应用GLEAMS模型评估我国东南地区农业小流域硝态氮的渗漏淋失

应用GLEAMS模型估算我国东南亚热带地区农业小流域硝态氮的渗漏淋失.在五川流域8种不同土地利用方式的农田中埋设渗漏监测装置,每月采集水样分析硝态氮含量.用2002年4-12月作物生长季节的实测数据进行模型校验的结果表明,模型对水稻田除外的其他土地利用方式下硝态氮渗漏淋失模拟效果较好.五川流域2002年硝态氮淋失模拟计算结果表明,不同土地利用方式下硝态氮淋失时空差异显著,全年渗漏量(以氮计)为4.64～38.39 kg·hm-2,流域面积加权平均为29.99 kg·hm-2.甘蔗地、香蕉地和蔬菜地的年硝态氮渗漏量最高,渗漏峰值一般出现在7-8月.降雨、土地利用和化肥施用等人类活动是影响硝态氮渗漏淋失的主要因素.     

应用HYDRUS-1D模型模拟农田土壤水渗漏及硝态氮淋失特征

在定位试验基础上,应用HYDRUS-1D模型对黄淮海平原典型土壤(黄潮土)中土壤水渗漏及硝态氮淋失动态进行了模拟分析。结果表明:在传统水氮管理模式下,黄潮土2m土体深处的土壤水渗漏和硝态氮淋失非常严重,2个轮作期内,土壤水渗漏总量占地表总入水量的23.7%,硝态氮淋失总量占总输入N量的15.9%,冬小麦生长季的硝态氮淋失量大于夏玉米生长季;改良灌溉和改良施肥模式下产生的硝态氮淋失量比传统灌溉和传统施肥模式减少74.7%,节约灌溉水211.5mm、节省施N423.5kg·hm-2。     

施肥对华北高产区土壤NO-3-N淋失与作物NO-3-N含量及产量的影响

利用4a的平衡施肥定位试验，研究太行山山前平原高产区冬小麦、夏玉米轮作制度下施肥对潮褐土中硝态氮的分布、移动、积累、植株吸收以及作物产量的影响。结果表明，土壤剖面中硝态氮含量与施肥量直接相关，过量施用氮肥使硝态氮在土壤中大量积累并向下层快速移动；氮磷对作物的养分供应存在着既相互促进又相互竞争的关系，施用适量磷肥可以促进小麦、玉米对氮素的吸收，提高作物产量，减少氮素在土壤中积累和淋失，但施磷量太高，由于氮磷之间的竞争作用，作物吸氮量反而下降，从而导致土壤中硝态氮的积累和淋失加剧，施用钾肥抑制了土壤硝态氮积累，促进了两季作物植株对氮素的吸收，从减少土壤硝态氮积累和淋失的角度，提出该区合理的施肥配比为组合N2P2K2，即ρA(N)=200kg hm^-2，ρA(P)=32．5kg hm^-2，ρA(K)=150kg hm^-2。图6参13。     

黄潮土的土壤水渗漏及硝态氮淋溶研究

在黄淮海平原 1hm2 小麦 -玉米轮作田块上 ,利用水量平衡模型对黄潮土的土壤水渗漏和硝态氮淋溶状况进行了定量研究。结果表明 ,黄潮土的土壤水渗漏和硝态氮淋溶状况非常严重 ,全耕作年土壤水渗漏量达到2 73 .9mm ,为灌溉水量的 60 .6% ;硝态氮淋溶达到 81.8kg·hm-2 ,为氮输入总量的 15 .7%。     

菜田土壤氮素淋失及其调控措施的研究进展

从菜田中硝态氮的动态变化、土壤氮素的矿化、硝态氮对地下水的影响等几方面概述了近年来国内外的研究进展，介绍了渗漏测定计法、土壤溶液提取器和15N同位素示踪技术等3种测定土壤氮素淋失的研究方法其应用前景；论述了影响菜田土壤氮素淋失的主要因素和降低菜田土壤氮素淋失的丰要调控措施；提出了今后菜田土壤氮素淋失应加强的研究方向。     

灌淤土施氮后土壤硝态氮的动态变化

通过室内模拟试验，探讨不同水分条件下灌淤土施用不同氮肥后硝态氮随时间的变化规律，并在田间条件下，测定不同氮肥形态和数量对土壤硝态氮含量的影响。灌淤土施氮后土壤硝态氮含量变化与土壤含水量及氮肥种类有关。施肥9d后，土壤中的硝态氮迅速增加；土壤水分低于田间持水量的50％或水分过饱和都明显影响灌淤土的硝化作用；施用大颗粒尿素产生的硝态氮最少，淋失或流失的几率小。灌淤土土体中硝态氮的残留与施氮种类及数量有直接关系。施肥使土壤表层硝态氮显著增加，施用大颗粒尿素尤为突出，但施大颗粒尿素后，60cm土体中残留的硝态氮总量最少。随着施氮量增加，表层土体中硝态氮含量增加。合理的施肥水平一般不会造成硝态氮的大量累积，而过量施氮则导致硝态氮明显积累，对通气透水性好的灌淤土，容易造成硝态氮淋失。     

麦季施用不同尿素的氮排水和渗漏损失

在太湖地区乌栅土的稻麦轮作条件下,利用大型原状土柱渗漏液采集器(monolithlysimeter),比较不同尿素品种和施肥量(普通尿素150、300kg·hm-2和包膜尿素100、150kg·hm-2)处理对麦季土壤氮随径流和渗漏损失的影响。结果表明:施用的包膜尿素当季氮不易随排水流失,但可能增加下季氮流失的风险。两麦季排水溶解氮均以NO-3 N为主,达76.7%以上,NH+4 N比例很小;麦季排水氮输出量年际差异明显,降雨产生排水与施肥时间间隔的不同是造成排水氮输出量差异的关键因素;施肥后20d内发生排水易产生较多的氮排放。渗漏液硝态氮浓度(最高为8.12mg·L-1)均未超过饮用水NO-3 N含量标准,但均已超过水体富营养化标准;对照处理麦季渗漏液量显著高于施肥处理;在150kg·hm-2的施N量水平下,普通尿素或包膜尿素均未显著增加氮的渗漏,但过量施用普通尿素则加大氮渗漏的风险。     

上海郊区旱作农田氮素流失研究

通过测坑和大田小区试验,研究了上海郊区旱作农田氮素降雨径流和降雨渗漏流失的特征、相关因素和流失负荷。结果表明:平水年重质土麦地总氮流失负荷为18. 38 kg·hm-2,其中降雨径流总氮流失负荷为4. 4kg·hm-2,渗漏为13. 98kg·hm-2;菜地总氮流失量为55. 65kg·hm-2,其中降雨径流总氮流失负荷为21. 6kg·hm-2,渗漏为34. 05kg·hm-2;旱田氮素流失以硝态氮为主,占总氮90%左右。施用有机肥可较大幅度地减少旱田的氮素渗漏流失。     

灌淤土施氮后土壤硝态氮的动态变化

通过室内模拟试验,探讨不同水分条件下灌淤土施用不同氮肥后硝态氮随时间的变化规律,并在田间条件下,测定不同氮肥形态和数量对土壤硝态氮含量的影响。灌淤土施氮后土壤硝态氮含量变化与土壤含水量及氮肥种类有关。施肥9d后,土壤中的硝态氮迅速增加;土壤水分低于田间持水量的50%或水分过饱和都明显影响灌淤土的硝化作用;施用大颗粒尿素产生的硝态氮最少,淋失或流失的几率小。灌淤土土体中硝态氮的残留与施氮种类及数量有直接关系。施肥使土壤表层硝态氮显著增加,施用大颗粒尿素尤为突出,但施大颗粒尿素后,60cm土体中残留的硝态氮总量最少。随着施氮量增加,表层土体中硝态氮含量增加。合理的施肥水平一般不会造成硝态氮的大量累积,而过量施氮则导致硝态氮明显积累,对通气透水性好的灌淤土,容易造成硝态氮淋失。     

小清河流域氮磷时空特征及影响因素的空间与多元统计分析

选取山东小清河流域为研究区,在2012—2013年汛期和非汛期的水质监测基础上,应用主成分分析(PCA)和聚类分析(CA)等多元统计方法识别流域不同形态氮磷浓度的时空分布特征,结合空间分析和相关分析方法辨析集水区不同土地利用方式对氮磷输出的影响。结果表明:流域氮污染严重,其中总氮超标率达100%。氨氮、磷酸盐浓度汛期显著高于非汛期,硝态氮浓度则非汛期显著高于汛期(P0.05)。以总磷、总溶解态磷为主要指标的主成分Z1对水质变化的贡献率接近50%,以总氮、氨氮和硝态氮为主要指标的主成分Z2对水质变化的贡献率接近20%。总氮、总磷、氨氮、磷酸盐和总溶解态磷浓度与集水区城市和工业建设用地的面积比例呈显著正相关(P0.05);硝态氮浓度与耕地面积比例呈显著正相关,与草地、林地面积比例呈显著负相关(P0.05)。空间上按氮磷分布特征不同子流域被划分为3类:第1类和第2类主要集中在干流及北部平原区,沿途接纳点源排放,氮磷浓度总体较高且空间差异较大;第3类流域主要位于南部山区,建设用地比例较小,污染程度相对较低。     

Eco-hydrological modelling in a highly regulated lowland catchment to find measures for improving water quality

Water quality modelling in the meso-scale Rhin catchment in the German federal state Brandenburg was done (1) to answer some specific questions concerning identification of point and diffuse sources of nutrient pollution in the catchment, (2) to assess the influences of possible climate and land use changes on water quantity and quality and (3) to evaluate potential measures to be done in order to achieve a “good ecological status” of the river and its lakes as required by the Water Framework Directive (WFD).The Rhin catchment is a typical highly regulated lowland river basin in Northern Germany. The regulations complicate water quantity and quality modelling in the catchment. The research was done by using the eco-hydrological model SWIM (Soil and Water Integrated Model), which simulates water and nutrient fluxes in soil and vegetation, as well as transport of water and nutrients to and within the river network. The modelling period was from 1981 until 2005. After calibrating the hydrological processes at different gauges within the basin with satisfactory results, water quality (nitrogen and phosphorus) modelling was done taking into account the emissions of different point sources (sewage treatment plants, etc.) and identifying the amount of diffuse pollution caused mainly by agriculture.For suggesting some feasible measures to improve water quality and to reduce diffuse pollution considering possible climate and land use changes, different reasonable scenarios were applied in consultation with the Environmental Agency of Brandenburg (LUA). The study revealed that the amount of water discharge has significant influence on the concentration of nutrients in the river network, and that nitrogen pollution, caused mainly by diffuse sources, could be notably reduced by application of agricultural measures, whereas the pollution by phosphorus could be diminished most effectively by the reduction of point source emissions.     

PCBs,PCDDs and PCDFs in soil samples from uncontrolled burning of waste electrical material for metal reclamation

PCDDs, PCDFs and PCBs have been analysed in soil samples where waste electrical equipment has been burned directly on the ground in three locations of Burgos (Spain). High levels of PCDDs, PCDFs and PCBs were detected in the centre of combustion sites. The results show PCB levels between 0.824 and 1.240 μg/g, and PCDDs and PCDFs levels between 8.73–36.37 ng/g and 12.79–50.95 ng/g. The I‐TEF values between 2.96–9.15 for dioxins and furans indicate that these soils are heavily polluted and may represent a risk for human and animal health.     

小集水区酸化过程观测研究

在贵阳市近郊一封闭的小集水区设置了环境酸化过程试验场.本文介绍了试验场中观测点的布置、各项观测的方法和要求、经过长时间的观测和试验,取得了从酸沉降开始,穿过树冠,渗入土壤,最后进入地面水的全过程中各个环节化学行为和互相影响的可靠数据,由此得知贵州省酸性黄壤对酸化的缓冲能力不强,即容易发生酸化,并且有毒铝离子容易释放等重要信息.     

南方城市化山地区小流域集水工程规划

为提高南方山地丘陵区充沛降水的利用效率 ,缓解山地城镇用水短缺、自然生境大量丧失、河道及水库干涸且污染严重等生态环境危机 ,文章利用GIS技术 ,对研究区所处的小流域原始地表水系网络和集水区进行了恢复和划分 ,结合土地利用类型特征对各集水区产流量进行了估算 ,在此基础上提出了小流域集水工程的布置方案。     

复合指纹识别泥沙来源:潜在泥沙源地的选择

复合指纹识别技术应用于泥沙源解析的前提是假设研究者能够确定流域内泥沙的潜在来源类型,并且各泥沙源地所占比例之和为1,对潜在源地预判的不确定性将会对结果产生一定的影响。以南京市九乡河上游流域为例,对不同源地各指纹因子做均值显著性检验,检验各个预判源地能否单独作为潜在泥沙源地,同时对比分析不同沙源地对复合指纹因子判断泥沙来源正确率的影响,定量分析沙源地预判过程中的不足,探讨如何减少沙源地选择对泥沙来源识别的影响。通过对比研究发现,预判的4种泥沙源地被重新调整为农田、林地和道路3种类型。调整后各源地指纹因子差异性明显提高,不同泥沙来源的正确判别率最高达到89.2%,泥沙贡献率从高到低依次为农田(39.9%~87.8%)、林地(0.1%~47.7%)和道路用地(0~25.6%)。     

Observations on metal concentrations in commercial landings of two species of tilapia (Oreochromis mossambicus and Oreochromis niloticus) from reservoirs in six river basins in Sri Lanka

Samples of the muscle of two species of tilapia (Oreochromis mossambicus and O. niloticus; 17–20 cm length) were obtained from at least one reservoir in each of the six river basins (Aruvi Aru, Kala Oya, Kirindi Oya, Ma Oya, Mahaweli, and Walawe Ganga catchments) in Sri Lanka. The metals Ca, Cu, Fe, K, Mg, Mn, Na, and Zn were consistently detected in the muscle tissue. Overall, there were few differences in the concentration of metals between the two species of fish, although there were also some statistically significant differences (p < 0.05) in the concentrations of some metals in fish obtained from some of the reservoirs. Aruvi Aru stands out as a river basin in which the two fish species have significantly lower concentration of metals when compared to other river basins. The concentration of the metals studied were below WHO and FSANZ guideline values for fish, suggesting that the consumption of the metals found in tilapia from these reservoirs poses little risk to human health.     

典型喀斯特表层岩溶带地下水化学特征——以贵州清镇王家寨喀斯特小流域为例

以喀斯特小流域为研究尺度,对清镇市王家寨退耕还林（草）示范区内的9个表层岩溶泉进行了一个水文年的系统监测,并借助SPSS统计软件开展了泉点的聚类分析研究,旨在从常规水化学角度为流域退化生态环境的恢复与重建提供科学依据。从结果来看,虽然所有泉点的水化学类型均为HCO3-Ca型,但是根据K＋、Na＋、Ca2＋、Mg2＋、F-、Cl-、NO3-、HCO3-、SO42-等指标的具体差异,还是可以将9个泉点分为3组：（1）位于流域上游分水岭处的S8、S9泉点,由于远离居民集聚区,受到人类活动的影响程度弱,泉水中EC和各主要离子的质量浓度均很低,[Ca2＋]＊与[HCO3-]的关系说明泉水流经地区的岩石类型主要为白云岩;（2）位于流域中部的S2、S3、S4、S5、S6和S7泉点,靠近居民点,受到人类活动的影响程度明显增强,泉水中EC和各主要离子的质量浓度也相应增大,[Ca2＋]＊与[HCO3-]具有与第一组泉水完全不同的特征,表明此组泉水流经地区的岩石类型为白云质灰岩;（3）位于流域下游的S1泉点,处于村寨下游,受到人类活动的影响最大,泉水中EC和各主要离子的质量浓度也很高,[Ca2＋]＊与[HCO3-]的关系与第二组泉点相似,但是[SO42-]和[F-]远高于前2组泉点,这可能是由于在泉水的运移路径上有富含石膏和氟的岩石存在。     

The effects of catchment land use on water quality and macroinvertebrate assemblages in Otara Creek,New Zealand

The effect of catchment land use on water quality and macroinvertebrate communities was examined by using data gathered during a 2004 reconnaissance of nine sites in the Otara Creek, New Zealand. Data collected included macroinvertebrate, water chemistry and sediments characteristics. Macroinvertebrate data were used in metric and index calculations. A total of 61 macroinvertebrate taxa, with 3032 total individuals, were identified from the macroinvertebrates samples collected from nine sites in Otara Creek. The greatest number of macroinvertebrate taxa was recorded within bush sites (mean>25), while the urban sites had the least number of taxa (mean=10). Pasture sites were intermediate with the mean>17. Taxa number differed significantly across land use. Mean macroinvertebrates abundance varied across the sites and land uses. The highest macroinvertebrates mean abundance was recorded in urban and pasture sites, while bush sites had significantly lower mean abundance. Physico-chemical parameters decreased from bush toward urban streams. Biotic indices were sensitive to changes in macroinvertebrates community structure across land uses with mean scores decreasing from bush to urban and pasture streams. Ordination of biological data showed a clear separation of bush from urban and pastures streams. Analysis of similarities revealed significant differences in macroinvertebrates between both stream groups and land-use groups. The observed macroinvertebrate assemblage pattern was best correlated with a single variable, conductivity, temperature, turbidity, nitrate and dissolved oxygen. The combination of these environmental variables best explained the changes in the macroinvertebrate assemblages between sites. This study demonstrates that catchment land use may significantly affect the water quality and macroinvertebrate communities in an ecosystem.