土壤重金属污染对农产品质量安全的影响及其防治措施

针对当前日益严峻的土壤重金属污染及其所引起的农产品质量安全问题,本文论述了土壤重金属污染物的主要来源、重金属在土壤与植物中的存在形态及危害,探讨了农产品产地土壤重金属污染的防治措施,以期为提升产地土壤环境质量和建立农产品质量安全监管体系提供理论依据。     

土壤中重金属污染现状与防治方法

文章阐明了土壤重金属污染来源与分布,同时对国内外土壤重金属污染治理的研究工作做了系统的综述,提出了土壤中重金属污染物防治的环境矿物学新方法,利用环境矿物材料治理土壤重金属污染物的方法,具有成本低,效果好,无二次污染及有用金属可回收利用等优点,展现出广阔的环境矿物学研究与应用前景。并提醒人们要提高土壤质量意识,保护生态环境。     

韶关土壤重金属污染状况

随着工矿业的迅猛发展,韶关土壤重金属污染日益严重,直接影响到农作物的安全生产。笔者对韶关土壤重金属污染来源及其现状作了概述,并针对污染状况及其当地农作物生产的特点提出了一些治理和修复建议。     

土壤重金属（CuZnCd）复合污染的研究现状

从土壤重金属复合污染对植物生长的影响、重金属复合污染的表征方式及重金属污染土壤的防治措施3个方面进行较全面的阐述,并对今后研究的发展方向提出一些看法。     

洞庭湖区土壤重金属污染现状及防治对策

位于湖南北部的洞庭湖区,是湖南省重要的粮食产区,其耕地重金属污染与粮食作物生产安全问题是全社会十分关注的问题。论文综述了洞庭湖粮食生产区耕地重金属污染的种类与程度,分析了其产生的原因与潜在的危害,总结了土壤重金属污染的主要防控和治理措施,并有针对性地提出了综合防治对策。旨在为洞庭湖区耕地的保护和可持续利用提供参考依据。     

土壤重金属污染修复技术

介绍了近年来国外开发,应用的七种较为成熟的创新性土壤污染修复技术,就其原理,实例,优缺点及合理运用等问题作了简要阐述。     

科学认识和防治耕地土壤重金属污染

农产品产地环境质量直接影响农产品质量。近年来,我国部分地区土壤重金属污染问题日益凸显,已成为影响农产品质量安全,并受到广泛关注和重视的突出的问题之一。本文在分析土壤重金属污染具有来源复杂、评价难度大和治理任务艰巨等特点的基础上,提出为科学防治耕地土壤重金属污染,必须本着科学认识、统筹规划、综合防治、分类指导、治用结合的原则,从加强普查监测、加强科技支撑、完善法律法规、培育环保产业、构建工作体系等方面入手,以切实加强和改进耕地土壤重金属污染防治工作。     

重庆市菜地土壤重金属污染现状与防治对策

通过对重庆市菜地土壤重金属的监测评价,发现菜地土壤不同程度受到重金属污染。监测的30个单元重金属综合污染指数表明部分蔬菜地土壤为中污染和轻污染,污染重金属主要为Cd,Hg,Pb;其中Cd污染较重,超过国家土壤环境质量二级标准的监测单元达70%。减少土壤重金属必须严格控制工业“三废”排放、农用化学物质使用、污水灌溉和“渣肥”施用。新建蔬菜基地做好前期规划工作,土壤重金属污染相对较重的菜地改作他用或种植富集能力弱的作物品种。     

大同市污灌区土壤重金属污染现状

通过对大同市主要污灌区域土壤中重金属污染状况进行调查监测和评价,并针对土壤修复及防治做一分析探讨。     

长江三角洲地区土壤重金属含量及其分异特征

以地学统计、浓度-面积分形方法和富集系数等方法分析了该地区土壤重金属元素含量的变化特征。结果显示:表层和深层土壤的重金属均具有多重分形特征,表层土壤中重金属元素分异性强,在该地区表层重金属含量平均值远远大于全国土壤背景值(除了As);土壤Hg、Cd、Pb含量分布显示了受人为影响强烈,而Cu、Zn主要受原始背景和人为活动综合影响;Cr、Ni、As主要受自然背景影响。研究结果为长江三角洲地区土壤质量评价提供可靠的依据。     

长江三角洲典型地区工业企业的分布对土壤重金属污染的影响

以长江三角洲地区近年来经济发展较快的张家港市为例,在密集的大田采样和大田与企业周围采样结合的基础上,评价了该市土壤Cd、Hg、Pb污染状况;讨论了两种不同采样方式对土壤污染状况评价的影响;用土壤表层与底层重金属含量的比值（后简称元素比值）为指标讨论了不同类型企业对周围土壤重金属积累的影响.总的来看,张家港市土壤重金属整体平均值与环境背景值接近,明显低于国家环境质量（GB 15618-1995）二级标准和中国绿色食品生产基地环境土壤污染限值（NY/T391-2000）.但存在少数样点超标和超限现象,空间上有小面积高含量土壤分布,且主要局限于企业周围的小范围内.采样方式对土壤污染的评价有明显的影响,对Cd和Pb而言,大田采样方式下他们的含量要明显低于两种方式结合的情况下（p＜0.05）,而Hg元素则相反,当大田采样与企业周围采样相结合可使得土壤中Hg元素高含量的分布面积明显增大.绝大部分企业周围土壤样品的元素比值要明显高于大田采集的土壤.除冶金类企业有着明显的Pb单一聚集外,化工、电子类企业往往导致了多个元素的积累,企业对周围土壤存在复合污染的可能性.这些结果为该市或类似地区的环境质量调查和评价、环境治理提供了重要的基础资料和决策依据.     

Effect of Flooding Lead Arsenate–Contaminated Orchard Soil on Growth and Arsenic and Lead Accumulation in Rice

Lead arsenate has been used as pesticide. Flooding soils contaminated by lead arsenate could increase plant arsenic and lead and become a human health risk. The objective was to determine the effects of flooding of lead‐arsenate soils on rice grain yield and arsenic and lead accumulation. Bagstown and Chashmont soils with high levels of arsenic and lead were planted with rice in the greenhouse under flooded and nonflooded conditions. Flooding reduced grain yield and increased grain arsenic concentration on both soils. Grain lead decreased with flooding for the Bagstown soil but increased for the Chashmont. Arsenic and lead concentrations in the straw were more than in grain. Grain arsenic and lead levels observed would not be expected to become a human health risk. However, bioavailability studies are needed. The high arsenic and lead in the straw may indirectly become a human health risk because rice straw is used for livestock feed and bedding.     

长江三角洲地区土壤盐酸可提取态重金属含量的空间变异特征

以江苏昆山市为典型区,对长三角地区土壤盐酸可提取态重金属含量的结构特征进行分析,得出该区盐酸可提取态重金属的空间分布格局并揭示了引起这种分布格局的成因和污染来源,结果表明：昆山市盐酸可提取态Cd、Cr、Cu、Pb、Zn、Hg属强变异,Ni和Co为中等变异。半方差函数模型拟合表明所有盐酸可提取态重金属元素均符合球状模型,8种重金属元素在一定范围内均存在空间相关性。采用Kriging最优内插法得到了盐酸可提取态重金属含量的空间分布格局,表明土壤盐酸可提取态重金属含量与工业活动、污水灌溉和大气降尘密切相关。通过主成分分析与地统计学相结合的方法,得出该区盐酸可提取态重金属由4个主成分构成,第一主成分为Cd、Cu、Pb、Cr和Zn,决定这一成分的主要因素为工业污水灌溉、大气降尘和元素地球化学特征;第二主成分为Ni,决定这一成分的主要因素为土壤内部因子;第三主成分为Hg,该成分主要受工业点源污染的影响;第四主成分为Co,该成分可能主要受地形影响。     

长江三角洲地区地表水污染的模式与对策

On the basis of field investigations, observations and experimental data combined with environmental monitoring information, the status and the spatial and temporal patterns of surface water pollution over thepast ten years in the Yangtze River Delta have been assessed. The water quality of large rivers is still verygood but most of the medium-sized and small rivers have been very seriously polluted. The appearance of black and odorous conditions in rivers in the urban areas has increased due to serious pollution by organic matter with consequent high oxygen demand. Annual increases in N and P concentrations in lakes haveaccelerated eutrophication. The water quality of rivers in small towns is rapidly deteriorating. The mainsources of surface water pollution include industrial and domestic sewage, animal manures, chemical fertilizersin farmland, and polluted sediments in rivers and lakes.Counter measures against these sources of pollution are presented. Regional laws and regulations for protection of surface waters and their enforcement are urgently required. A regional water environmental management agency should be established. The construction of sewage treatment plants of varying capacity must be accelerated to increase the proportion of sewage treated and to improve the quality of treated effluent. Animal wastes must be recycled effectively and efficiently, and the application rates of fertilizers and manures must be balanced with crop nutrient requirements to prevent diffuse pollution from agriculture. The comprehensive rehabilitation of medium-sized and small rivers should be intensified, and the delimitation and protection of the areas used as sources of drinking water should be strengthened.     

Surface water quality of factory-based and vegetable-based peri-urban areas in the Yangtze River Delta region,China

Detailed surveys of surface water in two contrasting peri-urban areas in the Yangtze River Delta region of China were conducted to determine the distribution of heavy metals, nitrogen (N) and phosphorus (P) as well as the speciation of N and P. A factory-based (FB) area was compared with a vegetable-based (VB) area during the dry season. The concentrations of heavy metals in the surface water in the FB area were higher than those in the VB area, suggesting modest contamination of surface water with Zn, Cu, Cr and Pb but not Cd, from discharge of factory effluent in the FB area but not the VB area. Although total N (TN) and total P (TP) levels in the surface water were high in both areas, the surface water in the VB area had significantly higher levels of nitrate N (NO₃–N), organic N (ON) and TN than those in the FB area. In both areas, the levels of water-soluble P (WP), organic P (OP) and TP were high in the river water that received municipal wastewater. The distribution of N and P species throughout the surface water system indicated that the NO₃–N and ON mainly came from vegetable fields, while ammonium N (NH₄–N), WP and OP were mainly from municipal wastewater. Treatment of municipal wastewater prior to discharge to reduce N and P by purification is recommended together with research and extension to develop more efficient use of N and P fertilizer by vegetable farmers.     

Geochemical behavior assessment and apportionment of heavy metal contaminants in the bottom sediments of lower reach of Changjiang River

Heavy metal contamination of bottom sediments of the Changjiang River is widely reported, however, the potential source and methods of transportation of these heavy metals in the contaminated sediments is poorly defined. This paper examines the correlation between heavy metals and geochemical indices, including Fe₂O₃, Al₂O₃, total organic carbon (TOC) and black carbon (BC), as well as magnetic susceptibility (MS). Using these indices we investigate the contamination characteristics of heavy metals in the sediments by with Principal Component Analysis (PCA). Results from 83 sediment samples collected in the lower reach of Changjiang River (from Nanjing to Shanghai) show that the first principal component accounts for 52.23% of the total variance, corresponding to the heavy metals, Co, Cr, Cu, Ni and Zn, and conservative components of Fe₂O₃, Al₂O₃ and TOC. This result indicates that heavy metal distributions are controlled by the transportation and sedimentation of fine particles which is also confirmed by particle size analysis. The second principal component explains 24.81% of the variance and is dominated by Cd, Pb and MS, which, collectively, result chiefly from industrial and transportation activities and, for MS, fly ash production. The third principal component accounts for 7.91% of the variance and corresponds solely to Hg. Principal component analysis/multiple linear regression (PCA/MLR) was used to estimate the contribution of the three principal components to each heavy metal. PCA/MLR results suggest that more than 50% of Co, Cr, Cu, Ni and Zn were influenced by the particle size effect. Particle size effect and fly ash account for 37.1% and 27.7% of As. Cd and Pb were mainly explained by fly ash. 98.9% of Hg was related to PC3, which represented black carbon (BC). Our study indicates that the combination of geochemical and multivariable statistical methods clearly characterizes the geochemistry of heavy metals in sediment of the lower reaches of the Changjiang River and suggests that power plants are the main source of heavy metal pollution.     

土壤重金属污染的植物修复与金属超富集植物及其遗传工程研究

本文综述了土壤重金属污染的植物修复、金属超富集植物及其遗传工程的最新研究进展及存在问题,并提出加紧筛选和发现野生高生物量的金属超富集植物,在现有高生物量作物种质资源中筛选金属超富集作物,应用遗传工程技术把野生植物的超富集基因转移到现有高生物量植物(作物)中,寻找综合、可持续的植物修复手段等对策。     

生物炭/石灰混施对重金属复合污染土壤的稳定化效应

采用室内模拟实验,以南方砷镉铅复合污染的酸性红壤为对象,利用化学钝化原理,探讨钝化材料对重金属稳定化的技术效果及应用配方,以期为砷镉铅复合污染红壤修复与安全利用提供依据。具体做法为：选择生物炭（BC）和石灰（SH）为钝化材料,以土壤重量的1%、4%为材料添加量,单一或混合施用于砷镉铅复合污染土壤,并于恒温（25℃）条件下培养60d,在实验进行至第1天、第30天、第60天时取样,测定红壤酸碱度（pH）和水溶态（Water soluble）有效砷（As）、镉（Cd）、铅（Pb）即WSAs、WSCd、WSPb含量,以及土壤重金属As、Cd、Pb结合态含量与占比的变化,明确生物炭石灰单/混施对重金属的稳定化效应。结果表明：生物炭/石灰无论单施或混施均能不同程度地降低土壤中水溶态WSCd和WSPb含量,钝化效率分别为33.51%～78.89%和9.05%～96.24%。而材料单施（1BC、4SH）和两者混施高用量（4BC4SH）处理,均能大幅降低土壤中有效As含量,钝化效率为10.25%～55.27%,其中以两者混施高用量（4BC4SH）处理对土壤重金属As、Cd、Pb协同钝化的效果最佳,当培养实验进行至第60天时,钝化效率依次达55.27%、76.39%和96.24%。培养后土壤中As形态由易被植物吸收的非专性吸附态、专性吸附态转化为稳定的残渣态,土壤中Cd和Pb则由活性最强的酸可提取态转化为残渣态,土壤中As、Cd、Pb的稳定化效应明显,迁移系数下降;此外,生物炭/石灰的单施及混合施用,均可导致土壤酸碱度（pH）显著提升（P<0.05）,有利于南方酸化土壤的改良。总体而言,本研究中生物炭/石灰两者混施高用量水平下（4BC4SH）土壤重金属的钝化效果最优,可实现对As、Cd和Pb复合污染红壤的稳定化修复。     

黄河三角洲中重度盐渍土棉田水盐运移规律研究

为充分利用黄河三角洲中重度盐渍土资源,通过前期微咸水压盐(2 g/L),选取中度(3.10～3.90 g/kg)和重度(4.60～5.70 g/kg)盐渍土,研究了不同程度盐渍化土壤棉花种植下土壤剖面水盐运移规律。研究结果表明:微咸水压盐后可以使剖面盐分处于相对均匀分布状况;覆盖促进了棉花对膜下水分的吸收利用,中度盐渍土棉花在苗期和蕾期主要耗水层为0～40 cm土壤表层,重度盐渍土棉花主要耗水层为0～30 cm土壤表层,后期由于作物生长引起深层水分(60～100 cm)消耗,且中度盐渍土深层水分吸收要高于重度盐渍土;生育期内中度盐渍土盐分上下土层波动范围为0.80～2.00 g/kg,重度盐渍土为2.00～5.60 g/kg,膜下土壤含盐量均要低于膜外土壤含盐量,至收获期中度、重度盐渍土剖面平均脱盐率分别为62.40%和55.83%,棉花产量分别为2 129.76 kg/hm2和823.66 kg/hm2。