失对水体影响现状、农田氮素流失途径、流失机理及其控制方法等的研究进展及其控制对策.在控制氮素流失对水环境影响方面,针对氮素地表径流流失和淋溶流失采取有效措施,减少氮素对地表水和地下水污染.氮素污染的治理关键是切断氮源和流失途径的联系,应根据氮污染源的等级划分因地制宜地采取治理措施,制定适合我国国情的BMPs(最佳管理措施)管理模式.     

京郊典型集约化"农田-畜牧"生产系统氮素流动特征

城郊畜牧业的集约化发展在满足人们日益增长的肉蛋奶等动物性产品需求的同时,也带来了巨大的环境压力。本文利用养分流动和模型分析的方法,分析北京市郊区某村三种不同类型"农田-畜牧"生产系统(大型集约化种猪场、种养结合小规模生态养殖园和集约化单一种植区)的氮素流动特征。结果表明:饲料是集约化种猪场和生态养殖园氮素输入的主要来源,饲料投入氮量分别为12469.0和9268.5 kg.hm-.2a-1);集约化种猪场农牧体系间生产脱节,致使农田氮素输入主要依赖于化肥投入,化肥氮输入量(435.0 kg.hm-.2a-1)占农田氮素输入量的82.7%。相反,生态养殖园农牧体系结合紧密,猪粪尿氮还田比例达28.6%,这使得园区化肥氮输入量仅为135.0 kg.hm-.2a-1,因此畜禽粪尿的合理循环利用可作为减少化肥投入的有效途径;集约化种猪场、生态养殖园和单一种植区农牧生产系统氮素利用效率分别为18.8%、20.6%和17.3%,均处于较低水平;集约化种猪场猪粪尿在猪舍和储藏处理过程的氮素损失率为15.8%和25.4%,分别低于小规模生态养殖园相应损失率约8.7和4.8个百分点;生态养殖园粪肥氮还田量高,导致农田氮素盈余量高达1962.8 kg.hm-.2a-1,未能实现生态型养殖的理想效果,优化氮素管理、确定合理的消纳畜禽粪尿的农田面积和调整畜禽养殖密度是解决该问题的关键。     

氮素营养对苗期菘蓝叶中硝酸还原酶活性与矿质元素吸收的影响

采用正交试验设计,研究铵态氮、硝态氮和酰胺态氮3种氮素形态及其不同浓度配比对苗期菘蓝的单株干重、叶内的硝酸还原酶活性及矿质元素吸收的影响。结果显示:(1)影响苗期菘蓝单株干重的氮素形态依次为酰胺态氮>铵态氮>硝态氮。(2)不同氮素形态对叶片硝酸还原酶活性影响有差异,铵态氮影响最大,其次是硝态氮和酰胺态氮。(3)不同形态氮素配合施用后均能促进P、K、Ca、Mg、Cd、Mn、Cr、Sr 8种元素的吸收,但不利于Ni和Fe的吸收;元素吸收受铵态氮影响最大的矿质元素有K、Ba、Se、Ni、B、Si、Fe 7种元素,受硝态氮影响最大的元素有P、Cd、Ti、Al、Cu 5种元素,受酰胺态氮影响最大的元素有Na、Ca、Mg、Zn、Mo、Mn、Cr、Sr 8种元素。研究表明,不同形态氮素对苗期菘蓝吸收矿质元素的影响存在很大的差异,应注重酰胺态氮与无机的铵态氮、硝态氮的配合施用;适宜氮素形态及其配比能提高叶中硝酸还原酶的活性并促进矿质元素的吸收,从而有效地促进菘蓝的生长。     

连续可调式沉水植物网床对河道水质的修复

在太湖贡湖水源保护区陆域的一条长约200 m的污染河道内构建了一系列连续可调式沉水植物网床,形成了以菊花草、苦草、伊乐藻、轮叶黑藻和菹草等沉水植物构成的水生植物群落;跟踪监测了总氮(TN)、铵态氮(NH4 +-N)、亚硝态氮(NO2--N)、硝态氮(NO3--N)、总磷(TP)和磷酸盐(PO43--P)等水质指标,分析沉水植物网床引导沉水植被恢复对污染河道的水质修复效果.结果表明:沉水植被网床构建后,水体透明度显著升高,由修复前的0.5m提高到1.7 ～1.8 m;在沉水植被网床构建后的第5天和第20天,TN和TP的削减率分别为35.6％、66.3％和29.4％、63.2％;5个月后,修复河道水体内NH4+-N、NO2--N、NO3--N、TN、PO43--p和TP的浓度比对照组显著降低,削减率分别达到92.4％、76.8％、72.7％、73.9％、90.5％和92.0％.由连续可调式沉水植被网床引导恢复的水生植物群落可用于河道,特别是陆域浅水污染水体的生态修复.     

Combined Multivariate Statistical Techniques,Water Pollution Index (WPI) and Daniel Trend Test Methods to Evaluate Temporal and Spatial Variations and Trends of Water Quality at Shanchong River in the Northwest Basin of Lake Fuxian,China

Understanding spatial and temporal variations in river water quality and quantitatively evaluating the trend of changes are important in order to study and efficiently manage water resources. In this study, an analysis of Water Pollution Index (WPI), Daniel Trend Test, Cluster Analysis and Discriminant Analysis are applied as an integrated approach to quantitatively explore the spatial and temporal variations and the latent sources of water pollution in the Shanchong River basin, Northwest Basin of Lake Fuxian, China. We group all field surveys into 2 clusters (dry season and rainy season). Moreover, 14 sampling sites have been grouped into 3 clusters for the rainy season (highly polluted, moderately polluted and less polluted sites) and 2 clusters for the dry season (highly polluted and less polluted sites) based on their similarities and the level of pollution during the two seasons. The results show that the main trend of pollution was aggravated during the transition from the dry to the rainy season. The Water Pollution Index of Total Nitrogen is the highest of all pollution parameters, whereas the Chemical Oxygen Demand (Chromium) is the lowest. Our results also show that the main sources of pollution are farming activities alongside the Shanchong River, soil erosion and fish culture at Shanchong River reservoir area and domestic sewage from scattered rural residential area. Our results suggest that strategies to prevent water pollutionat the Shanchong River basin need to focus on non-point pollution control by employing appropriate fertilizer formulas in farming, and take the measures of soil and water conservation at Shanchong reservoir area, and purifying sewage from scattered villages.     

基于“源-汇”景观的太湖宜兴段入湖港口水质时空变化

针对太湖流域非点源污染日益严重和近年来宜兴段土地利用方式变化状况,以太湖大堤西岸3km缓冲区内的景观为研究区域,基于"源-汇"景观理论,计算了其"源-汇"景观空间负荷对比指数(LCI),并结合宜兴市10条主要入太湖港口的实测水质数据,定量分析了太湖流域宜兴段非点源污染的时空变化特征。结果表明:时间上,2010年有8个入湖港口的LCI值较2004年有明显下降;对应的水质指标方面,铵氮浓度降低了41.0%,说明LCI降低对氨氮浓度影响较大,而其他水质指标改善不明显。空间上,景观类型通过相对重要性指数变化对LCI值产生相应影响,而LCI值与综合水质标识指数之间呈正相关关系,说明景观空间格局变化会显著影响水质指标。总之,LCI值与水质指标中的铵氮和总氮密切相关,LCI值的变化趋势与各港口水质的时空变化趋势基本一致,LCI能够较好地反映非点源污染的产生、转移过程。     

Analysis of isotope tracing of domestic sewage sources in Taihu Lake—A case study of Meiliang Bay and Gonghu Bay

Due to the difficulty of quantifying the temporal and spatial variations of the sewage sources of Taihu Lake, this paper collected water samples from Gonghu Bay and Meiliang Bay, in the northeast of Taihu Lake and from the inflow river of Wangyu River from January to December in 2012 and applied stable isotope techniques to trace the sources of the nitrogen pollutants. At the same time, a two-end-member mixing model of isotopes was used to determine the sources of domestic sewage. According to the results of nitrogen isotope values in the sampling points, the annual proportion of the sewage sources of the Meiliang Bay, Gonghu Bay and Wangyu River is 17.2%, 15.3% and 19.7%, respectively. More than 80% of the nitrogen pollution sources are from non-domestic sewage, which indicates that domestic sewage is not the primary source of nitrogen pollution in Taihu Lake. In addition, these three regions have demonstrated higher ratios of sewage sources during the winter season than during other seasons. Therefore, domestic sewage that flows into Taihu Lake during the winter season should be strictly limited. In the meantime, it is necessary to strengthen the treatment of nitrogen sources other than domestic sewage sources.     

Groundwater nitrogen pollution and assessment of its health risks: a case study of a typical village in rural-urban continuum, China

Protecting groundwater from nitrogen contamination is an important public-health concern and a major national environmental issue in China. In this study, we monitored water quality in 29 wells from 2009 to 2010 in a village in Shanghai city, whick belong to typical rural-urban continuum in China. The total N and NO(3)-N exhibited seasonal changes, and there were large fluctuations in NH(4)-N in residential areas, but without significant seasonal patterns. NO(2)-N in the water was not stable, but was present at high levels. Total N and NO(3)-N were significantly lower in residential areas than in agricultural areas. The groundwater quality in most wells belonged to Class III and IV in the Chinese water standard, which defines water that is unsuitable for human consumption. Our health risk assessments showed that NO(3)-N posed the greatest carcinogenic risk, with risk values ranging from 19×10(-6) to 80×10(-6), which accounted for more than 90% of the total risk in the study area.     

太湖地区氮素湿沉降动态及生态学意义：以常熟生态站为例

在常熟生态站2001年6月至2003年5月连续两年定位收集湿沉降,对太湖地区氮素湿沉降动态进行研究．结果表明,湿沉降氮输入量季节变化显著,夏、春季高,秋、冬季低．在湿沉降输入氮中NH4^+-N、NO3^--N和DON的比例分别为47．6％、35．1％和17．4％．湿沉降中NH4^+-N主要来自当地农田的氨挥发,湿沉降NH4^+-N月输入量随月降雨量增加而增加(R0=0．3178^**)．该地区空气中NO3^--N浓度相对比较稳定,湿沉降中NO3^--N浓度与降雨量呈负相关(R^2=0．4205^***)．湿沉降NO33^--N月输入量与月降雨次数呈直线正相关(R^2=0．6757***),而与月降雨量相关性较差(R^2=0．1985^*)．湿沉降TN年输入量为27．0kg·hm^-2,并在所有降雨中,氮浓度均超过水体富营养化阈值(0．2mg·L^-1)．     

洱海入湖河流弥苴河下游氮磷季节性变化特征及主要影响因素

入湖河流携带污染物对洱海水环境的影响日益明显,对洱海入湖水量最大的河流——弥苴河下游水体氮磷进行了连续采样分析,以期为河口湿地建设和水质改善提供基础数据.结果表明:1)弥苴河水质介于地表水Ⅲ-Ⅴ类之间,主要污染物为氮和磷,其中总氮平均浓度为1.17 mg/L,最高浓度达到2.00 mg/L;总磷平均浓度为0.06 mg/L;2)弥苴河下游总氮、总磷浓度丰水期高于枯水期,并呈现出季节性变化规律;3)弥苴河下游水体总氮、总磷年均浓度远高于洱海水体总氮、总磷年均浓度,其中总氮高出2.10倍,总磷高出2.90倍;4)弥苴河下游河段非点源污染占据主导地位.     

Anthropogenic impact on water quality of Chilika lagoon RAMSAR site: a statistical approach

This paper investigated the spatio-temporal variability of water quality parameters (transparency, salinity, dissolved oxygen, nutrients viz. NH₃-N, NO₂-N, NO₃⁻-N, PO₄³-P, total nitrogen, total phosphorous and chlorophyll-a) in Chilika lagoon during 2001–2003 in order to better understand its ecological characteristics. Marked spatial and seasonal variations were detected with respect to almost all parameters studied. Northern sector of the lagoon is more affected by the anthropogenic stress from the catchments than the southern sector. Addition of nitrogen and phosphorous compounds to the lagoon mainly occurred through the drainage from agricultural lands and river run off during the early months of paddy cultivating seasons. Phytoplankton productivity of the lagoon was nitrogen limited, as suggested by nitrogen to phosphorous ratio. Processes affecting the water quality of the lagoon system included agricultural drainage, sewage intrusion, macrophyte litter fall and exchange of water between lagoon and the sea (Bay of Bengal). Further in depth study pertaining to quantification of exogenous material input and their disposal is recommended to ensure proper management of the lagoon and its resources.     

Colonization of acidic mining lakes: <Emphasis Type="Italic">Chydorus sphaericus</Emphasis> and other Cladocera within a dynamic horizontal pH gradient (pH 3−7) in Lake Senftenberger See (Germany)

Spatio-temporal distribution of nitrogen was examined along the gradient from open water to lakeshore in Lake Taihu, China. Two types of undulating littoral zones were selected: natural reed belt and bare lakeshore. The reed belt affected nitrogen transformation and was sink for internal-lake nitrogen, whereas the bare lakeshore showed little effect. During the growing season, NO ₃ ⁻ -N concentration increased by up to 3–5 times from open water to reed belt, while NH ₄ ⁺ -N concentration decreased. It suggested that nitrification was the main nitrogen process in reed belt. Total dissolved nitrogen (TDN) showed little spatial variation, indicating that most of nitrogen released from sediment did not move into open water again. Significant temporal variation of dissolved nitrogen occurred and was similar in both the littoral zone and the open water. Maximum TDN and NH ₄ ⁺ -N concentrations occurred in January, and NO ₃ ⁻ -N in March. Minimum NH ₄ ⁺ -N and NO ₃ ⁻ -N concentrations occurred in July and August, respectively. An increasing total soil nitrogen was found in the surface sediments from reed belt to open water. This further suggested that the reed-covered littoral zone had strong nitrogen transformation potential.     

广东石岩、大镜山和大水桥三座水库的富营养现状

为了解污染源对水库富营养化的影响,于2000年的枯水期(6～7月)与丰水期(11～12月)对三座污染类型的水库:石岩水库、大镜山水库、大水桥水库进行采样,测定和分析水库的营养盐及浮游生物。根据相关加权的综合营养状态指数评估,石岩水库为富营养型水库,大镜山水库与大水桥水库为中-富营养型水库。这三座水库污染源不同,其富营养特征差异较为明显,特别是营养水平的季节动态不同。石岩水库的主要污染源为城镇生活污水,其主要富营养特点为:各种营养盐浓度、浮游生物丰度及COD值在三个水库中最高,有机污染严重;丰枯两期均有种类较多、丰度较高的耐污藻类--裸藻(Euglena Ehr.);枯水期富营养水平明显高于丰水期。大水桥水库主要受农业活动污染,其主要富营养特点为:受地表径流影响显著,PO₄-P和TP浓度以及浮游生物丰度丰枯两期差异比较明显,均为丰水期高于枯水期;丰水期浮游植物主要以蓝藻为主,枯水期则以硅藻为主。大镜山水库污染来源主要为其调水河流前山河,受工业污水污染比较严重,生活废水的污染也较为突出,其主要富营养特点为:总磷浓度及浮游动物丰度枯丰两期差异较为明显,受河流调水控制。