Mercury in an ultraoligotrophic North Patagonian Andean lake (Argentina): Concentration patterns in di erent components of the water column

The deep, ultraoligotrophic piedmont lakes of Northern Patagonia (Argentina) are located in pristine and barely impacted areas, along a wide latitudinal range. Several studies have reported moderate to high total mercury (Hg) concentrations and contrasting methylmercury (CH3Hg+) production in di erent lake compartments. Sources of Hg for western Patagonian terrestrial and aquatic ecosystems are still not clear; while point sources can be ruled out and atmospheric deposition is a plausible source, along with contribution from active volcanic areas of the Andes. In this investigation, we reported a noticeably seasonal, spatial (between lake branches), and vertical (between water column strata) heterogeneity in the total Hg concentrations found in the pelagic zone of Lake Moreno. Sterile water samples taken in a depth profile of the lake showed moderate to high concentrations of CH3Hg+ in autumn with a decreasing trend with depth. Our results indicated that Hg is largely allocated in the plankton fraction between 10–53 m; which dominated within the euphotic (epilimnetic) zone of the lake due to the high densities attained by two species of the dinoflagellate Gymnodinium. The 53–200 m planktonic size fraction (comprising rotifers, ciliates and immature stages of crustaceans) and the > 200 m fraction (calanoid copepods and cladocerans) were found to bear strikingly lower total Hg concentrations, suggesting that the magnification of Hg at the planktonic consumer level is negligible.     

玄武湖沉积物中重金属垂向分布及污染评价

采用电感耦合等离子体发射光谱仪(ICP-AES)测定了南京玄武湖3个不同湖区沉积物中的7种重金属元素(Cd、Cr、Cu、Mn、Ni、Pb、Zn)的浓度,对重金属元素的垂向分布规律进行了研究,并应用地质累积指数法对重金属的污染程度进行了评价。结果表明:不同湖区沉积物(0~20 cm)样品中重金属含量顺序为北湖>东南湖>西南湖,沉积物中7种重金属元素浓度由高到低的排列顺序为Mn>Zn>Pb>Ni>Cr>Cu>Cd,随着沉积物深度的增加,重金属浓度呈减小趋势;重金属Cd、Pb、Zn的平均浓度分别在1.1~1.7、33~38和150~400mg/kg的范围内波动,均大于南京土壤环境中的背景值;地累积指数法的评价结果表明,北湖的重金属污染程度最严重,产生污染的主要重金属元素为Cd和Zn,污染分级分别是中度和轻度偏中度污染。     

Spatial distribution and pollution assessment of mercury in sediments of Lake Taihu, China

Spatial distribution patterns of total mercury (THg) in 36 surficial sediment samples representing five regions of Lake Taihu were assessed using the ArcGis geostatistical analyst module. The pollution levels of THg were also evaluated from the same five lake regions. Concentrations of THg were in a ranged of 23-168 ng/g (mean 55 ng/g) in surfical sediments, which was significantly higher than those established baseline levels of the lake. Results of THg indicated that the northern region exhibited notably higher values, the bay regions showed elevated values relative to open areas, and the lakeside regions were higher than those observed in the central area. Lake Taihu suffered moderate to high Hg pollution, and expressed clear Hg enrichment status according to monomial pollution index I geo and human activity factors. The concentrations of THg in the surficial sediments of Lake Taihu showed moderate-strong variation (coefficient of variation 52%). Geostatistical analysis indicated a weak spatial self-correlation, suggesting the contamination of Hg in Lake Taihu is primarily the result of anthropogenic activities.     

后奥运时期京津冀区域大气本底夏季污染变化

为探索后奥运时期京津冀区域大气本底污染状况及变化趋势,在中国科学院华北兴隆大气本底观测站,对夏季大气主要污染物(NO_x、SO₂、O₃和PM_2.5)进行了连续3年的在线观测,结合气流轨迹模式对大气污染物的传输路径及贡献率进行了分析. 结果表明:兴隆站大气本底夏季ρ(NO_x)、 ρ(SO₂)、 ρ(O₃)和ρ(PM_2.5)的平均值分别为(11.5±5.9)、(8.3±7.0)、(137.6±38.4)和(50.9±33.0)μg/m3;首要污染物为O₃和PM_2.5,ρ(O₃)和ρ(PM_2.5)日均值超过GB 3095─2012《环境空气质量标准》二级标准〔ρ(O₃)为200 μg/m3,ρ(PM_2.5)为75 μg/m3〕的天数分别为102和60 d,占观测期间有效天数的39%和23%,表现为大气氧化性增强、二次污染逐年上升;受偏南气流影响,太行山沿线区域和山东半岛—渤海湾地区是兴隆夏季大气本底污染的主要贡献区域,特别是京津冀城市区域夏季高浓度O₃和PM_2.5,对华北区域大气本底污染物浓度的整体上升具有重要影响.      

芘在土壤不同粒径组分中的形态分布

以芘为PAHs代表物,采用土壤粒径分级和PAHs连续提取方法,研究了老化4周污染黄棕壤中芘在不同粒径组分中的形态分布.结果表明,供试土壤中芘主要以有机溶剂提取态和可脱附态存在,结合态残留量所占比例甚小;细砂粒、粉粒、粗黏粒和细黏粒中芘残留占原土总残留的比例分别为6.00%、4.66%、34.68%和40.88%.各粒径组分中各形态芘含量大小顺序为有机溶剂提取态>可脱附态>结合态,有机溶剂提取态和可脱附态是各粒径组分中芘残留的主要存在形态(占比98.82%以上),芘结合态残留量占比<1.18%.土壤中黏粒(包括细黏粒和粗黏粒)是芘可脱附态、有机溶剂提取态、结合态和可提取态残留储存的主要粒径组分.     

山地城市新建湖库氮磷营养盐时空特征研究

重庆市园博园龙景湖是一新建的山地河道型深水湖库.通过为期一年对龙景湖水库氮磷营养盐的监测,研究龙景湖水库氮磷营养盐的时空格局、变化特点和相互关系,分析园博园旅游区人为活动的特点以及上游流域来水水质对水库水质的影响.结果表明,龙景湖水库整体总氮和总磷年均浓度分别为(1.42±0.46)mg·L-1和(0.09±0.03)mg·L-1,存在丰水期平水期低于枯水期的季节性波动.湖库主水体区、开阔水体区和库湾区受所在区域影响因素不同,氮磷浓度分布存在时空异质性:主水体区季节变化特征与湖库整体基本一致;两个开阔水体区将主水体区分别与上游、库湾连接,顺水流方向的氮磷浓度沿程逐渐降低,开阔水体区氮磷营养盐受上游来水水质和周围园区功能布设影响;典型库湾区营养盐浓度高于主水体区和开阔水体区.湖库丰水期颗粒态的氮、磷占总氮、总磷质量分数分别为51.7%和72.8%,枯水期硝酸盐氮、活性磷酸盐分别占总氮、总磷质量分数为42.0%和59.4%,氨氮和溶解态有机氮占总氮质量分数相对稳定;氮磷比全年均值为18.429±7.883,营养物限制情况上,氮、磷为主要限制因素的时段分别为5.3%、21.2%.     

污灌区稻田汞污染特征及健康风险评价

选择天津北排污河灌区作为研究区域,调查了土壤和水稻总汞和甲基汞的含量及分布特征,评估污灌区稻米食用汞暴露风险,并对污灌区土壤-稻米甲基汞的影响因素进行了初步分析.结果表明,1.调查的29个污灌区稻田,土壤总汞含量为(367.04 ± 129.36) μg/kg,显著高于区域土壤Hg背景值73 μg/kg,甲基汞含量为(0.87 ± 0.77) μg/kg;水稻各部位总汞含量依次为稻叶 > 稻根 > 稻茎 > 稻米,稻米总汞含量为(12.80 ± 5.14) μg/kg,甲基汞含量依次为稻米 > 稻根 > 稻茎 > 稻叶,稻米对甲基汞具有很强的富集能力,甲基汞含量为(2.09 ± 1.20) μg/kg,甲基化率均值超过10%.污灌区稻米总汞每周摄入量为0.068~1.25μg/(kg·bw),甲基汞每周摄入量为0.0095~0.49μg/(kg·bw),污灌区稻米总汞及甲基汞暴露对居民健康风险总体仍在安全阈值内,但个别汞污染较严重地块甲基汞暴露风险值得高度关注.土壤甲基汞含量仅与土壤总汞含量及黏粒含量的相关性达到显著性水平,稻米甲基汞含量与土壤总汞含量、土壤甲基汞含量、稻米总汞含量及黏粒含量的相关性达到显著性水平.     

洱海湖滨带水质的时空变化规律

对洱海全湖128km湖滨带及其外围敞水区水质进行了为期1a的调查研究.结果表明,洱海湖滨带总氮、氨氮、总磷、高锰酸盐指数年平均处于Ⅲ类水平,主要污染因子是总氮和总磷;湖滨带水质季节性变化表现为夏、秋季水质污染重于冬、春季,最重时期是11月.水质空间变化表现为北部污染重于南部,西部重于东部;临近村落、农田区湖滨带总氮、总磷、高锰酸盐指数浓度均明显高于临近林地、山地区湖滨带;强风浪水动力扰动下,湖滨带近岸(离岸0~60m范围,水深￡2.5m)区域水体总氮、总磷、高锰酸盐指数浓度均明显高于远岸(离岸70~190m范围,水深3.0~8.0m)区域,而在弱风浪下,离岸远近水质差异不明显.     

Distribution of mercury and methylmercury in river water and sediment of typical manganese mining area

Manganese (Mn) ores contain substantial concentrations of mercury (Hg), and mining and smelting of Mn ores can bring Hg into the surrounding aquatic environment through atmospheric deposition, leaching of electrolytic Mn residue and Mn gangue dump. However, limited is known that how these processes influence the environmental behaviors of Hg in waterbody. Therefore, the seasonal distribution and existing form of Hg in water and sediment in one Mn ore area in Xiushan County, Chongqing were investigated. Our results showed that the mean Hg and methylmercury (MeHg) concentrations in water (n=35) were 5.8 ± 4.6 ng/L and 0.22 ± 0.14 ng/L, respectively. The mean Hg concentrations in retained riverbed and fluvial bank sediment (n=35) were 0.74 ± 0.26 mg/kg and 0.63 ± 0.27 mg/kg, respectively (the mean MeHg concentrations were 0.64 ± 0.40 µg/kg and 0.51 ± 0.30 µg/kg, respectively). It indicated that the mining and smelting of Mn ores were the main sources of anthropogenic Hg, and Mn may inhibit Hg methylation in rivers in Mn ore areas. Mercury in the bound to iron/ Mn (Fe/Mn) oxides of low crystallinity fraction (Hg-OX) accounted for 4.01% and 5.25% of the total Hg concentrations in the retained riverbed and fluvial bank sediment, respectively. The amount of Hg bound to Fe/Mn oxides in sediment increased significantly due to the manganese mining activities in the investigated area. Therefore, it could be hypothesized that high Hg concentrations in river sediment in Mn mining areas are closely related to high Mn concentration in sediment.     

Transport and fate of mercury under different hydrologic regimes in polluted stream in mining area

Seepage from Hg mine wastes and calcines contains high concentrations of mercury (Hg). Hg pollution is a major environmental problem in areas with abandoned mercury mines and retorting units. This study evaluates factors, especially the hydrological and sedimentary variables, governing temporal and spatial variation in levels and state of mercury in streams impacted by Hg contaminated runo . Samples were taken during di erent flow regimes in theWanshan Hg mining area in Guizhou Province, China. In its headwaters the sampled streams/rivers pass by several mine wastes and calcines with high concentration of Hg. Seepage causes serious Hg contamination to the downstream area. Concentrations of Hg in water samples showed significant seasonal variations. Periods of higher flow showed high concentrations of total Hg (THg) in water due to more particles being re-suspended and transported. The concentrations of major anions (e.g., Cl??, F??, NO3?? and SO4 2??) were lower during higher flow due to dilution. Due to both sedimentation of particles and dilution from tributaries the concentration of THg decreased from 2100 ng/L to background levels (< 50 ng/L) within 10 km distance downstream. Sedimentation is the main reason for the fast decrease of the concentration, it accounts for 69% and 60% for higher flow and lower flow regimes respectively in the upper part of the stream. Speciation calculation of the dissolved Hg fraction (DHg) (using Visual MINTEQ) showed that Hg(OH)2 associated with dissolved organic matter is the main form of Hg in dissolved phase in surface waters in Wanshan (over 95%).     

武汉城市湖泊表层底泥汞分布、风险评价及影响因素

底泥作为汞重要的"汇"及二次"源"，在湖泊系统汞生物地球化学循环中起到了重要作用。本文以武汉主要城市湖泊为研究对象，探究了表层底泥中总汞（THg）和甲基汞（MeHg）的分布特征、潜在生态风险及主要影响因素。结果表明，武汉15个城市湖泊表层底泥THg平均浓度为152±170 ng/g （24~611 ng/g），与国内其它湖泊系统相比处于较高水平；MeHg浓度为52.0±46.8 pg/g （ND~161.0 pg/g），低于其它湖泊系统。空间分布上，底泥THg浓度呈现由武汉市中心向外逐渐递减的趋势，MeHg含量并未呈现类似THg的分布趋势。潜在生态风险评价（PERI）结果显示，所有采样点位中汞潜在生态风险极高和高风险等级占比均为5.7%，且主要分布在市中心附近，说明武汉市中心附近湖泊底泥汞污染程度较重，而市中心外围湖泊底泥汞生态风险较低。相关性分析结果显示，有机质可能是影响武汉城市湖泊底泥THg分布的重要因素之一，而MeHg主要受控于无机汞的原位甲基化过程。底泥THg浓度-湖泊距市中心距离间显著的负相关关系、THg浓度-湖泊所在区GDP/人均GDP间的显著正相关关系均表明人为活动对武汉城市湖泊汞分布影响明显。     

Distribution and transportation of mercury from glacier to lake in the Qiangyong Glacier Basin, southern Tibetan Plateau, China

The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-elevation glacier basins on Tibetan Plateau. In this study, surface snow,glacier melting stream water and lake water samples were collected from the Qiangyong Glacier Basin. The spatiotemporal distribution and transportation of Hg from glacier to lake were investigated. Significant diurnal variations of dissolved Hg(DHg) concentrations were observed in the river water, with low concentrations in the morning(8:00 am–14:00 pm) and high concentrations in the afternoon(16:00 pm–20:00 pm). The DHg concentrations were exponentially correlated with runoff, which indicated that runoff was the dominant factor affecting DHg concentrations in the river water. Moreover, significant decreases of Hg were observed during transportation from glacier to lake. DHg adsorption onto particulates followed by the sedimentation of particulate-bound Hg(PHg) could be possible as an important Hg removal mechanism during the transportation process. Significant decreases in Hg concentrations were observed downstream of Xiao Qiangyong Lake, which indicated that the high-elevation lake system could significantly affect the distribution and transportation of Hg in the Qiangyong Glacier Basin.     

Comprehensive characterization of ambient nanoparticles collected near an industrial science park: Particle size distributions and relationships with environmental factors

We investigated the characteristics of ambient particles and their relationships with various environmental factors, including gaseous pollutants (CH4, non-methane hydrocarbons (NMHC), total hydrocarbons (THC), NOx, CO, SO2), meteorological parameters (humidity, temperature), and time (day/night, workday/weekend). We used an electrical low-pressure cascade impactor to measure the number and size distributions of ambient particles (0.007–10 m) that were collected approximately 1 km northwest of Hsinchu Science Park in Taiwan between February and May 2007. The number concentrations of particles were enhanced through photochemical reactions during the day. In addition, high traffic flow during workdays increased the formation of particulates. Except for SO2, all of the gaseous pollutants we studied (CH4, NMHC, THC, NOx, CO) correlated positively with the total number concentrations of ambient particles during daytime, indicating that they might contribute to the particulate burden. The poorer relationship between the SO2 level and the total number concentration of particles suggests that SO2 might participate indirectly in the nucleation process during particle formation, The high enrichment factors for Zn, Pb, Cu, and Mn, which mostly comprised the ultrafine particles (diameter: < 0.1 m) and fine particles (diameter: 0.1–1 m), presumably arose from emissions from traffic and high technology factories. Heterogeneous reactions on solid particles might play a role in the removal of SOx and NOx from the atmosphere. Sulfides and nitrides can further react with these local pollutants, forming specific Cu-containing compounds: CuO (39%), CuSO4 (34%), and Cu(NO3)2 (27%), within the ambient particles in this industrial area.     

基于传感器技术的渭南市道路环境颗粒物污染特征及影响因素研究

为深入了解渭南市街区道路环境颗粒物污染时空分布特征,利用车载颗粒物传感器于2019年3月1日—5月31日对渭南市道路环境空气中PM_2.5和PM₁₀浓度开展在线走航测量,分析了影响渭南市道路环境颗粒物污染时空分布的主要因素.研究表明:①渭南市区内所有道路PM_2.5平均浓度范围为37.7~51.9 μg/m3,浓度较高路段位于高新区东部和主城区;PM_2.5~10（粗颗粒物）平均浓度范围为65.8~119.1 μg/m3,浓度较高路段位于各功能区城郊.②工作日早高峰时段（07:00—09:00）主城区道路环境PM_2.5、PM_2.5~10污染较非工作日严重,3种类型道路工作日07:00 PM_2.5~10平均浓度呈支路（103.5 μg/m3）>主干道（102.1 μg/m3）>次干道（96.9 μg/m3）的特征.③对于高新区和老城区路段,除早晚高峰时段出现PM_2.5和PM_2.5~10浓度峰值外,凌晨时段渣土车行驶路段、裸地或施工现场周边路段易出现PM_2.5~10浓度峰值,其PM_2.5~10平均浓度最高达230.9 μg/m3（乐天大街西段的路段Ⅳ）.研究显示,工作日早晚高峰时段,特别是早高峰,机动车排放导致渭南市高新区东部和主城区路段的PM_2.5污染加重,夜间渣土车行驶导致高新区和老城区靠近城郊路段的颗粒物（PM_2.5和PM_2.5~10）污染加重.      

阳澄湖表层沉积物中氮磷及重金属的空间分布特征及污染评价

为了解阳澄湖表层沉积物中氮磷及重金属的空间分布和污染特征,对全湖开展了大范围调查,基于综合污染指数、地积累指数法和潜在生态风险指数法对沉积物污染风险进行评价.结果表明:阳澄湖表层沉积物中w(TN)、w(TP)平均值分别为3 433、379 mg/kg,湖区氮磷污染严重且空间差异明显,w(TN)高值区位于阳澄东湖,w(TP)高值区位于阳澄西湖;综合污染指数评价结果显示,整个阳澄湖TN均为重度污染状态,TP除阳澄西湖外大部分区域处于轻度污染状态.阳澄湖表层沉积物中w(Cu)、w(Zn)、w(Pb)、w(Cr)、w(Cd)、w(As)、w(Hg)、w(Ni)的平均值分别为35.0、141、12.6、62.6、0.36、27.5、0.145、47.6 mg/kg,分别是江苏省土壤重金属环境背景值的1.50、2.17、0.57、0.83、4.22、2.93、5.78、1.45倍,阳澄西湖的重金属含量要高于阳澄中湖和阳澄东湖.地积累指数法和潜在生态风险指数法评价结果均表明,Hg和Cd是主要的生态风险贡献因子,二者生态风险指数平均值分别为231.23、126.63.相关分析结果表明,阳澄湖表层沉积物中Cu、Zn、Pb、Cr、Cd、Hg和Ni的质量分数显著相关,说明其具有相似的来源,结合水系结构和周边企业分布,推测其主要来自于相城区和常熟市的工业企业.      

贵阳市不同粒级地表灰尘中As、Ni水平及权重

根据贵阳市城区土地利用的情况,在不同功能区地表采集灰尘样品,分析As、Ni含量及变异规律。结果表明:贵阳市地表灰尘As、Ni含量分别为17.4mg/kg和50.0mg/kg。工业区地表灰尘中As、Ni含量最高,商贸区和校园等区域As、Ni水平较低。贵阳市地表灰尘中不同颗粒物的质量百分比大小为细颗粒(<105μm)>中等颗粒(105～250μm)>粗颗粒(250～425μm)。As在不同粒径灰尘中含量差别不大,Ni在不同粒径灰尘中含量随粒径增加而降低。细颗粒对灰尘As、Ni的贡献分别为42%和47%。除垃圾站外,贵阳市各功能区地表灰尘不同粒径颗粒物百分比随粒径增大而减小,其中交通区地表灰尘细颗粒所占比例最大。垃圾站地表灰尘中不同粒径颗粒百分比则随粒径增大而增大,As、Ni在垃圾站地表灰尘中颗粒物贡献为中等颗粒>粗颗粒>细颗粒,其余功能区不同粒径颗粒物的贡献基本为细颗粒大于粗颗粒。     

巢湖不同富营养化区域甲烷排放通量与途径

为了更好的认识不同富营养化区域甲烷（CH₄）排放通量及途径的时空异质性,本文以我国典型富营养化浅水湖泊-巢湖为研究对象,设置西北湖湾、西湖心和中湖心3个研究点位,采用漂浮通量箱和经验模型分析等方法对其水-气界面CH₄排放通量与途径进行季节性研究.结果表明水体与沉积物中CH₄溶存浓度、水-气界面CH₄排放通量同水体营养盐水平及叶绿素a含量的空间变化相一致,且均表现为西北湖湾最高,其水体CH₄溶存浓度为（0.178 ±0.002）~（1.123 ±0.026）μmol/L、表层沉积物中CH₄含量为（70.5 ±30.7）~（189 ±97.0）μmol/L、CH₄总排放通量为（50.1 ±2.93）~（1232 ±28.6）μmol/（m²·h）;3个点位的CH₄扩散通量占总排放量的7.3%~42.9%,冒泡通量占57.1%~92.7%,富营养化程度最高的西北湖湾冒泡通量占比最高;CH₄排放通量大小与途径同时受季节变化影响,夏季CH₄冒泡与总排放通量均最高,其中冒泡对总通量的贡献高达98.1%.     

三峡库区内陆腹地典型水库型湖泊中DOM吸收光谱特征

溶解性有机质(DOM)是湖泊生态系统重要组成部分,其性质和结构决定了其在污染物(例如汞)环境行为中扮演着重要角色.本研究选取三峡库区内陆腹地典型水库型湖泊——长寿湖,采用吸收光谱表征方法,通过1年时间对DOM地球化学变化规律进行了定性定量分析,并结合汞观测数据,讨论了DOM对不同形态汞浓度的影响.结果表明,和1月相比,长寿湖4~11月DOC差异性低于CDOM,4~11月间差异性不显著.有色组分变化是解释DOM季节性变化的重要原因.DOM中主要生色团仍然来自于大分子量的芳香性组分.而CDOM三波长模型可较好对DOC的年际观测进行反演.同时,SUVA254和S275~295季节性变化特征较明显,1月芳香性和分子量均最小,4月上升.与其他类型湖泊相比,长寿湖水体DOM芳香性和分子量大小均低于森林湖泊,但高于高原湖泊.周边生态系统和土地利用类型对湖泊DOM差异影响明显.另外,SUVA254和DOC与各形态Hg无明显相关性,但水体生色组分和分子量大小是控制溶解态和活性汞的重要因素;而湖区甲基汞变化可能与湖泊初级生产力导致的有机质富集和迁移关系密切.     

宿州市街尘重金属的粒径分布特征及污染评价

在宿州市不同功能区采集23个街尘样品,利用X-Ray荧光光谱法测定了样品中重金属Cu、Zn、Pb、Mn、Cr、V的含量,分析了街尘重金属的粒径分布特征,并利用地累积指数法对其污染状况进行了评价。结果表明:(1)宿州市街尘中细颗粒质量比重较高,在<75μm、75～150μm、150～250μm、250～500μm四个粒径段的街尘质量比例分别为39.73%、27.52%、22.57%和10.18%;(2)街尘中各重金属元素的含量最大值均出现在<75μm和75～150μm粒径范围内,说明重金属易在细颗粒中富集;(3)各重金属元素在<75μm粒径范围内的赋存比例均高于其他3个粒径级别,达40%左右;(4)随着街尘粒径的由粗到细,其重金属污染程度从无污染到轻度污染,各重金属元素的污染程度依次为:Zn>Pb>Cr>Cu>V>Mn。     

近年渤海与黄海北部沿岸底栖贝类体内微污染物的分布特征

根据近几年的海洋常规监测数据,确定渤海及黄海北部沿岸底柄贝类体内典型微污染物的含量及其空间分布.结果表明,在36%以上的站点中,贝类体内石油烃含量超过国家海洋生物质量第1类标准(15μg/g,湿重,下同),尤其是大连湾和河北新村附近海域贝类体内含量甚至高出第Ⅲ类标准(80μg/g,以湿重计),并且,近年来大部分海域贻贝...