GC法测定水产品中的甲基汞残留

采用气相色谱(GC)法测定水产品中的甲基汞残留。样品前处理方法在HZ-HJ-SZ-0097(《环境甲基汞的测定气色谱法》)所规定的基础上,增加萃取溶剂体积;色谱条件优化如下院毛细管色谱柱Supelcowax-10(30m×0.53mm×0.5μm),柱温为210℃,进样口温度为210℃,ECD检测器温度为300℃,尾吹(N2)50mL/min,流速为7.0mL/min,不分流进样。测定结果表明,甲基汞的峰形尖锐,响应灵敏度高,标准的线性相关系数为0.9992,加标样品测定的相对标准偏差(RSD)为2.1%(n=6),最小检出限为0.1μg/kg,回收率均为85%～92%。测定结果显示,该方法具有快速、灵敏尧可靠尧简便尧重现性好等特点。     

Behavior of Mercury in Soil Profiles: Impact of Increased Precipitation, Acidity, and Fertilization on Mercury Methylation

The behaviour of Hg in mineral pine forest (Pinussylvestris soil profiles (0–16 cm) was studied usinga lysimeter experimental design combined with thelabeling technique with ²⁰³HgCl₂. Thelabeled surface soils were exposed to four differenttreatments: (i) normal precipitation (600 mma^-1), (ii) four-fold precipitation, (iii) soilP-K fertilizing with normal precipitation, and (iv) the increased acidity in the rainwater with normalamount of precipitation. After the treatment period of97 days the ²⁰³Hg and methyl ²⁰³Hg weremeasured. The distribution of Hg in different soilmatrices was determined by extracting the soil withdistilled water, 1 M NH₄-acetate, 1 M HCl, and 0.1 M NaOH.The results showed that the organic surface layer,especially the living moss (Pleuroziumschreberi), was the dominant scavenger of the added²⁰³Hg. Methyl ²⁰³Hg formation was mostintensive in this layer, too. Increased precipitationmobilized a part of the ²⁰³Hg from the moss layerto the deeper layers and leachate water. In thefertilized soil with increased pH, the accumulation ofboth total ²⁰³Hg and methyl ²⁰³Hg wasrecorded in the organic surface soil. A small increasein rainwater acidity had no clear effect on thebehavior of ²⁰³Hg in soil. ²⁰³Hg was mainlyassociated in the organic fraction (NaOH-extractable)whether in the living moss or humus layer. Thefertilized soil yielded the highest concentration ofwater extractable ²⁰³Hg. In view of the climatechange with increasing precipitation, the use offertilizers, in the watersheds should be minimal andwell-controlled. This is, because soil fertilizingseems to increase the availability of Hg formethylation, and because the mobilization of bothtotal Hg and methyl Hg from watershed soils to lakes,and probably to ground water, increases whenprecipitation increases.     

Toxic effects of methylmercury,arsanilic acid and danofloxacin on the differentiation of mouse embryonic stem cells into neural cells

This study was performed to assess the neurotoxic effects of methylmercury, arsanilic acid and danofloxacin by quantification of neural-specific proteins in vitro. Quantitation of the protein markers during 14 days of differentiation indicated that the mouse ESCs were completely differentiated into neural cells by Day 8. The cells were treated with non-cytotoxic concentrations of three chemicals during differentiation. Low levels of exposure to methylmercury decreased the expression of GABA_A-R and Nestin during the differentiating stage, and Nestin during the differentiated stage. In contrast, GFAP, Tuj1, and MAP2 expression was affected only by relatively high doses during both stages. Arsanilic acid affected the levels of GABA_A-R and GFAP during the differentiated stage while the changes of Nestin and Tuj1 were greater during the differentiating stage. For the neural markers (except Nestin) expressed during both stages, danofloxacin affected protein levels at lower concentrations in the differentiated stage than the differentiating stage. Acetylcholinesterase activity was inhibited by relatively low concentrations of methylmercury and arsanilic acid during the differentiating stage while this activity was inhibited only by more than 40 µM of danofloxacin in the differentiated stage. Our results provide useful information about the different toxicities of chemicals and the impact on neural development.     

小麦生长周期的甲基汞器官分布

通过温室模拟,动态监测了小麦生长周期中各器官中甲基汞的浓度及总量分布的变化,探讨了小麦生长周期中,甲基汞是否在子实中富集及其过程.研究结果表明,甲基汞从土壤中经根系吸收进入小麦体内并逐步向地上部分转运.小麦生长过程中,土壤和小麦根部的甲基汞浓度随着小麦生长变化不明显,茎、叶中甲基汞浓度先上升后稳定,子实中甲基汞浓度不断上升.茎、叶在小麦生长过程中向子实输送甲基汞,甲基汞富集于小麦子实之中.研究证实了在属于陆生植物的小麦子实中存在甲基汞的富集现象.     

微波辅助提取-高效液相色谱-电感耦合等离子体质谱法测定水产品中甲基汞和乙基汞

建立了水产品中甲基汞和乙基汞的微波辅助提取-高效液相色谱-电感耦合等离子体质谱（HPLC-ICP -MS）测定方法。为保证样品中汞的各形态能完全提取并准确分析,通过条件优化,使用5 mol/L盐酸溶液微波辅助提取样品中的甲基汞和乙基汞,流动相为0.01 mol/L乙酸氨、0.12%(V/V) L-半胱氨酸、8% (V/V) 甲醇-水溶液。提取液在液相色谱中分离后,进入电感耦合等离子体质谱检测,5 min内完成甲基汞和乙基汞的定量分析。在优化的检测条件下,甲基汞和乙基汞检出限分别可达到0.024、0.042 μg/L吗,在0.05~20 μg/L范围内均具有良好的线性关系,相关系数均为0.9999,平均加标回收率为84.0%~94.5%。两种汞形态的批内和批间相对标准偏差分别在2.1%~4.1%和2.6%~4.3%的范围内。该方法具有简单、快速、灵敏度高和定性准确等优点,满足汞形态定量分析的要求。     

秸秆覆盖还田对稻麦轮作体系中土壤及作物甲基汞累积的影响

以贵州万山汞矿区的汞污染稻田土为研究对象,采用盆栽模拟探究了小麦-水稻轮作情况下秸秆覆盖还田对土壤及小麦与水稻在重要生育期(出苗期、分蘖期、拔节期、扬花-灌浆期、乳熟-收获期)甲基汞累积的影响。结果表明:秸秆还田能提高土壤中甲基汞含量,且不同作物秸秆还田对土壤甲基汞及作物甲基汞的影响存在显著差别,其中,小麦秸秆还田后土壤甲基汞含量增加127.1%,水稻秸秆还田后土壤甲基汞含量增加25.1%,这可能缘于迥异的种植条件。同时,作物秸秆还田后小麦、水稻植株体内甲基汞含量也呈增加趋势,其中,小麦根部、地上部(茎叶)和籽粒甲基汞含量分别增加124.6%、79.2%和169%,水稻根部、地上部和籽粒甲基汞含量依次增加40.1%、61.7%和25.9%,表明作物甲基汞吸收累积量的上升可能主要源于土壤甲基汞含量的上升。因此,汞污染地区传统农艺措施中惯常采用的秸秆还田可能会显著增加人体甲基汞暴露风险,在汞污染地区推广作物秸秆还田措施时应持谨慎态度。     

大连湾表层沉积物中汞的赋存形态与生物可利用性研究

为了解大连湾沉积物中汞的赋存形态和生物可利用性,对大连湾表层沉积物中总汞(THg)和甲基汞(Me Hg)的含量进行了分析,并采用选择连续提取法对表层沉积物中汞的赋存形态进行了研究,探讨了沉积物中汞的赋存形态与甲基汞的关系。结果表明:大连湾表层沉积物中总汞和甲基汞的平均含量分别为95.1、0.71 ng/g,甲基汞占总汞的比例(甲基化率)为0.76%,与自然背景值相比,沉积物中总汞含量明显受到了人类活动的影响;大连湾表层沉积物中各赋存形态汞比例的平均值由小至大依次为水溶态汞(Hg-w)(3%)胃酸溶解态汞(Hg-h)(10%)硫化物结合态汞(Hg-s)(24%)有机结合态汞(Hg-o)(31%)强络合态汞(Hg-e)(32%),Hg-e、Hg-o和Hg-s为主要存在形态;沉积物中Hg-w、Hg-h和Hg-o与甲基化率呈正相关,显示Hg-w、Hg-h和Hg-o具有较高的生物可利用性。研究表明,采用选择连续提取法进行沉积物中汞赋存形态的研究,对了解沉积物中汞的生物可利用性具有较好的指示意义。     

Synergistic effects of dietary vitamin E and selenomethionine on growth performance and tissue methylmercury accumulation on mercury‐induced toxicity in juvenile olive flounder,Paralichthys olivaceus (Temminck et Schlegel)

An 8‐week feeding trial was conducted to evaluate the synergistic effects of dietary vitamin E and selenomethionine (SeMet) on induced methylmercury (MeHg) toxicity in juvenile olive flounder Paralichthys olivaceus. Nine semi‐purified diets were formulated to contain three different vitamin E levels as DL‐α‐tocopheryl acetate (0, 100 and 200 mg TAkg^?1 diet) and three different selenium (Se) levels (0, 2 and 4 SeMet mg kg^?1 diet) on the constant mercury toxicity level (20 mg MeHgkg^?1 diet). Nine experimental diets, in a 3² factorial design (E₀Se₀, E₀Se₂, E₀Se₄, E₁₀₀Se₀, E₁₀₀Se₂, E₁₀₀Se₄, E₂₀₀Se₀, E₂₀₀Se₂ and E₂₀₀Se₄), were fed to triplicate groups of fish averaging 2.3 ± 0.04 g (mean ± SD) in the semi‐recirculation system. After 8 weeks of feeding trial, vitamin E and Se showed significant effects on weight gain (WG) of fish (P < 0.05). We found that there was a clear trend of increasing WG with elevating vitamin E and Se levels in the diets. Feed efficiency (FE), specific growth rate (SGR), protein efficiency ratio (PER) and survivability exhibited a similar trend with WG. Both antioxidants had significant interaction effects on FE and PER (P < 0.05). Methylmercury concentrations in fish muscle, liver and kidney decreases in a dose‐dependent manner as dietary vitamin E and Se levels increase. Interestingly, the most significant interactive effects of vitamin E and Se were found in liver tissue for depleting Hg concentrations (P < 0.05). These findings suggest that dietary vitamin E more than 100 mg TA kg^?1 diet with 2 or 4 mg SeMet kg^?1‐supplemented diets could have synergistic effects on growth and liver mercury bioaccumulation on MeHg‐induced toxicity in juvenile olive flounder.     

广州市典型食用鱼类甲基汞含量及风险评估

通过分析广州市区居民消费量较大的7种淡水鱼和5种海水鱼肌肉中甲基汞（MeHg）含量,评估人体通过食鱼摄入MeHg的暴露风险。结果显示,广州市鱼体肌肉中MeHg含量范围为2.39～349μg·kg-1,平均含量为43.4μg·kg-1。不同食性鱼类MeHg含量水平依次为：肉食性〉杂食性〉草食性,处于食物链不同环节解释了这种含量差异。从生长环境来看,海水鱼肌肉的MeHg含量总体上高于淡水鱼。所有鱼中MeHg含量均低于国内外相关标准限值。与国内其他地区商品鱼相比,广州市商品鱼中MeHg含量相当,但明显低于野生鱼。居民通过食鱼摄入的MeHg范围为0.035～0.087μg·kg-1·d-（1bw）,均值为0.050μg·kg-1·d-（1bw）,远低于美国EPA规定的MeHg暴露参考剂量（RfD）值（1.1μg·kg-·1d-1）,也低于WHO和FAO制定的临时性周可承受摄入量（PTWI）（1.6μg·kg-1）。研究结果表明,广州居民食鱼MeHg暴露风险较小,但儿童等敏感人群食用特定鱼类的量和频次要引起一定注意。     

大米汞污染与摄食大米甲基汞暴露研究进展

本文汇总了环境与大米汞污染的来源、汞与甲基汞对人体的健康危害、水稻对甲基汞的吸收与累积、包括大米在内的食品中汞的含量与形态分析方法、全球大米汞污染的现状,以及人群摄食大米的甲基汞暴露方面的研究进展。我国贵州和东南亚汞矿开采地区产出的大米存在严重的汞污染,且大米为当地居民的主要粮食,摄食大米给当地居民带来了严重的甲基汞暴露健康风险。未来有必要在全球更广泛地开展大米汞污染与相应的人群摄食暴露健康风险评估工作,并加强水稻对环境中汞的吸收、转运和累积机制以及这一系列过程中汞形态转化方面的研究。