Maternal transfer of mercury to the developing embryo/fetus: is there a safe level?

Mercury (Hg) exposure is ubiquitous in modern society via vaccines, fish/crustacea, dental amalgam, food, water, and the atmosphere. This article examines Hg exposure in the context of primary exposure to pregnant women and secondary exposure experienced by their unborn babies. Babies in utero are particularly at risk of higher Hg exposure than adults (on a dose/weight basis through maternal Hg transfer via the placenta), and are more susceptible to adverse effects from mercury and its biologically active compounds. It is, therefore, critical that regulatory advisories around maximum safe Hg exposures account for pregnant women and secondary exposure that children in utero experience. This study focused on standardized embryonic and fetal Hg exposures via primary exposure to the pregnant mother of two common Hg sources (dietary fish and parenteral vaccines). Data demonstrated that Hg exposures, particularly during the first trimester of pregnancy, at well-established dose/weight ratios produced severe damage to humans including death. In light of research suggestive of a mercuric risk factor for childhood conditions such as tic disorders, cerebral palsy, and autism, it is essential that Hg advisories account for secondary prenatal human exposures.     

Reproductive toxicity of metals in calanoid copepods

This study investigated the effect of exposure route on metal accumulation, tissue distribution, and toxicity in the marine copepods Acartia hudsonica and A. tonsa. Sublethal toxicity was measured as decreases in egg production, hatching rate, ovarian development and protein (yolk) content of the egg. When algal food, exposed to Hg at 1 nM or Cd at 5 nM resulting in cells containing 34 and 64 nmol metal g^-1 dry weight, respectively, was ingested over a 4-h period by copepods, the total copepod body burden increased nine-fold for Hg and two-fold for Cd over background concentrations, and egg production decreased by 50%. Sublethal concentrations of metals were >2 orders of magnitude lower than LC₅₀ concentrations. Hatching rate, ovarian development and egg protein content all decreased following trophic exposure to metals, implying that the process of yolk accumulation (vitellogenesis) was affected. Exposure to dissolved Cd had no effect, but dissolved Hg at concentrations as low as 0.25 nM did affect egg production. Different toxic effects following different exposure routes were related to different metal distributions in the copepods: exposure to dissolved metal resulted in metal deposition in the exoskeleton, whereas exposure to dietary metal resulted in metal deposition in internal tissues. These findings indicate that enrichment of metal concentrations in internal tissues, which occurs primarily after exposure to dietary metal, affects vitellogenesis. The reproduction rate decreases by about 75% at metal concentrations only moderately higher than levels in coastal waters. Toxicity tests involving aquatic animals need to consider effects following uptake by different pathways, including the trophic transfer of metals.     

Mitochondrial dysfunction,impaired oxidative-reduction activity,degeneration, and death in human neuronal and fetal cells induced by low-level exposure to thimerosal and other metal compounds

Thimerosal (ethylmercurithiosalicylic acid), an ethylmercury (EtHg)-releasing compound (49.55% mercury (Hg)), was used in a range of medical products for more than 70 years. Of particular recent concern, routine administering of Thimerosal-containing biologics/childhood vaccines have become significant sources of Hg exposure for some fetuses/infants. This study was undertaken to investigate cellular damage among in vitro human neuronal (SH-SY-5Y neuroblastoma and 1321N1 astrocytoma) and fetal (nontransformed) model systems using cell vitality assays and microscope-based digital image capture techniques to assess potential damage induced by Thimerosal and other metal compounds (aluminum (Al) sulfate, lead (Pb)(II) acetate, methylmercury (MeHg) hydroxide, and mercury (Hg)(II) chloride) where the cation was reported to exert adverse effects on developing cells. Thimerosal-associated cellular damage was also evaluated for similarity to pathophysiological findings observed in patients diagnosed with autistic disorders (ADs). Thimerosal-induced cellular damage as evidenced by concentration- and time-dependent mitochondrial damage, reduced oxidative–reduction activity, cellular degeneration, and cell death in the in vitro human neuronal and fetal model systems studied. Thimerosal at low nanomolar (nM) concentrations induced significant cellular toxicity in human neuronal and fetal cells. Thimerosal-induced cytoxicity is similar to that observed in AD pathophysiologic studies. Thimerosal was found to be significantly more toxic than the other metal compounds examined. Future studies need to be conducted to evaluate additional mechanisms underlying Thimerosal-induced cellular damage and assess potential co-exposures to other compounds that may increase or decrease Thimerosal-mediated toxicity.     

Changes in methylmercury accumulation in the brain of rat offspring throughout gestation and during suckling

Higher methylmercury (MeHg) accumulation and susceptibility to toxicity in the fetus than in the mother at parturition is well known. However, the degree of MeHg accumulation in the brain during the late pregnancy period when the human brain is most vulnerable is not clear. In addition, changes in MeHg accumulation in the developing rat tissues with consecutive exposure throughout gestation and lactation periods have not been well studied. The purposes of this study were to evaluate the changes in MeHg accumulation in the brain and other tissues of the offspring, based on constant and consecutive doses of MeHg to mothers throughout gestation and lactation. Adult female rats were given a diet containing 5?ppm?Hg (as MeHg) for 8 weeks. Then they were mated and subsequently given the same diet throughout gestation and lactation. On embryonic days 18, 20, 22 and at parturition, the concentrations of Hg in the brains of the offspring were approximately 1.5–2.0 times higher than those in the mothers. On the other hand, during the suckling period Hg concentrations in the brain rapidly declined to about 1/10 of that during late pregnancy. Changes in MeHg accumulation in the blood and liver after parturition were similar to those in the brain. Thus, although mothers are subjected to constant and prolonged MeHg exposure throughout both the gestation and lactating periods, the risk to the offspring may be especially high throughout the late gestation period but rapidly decreases during the suckling period     

不同价态无机砷对罗非鱼肝脏砷积累及GSH/GST解毒代谢的影响

低剂量中长期暴露下的氧化胁迫是砷对水生生物致毒的重要机制之一。本文通过对罗非鱼进行32 d的食物相砷暴露,测定不同时间点罗非鱼肝脏中谷胱甘肽(glutathione,GSH)含量和谷胱甘肽巯基转移酶(glutathione S-transferase,GST)活性,揭示不同价态无机砷对罗非鱼肝脏中GSH/GST的影响机制。经三价砷(As(III))暴露后,砷含量在2 d内显著增加而在随后的30 d内无显著性差异; 0～2 d内GSH含量显著增加,后降低,13 d后GSH含量均低于空白组; 0～6 d GST活性均大于空白组,6～8 d GST活性降低,8 d后活性高于空白组,且32 d达到最大值。经五价砷(As(V))暴露后,罗非鱼肝脏中砷含量逐渐增加,在20 d时达到最大值而后无显著性差异; 0～2 d时GSH含量降低,随后逐渐增加,在16 d达到最大值,16 d后GSH含量均低于空白组; 0～8 d时GST被大量诱导合成,8～20 d时GST合成被抑制,20 d后活性增加,在32 d达到最大值。As(III)和As(V)对罗非鱼GSH/GST的不同影响与其在罗非鱼体内的积累量有关。As(III)暴露后各时间点罗非鱼肝脏中的砷含量与GSH含量呈统计学正相关,而As(V)暴露无明显相关性。这是因为As(V)进入罗非鱼肝脏后会还原为As(III),进而GSH作为可提供巯基的还原剂而被大量消耗。另外,As(III)暴露后各时间点罗非鱼肝脏中的砷含量与GST活性呈显著负相关,而As(V)暴露却呈现出很强的滞后性,这是由于进入生物体内的As(V)需转化为As(III)后,才可直接作用于酶系统。可见,不同形态砷对水生生物的致毒机制需进一步深入研究。     

Influence of marine alga against mercury-induced biochemical changes,structural destabilization,and genotoxicity in marine tiger fish,Therapon jarbua

This study elucidated the protective role of alga against mercury (Hg)-induced toxicity in marine fish. Bath immersion with mercury chloride (HgCl) [0.125 and 0.25?ppm] in combination with the algal extract (3?ppm) to Therapon jarbua offered a significant protection against Hg only induced disturbed liver function, damaged histoarchitecture, elevated oxidative stress, and DNA fragmentation of tissues. Mercury exposure decreased hepatic superoxide dismutase (SOD), catalase (CAT) activities, and the level of nonprotein-soluble thiol (NPSH, GSH), with a concomitant increase in thiobarbituric acid reactive substances (TBARS) in the gill, kidneys, liver, and blood. Algal supplementation diminished the rise in TBARS restoring CAT, SOD, and GSH levels to control. Reduced generation of free radicals may be correlated to protect DNA stability and morphology. This study indicates the ability of alga to ameliorate Hg-mediated injuries. In conclusion, Kappaphycus alvarezii extract did not show any toxicity and its safety is suggestive for using as a supplement in fish food.     

汞和砷单一及联合暴露对日本沼虾的氧化应激效应

为深入探讨汞(Hg)和砷(As)对水生生物的慢性毒性效应,以日本沼虾(Macrobrachium nipponense)为受试生物,以超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、金属硫蛋白(MT)和丙二醛(MDA)为测试分子标志物,研究上覆水中不同浓度Hg和As单一及联合暴露对日本沼虾肝胰腺的氧化损伤及联合作用机制。结果表明:Hg和As单一及联合暴露对4种分子标志物均可产生不同程度的抑制或激活效应。其中,SOD活性均受到抑制,且高浓度As(1000μg·L-1)暴露10 d的抑制率最大,高达59.13%;而CAT活性整体被激活,Hg单独暴露下的激活效应要高于As,且在联合暴露组中随着暴露时间的增加呈现出显著的剂量效应关系(P0.05);MT和MDA含量在Hg和As的暴露下均显著增加(P0.05)。其中MT对Hg的螯合能力大于As,As单独暴露3 d后MDA变化较小,但10 d后其含量显著增加(P0.05)。析因方差分析发现,Hg-As对机体的联合作用机制主要表现为协同作用。综合生物标志物响应指数(IBR)评价证实,联合毒性要高于单独毒性,Hg与As在高浓度下联合暴露10 d的IBR值最大,毒性最强,高浓度As单独暴露处理组的毒性次之;同时,机体自身随暴露时间延长对Hg也表现出一定的解毒功能。     

汞的环境光化学

作为一种全球污染物,汞在水体、底泥、土壤、大气等介质中以各种不同形态存在.各种汞形态具有不同的理化特性及毒性.汞形态的转化对于汞的迁移、毒性、食物链富集放大效应等具有重要影响.光照在汞的形态转化中起着重要作用,主要涉及光氧化、光还原、甲基汞的光降解以及无机汞的光化学甲基化等四个方面.本文对不同环境介质中汞的光化学转化过...     

Cadmium accumulation and toxicity in the kidney of the bay scallop Argopecten irradians

Specimes of bay scallops, Argopecten irradians, collected from shallow-water eel-grass beds near Beaufort, North Carolina (USA) in September 1979, were exposed to 0.7 ppm cadmium in flowing seawater for 5 d. This exposure resulted in a massive extrusion of the calcified concretions of most of the kidney epithelial cells, although marked morphological damage consisting of cytoplasmc degeneration was apparent in only a few focal areas of the kidney. In addition, unique cytoplasmic membrane-bound bodies were observed in epithelial cells of cadmium-treated but not control scallop kidneys. In some cells, these bodies appeared to fuse with the main concretion vacuole. Kidneys of cadmium-treated scallops accumulated cadmium to 200 ppm on a wet wt basis; of this 60% was associated with concretions (2 000 ppm dry wt) and 38% with the membranous pellet obtained after ultracentrifugation at 105 000 g for 1 h. Approximately 2% of total kidney cadmium was associated with the cytosolic fractions but, unlike zinc or manganese, which were bound to either high or low molecular weight species, a large component of the cadmium in this fraction was bound to a protein peak of approximately 21 000 daltons. Results of this study indicate that kidney concretions of A. irradians play a major role in the control of renal cadmium accumulation and excretion and hence the toxicity of cadmium to this organism.     

Effects of sublethal concentrations of mercuric chloride on ammonium-limitedSkeletonema costatum

The effect of sublethal additions of mercuric chloride on the marine diatomSkeletonema costatum (Grev.) Cleve grown in NH₄-limited chemostats and batch cultures was assessed. In short-term Hg exposure experiments (up to 5 h), the effect of Hg on ammonium uptake rates was studied by simulatneously perturbing the culture with 5 M NH₄ Cl and Hg concentrations ranging from 0.04 to 5.52 nM HgCl₂. The threshold of Hg toxicity occurred between 1.8 and 3.7 nM, based on a decrease in ammonium uptake rates. When the NH₄-limited culture was starved of ammonium for 30 h, the threshold of Hg toxicity decreased about an order of magnitude to 0.2 nM. In long-term Hg exposure experiments (679.5 h), NH₄-limited continuous cultures were semi-continuously exposed to 0.37 and 3.68 nM HgCl₂. After 4 days, the cell density in the Hg-treated chemostats began to drastically decline. After about 16 days these populations recovered, even though Hg additions continued. At the end of the experiment (26 days), cell densities had reached the levels observed at the beginning of the experiment. The reason for the recovery is unknown, but several possibilities are discussed. Ammonium uptake rates determined during the time-course of this long-term Hg exposure, indicated that these NH₄-limited cultures exhibited a significant loss in their ability to take up ammonium at low concentrations (e.g. 1 M). Thus, mercury pollution may seriously decrease the ability of a species to utilize the limiting nutrient during periods of seasonal nutrient limitation.     

镉在鲤鱼组织内的蓄积及对血浆指标的影响

随着工业的迅速发展,水环境中的镉污染日趋严重,镉的蓄积性强,毒性高。为了进一步研究镉在鱼类不同组织内的蓄积及其对血浆指标的影响,以鲤鱼(Cyprinus carpio)为受试生物,设置3个浓度梯度,镉浓度分别为0(对照组)、5和50μg·L-1,试验周期为30d。结果显示,随着暴露时间的延长,染毒组鲤鱼鳃、肝胰脏和肾脏中镉蓄积量与对照组相比均显著升高(p<0.05),其中肾脏蓄积量最大,其次为肝胰脏和鳃,且50 μg·L-1染毒组各组织镉蓄积量显著高于5 μg·L-1染毒组(p<0.05);30d时,5和50 μg·L-1染毒组鳃、肝胰脏和肾脏中镉蓄积量分别为对照组的12.3和43.5倍、5.1和27.3倍、11.9和70.8倍;鲤鱼肌肉中仅检测到微量镉(0.02～0.04mg·kg-1),且暴露时间和镉暴露浓度不影响肌肉中镉的蓄积量。整个试验期间,各染毒组血浆中钙和磷含量、超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量和谷草转氨酶(GOT)活性与对照组相比无显著差异(p>0.05)。研究表明,不同程度的水体镉污染均能造成鲤鱼各组织(肌肉除外)内较高浓度的镉蓄积,但对血浆指标无显著影响。     

Single walled carbon nanotubes induce cytotoxicity and oxidative stress in HEK293 cells

The aim of the present study was to evaluate the potential toxicity and general mechanisms involved in single walled carbon nanotubes (SWCNTs)-induced cytotoxicity using human embryonic kidney cell line (HEK293) cells. Carbon nanotubes (coded as CNT) used in this study were synthesized by the chemical vapor deposition method. To elucidate the possible mechanisms underlying SWCNT-induced cytotoxicity, cell viability, cell membrane damage (lactate dehydrogenase activity (LDH) assay), reduced glutathione (GSH), interleukin-8 (IL-8) and lipid peroxidation products levels were quantitatively assessed following SWCNT exposure for 48 hr using HEK293 cells. Exposure of cells to SWCNT at 3–300 μg/ml produced significant reduction in cell viability in a concentration-dependent manner. The IC₅₀ value of SWCNT was found to be 87.58 μg/ml. Exposure of HEK cells to SWCNT at 10–100 μg/ml resulted in concentration-dependent cell membrane damage, increased production of IL-8, elevated levels of thiobarbituric acid reactive substances like malondialdehyde and decreased intracellular GSH levels. In summary, exposure to SWCNT resulted in a concentration-dependent cytotoxicity in cultured HEK293 cells that was associated with increased oxidative stress.     

锌对汞胁迫下小麦幼苗生理特性的影响

通过沙基培养方法研究不同浓度锌(Zn)对汞(Hg)胁迫下小麦幼苗叶绿素相对含量(SPAD)、丙二醛(MDA)与脯氨酸的积累及抗氧化酶活性等的影响.结果表明:单独Hg(10 mg L-1)胁迫下,小麦幼苗叶绿素含量降低,超氧化物歧化酶(SOD)与过氧化氢酶(CAT)活性受到抑制,MDA与脯氨酸含量升高.加入10 mg L-1Zn后,叶绿素含量比Hg单独胁迫升高了5.6%,MDA含量降低了32.4%,表明该浓度Zn在一定程度上缓解了Hg对小麦幼苗的毒害;Zn浓度高于10 mg L-1的处理中,叶绿素含量逐渐降低,MDA则呈升高趋势,表明随Zn浓度升高,Zn对Hg毒害的缓解作用逐渐降低.低浓度Zn(10~20 mg L-1)提高了Hg胁迫下小麦幼苗SOD与CAT活性,其活性随Zn浓度升高逐渐增加,20mg L-1Zn处理下,两种酶活性比Hg单独胁迫分别升高了103.3%与71.0%,高浓度Zn(50~100 mg L-1)处理下,两种酶活性则呈下降趋势,表明Zn对Hg胁迫下两种酶活性的促进作用逐渐减弱.在试验设置的Zn浓度范围内,脯氨酸含量均低于Hg单独胁迫,并且低于对照,说明外加Zn抑制了脯氨酸的生成.综上所述,10~20 mg L-1的Zn可以在一定程度上缓解10 mg L-1Hg对小麦幼苗造成的毒害.     

立方体和八面体微/纳米氧化亚铜对大型水蚤(Daphnia magna)的氧化胁迫和生理损伤

为了实现特定的功能和应用,越来越多不同结构特性的纳米材料逐渐被人们精确合成。一些研究指出纳米材料的物理化学特性能够显著影响纳米材料对水生生物的毒性作用,但是对于不同特性的纳米氧化亚铜的毒性研究依然比较缺乏。本研究制备了2种不同形貌和结构的微/纳米氧化亚铜(micro/nano-Cu_2O)晶体,通过对大型水蚤(Daphnia magna)进行72 h的急性暴露实验,测定了大型水蚤体内还原型谷胱甘肽(GSH)的含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和钠/钾腺苷三磷酸酶(Na+/K+-ATPase)的活性变化。结果表明在2种不同特性的微/纳米氧化亚铜暴露体系中,大型水蚤体内Cu的积累量差别不大,但是不同结构的micro/nano-Cu_2O对大型水蚤抗氧化酶活性和钠/钾腺苷三磷酸酶活性影响存在差别。与立方体相比,八面体micro/nano-Cu_2O能够暴露更多的{111}面,并且其原子排列使其具有较高的表面能量,因此更容易在大型水蚤肠道内诱导产生活性氧(ROS)及溶出更多Cu2+,对大型水蚤产生更强的氧化胁迫和膜损伤。     

云南疣柄牛肝菌属真菌中汞含量及食用健康风险分析

汞(Hg)对人类健康有明显的毒害作用,多数野生食用菌对Hg有很强的富集能力,测定野生食用菌中总Hg含量,并对其进行食用安全评估有重要意义。采用冷原子吸收光谱法测定云南常见疣柄牛肝菌属真菌菌盖、菌柄中总汞(Hg)含量,分析样品对Hg的富集特征;以FAO/WHO现行每周Hg允许摄入量(provisional tolerable weekly intake,PTWI)标准,评估疣柄牛肝菌属真菌的食用安全性。结果显示,不同产地、种类及不同采集时间疣柄牛肝菌属真菌的总Hg含量差异明显,菌盖中总Hg含量在0.54~4.80 mg·kg-1dw之间,菌柄总Hg含量在0.32~2.80 mg·kg~(-1)dw之间,同一种牛肝菌菌盖总Hg含量均大于菌柄(Q(C/S)1),表明疣柄牛肝菌属真菌对Hg的积累量与生长环境、种类、部位等有关。根据FAO/WHO暂行的每周Hg允许摄入量标准(0.004 mg·kg-1bw),成年人(60 kg)每周食用300 g(鲜重)采自云南的疣柄牛肝菌属真菌,Hg摄入量远低于PTWI标准,对人体Hg暴露风险较低。     

An interaction of extra- and intracellular osmoregulatory mechanisms in the bivalve mollusc Rangia cuneata

We have studied the interaction of extra- and intracellular osmoregulatory mechanisms which the estuarine bivalve Rangia cuneata utilize to tolerate salinities ranging from freshwater to 25 ppt. The normally occurring intracellular free amino acid (FAA) accumulation in hyperosmotically stressed R. cuneata isolated ventricles was significantly reduced in the presence of divalent cation concentrations lower than that normally found in the blood. The effect of the divalent cations was not on the intracellular biosynthetic pathways responsible for FAA synthesis but rather on the myocardial membrane permeability to FAA. These data indicate that the effectiveness of the intracellular FAA mediated volume regulatory response in R. cuneata is dependent on both intracellular FAA accumulation and on the extracellular regulation of blood divalent cation concentration. This dependency indicates one interaction of extra- and intracellular osmoregulation in R. cuneata.     

贵州省典型矿区土壤重金属污染对蚯蚓的毒性效应评估

选取我国贵州省某矿区典型的重金属复合污染土壤开展28 d慢性毒性暴露试验,以蚯蚓体内2种抗氧化酶活性——过氧化氢酶(CAT)和超氧化物歧化酶(SOD)、8-羟基脱氧鸟苷(8-ODHG)和金属硫蛋白(MT)含量为生物指标,评估了以上生物指标与土壤重金属含量的相关性,探讨该研究方法用于矿区土壤重金属生态风险评估的可行性。结果表明,CAT和SOD在暴露周期内均出现先诱导后抑制的动态响应过程,表明蚯蚓通过提高CAT和SOD的活性来清除机体因污染胁迫而产生的自由基,以适应环境变化,在毒性缓解后,蚯蚓体内代谢产物的积累抑制了抗氧化氢酶活性,CAT和SOD活性下降并趋于稳定。暴露于重金属污染亚致死浓度时,蚯蚓体内的8-OHDG含量随着暴露时间的延长显著降低,随着暴露浓度的增加,损伤存在由低到高的转变。在28 d暴露周期内,蚯蚓体内MT在重金属胁迫下发挥了解毒作用,MT含量在蚯蚓暴露后第7天增加,随后逐渐降低。本文基于生物毒性试验综合评估了矿区典型重金属污染土壤的生态风险,研究结果对指导重金属复合污染土壤的修复与再利用具有重要意义。     

Assessment of individual and combined toxicities of three heavy metals (Cu,Cd and Hg) by using Tigriopus fulvus

The toxicities of copper, cadmium, and mercury ions and their binary and ternary mixtures were studied using the copepods Tigriopus fulvus. The LC50 values measured after 48 h exposure to single metal solutions revealed a toxicities rank as follows: CdT. fulvus. The combined effect of the metals was found to be antagonistic for Cu?Cd, Hg?Cd, and Cu?Cd?Hg, additive for Hg?Cu.     

Toxicity and bioaccumulation of cadmium and lead in Salvinia cucullata

The toxicity and accumulation of heavy metals, cadmium (Cd) and lead (Pb) in aquatic fern, Salvinia cucullata were studied. Plants were cultured in Hoagland's medium which was supplemented with 0.5,1,2, and 4 mg/l of Cd and 5, 10, and 40 mg/l of Pb and were separately harvested after 2,4,6, and 8 days. The toxicity symptoms of Cd and Pb to S. cucullata showed chlorosis on leaves. There were significant derceases in the relative growth, biomass productivity and total chlorophyll content when the exposure time and concentration were increased. The accumulation study showed the significant increases of both metals when the exposure time and concentration were increased. The roots of S. cucullata had higher Cd and Pb contents than leaves suggesting that the metals were bound to the root cells and were partially transported to the leaves.     

Laboratory studies on the accumulation of inorganic mercury and methylmercury by the mussel (Mytilus galloprovincialis Lam) in relation to the presence of sediment

A comparative study on the accumulation of inorganic mercury and methylmercury by the mussel Mytilus galloprovincialis was based on nine days of exposure to 25 µg L^?1 HgCl₂ or to 2.5 µg L^?1 methylmercury in laboratory microcosms. Mercury (Hg) content was evaluated in the gills, digestive gland, and mantle. A higher accumulation occurred in the gills than in other tissues. The effect of the sediment on the bioaccumulation of the Hg species was evaluated. The results showed that the sediment accumulated the inorganic Hg more efficiently than the methylmercury. In both cases, the bioaccumulation in the tissues was reduced. The observed differences emphasized the need for caution when field results are compared with the results of laboratory experiments. The fate of either inorganic or organic Hg was depicted considering the absolute total amount given and the amount found in all the matrices (organism, sediment, and seawater).