【作者】 袁波；

【导师】 傅瓦利；

【作者基本信息】 西南大学 ， 自然地理学， 2012， 硕士

【摘要】 近年来,土壤污染越来越严重,其中尤以重金属污染问题最严重。土壤被重金属污染后,重金属元素将通过食物链富集到人体,对人体健康造成危害,所以在蔬菜种植区选取中种植区土壤环境是否满足健康蔬菜的生产是最基本的一个条件。为了保证蔬菜质量、保障居民身体健康,本文对北碚区菜地土壤中铅和镉全量、有效态量进行了测定,对全量特征进行了分析,采用不同标准对菜地土壤铅、镉的环境质量做了评价,对研究区菜地土壤有效态含量进行了分析,并对菜地规划区内不同土地利用方式下土壤的铅、镉含量进行了研究,结果表明：(1)研究区菜地土壤铅含量平均值为43.92 mg/kg,变异系数为37.3%；镉含量平均值为0.212mg/kg,变异系数为28.3%。在研究区内若以乡镇为统计单元,全铅含量为三圣镇>槽上蔬菜基地>柳荫镇>天府镇>复兴镇>东阳镇>澄江镇>静观镇,全镉含量为天府镇>复兴镇>三圣镇>东阳镇=静观镇>澄江镇>柳荫镇>槽上蔬菜基地。从新规划菜地和原有菜地来看,全铅含量是新规划菜地略大于原有菜地,全镉含量是原有菜地大于新规划菜地。土壤类型和距离公路距离对研究区菜地土壤全铅含量影响显著,对全镉含量没有显著影响。通过相关分析表明研究区菜地土壤全铅含量与土壤有机质、黏粒和pH值有明显的相关关系,而全镉含量只与有机质含量有极显著关系。(2)从研究区菜地土壤铅、镉的整体累积状况来看,铅、镉的累积指数都大于1,研究区内菜地土壤铅、镉都有不同程度的累积；从不同程度累积指数分布来看,铅主要分布在重度累积和轻度累积,镉主要分布在轻度累积和中度累积。地质累积指数表明,研究区土壤都不同程度的受到铅、镉污染,且研究区菜地土壤铅的污染程度要大于镉的。单项污染指数法表明,研究区及各乡镇的菜地土壤在铅含量水平上、镉含量水平上完全满足无公害蔬菜的生产,基本满足绿色蔬菜的生产；综合污染指数法表明,在无公害标准下研究区及各乡镇的菜地土壤未受到铅、镉的综合污染,在绿色标准下污染指数都处于警戒限。从潜在生态危害指数来看,研究区及各乡镇的菜地土壤铅、镉的潜在生态风险是铅处于低等,镉处于中等；从总的潜在生态危害指数来看研究区及各乡镇的菜地土壤在铅、镉的作用下处于轻度生态危害。从原有菜地和新规划菜地来看,新规划菜地与原有菜地土壤全铅、全镉含量在平均含量上都满足无公害、绿色蔬菜的生产；但以地质累积指数评价结果看出,其Igeo值都大于0,整体上新规划菜地和原有菜地土壤都受到了一定的铅、镉污染,且原有菜地土壤的镉污染要比新规划菜地的严重；新规划菜地和原有菜地土壤在绿色蔬菜产地标准要求下其PN值小于1大于0.7,处于污染的警戒限,这说明在综合作用的影响下,两类土壤有污染的趋势；而在无公害标准下其PN值小于0.7,这说明在此标准下两类土壤未受到铅、镉的污染。从总的潜在生态危害指数来看新规划和原有菜地土壤在铅、镉的作用下都处于轻度生态危害。(3)研究区菜地土壤铅、镉有效态平均含量为3.114,0.051 mg/kg,都显著低于重庆市土壤环境背景值,其变异系数分别为30.4%,38.9%；生物有效性系数分别为7.7%,25.1%,从生物有效性系数来看,研究区菜地土壤镉的潜在生态风险要大于铅的。研究区菜地土壤铅、镉有效态与全量之间相关性呈极显著,铅、镉全量是决定有效态含量的主要因素；同时,铅、镉全量和有效态含量的变化趋势也不完全一致,铅、镉全量值较大有效态含量不一定较大,在生态风险表征时要结合有效态含量进行分析。通过相关分析发现,研究区菜地土壤pH对有效态镉有显著影响,砂粒、黏粒和有机质对有效态铅含量有显著影响；土壤类型对铅、镉有效态含量也有影响,紫色土有效态铅含量明显小于石灰土,而有效态镉含量是紫色土大于石灰土；在人类活动中交通对有效态铅含量有明显影响。(4)通过SPSS描述统计与方差分析表明,菜地规划区内前期不同土地利用方下土壤镉全量、有效态含量、生物有效性系数有不同程度的差异,土地利用方式对其有不同程度的影响；3种土地利用方式中土壤铅全量是混作地>水田>原有菜地,镉全量是原有菜地>水田>混作地；土壤有效态铅含量是水田>混作地>原有菜地,有效态镉含量是原有菜地>混作地>水田。土壤铅生物有效性系数是水田>原有菜地>混作地,镉生物有效性系数的混作地>原有菜地>水田。对本区不同土地利用方式下土壤铅、镉全量与有效态含量差异的影响因素分析发现,车辆废气、肥料的施用的差异是影响全量差异的可能因素；土壤pH值差异、铅镉全量差异是影响有效态的可能因素。生物有效性系数主要受铅、镉全量与有效态含量影响,同时还受其他因素的影响。以重庆市土壤铅、镉背景值为标准,通过地质累积指数法计算得出,研究区菜地规划区土内壤铅、镉受轻度污染,其中混作地与水田土壤铅污染程度较原有菜地的明显,原有菜地土壤镉污染程度较水田与混作地的明显。更多还原

【Abstract】 In recent years, soil pollution is becoming more and more serious; especially that the heavy metal pollution is the most serious problems. If the soil was contaminated by heavy metals, the heavy metals will be enriched to the human body through food chain, which could cause harm to human health, so the selected plant area’s environment whether meet the health vegetable production is the most fundamental condition in vegetable cultivation area. In order to ensure the quality of vegetables and safeguard the health of residents in Beibei District, this paper will determine the content of lead and cadimium, available volumes in soil. What’s more, analyzed the features of total capacity, using different standards of lead, cadmium in vegetable soil environment quality to evaluate, analysis the available content of lead and cadmium on the planning area, and analysis the field soil’s lead and cadmium content under different land use patterns. The results showed that:(1) The content of lead average levels was 43.92 mg/kg in Beibei District vegetable soil, the coefficient of variation was 37.3%; the content of cadmium levels average was 0.212mg/kg, the coefficient of variation was 28.3%. If using the township as a statistical unit in the research area, the content of lead is that the first is SanSheng town, second is slot vegetable base, third is LiuYin town, forth is TianFu town, fifth is FuXing town, sixth is Dong Yang town, seventh is ChengJiang town, and the last is JingGuan town. The content of cadmium is that he first is TianFu town, second is FuXing town, third is SanSheng town, forth is DongYang town and JingGuan town, fifth is ChenJiang town, sixth is LiuYin town,and the last is slot vegetable base. From the point of the new planning of the vegetable and original vegetable plot, the new planning of the vegetable’s content of lead was slightly larger than the original planning of the vegetable vegetable plot, the new planning’s total content of cadmium was greater than the original planning of the vegetable. Soil type and distance to highway distance has significant influence to soil total lead content, no significant effect on the content of cadmium, Through the correlation analysis showed that the study area the total content of lead in vegetable soil has significant relationship to soil organic matter, clay and pH value, and the total content of cadmium only has significant relationship with the content of organic matter.(2) From the study area of lead, cadmium in Vegetable Soils in the overall cumulative situation, lead, cadmium accumulation index were more than 1, the study area of lead, cadmium in vegetable soils had different accumulation from different degree; cumulative index distribution of lead, mainly distributed in severe and mild cumulative cadmium accumulation, mainly distributed in mild and moderate accumulation accumulation. Geo accumulation index shows, the study area vegetable soil had been different level of lead and cadmium pollution, and the lead pollution was larger than the cadmium.The individual pollution index indicates that, the study area and each towns’ vegetable soil fully meet the pollution-free vegetable production in the lead and cadmium level, and basically meet the needs of green food vegetables; comprehensive pollution index method show that, under the lead and cadmium working together the study area vegetable soil and each town’s soil were not polluted by the lead and cadmium, but the pollution index were all at the level of alertness. From the point of potential ecological risk index, the study area and each town’s vegetable soil potential ecological risk is that, the lead was at the low level, cadmium at the middle level. From the point of the total potential ecological risk index, the study area and each town’s vegetanble soil were in the mild ecological hazard under the effect of lead and cadmium.From the view point of the original vegetable plantation and the new planning vegetable plantation, the new planning vegetable plantation and the original vegetable soils’average content of lead and cadmium all meet the pollution-free and green vegetable production. But from the point of the geoaccumulation evaluation index results showed that, the Igeo value is greater than 0, the the original vegetable plantation and the new planning vegetable plantation were both affected by the lead and cadmium pollution overall, the original was more serious than the new. Uner the green vegetable production standards, the new and originals’ PN value were more than 0.7 and lower than 1, at the alertness level. This showed that under the comprehensive effected, two types of soil were affected by the pollution; but under the no social effects of pollution standsards, the PN value was lower than 0.7. This showed that the two types of soil were without lead and cadmium pollution. From the total potential ecological risk index to see, the new planning and the original vegetable soil were under mild ecological hazard of lead and cadmium.(3) The average content of availability lead, cadmium is 3.114,0.051 mg/kg in the study area of vegetable soil, which were significantly lower than the Chongqing soil environmental background values, and its coefficient of variation were 30.4%,38.9%; biological validity coefficients were 7.7%, 25.1%. From the point of biological effectiveness coefficient, the study area vegetable soil cadmium’s potential ecological risk was greater than the lead. The study area’s vegetable soil content of lead and cadmium had significant correlation whith the full amount, lead and cadmium total value was main factor to determine the effective content, and lead and cadmium content’s change trend was not entirely consistent with the available content. The lead and cadmium was larger, but the effective content was not greater. Through correlation analysis found that, the study area soil PH value had a significant effect to cadmium, sand, clay and organic matter had significant effect to lead. The soil type had an impact to lead and cadmium content, the purple soil’s lead content was smaller than the lime soil, and the available cadmium content was that, the purple soil greater than the lime soil. From the human activeties, the traffic had obvious effect to the lead content.(4) Through the SPSS statistics descriptive and analysis of variance indicated that, under different land using manners, the early planning area cadmium, available and biological validity coefficients had different degrees, land using manner had influence to it. From the three kinds of land using manners, the lead content was mixed cropping land at first, second was paddy field, the last was original vegetable.Cadmium was original vegetable plantation at first, second was mixed cropping, and the last was paddy field.Soil available Pb content was mixed cropping land at first, second was paddy field, and the last was original vegetable plantation.Available cadmium content was original vegetable plantation at first, second was mixed cropping land, and the last was paddy field.Soil lead bioavailability coefficient was paddy field at first, second was original vegetable plantation, and the last was mixed cropping land. The cadmium was original at first, second was mixed, and the last was paddy field.From the analysis of the influence factors to lead, cadmium and effecitive content diversity under different land using manners found that, the diversity of vehicle exhaust and the application of fertilizer was possible factors to the different effective content.Soil PH value difference and lead, cadmium content difference were possible factors to the fifferent effective content.Biological effectiveness coefficient was mainly affected by lead, cadmium and available content, but also influenced by other factors. Uner the standard of Chongqing city soil lead and cadmium background values, through calculation of geo accumulation method showed that, the study area was lightly polluted by lead and cadmium. Mixed and paddy soils pollution degree was apparent than the original vegetable, original vegetable soil cadmium pollution degree was more obvious than the paddy field and mixed cropping.更多还原