中国“镉米”议题与传媒社会预警

近年来我国重金属污染所造成的危害逐渐显露,环境风险日渐突出。在将责任归因于地方与企业、经营者之外,传媒预警缺陷也值得反思。有关重金属污染带来的危害早有专家披露,但关于此类事件的信息公开仍明显处于滞后状态。在专家、传媒、受害者共同参与的议题建构中,特别需要传媒加大对重金属污染征兆的报道力度,揭露地方污染个案,更好地担负起守望职责。

从“镉米第一案”看土壤污染鉴定

土壤污染的环境诉讼是一类高度专业背景下的诉讼,并不能简单通过几个重金属数值超不超标来判断。我们应当推动环境公益诉讼发展,构建健康中国,从而从法律上倒逼土壤污染的治理和修复2015年3月,湖南省衡阳市衡东县一名稻农因稻米减产将周边一家企业告上法庭,这起案件被称为'中国镉米第一案'。同年6月3日开庭审理,9月10日,湖南省衡东县法院作出一审判决,驳回原告的诉讼请求。

不同镉浓度对镉低吸收晚稻品种产量形成及其糙米镉含量的影响

【目的】为明确镉低吸收晚稻品种的产量形成及米镉含量变化。【方法】2022年在湖南省益阳市赫山区泥江口镇(全Cd浓度7.28 mg/kg)、赫山区兰溪镇(全Cd浓度0.43 mg/kg)开展镉低吸收晚稻品种对比试验。观测生育期、干物质积累、产量及产量构成和米镉含量变化。【结果】两个镉低吸收品种较对照品种五优308,镉胁迫导致产量下降,但安两优2号产量仅在高镉田块下降2.8%,其具有更高的有效穗数,在生育前期具有更高的干物质积累和群体生长速率;在两个地点均表现出明显的降镉效果,在Cd浓度0.43 mg/kg,安两优2号和清莲丝苗的糙米镉含量分别为0.010 mg/kg和0.013 mg/kg,较对照品种分别降低96.15%和95.00%。在Cd浓度7.28 mg/kg,安两优2号的糙米镉含量为0.21 mg/kg,较对照品种降低87.5%;清莲丝苗的糙米镉含量为0.19 mg/kg,较对照品种降低88.69%。【结论】两个镉低吸收品种均有很好的降镉能力,在中度镉污染的稻田中可安全种植,但在高镉污染田块直接种植存在糙米镉超标风险,应当配合其他降镉栽培措施实现安全种植,安两优2号在高镉污染地区产量表现更稳定,两个镉低吸收晚稻品种在高镉污染地区种植可配合栽培措施提高结实率,从而实现高产,可在中度及以下镉污染区域进行推广。

从“镉米杀机”到“土十条”

本采访首先就中国土壤环境的现有问题进行了探讨,包括全国土壤总体污染情况、健康土壤的结构,以及在城市建设中景观设计师普遍存在的对土壤的误解和知识缺失。话题随后转向更为严峻且严肃的土壤领域,受访人对中国在生态土壤管理方面存在的不完善,以及有关土壤保护和防治的法律体系和立法过程等议题阐述了自己的见解。

湖南镉大米事件的分析

食品安全问题是当今社会的一个难解的症结，一直困扰着全世界的人们的健康问题。近年来，社会上不时爆发食品安全事件，对人们的健康产生极大的威胁。目前国内发生的“湖南镉大米”事件，即大米中镉含量超过标准规定值0．2mg／kg，这事件一时间引起国人的担忧与恐慌。因为镉是会对泌尿系统造成损害的一种重金属，如果长期积累量过多或一阶段较大量地吸收，会引起近端肾小管功能障碍为主的肾损害，甚至造成结缔组织损伤、生殖系统功能障碍、肾损伤、致畸和致癌，从而影响人们的身体健康。为预防近端肾小管功能障碍等疾病，保护受镉污染影响的人群，就要对做好相应的准备。本文主要介绍了镉大米事件的概念、诊断标准，综述了镉对肾小管的作用机制、影响因素和应对措施等方面的研究进展，并探讨了镉大米事件对我国食品界的启示，为预防镉大米事件再度发生，保障公众健康提供有益借鉴。

镉超标稻谷饲料化的可行性分析

近年来,我国土地重金属污染日益严峻,镉污染尤为严重。在众多农作物中,水稻对镉有较强的生理耐受和富集能力,大多数被污染土壤区域收获的稻谷镉含量超标,不适合人类直接食用。这部分稻谷来源广、数量大,如何消耗这些"镉米"是近期迫切需要解决的问题。"镉米"所含有的营养成分与普通稻谷并无明显差异。在饲料原料紧缺的情况下,将"镉米"饲料化,通过动物的首过代谢减少其对人的毒害作用是一不错的消耗"镉米"的途径。文章就我国"镉米"生产现状、镉直接暴露对机体的危害、镉米饲料化可行性、能量饲料原料的替代需求及镉在机体内的吸收沉积规律和阻控等进行了梳理分析。

镉低积累水稻品种筛选及其在镉超标稻田的表现评价

【目的】筛选镉低积累型水稻品种并开展镉超标稻田表现评价研究,为广西中低度镉污染稻田生产安全稻米提供品种和数据参考。【方法】以114份(V1~V114)水稻低镉品种育种材料为试验对象,从中筛选综合性状优良且籽粒表现为镉低积累的目标材料;对目标材料进行大田试验和盆栽试验验证,测定其在广西不同试验点的农艺性状和精米镉含量。【结果】初步筛选试验的114份参试材料中,除V102的精米镉含量低于最低检测值外,其余113份水稻育种材料的精米镉含量范围在0.01~0.35 mg/kg,平均值为0.10 mg/kg,筛选得到综合性状优良且精米镉含量较低的材料V111(审定后名称为桂育12)。桂育12在中低度镉污染区大田验证种植时,精米镉含量(0.01~0.10 mg/kg)未超出国家标准GB 2762—2017《食品安全国家标准食品中污染物限量》规定的限值(0.20 mg/kg)。盆栽试验结果表明,在pH为5.0,土壤镉含量3.0 mg/kg条件下,桂育12精米镉含量(0.34 mg/kg)有超标风险;各试验中土壤镉含量对桂育12部分农艺性状指标影响显著(P<0.05),但属于品种种植的正常波动范围,对米质和产量的综合影响有限。【结论】从114份水稻材料中筛选出的镉低积累品种桂育12,经多年多点试验验证,在中低度镉污染稻田产出的稻米镉含量不超标,籽粒镉低积累性状较稳定,综合性状表现受土壤镉含量影响较小,可在广西中低度镉污染稻田推广应用。

厦门、泉州地区食用稻米中Cd2+含量的研究和食用风险评估

为了评价不同产地水稻品种中镉的积累差异及对人体的健康风险,本文收集厦门和泉州部分家庭、超市及米店中常见的大米,采用石墨炉原子吸收光谱法测定稻米中镉含量,筛选含镉量较低的水稻品种,并通过概率模型评估经食用稻米摄入镉的健康风险。结果表明,黑龙江省产地样品含镉量均值较低,其中最低为产地为黑龙江省哈尔滨市产的长粒香,其样品中镉含量仅有0.0087mg·kg-1,建议在选购大米的时候可以将该类大米作为优先选项,同时,通过对稻米淘洗水样品的消解及测定,发现其中含有微量镉,因此建议在煮饭前,需提前淘洗稻米1~2次,减少日常Cd2+的摄入。

江西省某县大米镉污染情况追踪调查

目的了解镉污染区19年后当地产大米镉污染情况。方法在全县主要水稻种植乡镇采集当地2006年晚米。使用电感耦合等离子质谱(ICP-MS)分析测定米镉含量。结果2006年产大米镉含量均值为:污染区0.59mg/kg,对照区0.05mg/kg。与1987年测定结果相比大米镉含量增加近30%。全县2006年产受污染大米镉含量均值为0.26mg/kg,大于国家卫生标准值,明显高于对照米样镉含量均值(0.06mg/kg)。其中有64%的大米样品大于国家卫生标准值,23.17%的大米样品≥0.4mg/kg、11%的大米样品为≥1.0mg/kg的"镉米"。部分乡村"镉米"检出比例更高,达到33.3%以上。结论当地1987年调查点环境镉污染近19年来仍在持续,米镉含量均值较19年前增加约30%,达到0.59mg/kg。全县污染区2006年产米镉均值超过国家卫生标准值,环境镉污染仍在持续加重,迫切需要采取环境治理与人群暴露阻断措施。

国内土壤污染现状、特点和一些修复浅见

介绍了国内土壤污染现状及其特点,以及欧美等国对土壤修复概况,并对各种修复技术方法进行对比。现国内对此刚起步,无成熟经验,先选取几个土壤污染类型修复进行示范,待取得成功经验再推广。

不同栽培条件对水稻籽粒镉含量及主要性状的影响研究

为筛选高效低成本降镉栽培措施,以2份水稻低镉准品种(V1、V2)为试验材料,设空白(A0)、淹水(A1)、喷施锌肥+淹水(A2)、施生石灰+淹水(A3)、喷施锌肥+施生石灰+淹水(A4)5个栽培处理,分析各处理对材料农艺性状和精米镉含量的影响。结果表明,除V2材料晚稻A1和A2处理出现镉超标情况外,其他降镉处理镉含量均合格。V1材料晚稻A3处理对精米率、有效穗数和产量呈负向影响,V2材料晚稻A3处理对长宽比和蛋白质含量呈负向影响,A4处理对垩白粒率、垩白度呈负向影响,其他处理负向效果不显著。综合来看,V1、V2早稻和V1晚稻选用A1处理,V2晚稻选用A3处理,成本相对较低,精米镉含量不超标,对产量、米质影响较小,综合效果最优。V1、V2可在审定后搭配降镉栽培技术在广西中度镉污染稻田推广应用。

中国台湾地区污染场地管理经验及启示

中国台湾地区从70年代开始发展重工业,经过了数十载的经济成长,带来可观经济效益的同时,也造成环境污染负荷日益增加。废水、废气、废弃物或毒性物质不当排放、泄漏或弃置,衍生出许多土壤及地下水污染问题。中国台湾地区的云林虎尾镉米事件、台湾美国无线电公司（RCA）、台南中石化安顺厂等污染事件,对环境造成冲击,也对周遭居民的身体健康留下了永久的伤害。

Effects of Combined Pollution of Pb and Cd on Growth and Yield of Rice

[Objective] The aim was to study the damage and the mechanism of combined pollution of Pb and Cd on rice growth,yield and quality of rice. [Method]Effects of combined pollution of Pb and Cd on the growth and yield of rice were studied by pot experiment with cultivating rice. [Result] Pb and Cd could promote rice growth at low concentration while inhibit plant height at high concentration; Pb and Cd stress reduced the number of rice tillers significantly,with the increasing of stress concentration,the decrease amplitude of the number of tillers was greater; the panicle per pot,seed setting rate,1 000-grain weight and yield of rice were reduced significantly by Pb and Cd stress,the grain number per panicle decreased significantly under low concentration of Pb and Cd but increased significantly under high concentration; the brown rice rate and milled rice rate increased significantly under low concentration of Pb and Cd while at high concentration of Pb and Cd,the both two reduced significantly,the head milled rice rate reduced significantly with the decreasing of concentration; The Pb and Cd content of grains were significantly positively related to the concentrations of Pb and Cd content in soil,it had excessively exceeded hygienic standard when the concentrations of Pb and Cd in soil were medium-high and the unqualified rate reached 333% and 122%. [Conclusion]The study had provided basis for the establishment of rice cultivation system in pollution areas.

Metal Contamination in Field Grown Rice

[Objective] Detecting the concentration of metals （lead, cadmium and arsenic） in the rice from one test field was to provide a snapshot of the current status of metal contamination in rice, coming up with a scientific basis for further research. [Method] The research divided 15 adjacent fields into five groups. Two samples were randomly selected from each field. Metal contamination was evaluated based on GB standards and the overall pollution score （OPS）. [Result] The percentages of samples with above-standard levels of the three metals are 83.3%, 100% and 36.7%, respectively. The values of OPSs are ranged from five to seven, with Pb＇s pollution index constituting the most percentage between three metals in OPS. [Conclusion] A metal contamination in the grown rice of this test field is observed, in which Pb may be the most important factor, and Cd contents in all of the samples exceed the safety value.

Analysis of Heterosis, Combining Ability and Heritability of Cadmium Content in Brown Rice of Three-line Indica Hybrid Rice

Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level （P〈0.01）, indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.

镉污染区人群累积米镉暴露水平两种估算方法的比较

目的探究更为准确估算人群累积米镉暴露水平的方法。方法利用现有的膳食调查和大米检测数据,分别采用年龄系数法和拟合的人群大米消费量曲线方程来估算人群累积米镉暴露水平,对两种估算结果进行比较分析。结果两种方法估算结果基本一致,但拟合方程计算值与调查值更为接近,并且不同性别间结果也相差不大。而由系数法计算所得的累积米镉暴露水平在不同性别间相差很大。结论在以大米为膳食镉摄入主要介质的地区,累积米镉暴露水平两种估算方法结果之间差异不明显,采用拟合的大米消费量曲线方程来估算人群累积米镉暴露水平较为切实可行。

Purification of Starch from Cadmium-Contaminated Rice and Development of Functional Recombinant Rice

In order to provide a new utilization method for cadmium-contaminated rice,a preliminary study of the removal of rice starch cadmium by water,calcium hydroxide,sodium hydroxide and citric acid was conducted,the damage degree of starch was compared by SEM,and then the recombinant rice was obtained by a twin-screw extruder using the starch which met the safety standard.The physical and chemical properties of recombinant rice were analyzed by acid hydrolysis and texture analyzer.The results showed that citric acid was a good rice cadmium removal agent.The quality of recombinant rice prepared from cadmium-removed rice starch was improved;the acid resistance was increased.Heavy metal contaminated rice can be a staple food with better quality and higher value through processing.

Subcellular Accumulation of Cadmium in Corn and WheatPlants at Different Levels of Phosphorus

Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0, 0.12,0.60 and 3.0 mmol L-1) and two levels of cadmium (0 and 4.0 pmol L--1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall, cytoplasm and vacuoles of roots and leaveswere examined by cell fractionation techniques. With increasing phosphorus in medium, the contents of Pin cell wall, cytoplasm and vacuoles of corn and wheat roots and leaves increased. The highest content of Pwas observed in cell wall, next in vacuoles, and the lowest in cytoplasm. The wheat subcellular fractions inboth roots and leaves had higher concentrations of phosphorus than those of corn. Increasing phosphorus inmedium significantly inhibited the intracellular Cd accumulation in both species. However, at P concentrationup to 3.0 mmol L--1, the Cd content in cell wall was increased. Increasing phosphorus resulted in reductionof the subcellular Cd content in corn and wheat leaves. Compared with corn, the wheat roots had a higherCd content in the cell wall and vacuoles and a lower in cytoplasm, while in leaf subcellular fractions thewheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm. The results indicate thatphosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vacuoles by forminginsoluble Cd phosphate.

Adaption of Au Nanoparticles and CdTe Quantum Dots in DNA Detection

A DNA fluorescence probe system based on fluorescence resonance energy transfer （FRET） from CdTe quantum dot （QD） donors to Au nanoparticle （AuNP） acceptors is presented. CdTe QDs, 2.5nm in diameter, as energy donors, were prepared in water. Au nanoparticles, 16nm in diameter, as energy acceptors, were prepared from gold chloride by reduction. CdTe QDs were linked to 5＇-NH2-DNA through 1-ethyl-3-（dimethylaminopropyl）car- bodiimide hydrochloride （EDC） as a linker, and the 3＇-SH-DNA was self-assembled onto the surface of AuNPs. The hybridization of complementary double stranded DNA （dsDNA） bound to the QDs and AuNPs （CdTe-dsDNA-Au） determined the FRET distance of CdTe QDs and Au nanoparticles. Compared to the fluorescence of CdTe-DNA, the fluorescence of CdTe-DNA-Au conjugates decreased extremely, which indicated that the FRET occurred between CdTe QDs and Au nanoparticles. The fluorescence change of this conjugate depended on the ratio of Au-DNA to CdTe-DNA. When the AuNPs-DNA to QD-DNA ratio was 10：1, the FRET efficiency reached a maximum. The probe system would have a certain degree of fluorescence recovery when a complementary single stranded DNA was introduced into this system, which showed that the distance between CdTe QDs and Au nanoparticles was increased.

Effects of Soil pH，Texture，Moisture，Organic Matter and Cadmium Contenton Cadmium Diffusion Coefficient

The supply of cadmium from soil to plant roots mainly depends on the diffusion process. This work was conducted tostudy the effect of some soil properties on cadmium diffusion coefficient (D) in soil. Measurements were made using the Shofield and Graham-Bryce's isotopic labelling method. Cadmium diffusion coefficients varied from 10￣(-7) to 10￣(-9) cm￣2s￣(-1),Higher values were observed in acid sandy soils and lower values in calcareous clay soils. Liming an acid soil resulted in a sub-stantial decrease of D. Addition of cadmium as nitrate salt generally increased D, while addition of sewage sludge and organ-ic matter resulted in a significant decrease of cadmium diffusion. The rhizospheric activity also induced a moderate reduction in D. The relationships between D 10￣(-9)cm￣2s￣(-1)) on the one hand and soil PH, moisture (Mc, g kg￣(-1)), organic matter (OM, gkg￣1 ), clay (Cy, g kg￣(-1)) and cadmium content (Cd, mg kg￣(-1)) on the other were obtained by the multigle regression:D=182. 1-29.g1 pH+0.210Mc-0.303OM+0.011Cy+1.64Cd (R￣2=0.859,n=22 ).