【作者】 储彬彬；

【导师】 罗立强； 孙青； 詹秀春；

【作者基本信息】 中国地质科学院 ， 地球化学， 2012， 博士

【摘要】 铅锌矿产资源的开发和利用引发的环境问题一直备受关注,其重金属的形态和传播方式直接影响了当地居民健康,但是重金属如何由矿石进入环境、污染传播的介质及其作用等仍然不清楚,另外污染物的形态及其与大分子的结合方式也有待研究。因此,为揭示重金属迁移转化规律、探讨重金属形态与其耐受性的关系,选取了己开采50多年的南京栖霞山铅锌矿区为主要的研究区,并以开采不足十年的张北蔡家营铅锌矿区和北京周边无矿区为参考,采集了多种类型的生物地球化学样品,利用EDXRF和ICP-MS开展了矿区重金属分布特征和铅同位素污染示踪的研究,运用同步辐射XANES和XRF分析了矿区土壤和植物的重金属形态及其微区分布特征,并综合亲和层析柱、电泳、LC-MS/MS等技术,开展了矿区富铅植物的铅结合蛋白的研究,具体取得了以下几点认识和成果。第一,不同地区的调查发现,污染主要集中在南京栖霞山铅锌矿区。该矿区水中的Pb以及土壤中的Pb、As、Cd和Zn均超过了标准值,另外植物中的Pb和As的含量也较高。第二,铅同位素示踪表明南京栖霞山铅锌矿区污染主要来自矿山,大气沉降是当地污染传播的主要方式之一第三,生物膜中重金属的含量比其周围环境水、土和植物均高,证实了生物膜对重金属的富集功能。第四,土壤的XANES分析表明选矿厂表层土壤中铅为硫酸铅和硝酸铅,菜园地下1.0.1-2米的剖面土中铅主要为有机的氯化三甲基铅。然而,选矿厂、矿区排气口以及矿区菜园表层和剖面的土壤中砷形态相同,均为五价砷化合物。第五,植物XANES分析表明,矿区浮萍中砷为三价砷,铅为含硫的有机酸铅。另外,实验室培养的黄瓜和花叶笋的铅形态不同于培养液硝酸铅的形态,而与浮萍铅形态相同,且在根、茎和叶中无形态差别,为含硫的有机酸铅,表明植物具有将无机铅转化为有机铅的功能。第六,在矿区富含重金属的浮萍植物中,不仅发现了砷元素具有显著的叶脉分布特征,而且成功鉴定了44个铅结合蛋白。其中有7个铅结合蛋白存在的可能性极大,分别是1,5-二磷酸核酮糖羧化酶大亚基、ATP合成酶β亚基、热激蛋白HSP83A和HSP81-1,以及葡萄糖调解蛋白GRP-78、GRP-78.5和GRP-94homologo热激蛋白和葡萄糖调解蛋白是常见的金属结合蛋白,但1,5-二磷酸核酮糖羧化酶大亚基和ATP合成酶β亚基与金属结合的报道不多,它们与铅的结合还未见报道。另外,与这7个铅结合蛋白所匹配的肽段中,含有较多的谷氨酸、天冬氨酸、组氨酸和甲硫氨酸,研究发现这些氨基酸残基易与铅结合。故浮萍富含并耐受铅可能与这些易与铅结合的氨基酸残基大量存在有关。总之,随着铅锌矿矿产资源开采以及时间的累积,矿石中的重金属会不断地进入环境,其中大气沉降和生物膜分别在宏观和微观上对重金属的污染传递起着重要的作用。矿区土壤和植物中重金属形态差异显著,其中矿区的水生植物浮萍不仅富含重金属,而且浮萍中的砷元素具有显著的叶脉分布特征,浮萍中的铅结合蛋白也含有较多的易与铅结合的配体。这些认识和发现为理解重金属的传播规律、探讨植物对重金属的耐受机理提供了一定的参考。更多还原

【Abstract】 Environmental problems from exploitation and utilization of lead-zinc mine have received public attention. Speciation and transmission way of heavy metals have a direct impact on the health of local residents. However, it’s not clear that how heavy metals migrate from ore into environment and what the media is. It’s also need to deeply study the speciation of pollutants and their binding mode with macromolecules.Therefore, in order to reveal migration and transformation law of heavy metals and investigate the relationship between speciation and tolerance of heavy metals, some studies are carried out. Lead-zinc mining area of Nanjing Qixiashan, which has been exploited over50years, is selected as a main study area, and lead-zinc mining area of Zhangbei Caijiaying with less than a decade exploitation and non-mining area around Beijing are selected as reference areas. Many biogeochemical samples are collected. EDXRF and ICP-MS are used to study the characteristics of heavy metals distribution and pollution tracer of lead isotope. Synchrotron radiation XANES and XRF are used to analyze the speciation and micro-distribution of soil and plants in mining area. Affinity column, electrophoresis, and LC-MS/MS are used to study lead-binding protein of plants with high Pb concentration in mining area. Several results from analyses are concluded as below.Studying of different areas, we found that the pollution is mainly distributed in lead-zinc mining area in Nanjing Qixiashan. Lead concentration of water is over the standard value, and concentrations of Pb, As, Cd, and Zn are also over the standard values in soil. Besides, the concentrations of Pb and As are very high.Lead isotope analysis shows that the pollution source is mainly from the mine in Qixiashan, and atmospheric deposition is one of the main pathways of pollution spread over there.Concentrations of heavy metals in biofilm are higher than the ambient water, soil and plants, which confirmed the enrichment function of heavy metals in biofilm.Soil XANES analysis shows that the speciation of lead is lead sulfate and lead nitrate in the surface soil around dressing plant, but mainly organic chloride methyl lead in the underground soil of1.0-1.2m depth in garden. However, soil accumulate arsenic as As(V), no matter the sources of soil from dressing plant, vent, surface or profile soil around mining area. Plant XANES analysis shows that duckweeds accumulate arsenic as As(Ⅲ) and lead as sulfur-containing organic acid lead. In addition, the lead speciation in cucumber and mosaic shoot growing in lab is different from Pb(NO3)2that was added for cultivation, but is the same with lead speciation of duckweed. There is no difference of lead speciation among roots, stems and leaves of cultivated plants, which preserved lead as sulfur-containing organic acid lead. This result showed that plants are able to transform the inorganic lead into organic lead.Duckweeds from mining area, which is rich in heavy metals, are found the significant distribution of arsenic along veins, and are indentified44lead-binding proteins. There are seven lead-binding proteins of high significance. They are ribulose bisphosphate carboxylase large chain (RuBisCO large subunit), ATP synthase subunit beta, heat shock protein83(HSP83A), heat shock protein81-1(HSP81-1),78kDa glucose-regulated protein homolog (GRP-78),78kDa glucose-regulated protein homolog5(GRP-78-5) and glucose-regulated protein94homolog (GRP-94homolog). Heat shock proteins and glucose-regulated proteins are common metal-binding proteins. However, there is little literature about metal ion binding for RuBisCO large subunit and ATP synthase subunit beta, and there is no literature about lead binding for these two proteins. In addition, there are some amino acid residues of glutamates, aspartates, histidines and methionines in matched peptides for these seven proteins, which were reported to bind with lead easily. Thus, it is suggested that these amino acid residues may play a role for the lead tolerance mechanism of duckweed.In conclusion, with the exploitation and utilization of lead-zinc mine for a long time, the heavy metals of ore are transferred into environment continually. Atmospheric deposition and biofilm play an important role in heavy metals migration on macroscopic and microscopic views respectively. The significant difference of speciation is found between soil and plants. The aquatic duckweed from mining area is not only rich in heavy metals but has significant distribution of arsenic along veins. In addition, there are some ligands binding with lead easily in lead-binding proteins of duckweed. These results and discovery provide a certain reference in understanding the propagation law of heavy metals and exploring the tolerance mechanism of heavy metals in plants.更多还原