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1.
底泥是水库生态内源污染重要释放源。为全面了解山东省黄岛区主要水库底泥中重金属含量及其潜在生态危害程度，采集了黄岛区狄家河水库在内的10个水库的水样，测试了底泥中Hg、Cd、Pb、Cr、Cu、Zn、Ni、Fe、Mn和As等10种重金属含量，分析了各元素的含量，利用多方法综合对水库底泥污染程度及潜在的生态风险进行评价，并结合周边生活、生产环境分析了重金属的可能来源。结果表明，西寨水库Hg含量超过标准要求，花沟水库Cd含量超过标准要求，其余水库各重金属含量均未超过标准要求；底泥重金属污染程度由强到弱依次为：Hg>Cd>Zn>Pb≥Cu≥As>Ni≥Cr,Hg、Cd为最主要的重金属污染元素；重金属潜在生态危害由强到弱依次为：Hg>Cd>As>Pb>Cu>Cr>Ni>Zn,Hg、Cd是潜在的生态危害元素。花沟水库、吉利河河道、西寨水库、狄家河水库，尤其是西寨水库，污染程度较为严重，水库污染的因素主要为人为因素，主要来源为工业污水和生活用水排放。 相似文献
2.
为研究泗河表层沉积物中重金属含量及其潜在生态危害程度,在泗河干流及支流共采集了7个底泥样品,分析测试了Hg、As、Cd、Pb、Cr、Ni、Cu、Zn、Mn共9种重金属元素,采用地累积指数法和潜在生态危害指数法对泗河表层沉积物中重金属的污染进行了分析和评价。结果表明,泗河表层沉积物中重金属污染主要以Hg和Cd为主。各种重金属的污染程度由强至弱依次为：Hg＞Cd＞Mn＞Zn＞Ni≈Pb≈Cu＞Cr＞As;各种重金属污染对泗河流域构成的潜在生态危害程度由强至弱的次序为：Hg＞Cd＞As＞Pb≈Cu＞Cr≈Zn。 相似文献
3.
底泥污染是造成茅洲河流域水质黑臭的关键因素之一.本文通过对底泥勘查取样检测,采用底泥沉积物单因子污染指数法对底泥营养盐污染进行分析评价,结果显示,营养盐、有机质污染均达到了重度污染等级.采用单一重金属潜在生态风险系数和多金属潜在生态风险系数法对重金属污染程度进行分析评价,结果显示,重金属污染达到了极强生态风险等级.根据... 相似文献
4.
以广西龙江河为研究对象,采集12个样点的表层沉积物样品,分析测试了Cd、Cu、Pb、Zn重金属元素的含量,通过相关性分析,以及地累计指数法和潜在生态危害指数法,对龙江河沉积物中重金属的潜在生态风险进行了分析和评价。结果表明：水工建筑物的存在对沉积物中重金属的含量有一定影响;龙江河重金属污染主要位于中游河段,沉积物重金属污染主要以Cd为主,其次还存在一定程度的Pb污染; Cu、Pb、Zn元素相关性显著（P＜0.01）,污染程度具有一定的相似性或有相似的污染来源;重金属污染严重程度为：Cd＞Pb＞Zn＞Cu;生态风险危害程度最大的重金属元素为Cd。 相似文献
5.
本文对松滋河河口段不同区域泥沙进行取样,分析了各河段泥沙粒径、化学组分、重金属含量等指标,进而对泥沙潜在生态风险进行评价.结果表明,河口段泥沙以中细砂为主,松滋河大口下游含沙量高于上游;SiO2、Al2 O3和CaO是泥沙的主要化学成分;主要重金属指标均低于国家土壤污染风险筛选值;从潜在生态风险评价来看,总体属于低潜在... 相似文献
6.
对赣江中下游城市断面10个监测断面的水体及底泥重金属含量进行了调查与分析。结果表明,水体中的重金属除Cu的含量超出地表水环境质量标准III类标准外,其它各项监测指标均能达到地表水环境质量III类标准。沉积物7种重金属Cu、Zn、Pb、Cd、Cr、Ni和As含量范围和均值分别为8.29~70.87、27.07;5.98~40.59、18.10;8.33~129.64、35.60;0.55~110.33、14.122;3.96~35.06、11.91;11.67~42.03、25.65和0.31~21.13、5.49 mg/kg;沉积物中重金属的污染程度较高,Cd与Cu是主要的污染因子。潜在生态风险评价显示：沉积物中重金属潜在生态风险指数RI的平均值为608.82,属较强生态危害,5种重金属潜在生物毒性风险大小依次为Cd >Cu>Pb >Cr>Zn。 相似文献
7.
通过分析观澜河底泥量和污染状况,预测底泥清理对水质的影响,探讨清理观澜河底泥的方式、工艺及处理处置方案。主要结论:观澜河底泥总量为38.8万m3,其中泥量为19.3万m3;观澜河底泥主要污染为有机质、Ni,Cr,Zn,Cu及Hg;清理工艺流程主要包括挖泥车下河挖泥、格栅分离石块、除砂、絮凝及重金属稳定等。 相似文献
8.
以吉林市表层土壤为研究对象,采用Hakanson提出的潜在生态危害指数法对重金属的潜在生态危害进行了评价。结果表明,吉林市表层土壤受到Hg、Cd、As、Cu、Pb、Cr及Zn的污染,且这些元素对吉林市表层土壤污染程度不同,其中Zn、Hg、Cr、Cd和Pb的污染程度较高,特别是分别存在Hg和Cd的强生态危害及中等生态危害;各元素生态危害等级排序为：Hg>Cd>As>Cu>Pb>Cr>Zn;表层土壤重金属污染潜在生态危害总体达中等及中等以上危害程度。 相似文献
9.
对扎龙湿地底泥-水体以及丹顶鹤体内的重金属Zn、Cd、Cu、Pb、Cr进行分析。结果表明,扎龙湿地底泥富集重金属状态较明显,5种金属的平均质量分数均远超过该地区土壤背景值。各金属的富集程度为Zn>Cu>Pb>Cr>Cd。扎龙湿地底泥重金属元素特征在空间上存在明显的差异性。工、农业活动较频繁的林甸县和富裕县所属的湿地区的底泥污染最重,具有很强的潜在生态风险,湿地核心区内的底泥重金属属于轻微-中等生态风险程度。Zn是扎龙湿地栖息的东方白鹳和丹顶鹤体内富集的主要元素,Zn的富集,粪便>羽毛>蛋壳。除了Zn富集明显外,其他重金属富集顺序为Cu>Cr>Pb>Cd,各种元素在2种水禽不同附属物中质量分数高低顺序与Zn一致。 相似文献
10.
实地采集了15个土壤剖面样品,并对其中的Pb、Cd、Hg、As、Cu、Cr、Zn和Ni含量进行分析监测,采用潜在生态危害风险评价法对研究区域土壤中重金属的污染状况进行了评价,并通过工程措施进行了污染土壤修复治理。结果表明,在0~20 cm土层范围内,Zn质量比在89.80~724.03 mg/kg之间,Cu质量比在28.89~1 271.81 mg/kg之间,Hg质量比介于0.04~4.48 mg/kg之间,Pb质量比介于48.69~12 021.15 mg/kg之间。Cd质量比在0~120 cm范围内均超过了土壤环境质量二级标准,而且Pb、Cd、Hg、Cu和Zn在0~120 cm范围内全部超过了关中塿土背景值。潜在生态危害风险评价表明,Cd的潜在生态危害系数范围为26.0~21 118.6,轻微、中等、较强、很强和极强的生态危害频率分别为4.3%、15.2%、19.6%、15.2%和37%;Pb的潜在生态危害系数范围为0.1~120.2,轻微、中等和较强的生态危害频率分别为93.5%、4.3%和2.2%;Hg的潜在生态危害系数范围为0.1~83.4,轻微、中等和较强的生态危害频率分别为59.3%、39.4%和1.3%;As、Ni、Zn和Cu均具有轻微生态危害。研究区域土壤重金属污染主要是Cd、Hg和Pb等形成的复合污染。采用原位挖掘-异位固化-客土回填法,对研究区域进行污染土壤工程修复,可获得良好的修复效果。 相似文献
11.
对饮料中的柠檬黄含量进行了测定和不确定度分析,通过对各影响因素的不确定度评定,试验重复性对饮料中合成着色剂的测量结果不确定度的影响最大,其次是样品处理回收率和标准曲线拟合引入的不确定度对试验结果也有较大的影响。结果表明:饮料中柠檬黄的含量为（103.5?3.5）mgkg,k＝2。 相似文献
12.
Adoption of a new technology, such as irrigation, is a complex phenomenon. Several factors of economic and social nature contribute to the farm-level decisions affecting adoption. In this study, the role played by attitudes of potential adopters towards irrigation and its subsequent adoption on their farm unit was estimated. Two models were estimated, one incorporating only adopters' socio-economic characteristics, and the other, only their attitudes towards irrigation. Results suggest that adopters' attitude, particularly with respect to economic and environmental effects of irrigation, were significant determinants of their decision to proceed with adoption of irrigation, and have a role to play in adoption of irrigation over and above that explained by socio-economic characteristics. In particular, these results suggest that negative perceptions with respect to economics of irrigation and those related to its detrimental impacts on environmental quality, particularly through soil salinity, may be significant deterrents for adoption of irrigation. The study suggests that planning of large scale water development projects, particularly those involving irrigation, must be cognizant of attitudes of potential adopters. Furthermore, during the planning stages, more attention should be paid to the development of proper educational programs, as well as extension packages, to ensure that potential adopters formulate correct attitudes towards the new technology. 相似文献
13.
数学作为一门基础性学科，在学生的各个学习阶段都起到了不可替代的作用，在工科院校中数学教学的重要性更是升到了一个新的高度。通过数学的学习，可以培养学生的应用能力和探究思维，通过对数学知识的学习和灵活运用，学生的综合能力会得到系统性的提高。对于数学的教学工作，应当做到有针对性、有目标，在教学工作中，充分做到对症下药、有的放矢，让学生通过对数学的学习，提高自身的综合能力，更好地为社会建设贡献力量。 相似文献
15.
本试验通过沼气燃烧,提高冬季温室温度,促进西红柿生长发育.试验结果表明:增温可有效提高冬季温室温度,为西红柿越冬生产提供良好条件,有利于西红柿植株茎粗增加及果实膨大速率提高;可使西红柿坐果期提前10天左右,采收期延长20天左右,并提早上市.同时,增温可显著提高西红柿产量,亩增产800kg. 相似文献
16.
分析了四川简阳地区砂岩和土壤中的水分运动特性和砂岩中储存的水分对土壤水分补给量的多少。对当地的砂岩和土壤进行了水分特征曲线的测定试验、入渗试验和蒸发试验,并采用研究中常用模型对试验结果进行了拟合,通过对拟合结果的分析,得出了当地土壤和砂岩的水分特性,总结出了该地区表面土层在缺水时水分很容易被下部砂岩层补给,砂岩中的水分是作物利用的重要水资源的结论。这对于充分利用当地水资源,合理确定类似地质条件地区灌溉定额,解决无灌溉条件丘陵区作物缺水问题,实现农业节水灌溉有一定的参考价值。 相似文献
17.
Agricultural ecosystems and their associated business and government systems are diverse and varied. They range from farms, to input supply businesses, to marketing and government policy systems, among others. These systems are dynamic and responsive to fluctuations in climate. Skill in climate prediction offers considerable opportunities to managers via its potential to realise system improvements (i.e. increased food production and profit and/or reduced risks). Realising these opportunities, however, is not straightforward as the forecasting skill is imperfect and approaches to applying the existing skill to management issues have not been developed and tested extensively. While there has been much written about impacts of climate variability, there has been relatively little done in relation to applying knowledge of climate predictions to modify actions ahead of likely impacts. However, a considerable body of effort in various parts of the world is now being focused on this issue of applying climate predictions to improve agricultural systems. In this paper, we outline the basis for climate prediction, with emphasis on the El Niño-Southern Oscillation phenomenon, and catalogue experiences at field, national and global scales in applying climate predictions to agriculture. These diverse experiences are synthesised to derive general lessons about approaches to applying climate prediction in agriculture. The case studies have been selected to represent a diversity of agricultural systems and scales of operation. They also represent the on-going activities of some of the key research and development groups in this field around the world. The case studies include applications at field/farm scale to dryland cropping systems in Australia, Zimbabwe, and Argentina. This spectrum covers resource-rich and resource-poor farming with motivations ranging from profit to food security. At national and global scale we consider possible applications of climate prediction in commodity forecasting (wheat in Australia) and examine implications on global wheat trade and price associated with global consequences of climate prediction. In cataloguing these experiences we note some general lessons. Foremost is the value of an interdisciplinary systems approach in connecting disciplinary knowledge in a manner most suited to decision-makers. This approach often includes scenario analysis based on simulation with credible models as a key aspect of the learning process. Interaction among researchers, analysts and decision-makers is vital in the development of effective applications — all of the players learn. Issues associated with balance between information demand and supply as well as appreciation of awareness limitations of decision-makers, analysts, and scientists are highlighted. It is argued that understanding and communicating decision risks is one of the keys to successful applications of climate prediction. We consider that advances of the future will be made by better connecting agricultural scientists and practitioners with the science of climate prediction. Professions involved in decision making must take a proactive role in the development of climate forecasts if the design and use of climate predictions are to reach their full potential. 相似文献
18.
Pesticides degrade principally through biodegradation processes, whereas antibiotics kill microorganisms or inhibit their growth in soils and thus may affect the fate of pesticides. In this study, the impact of antibiotics on the degradation of atrazine in a sandy soil is investigated in lysimeters over a ninety-day period. Four treatments, monensin, narasin, salinomycin and non-antibiotic, were assigned in triplicate to twelve PVC lysimeters. Both soil and leachate samples were collected and analyzed at predetermined time intervals. In all treatments, atrazine was found to leach down through the soil profiles with the concentration level decreasing with depth, and only trace amounts of atrazine were found in the leachate. However, the statistical analysis of the results showed that all the three antibiotic treatments yielded a significantly slower dissipation of the atrazine level as compared to the non-antibiotic treatment; the mass balance analysis indicated an increased half-life of atrazine in the presence of antibiotics. 相似文献
19.
为明确北京东南郊灌区表层土壤和农作物多氯联苯(PCBs)含量和污染水平以及人体健康风险,2015年在该灌区采集了20个土壤样品和28个作物样品,利用气相色谱-质谱联用仪分析了样品中7大类PCBs含量。研究结果表明,灌区表层土壤PCBs质量比为ND(低于检出限)到0.711 776μg/kg,均值为0.43μg/kg,总体上土壤PCBs含量随污灌历史年限增加而增加。本研究区表层土壤PCBs含量处于较低水平,土壤未受到PCBs污染且其生态风险概率均小于10%。灌区采集的冬小麦籽粒、大葱、茄子、梨、白薯、芥蓝PCBs含量均低于实验检出限,未检出;夏玉米籽粒、菜心和油菜PCBs总量分别为0.17~0.47μg/kg、1.63μg/kg和5.91μg/kg。不同污灌历史年限并未显著影响夏玉米籽粒PCBs含量。本研究区农产品PCBs含量处于较低水平,均低于美国卫生及公共服务部建议限量。采集的土壤和农产品样品仅四氯联苯含量高于实验检出限,能检测出;一氯联苯到三氯联苯和五氯联苯到七氯联苯均低于实验检出限,未检出。本研究中成人和儿童PCBs致癌风险分别为8.49×10-7和4.66×10-7,非致癌风险分别为1.41×10-1和3.88×10-1,均低于US EPA规定限值,说明PCBs未对人群产生明显的健康危害。致癌危害和非致癌危害均以口-作物(玉米和蔬菜)为主,其对人体健康所造成的风险占总个人年风险的比例分别为99.79%~99.95%和99.81%~99.94%。 相似文献
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