河套灌区地下水氮污染状况

河套灌区浅层地下水氮浓度和地下水埋深的季节变化规律调查结果表明:3月地下水NO3--N和TN浓度显著高于5、7和9月,地下水埋深也比5月和7月深。不同类型的井水N浓度差异较大:农田与庭院的井水NO3--N浓度显著高于村庄附近的井水,而NH4+-N和TN则表现为庭院井水浓度显著高于农田和村庄。地下水氮形态以NO3--N为主,全年17.1%的水井地下水NO3--N浓度高于10 mg.L-1,最高达184.4 mg.L-1。在灌溉量和其他生产条件相同的情况下,沙壕渠试验站农场内施肥区井水NO3--N浓度[(17.55±15.02)mg.L-1]明显高于未施肥区[(7.67±4.48)mg.L-1],且65.5%的水样NO3--N浓度超过WHO规定的生活饮用水NO3--N浓度上限值(10 mg.L-1),而未施肥区仅有27.6%的水样超标。井水NO3--N的来源主要为农田氮肥与动物粪肥,当地地下水NO3--N污染已不容忽视。     

川中丘陵区典型小流域地下水硝酸盐污染分析

对川中丘陵区典型小流域地下水N素含量及形态分配的监测结果表明,硝酸盐(NO3--N)是该地区地下水N素存在的主要形态。川中丘陵区54.5%的地下水NO3--N含量超过世界卫生组织(WHO)饮用水准则规定的10mg.L-1标准,另有27.3%的地下水NO3--N含量接近这一标准,表明该区地下水已经大范围地受到NO3--N污染的威胁。土地利用状况可能是影响川中丘陵区地下水NO3--N含量的主要因素。降雨量和水井深度也影响该区地下水NO3--N含量。紫色土坡耕地NO3--N随壤中流向浅层地下水迁移,可能是造成该区地下水NO3--N含量较高的最重要原因。     

运用氮、氧双同位素技术研究永安江硝酸盐来源

以洱海入湖河流永安江为研究对象,利用硝酸盐δ15N和δ18O双同位素技术对永安江水体的硝酸盐氮来源进行识别。在永安江沿程共布置9个监测点,分析硝酸盐的污染特征,并利用离子交换树脂法对水样进行预处理后测试硝酸盐δ15N和δ1 8O。结果表明,永安江硝酸盐氮源负荷占永安江总氮源污染的50%左右,各采样点ρ(硝酸盐)为0.07~5.22 mg·L-1,均值为1.00~2.39 mg·L-1。经同位素测试,各采样点δ15N-NO3-均值为6.12‰~13.88‰,δ18O-NO3-均值为8.24‰~11.72‰;永安江河水中硝酸盐主要来自于流域内化学肥料、牲畜粪便、生活污水和土壤有机氮硝化;利用Iso Source混合模型对4种形态的硝酸盐来源进行定量分析,发现化学肥料占37.3%,牲畜粪便占34.6%,村落污水占18.2%,土壤有机氮占9.9%。利用Iso Source混合模型可为河流硝酸盐来源定量研究提供新的研究思路,硝酸盐贡献比例与河流流经村落位置及土地利用类型有关。     

北京密云水库小流域地下水硝酸盐污染来源示踪

为确定北京密云水库小流域地下水中氮污染特征及来源,分别在雨季和旱季采集34个地下水样进行分析.结果表明,该流域地下水中NO-3-N污染严重,雨季和旱季NO-3-N的平均含量分别为15.86 mg·L-1和14.67 mg·L-1,均超过世界卫生组织饮用水标准(10 mg·L-1),污染主要分布于人口密集、农业活动频繁的中部地区.研究区域NH+4-N和NO-2-N的含量较低,其中,NO-2-N分布极不均匀.雨季和旱季δ15N的变化范围分别为5.00‰—20.16‰和-5.90‰—12.28‰,表明地下水硝酸盐的主要来源为人畜粪便和污水的排放,也可能为土壤有机氮和农业施肥的混合,表明旱季发生反硝化作用造成同位素的分馏.雨季,硝态氮与村镇面积呈正相关;氨氮与村镇及地表水面积呈显著正相关关系.旱季,硝态氮与村镇面积呈正相关,氨氮与草地面积呈正相关,亚硝态氮与地表水面积呈显著的正相关关系.     

有机肥对土壤NO3--N累积的影响

长期定位试验和调查取样的结果表明,土壤中NO3--N的累积量随有机肥施用量的增加而增加,过量施用有机肥会引起2 m以下深层次土壤中NO3--N的大量累积。当有机肥和无机肥配合施用时,土壤中NO3--N的累积量随总施N量的增加而增加。有机肥对土壤NO3--N累积的影响和对地下水的潜在威胁不容忽视。     

酿造污泥的农业利用对地下水的影响

本文通过模拟渗滤实验对酿造残渣(NovoGro)在天津地区农业利用可能产生的环境影响-氮素对地下水的潜在污染———进行了比较系统的研究。结果表明,氮素(主要是NO3-)在土壤中的迁移和积累行为在不同作物和土壤条件下是有差异的。在水田中施用NovoGro,不会引起水体的氮素污染问题;旱田(小麦)表层土壤和下渗水中NO3--N的含量则随NovoGro的施用量的增加而增加,当施用量达到45t/hm2时足以造成地表径流和地下水的NO3--N污染。     

水溶性有机质对土壤硝化作用过程的影响

以江苏省宿迁市潮土为供试土壤,设置DOC220、DOC440和DOC880 3个添加水溶性有机质(DOM)处理,分别含有机碳(DOC)220、440和880 mg.L-1。试验结果表明,DOM对硝化过程有一定的抑制作用,在培养第16天时,未添加DOM的对照中NH4 -N几乎100%已经转化为NO3--N,而添加DOM的3个处理硝化率分别比对照降低7.83%、13.60%和19.12%;与对照相比,添加DOM的处理中NH4 -N含量降低缓慢,但培养过程中亚硝酸盐的积累显著增加,对照在第12天时NO2--N达到最大积累量67.83 mg.L-1,而DOC220、DOC440和DOC880处理土壤中NO2--N积累量分别在第12、14和16天达到最大值,与对照相比积累量分别增加21.17%、33.91%和59.90%。此外,DOM的添加也降低了NO3--N的生成速率,到第16天时,对照已经达到最大积累量143.61 mg.L-1NO3--N,但此时DOC220、DOC440和DOC880处理中NO3--N含量比对照分别低41.97、78.09和91.30 mg.L-1。为排除因添加DOM带来外源氮所引起的影响,同时进行了相同初始氮量下添加DOM与单施(NH4)2SO4对硝化作用影响的比较试验,结果同样表现出亚硝酸盐积累量的增加和NO3--N生成速率的降低,表明DOM中所含的有机碳及小分子化合物影响了硝化作用。高有机质环境下存在潜在的亚硝酸盐积累风险,对土壤和水体生态系统健康可能有一定影响。     

不同施肥水平下菜地径流氮磷流失特征

研究施肥对菜地径流氮、磷流失的影响,对控制水体富营养化有重要意义。采用田间小区监测的方法,研究常规施肥、减量施肥1和减量施肥2等三种施肥水平对菜地径流氮磷流失的影响。结果表明,（1）不同施肥水平的径流氮、磷流失浓度均较高,径流TN、NH4＋-N、NO3--N的平均流失质量浓度分别在20.5~34、2.2~2.4、6.3~9.5 mg L-1之间,径流TP、DP的平均流失质量浓度分别在7.7~11.1、2.1~2.4 mg L-1之间,菜地土壤径流氮、磷流失风险较大。（2）减量施肥可明显降低径流TN和NO3--N的流失浓度,与当地常规施肥相比,减施肥料20%和30%可分别降低径流TN流失浓度的40%、32%和NO3--N流失浓度的23%、35%,而减量施肥对径流TP、DP的流失浓度影响不大。（3）不同施肥水平的径流TN、NO3--N流失负荷分别在5.8~7.6、1.6~2.3 kg hm-2之间,与常规施肥相比,减施肥料20%和30%可分别减少TN、NO3--N流失负荷的24%、19%和11%、29%。不同施肥水平的径流TP、DP流失负荷分别在1.7~2.9、2.5~2.7 kg hm-2之间,减量施肥并不能减少径流TP、DP的流失负荷。     

浅水体浮萍污水净化系统的除氮途径

以稀释的猪场厌氧污水为供试水样,少根紫萍为供试生物材料,对夏、冬2季浅水体浮萍污水净化系统TN、NH4 -N和NOx--N(NO2--N与NO3--N之和)的去除途径进行了试验研究。结果表明,在夏季气温条件下,TN通过气态氨挥发、浮萍系统吸收/吸附NH4 -N和NOx--N得以去除,3途径去除的N分别占TN去除量的30.5%、15.9%和53.6%;NH4 -N通过气态氨挥发、浮萍系统吸收/吸附和硝化反应得以去除,3途径去除的N分别占NH4 -N总去除量的33.1%、17.3%和49.6%;NOx--N则完全通过浮萍系统吸收/吸附得以去除。在冬季气温条件下,TN通过气态氨挥发和浮萍系统吸收/吸附NH4 -N得以去除,2途径去除的N分别占TN去除量的31.7%和68.3%;NH4 -N通过气态氨挥发、浮萍系统吸收/吸附和硝化反应得以去除,3途径去除的N分别占NH4 -N总去除量的28.9%、69.5%和1.6%;而水体中的NOx--N含量始终保持稳定。     

上海市浦东农业区降水氮浓度的时间分布

于2008年在上海市浦东农业区设置采样点按月收集降水样品,测定降水NO3--N和NH4+-N浓度,分析氮浓度的变化规律及其影响因素,并计算氮沉降通量。结果表明,浦东农业区降水氮浓度和年沉降通量均较高,ρ(NO 3--N)平均值为0.44 mg.L-1,年沉降通量为5.19 kg.hm-2.a-1;ρ(NH 4+-N)平均值为1.36 mg.L-1,年沉降通量为15.91 kg.hm-2.a-1;TN年沉降通量为21.10 kg.hm-2.a-1,其中NH4+-N占75.4%。降水NO3--N和NH 4+-N浓度在主要生长季(4—10月)低于非主要生长季(11月至次年3月);而NH 4+-N沉降量在主要生长季高于非主要生长季,NO3--N沉降量在主要生长季和非主要生长季差异较小,这主要是人为活动、降水日数与降水量以及风向等因素的综合作用所致。降水氮输入对研究区初级生产力的提高具有积极意义,但降雨氮浓度已超过水体富营养化阈值,可能加剧农业区内水体富营养化。     

Is there a relationship between soil and groundwater toxicity?

Part IIA of the Environmental Protection Act 1990 requires environmental regulators to assess the risk of contaminants leaching from soils into groundwater (DETR, 1999). This newly introduced legislation assumes a link between soil and groundwater chemistry, in which rainwater leaches contaminants from soil into the saturated zone. As the toxicity of both groundwater and overlying soils is dependent upon the chemicals present, their partitioning and their bioavailability, similar patterns of soil, leachates and groundwater toxicity should be observed at contaminated sites. Soil and groundwater samples were collected from different contaminated land sites in an urban area, and used to determine relationships between soil chemistry and toxicity, mobility of contaminants, and groundwater chemistry and toxicity. Soils were leached using water to mimic rainfall, and both the soils and leachates tested using bioassays. Soil bioassays were carried out using Eisenia fetida, whilst groundwater and leachates were tested using the Microtox test system and Daphnia magna 48 h acute tests. Analysis of the bioassay responses demonstrated that a number of the samples were toxic to test organisms, however, there were no significant statistical relationships between soil, groundwater and leachate toxicity. Nor were there significant correlations between soil, leachates and groundwater chemistry.     

北京市郊再生水灌区土壤有机氯农药垂向分布特征

在北京市郊再生水灌区采用正三角型布点法进行了3个钻孔的采样工作,钻孔间隔为1m,从表层开始每隔0.5m取一个样,3个钻孔共36组样品,同时采集钻孔附近的灌溉水及地下水,分别测试了土壤的理化参数及其土壤、灌溉水及地下水中9种有机氯农药的质量分数。测试结果表明：表层土壤是有机氯农药的主要残留层,表层土壤中检出的DDTs和BHCs质量分数较高,分别为2814.21ng·kg^-1和1130.41ng·kg^-1,但均符合土壤环境质量一级标准,残留污染程度较轻;其他层位以七氯和艾氏剂为主要检出物,最高质量分数分别为1286.19ng·kg^-1和781.23ng·kg^-1;其中艾氏剂未在表层土壤中检出;灌区内未检出的γ-BHC和（DDE＋DDD）/DDT的计算值为1.80,都说明近期内没有新污染源的输入;检出的有机氯农药在土壤剖面上的迁移能力有HEP〉ALD〉BHCs〉DDTs〉HCB,与地下水中检出的规律一致。     

焦化厂多环芳烃污染场地的环境评价实证研究

通过实地调查某焦化厂污染场地污染现状,结果表明：该场地土壤和地下水以多环芳烃（PAHs）有机类污染为主,土壤中苯并（仅）芘和多环芳烃污染以1．5m以内表层土污染为主,随着深度的增加浓度逐渐降低,弱透水层表现出良好的阻隔作用。沿着地下水流动方向,地下水中多环芳烃浓度逐渐降低,经过约400m的迁移,由17296μg／L降至111μg/L;苯并（α）芘经过200m的迁移,由18．3μg／L降至0,地下水流动导致污染物在包气带横向扩散。1号孔、3号孔和4号孔所在地表层土壤中苯并（α）芘的单个污染物的致癌风险分别为0．0278、0．0209和1．496,远远超出可接受水平,因此上述孔位所在地附近表层土壤需重点治理。     

Optimum nitrogen use and reduced nitrogen loss for production of rice and wheat in the Yangtse Delta region

A long-term field and lysimeter experiment under different amount of fertilizer-N application was conducted to explore the optimal N application rates for a high productive rice-wheat system and less N leaching loss in the Yangtse Delta region. In this region excessive applications of N fertilizer for the rice-wheat production has resulted in reduced N recovery rates and environment pollution. Initial results of the field experiments showed that the optimal N application rate increased with the yield. On the two major paddy soils (Hydromorphic paddy soil and Gleyed paddy soil) of the region, the optimal N application rate was 225-270 kg N hm(-2) for rice and 180-225 kg N hm(-2) for wheat, separately. This has resulted in the highest number of effective ears and Spikelets per unit area, and hence high yield. Nitrogen leaching in the form of NO(3-)-N occurs mainly in the wheat-growing season and in the ponding and seedling periods of the paddy field. Its concentration in the leachate increased with the N application rate in the lysimeter experiment. When the application rate reached 225 kg N hm(-2), the concentration rose to 5.4-21.3 mgN l(-1) in the leachate during the wheat-growing season. About 60% of the leachate samples determined contained NO(3-)-N beyond the criterion (NO(3-)-N 10 mg l(-1)) for N pollution. In the field experiment, when the N application rate was in the range of 270-315 kg hm(-2), the NO(3-)-N concentration in the leachate during the wheat-growing season ranged from 1.9 to 11.0 mg l(-1). About 20% of the leachate samples reached close to, and 10% exceeded, the criterion for N pollution. Long-term accumulation of NO(3-)-N from leaching will no doubt constitute a potential risk of N contamination of the groundwater in the Yangtse Delta Region.     

Origin and assessment of groundwater pollution and associated health risk: a case study in an industrial park,northwest China

Groundwater quality which relates closely to human health has become as important as its quantity due to the demand for safe water. In the present study, an entropy-weighted fuzzy water quality index (WQI) has been proposed for performing groundwater quality assessment in and around an industrial park, northwest China, where domestic water requirements are solely met by groundwater. The human health risk was assessed with the model recommended by the United States Environmental Protection Agency. In addition, the sources of major ions and main contaminants were also analyzed. The study shows that groundwater in the study area has been contaminated conjunctively by natural processes and industrial and agricultural activities. Nitrate, manganese (Mn), fluoride, total dissolved solids, total hardness and sulfate are major contaminants influencing groundwater quality. Nitrate and heavy metals such as Mn are mainly affected by human agricultural activities and industrial production, while other contaminants are mainly originated from mineral weathering and water–rock interactions. The results of water quality assessment suggest that half of the groundwater samples collected are of medium quality thus require pretreatment before human consumption. The mean health risk caused by the consumption of contaminated groundwater in the area is 8.42 × 10^?5 per year which surpasses the maximum acceptable level (5 × 10^?5 per year) recommended by the International Commission on Radiologic Protection. The entropy-weighted fuzzy WQI proposed in this study can not only assign proper weights to parameters but also treat uncertainties associated with water quality classification. This study will be of interest to international environmentalists and hydrogeologists. It will also be useful in regional groundwater management and protection.     

Cadmium and lead in livestock feed and cattle manure from four agricultural areas of Bursa,Turkey

The cadmium and lead contents in cattle manure taken from four agricultural areas exposed to different degrees of environmental pollution and in the livestock feeds grown in those places were measured by Atomic Absorption Spectrophotometer (AAS). The levels of cadmium and lead contamination in the manures of the cattle, which were fed in the areas far from industries, traffic or urbanization, were less than those that were closer to heavy traffic and industrial activities. The highest heavy metal content was found in cattle manure collected from the region with heavy traffic, followed by the industrial region and the rural region. Among the live stock feeds used in the present study, the highest levels of lead were found in grass; and the lowest levels were obtained from the samples of straw.     

华北平原地下水有机污染特征初步分析

各种污染造成地下水中有害物质逐年增加,地下水水质逐渐下降,严重危及了饮用水安全。针对此情况,按照相关的要求,采集了245组水样。样品由有资质的测试单位测定。依据对地下水质调查的初步分析,华北平原地下水中已有机物检出。对所有水样测试结果的统计显示：检出的有机污染物共有32种。检出率大于4.5%的有氯仿、甲苯、四氯乙烯、苯并[a]芘、氯苯、苯和1,2-二氯苯,其中个别水样中的四氯化碳、苯并[a]芘和挥发性酚类三项超过了饮用水标准（据地下水质量标准报批稿,中国地质调查局,2007）,超标率分别为1.22%、2.45%和1.90%。个别在深层地下水样品中也检出了微量有机污染物,这可能与取样井的混合开采、止水不佳有关。从区域上来看,在人类活动相对强烈的城镇地区地下水中,有机物检出率相对较高,特别是在渗透性好的山前地带,污染物较易进入到地下水中。通过分析发现,地下水有机物的高检出率与地下水硬度的升高有一定相关性。由于地下水有机污染在时间和空间上差异一般较大,建议对已发现的异常点进行重复取样测试,积累水质数据,以利于将来的综合分析。     

A comparative study of microbial communities in soils amended by manures from pigs fed with organic versus synthetic feeds

We applied pyrosequencing to determine bacterial communities in soil samples taken from test fields amended by manures of pigs fed with green feeds (GPMS), synthetic feeds (APMS), and the reference field without swine manure amendment (NPMS), respectively. For each sample, 7050 effective sequences were selected and utilized to do the bacterial diversity and abundance analysis, respectively. In total, 2986, 2873, and 1602 operational taxonomic units were obtained at a 3% distance cut-off in GPMS, APMS, and NPMS, respectively. Bacterial phylotype richness in GPMS was higher than the other samples. NPMS had the least richness. The most dominant class in both GPMS and APMS is Betaproteobacteria, whereas Alphaproteobacteria is dominant in NPMS. Circa 7.5% sequences in GPMS were found to be affiliated with Burkholderiales order. Bacterial diversity and abundance in the soil varied with swine manure amendment, due to nutrient elements as well as toxic metals in swine manures. Compared with the soil amendment by manures from pigs bred with synthetic feeds, more bacterial diversity but less potentially pathogenic bacterial genera in the soil amended by manures of pigs fed with green feeds were found, which indicated that these manures were better land-applied organic fertilizers.     

BTEX在河流渗滤系统中的降解行为实验模拟研究

河流渗滤是一种自然净化过程,污染河水通过该过程在河流沉积层中发生各种物理、化学和生物作用,使得污染物浓度降低,河水水质得到净化,从而达到增加地下水开采量的目的。本项研究通过淋滤实验,利用自行设计的土柱实验装置和人工配制的淋滤液,模拟了BTEX污染河水在下渗通过河流渗滤系统的过程中发生的降解行为。实验历时48 d,获得了该过程中BTEX各组分和电子受体的质量浓度变化历时曲线,得出的结论包括：污染河水中的BTEX在通过河流渗滤系统时将发生两种环境行为—吸附和降解。其中,吸附作用对于BTEX的净化效果较为有限,当吸附达到饱和之后,在存在电子受体的情况下,BTEX能够发生厌氧微生物降解,降解作用能够更有效的去除BTEX污染物。其中去除效率最高的是间二甲苯,在以NO3-为电子受体的情况下平均去除率为85.5%,在以SO42-为电子受体的情况下平均去除率为82.4%,其次是乙苯、甲苯,去除率最差的是苯,在两种电子受体的系统中平均去除率分别为68.5%和63.5%。由于吸附作用的影响,微生物降解相对于BTEX浓度变化存在一个滞后期,BTEX各组分的土壤-水吸附分配系数Kd越大,总的降解效率也就越低。通过河流渗滤系统这一自然净化过程,可以有效地去除浓度较高的BTEX混合污染,各组分平均去除效率都超过了60%,最高去除率均超过了80%。对于持续不断入渗的污染河水,当土壤吸附达到饱和、微生物活性受到抑制,去除效率会大大降低,从而使BTEX穿透河流沉积层进入含水层,对地下水产生危害。     

Distribution of nitrogen species in groundwater aquifers of an industrial area in alluvial Indo-Gangetic Plains—a case study

The groundwater samples collected from the shallow and deep groundwater aquifers of an industrial area of the Kanpur city (Uttar Pradesh, India) were analyzed for the concentration levels and distribution pattern of nitrogenous species, such as nitrate-nitrogen (NO₃-N), nitrite-nitrogen (NO₂-N), ammonical-nitrogen (NH₄-N), organic-nitrogen (Org-N) and total Kjeldahl-nitrogen (TKN) to identify the possible contamination source. Geo-statistical approach was adopted to determine the distribution and extent of the contaminant plume. In the groundwater aquifers NO₃-N, NO₂-N, NH₄-N, TKN, Org-N and Total-N ranged from 0.10 to 64.10, BDL (below detection limit)-6.57, BDL-39.00, 7.84–202.16, 1.39–198.97 and 8.89–219.43 mg l⁻¹, respectively. About 42% and 26% of the groundwater samples of the shallow and deep groundwater aquifers, respectively, exceeded the BIS (Bureau of Indian Standards) guideline value of 10 mg l⁻¹ for NO₃-N and may pose serious health hazards to the people of the area. The results of the study revealed that the groundwater aquifers of the study area are highly contaminated with the nitrate and indicates point source pollution of nitrate in the study area.