Sub-tropical urban environment affecting content and composition of non-structural carbohydrates of Lolium multiflorum ssp. italicum cv. Lema

This study analyzed the relationship between environmental factors, especially air pollution and climatic conditions, and non-structural carbohydrates (NSC) in plants of Lolium multiflorum exposed during 10 consecutive periods of 28 days at a polluted site (Congonhas) and at a reference site in São Paulo city (Brazil). After exposure, NSC composition and leaf concentrations of Al, Fe, Cu, Zn, Pb and Cd were measured. The seasonal pattern of NSC accumulation was quite similar in both sites, but plants at Congonhas showed higher concentrations of these compounds, especially fructans of low and medium degree of polymerization. Regression analysis showed that NSC in plants growing at the polluted site were explained by variations on temperature and leaf concentration of Fe (positive effect), as well as relative humidity and particulate material (negative effect). NSC in the standardized grass culture, in addition to heavy metal accumulation, may indicate stressing conditions in a sub-tropical polluted environment.     

Impact of a smelter closedown on metal contents of wheat cultivated in the neighbourhood

BACKGROUND: The contamination of soils by heavy metals engenders important environmental and sanitary problems in Northern France where a smelter has been located for more than one hundred of years. It has been one of the most important Pb production sites in Europe until its closedown in March 2003. Ore smelting process generated considerable atmospheric emissions of dust. Despite an active environmental strategy, these emissions were still significant in 2002 with up to 17 tonnes of Pb, 32 tonnes of Zn and 1 tonne of Cd. Over the years, the generated deposits have led to an important contamination of the surrounding soils. Previous studies have shown pollutant transfers to plants, which can induce a risk for human and animal health. The objective of this study was to evaluate the consequences of the smelter closedown on the Cd and Pb contents of wheat (grain and straw) cultivated in the area. METHODS: Paired topsoil and vegetable samples were taken at harvest time at various distances to the smelter. The sample sites were chosen in order to represent a large range of soil metal contamination. Sampling was realised on several wheat harvests between 1997 and 2003. 25 samples were collected before the smelter closedown and 15 after. All ears of about 1 m long of two rows were manually picked and threshed in the lab. Similarly, straw was harvested at the same time. Total metal contents in soil and wheat samples were quantified. RESULTS: A negative correlation between metal concentrations in soil and the distance to the smelter was shown. The wheat grain and straw showed significant Cd and Pb contents. The straw had higher metal contents than the grain. During the smelter activity, the grain contents were up to 0.8 mg kg(-1) DM of Cd and 8 mg kg(-1) DM of Pb. For the straw, maximum contents were 5 mg kg(-1) DM of Cd and 114 mg kg(-1) DM of Pb. After the smelter closedown, we observed a very large decrease of Pb in the grain (82%) and in the straw (91%). A smaller decrease was observed for Cd in grain. Despite this improvement, 80% of the studied samples remained non-acceptable for human consumption, according to the European legislation values, due to a high Cd content. DISCUSSION: Results highlighted a difference in metal accumulation in the plant organs as well as a difference in metal uptake. The approach pointed out the importance of atmospheric fallout in the wheat contamination pathways for Pb. The smelter closedown has lead to a decrease of the Pb content in wheat. It is interesting to relate this finding with the lead blood levels in children living close to the smelter. CONCLUSIONS: Those results have confirmed the importance of dust fallout in the plant contamination pathways. Before the closedown, Pb measured in the plant was principally originating from the smelter dust emissions. It raised the question of the sanitary risks for humans and animals living in the surrounding a of the smelter. RECOMMENDATIONS AND PERSPECTIVES: In the literature, very few articles take the dust deposit as contamination pathways for crops into consideration. However, in highly contaminated sites, this pathway can be very important. Thus, it would be worthy studying the uptake of metal contaminants by plants through the foliar system.     

淮安市农产品中重金属及有机氯、有机磷农药残留量调查

淮安市环境监测中心站于1999年－2000年对淮安市农产品中重金属以及有机氯、有机磷农药残留量进行了调查。结果表明，粮食和蔬菜作物中，六六六的4种同分异构体只有γ－六六六能检出，检出率分别为24．0％和51．7％，都未超标；DDT的4种同分异要体均未检出；有机磷农药的检出率分别为5％和25％，其中蔬菜中敌敌畏含量出现个别超标现象，倍硫磷、乐果和杀螟松在粮食和蔬菜作物中的含量都不超标。重金属中金属“五毒”在粮食和蔬菜作物中，只有Cr和Pb能检出，Cd、Hg和As都未检出，Cu、Zn和Mn能检出，但不超标。提出，应严格按照农牧渔业部和卫生部颁发的《农药安全使用规定》用药，多使用高效低残留量的“绿色农药”；农业、环保和卫生部门必须加强合作，对蔬菜生产销售的全过程进行监督监测，以确保生产无公害蔬菜。     

渤海湾表层沉积物重金属污染状况及年际变化分析

根据2014～2018年渤海湾海洋生态环境沉积物质量业务化监测数据,对沉积物中Hg、Cu、Pb、Cd、Cr、Zn和As等7种重金属元素的含量及年际变化趋势进行了分析.通过单因子污染指数法、地累积指数法和潜在生态风险指数法,评价了研究区近岸海域沉积物重金属污染状况和潜在生态风险程度.结果显示,符合一类标准的站位达92%以上,主要超标因子为Cd和Hg,这两种重金属含量的高值区一般分布在渤海湾南北两侧近岸地区,包括北侧天津港、黄骅港附近,南侧滨州、东营近岸.Hg、Cu、Pb、Cd、Cr、Zn和As等单个重金属含量年际变化有所不同,年平均单因子污染指数均不大于1,年平均地累积指数均小于0,表明研究海域沉积物质量状况良好,其中Cu单因子污染指数较大,近5年的平均值达到0.653;Cd地累积指数相对较大,对其监测工作值得重点关注.2014～2018年研究区域沉积物重金属的总潜在生态危害程度为轻微等级,仅Hg和Cd部分站位出现强和中等的生态危害程度,各类重金属元素对渤海湾海域生态构成潜在危害风险顺序为Cd>Hg>As>Pb>Cu>Cr>Zn;RI基本表现为先升高后...     

基于Monte-Carlo模拟的湖南省典型工厂周边农田土壤重金属区域潜在生态风险特征及来源解析

为探究湖南省典型工厂周边农田土壤重金属的污染特征、生态风险和来源,以氟化工厂、皮革工厂和电镀工厂为研究对象,分析其周边农田土壤中8种重金属的污染特征,利用地累积指数和潜在生态风险指数对重金属污染进行评估和风险评价,利用相关性分析、聚类分析和主成分分析对重金属污染来源进行解析,利用Monte-Carlo模型对于区域生态风险进行概率风险评估.结果表明,土壤中主要污染元素为Cd和Zn,其均值为背景值的4.46和2.73倍;3个典型工厂周边土壤中Zn处于轻度污染水平,氟化厂周边土壤中Cd处于偏中度污染水平;典型工厂周边土壤中重金属主要来自自然源、工业活动源（“三废”排放、矿产挖掘、金属冶炼等活动）和交通源.潜在生态风险评价结果表明,氟化厂周边土壤中重金属污染的生态风险处于高风险等级,皮革厂和电镀厂生态风险处于较高风险等级,Cd是主要贡献元素.Monte-Carlo概率生态风险评价结果降低了确定性评价的不确定性,可为区域实现精准风险管控提供科学依据.     

城市土壤和地表灰尘重金属污染研究进展与展望

随着城市化和工业化的不断推进,城市土壤和地表灰尘重金属污染日趋严重,对城市环境和人类健康构成威胁,已成为国内外城市环境研究的热点问题.从重金属污染水平及其时空特征、污染源解析方法、生态和健康风险这3个主要方面,对国内外城市土壤和地表灰尘重金属研究成果进行了梳理和归纳.分析了当前研究存在的不足,并对未来研究进行了展望,即研究土壤和地表灰尘重金属在不同条件下的相互影响机制,通过丰富验证方法加强重金属来源解析模型结果的可靠性研究,加强来源驱动下重金属化学形态差异和地表灰尘短期累积污染过程的研究,完善暴露参数并深入探究重金属的化学形态对其生态和健康风险的影响,以提高风险预测水平.     

银川市典型湖泊沉积物细菌群落结构及其对重金属的响应关系

湖泊湿地是极其重要而又特殊的生态系统,在区域水资源调蓄、环境保护和生物多样性维持等方面具有重要意义.沉积物细菌是湖泊生态系统重要的组成部分,是湖泊生物地球化学循环的主要驱动力.为探明银川市典型湖泊沉积物细菌的群落结构及其影响因素,选取银川市3个典型湖泊（阅海湖、鸣翠湖和犀牛湖）为研究对象,于2021年1月、4月、7月和10月采集表层沉积物,应用16S rDNA高通量测序技术研究沉积物细菌群落组成,并探究其与重金属之间的响应关系.结果表明,银川市3个典型湖泊沉积物重金属生态危害系数远小于40,生态危害指数远小于150,危害程度均为生态轻微危害.3个湖泊的细菌群落多样性无显著差异,但各湖泊不同季节多样性有显著变化,群落组成也存在显著差异.阅海湖、鸣翠湖和犀牛湖的优势种菌门（相对丰度排名前3）均为：变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）和绿弯菌门（Chloroflexi）,优势下级阶元为γ-变形菌纲（Gammaproteobacteria）、α-变形菌纲（Alphaproteobacteria）和δ-变形菌纲（Deltaproteobacteria）.银川市典型湖泊门水平分类上出现的主要差异物种为变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）、广古菌门（Euryarchaeota）、厚壁菌门（Firmicutes）、放线菌门（Actinobacteria）和酸杆菌门（Acidobacteria）.阅海湖沉积物细菌群落结构与Cu、Fe、Mn、Zn、As和Pb显著相关,鸣翠湖沉积物细菌群落结构与Fe、Pb和Cr显著相关,犀牛湖沉积物细菌群落结构与重金属相关关系不显著.沉积物重金属的种类和含量对银川市阅海湖和鸣翠湖沉积物细菌群落结构有显著影响,是引起湖泊沉积物细菌群落结构变化的重要环境因子.     

基于Meta分析的蚯蚓堆肥对堆肥质量和重金属的影响效应

为了综合评估蚯蚓堆肥在不同控制条件下堆肥质量和重金属的转化规律,综述了109篇文献,通过Meta分析定量探讨了蚯蚓种类、预堆肥时间、通风方式、初始C/N、初始pH和初始含水率对提高蚯蚓堆肥质量和降低重金属毒性方面的影响.结果表明,以上6分组因子均显著影响堆肥的质量和重金属毒性.经过蚯蚓堆肥后,以下营养指标含量显著增加：NO₃^--N（116.2%）、TN（29.1%）、TP（31.2%）和TK（15.0%）;而NH₄⁺-N含量（-14.8%）和C/N（-36.3%）显著降低;同时也显著降低了最终堆肥中Cu和Cr总量及其生物有效性.综合考虑不同分组因子对堆肥质量和重金属影响的显著程度,若堆肥以促进腐熟和富集营养元素为目的,则建议堆体物料的初始含水率调节为70%~80%、C/N为30~85和pH为6~7,并进行0~15 d的预堆肥,通风方式采用自然放置方法;若以削弱物料中重金属危害为主要目的,则建议调节物料初始含水率为50%~60%、C/N小于30和pH为7~8,不进行预堆肥,定时翻堆,引用Eudrilus eugeniae种类进行蚯蚓堆肥.     

环境中金属生物有效性的预测模型——生物配体模型研究进展

生物配体模型(BLM)是一种用于预测环境中金属生物毒性的机理性模型.模型理论起源于自由离子活度模型(FIAM)和鱼鳃络合模型(GSIM),考虑了自由金属离子的活度以及自然环境存在的其他离子(如Ca2+、Na+、Mg2+、H+)、非生物配体(如可溶性有机质、氯化物、碳酸盐、硫酸盐)和生物配体的竞争.目前,在水生生态系统中,基于鱼鳃络合模型的框架基础,通过生物化学实验手段并结合数学方法,建立了预测铜、锌、银、镍对Rainbowtrout(虹鳟鱼)、Fatheadminnow(黑头呆鱼)和Daphniamagna(水蚤)的急、慢性毒性的BLM版本,并积极探索其在陆地生态系统中的应用.虽然生物配体模型在实验室模拟条件下取得了较为满意的结果,但其中包含着一些假设,在实际应用中还具有一定的局限性,尤其是陆地生态系统生物配体模型的发展还需要做许多研究工作.本文主要论述了生物配体模型的理论基础、实现手段和应用情况,讨论了生物配体模型的优势和局限性并对其未来研究方向进行了展望.