Occurrence of Sexual Hormones in Sediments of Mangrove in Brazil

The presence of sexual hormones (female estrogens) was assessed in sediments of a mangrove located in the urban region of southern Brazil. The estrogens are involved in human sexual reproduction. They act as the chemical messengers, and they are classified as natural and synthetic. The estrogens inputs in the environment are from treated and untreated sewage. The presence of estrogens in sewage is excretion from the female due to natural production and use of contraceptives (synthetic estrogens). With the indiscriminate release of sewage into the environment, estrogens can be found in rivers, lakes, and even in oceans. In this work, the presence of estrone (E1), 17-??-estradiol (E2), and 17-??-ethynilestradiol (EE2) in eight sedimentary stations in Itacorubi mangrove located on Santa Catarina Island, south Brazil, was investigated. Historically, the Itacorubi mangrove has been impacted by anthropogenic activities because the mangrove is inserted in the urban area of the Florianopolis. The estrogen EE2, used as contraceptive, had the highest concentration in mangrove sediment, 129.75?±?3.89 ng/g. E2 was also found, with its concentration ranging from 0.90?±?0.03 to 39.77?±?1.19 ng/g. Following the mechanism, under aerobic or anaerobic conditions, E2 will first be oxidized to E1, which is further oxidized to unknown metabolites and finally to CO₂ and water (mineralized). EE2 is oxidized to unknown metabolites and also finally mineralized. Theoretically, under anaerobic conditions, EE2 can be reduced to E1 even in environments such as mangrove which is essentially anaerobic.     

Removal of Zinc from Tidal Water by Sediments of a Mangrove Ecosystem: A Radiotracer Study

The removal of ⁶⁵Zn from tidal water by underlaying sediment cores collected in a mangrove forest and a tidal creek that drains this forest in Sepetiba Bay (SE Brazil) was investigated. After 30-h experiments in laboratory microcosms, the ⁶⁵Zn half-removal times from tidal creek and mangrove forest sediments were 8.7?±?1.8 and 9.2?±?0.9 h respectively. Depth penetration of ⁶⁵Zn was mainly restricted to the upper 3 cm in mangrove forest cores, while detectable ⁶⁵Zn activities were found in all layers (0–7 cm depth) of tidal creek cores. An unexpected ⁶⁵Zn release back to the overlaying water was observed for one of the tidal creek experiments in the 12–18 h interval (corresponding to a return of 17% of the initial ⁶⁵Zn activity in overlaying water), suggesting a reversibility of the ⁶⁵Zn removal process (e.g., by adsorption) in tidal creek sediments. The results indicate that mangrove-vegetated sediments allowed a lower vertical mobility of Zn than observed in creek sediments and mangrove sediments appear to be less susceptible to a reversion in the process of zinc removal from overlaying water, suggesting a greater capacity to retain this metal near the water–sediment interface. This first radiotracer approach on the mangrove sediments removal of Zn from tidal waters supports earlier experimental studies employing stable Zn, contributing for a better understanding of the metal uptake kinetics by such sediments and suggesting that these sediments act as active sinks for trace metals.     

Evolution of Mercury Contamination in Brazil

This paper reviews the history of Hg contamination in Brazil by characterizing and quantifying two major sources of Hg emissions to the environment: industrial sources and gold mining, industry was responsible for nearly 100% of total Hg emissions from the late 1940's to the early 1970's, when efficient control policies were enforced, leading to a decrease in emissions. Gold mining, on the other hand was nearly insignificant as a Hg source up to the late 1970's, but is presently responsible for over 80% of total emissions. Presently, over 210 t of Hg are released into the environment in Brazil annually. Nearly 170 t come from gold mining operations. 17 t come from chlor-alkali industry and 10 t come from all other industrial uses. Emissions to the atmosphere are the major pathway of Hg releases to the environment and reach over 160 t.yr-1 with approximately 136 t.yr-1 from gold mining.     

Variations of Soil Nutrient and Organic Matter Content in a Subtropical Mangrove Ecosystem

Variations of soil nutrient and organic matter content along tidal gradients of a small mangrove forest in Hong Kong were investigated. Effects of sampling months on nutrient status were also analysed. Two transects, A and B, were established perpendicular to the shoreline. Transect A transverse a wider band of vegetation and was less disturbed by human activities; while Transect B was close to human settlement and all mangrove plants were more frequently flooded by incoming and outgoing tides. Surface soils at 5 and 10 m intervals along Transects A and B, respectively, were collected in December 1989, March 1990, July 1990 and September 1990. Concentrations of soil organic matter, total and extractable nitrogen, phosphorus and potassium were high in landward sites and decreased gradually along tidal gradients; while pH and salinity increased with distance from landward to seaward sites. These trends along tidal gradients indicate the importance of tidal frequency and amplitude on soil properties. Significant differences in soil properties were also found between two transects. Transect A had significantly higher organic matter and nutrient content than Transect B. In both transects, there were sites with extraordinarily high levels of nutrients and organic matter (5–10 times higher than the average values) suggesting local contamination. Most of these contaminated sites were located at the landward edges. Positive correlations between organic matter, N, P and K content were found suggesting that these nutrients were from similar input sources. Variations along tidal gradients and local contaminated sites at the landward edges suggest that human discharges, litter deposition and surface runoff were major nutrient inputs. In both transects, no definite seasonal periodicity was found and temporal variations existed in a more random manner than variations along tidal gradients.     

Speciation and Concentrations of Mercury in Certain Coastal Marine Sediments

Concentrations of total mercury (Hg), methyl Hg and Hg(II) were determined in coastal marine sediments collected from the Baltic, South China and the Bering Seas. Methyl Hg concentrations in sediments were between 0.01 and 2 ng g-¹ on a dry weight basis, accounting for only <1% of the total Hg concentrations. The percentage of Hg(II) (i.e. available Hg) in total Hg was between 5 and 13 suggesting that most of the Hg in sediments was bound as HgS and/or Hg-humic complexes. Relatively larger proportion of methyl Hg was found in less polluted freshwater sediments than in marine sediments. Methyl Hg concentrations in marine sediments were not found to be correlated with total Hg and/or Hg (II) concentrations.     

Influence of Physical and Chemical Characteristics on Mercury in Aquatic Sediments

Given the variation observed in mercury in fish from natural lakes, it is difficult to determine what represents a background mercury level. Mercury in aquatic sediments is a potential source of this trace metal to biota, notably fish. Site specific factors, such as acidity and dissolved organic carbon have been shown to affect the mobilization of mercury and methylation of mercury. Methyl mercury is the most toxic form of this metal and the form most readily accumulated by biota. Thirty-four headwater lakes, selected for a range in pH, were sampled for sediment mercury levels as part of an investigation of the impacts of acid rain on insular Newfoundland lakes. Selected physical and chemical data were also collected on all of the study sites. Acidity was not found to be significantly related to sediment mercury concentrations despite the wide range in pH. Pearson correlation analysis indicated that sediment mercury level was positively correlated with WA:LA (watershed to lake area ratio). WA:LA was also correlated with Secchi depth and colour. Linear regression was used to estimate the parameters of a model relating sediment mercury to WA:LA. Watershed area to lake area ratio was more important than site specific factors in governing the concentration of sediment mercury in lakes without industrial input.     

猪发酵床不同垫料中、累积规律

为研究在发酵床养猪过程中不同组成垫料的As、Hg累积规律,本文以木屑、稻壳和秸秆为原料,配制成3种垫料处理,分别为木屑（S）、木屑+稻壳（SR）和木屑+稻壳+秸秆段（SRS）,在一年半的时间里,测定了4批育肥猪养殖结束时不同层次垫料中As、Hg含量,分析了长期使用后不同发酵床垫料中As、Hg累积情况,为发酵床废弃垫料的后续农用提供理论依据。结果表明,随着猪养殖批次的延长,3种处理及其不同层次垫料As、Hg含量均存在不同程度增加。4批猪养殖结束时,As累积量最大的是SRS处理的发酵床,为1921.7 mg·栏-1,Hg累积量最大的也是SRS处理的发酵床,为21.1 mg·栏-1。S、SR、SRS处理的As、Hg含量分别为2.921、2.190、2.621 mg·kg-1和0.048、0.036、0.042 mg·kg-1,均符合《农业行业标准有机肥料》（NY 525—2012）、《食用农产品产地环境质量评价标准》（HJ/T 332—2006）的标准限值。     

Mercury Accumulation in Foliage over Time in Two Northern Mixed-Hardwood Forests

Concentrations of mercury (Hg) in live foliage increased ten-fold from spring bud break (mean ± std. dev. from bothsites: 3.5±1.3 ng g^-1) to autumn litterfall(36±8 ng g^-1). Mercury in foliage did not behavesimilarly to eight other elements with known soil or aerosolsources (Aluminum (Al), Vanadium (V), Strontium (Sr), Rubidium(Rb), Copper (Cu), Zinc (Zn), Barium (Ba), and lead (Pb)),suggesting that Hg originated from a distinct pathway. Based onmeasured and modeled data, uptake of only 25% of the availableambient dry deposited Hg⁰ could explain all of the Hgmeasured in foliage throughout the growing season. Estimates ofgaseous elemental Hg (Hg⁰) uptake from soil water accountedfor 3–14%% of the Hg in litterfall. Mercury deposition toforested sites in the Lake Champlain and Lake Huron basins washighest in litterfall (40%), followed by total throughfall(33%), and precipitation (27%). The Hg flux in litterfall was15.8±1.9~μg m^-2 yr^-1 to the Lake ChamplainWatershed in 1995 and was 11.4±2.8~μg m^-2 yr^-1 to the Lake Huron Watershed in 1996. In comparison, the Hg fluxes in precipitation and total throughfall were 9.0±0.6 and 11.6±0.7~μg m^-2 yr^-1in the Lake Champlain Watershed (1995), and 8.7±0.5 and 10.5±1.0~μg m^-2 yr^-1 in the Lake Huron Watershed (1996).     

Heavy Metals in Mangrove Sediments of the United ARAB Emirates Shoreline (Arabian Gulf)

Water, Air, &; Soil Pollution - The levels and distributions of eight heavy metals in the sediments of four mangrove areas, namely Abu Dhabi, Umm al-Quwain, Ras al-Khaimah, and Khor Khuwair...     

三种有机物料对稻田土壤汞甲基化及水稻汞积累的影响

施用有机物料是水稻生产过程中提高产量的一条重要途径，明确有机物料的施用对糙米Hg积累的影响，对于Hg污染稻田的安全利用具有重要的指导意义。本研究采用盆栽实验，设置等量（3%，w/w）的油菜秸秆、猪粪和水稻秸秆生物炭，对比分析3种有机物料的施用对水稻产量及其对Hg在稻田系统的迁移转化的影响。结果表明，3种有机物料的施用均显著提高了水稻产量，但对土壤Hg甲基化和糙米Hg的积累影响则并不一致。油菜秸秆、猪粪和水稻秸秆生物炭处理下水稻产量分别提高17.6%、33.0%和39.9%。与相同水平土壤Hg处理相比，施用猪粪提高了土壤Hg的生物有效性，促进了土壤MeHg的生成，提高了糙米THg的富集系数，使糙米THg和MeHg的含量分别提高了34.5%和30.3%；施用油菜秸秆降低了土壤Hg的生物有效性，抑制了土壤Hg甲基化过程和水稻对Hg的富集，糙米THg和MeHg的含量分别降低了34.6%和36.2%；施用水稻秸秆生物炭降低了土壤Hg生物有效性和糙米THg的富集系数，糙米THg和MeHg的含量分别降低了46.9%和48.4%。因此，在Hg污染稻田中应慎重施用猪粪，可选择施用水稻秸秆生物炭和油菜秸秆，达到提高产量和阻控糙米Hg积累的双重效果。     

Human and Environmental Contamination by Mercury from Industrial Uses in Brazil

The amount of Hg used for industrial purposes in Brazil has been estimated as 105 t.yr-1, of which, 50% is released into the environment. As the industries that use this Hg are located in the neighborood of highly populated areas, the number of people exposed to the risk of contamination is high. Severe cases of chronically poisoned workers have been reported, most of them presenting neuropsychological disorders. Contamination of air, soil, and water resources are also observed. Analysis of sediments, water and biota of Guanabara Bay, Rio de Janeiro, show contamination of all segments by Hg originating mainly from a chlor-alkali plant located nearby. Higher concentrations of Hg were found in the sediments (0.7 to 20 mg.kg-1) where it is associated with organic matter usually under anoxic conditions. Mercury can became bioavailable by organification or by changes in the actual environmental conditions and is thus an important source of environmental contamination of people who consume its biota.     

有机肥对水稻中汞/甲基汞累积的影响

稻米对甲基汞的累积危害居民身体健康。本文通过施用厌氧腐熟有机肥的盆栽试验,探讨有机肥施用对水稻中汞-甲基汞累积的影响。结果表明,有机肥施用水稻土中甲基汞含量显著增加,对照(10.43μg/kg)1%豆饼粉肥(16.80μg/kg)1%鱼粉肥(24.10μg/kg)2%豆饼粉肥(33.53μg/kg)2%鱼粉肥(38.46μg/kg),可能是施加有机肥后,增加了土壤微生物数量,提高了酶活性,导致水稻土中甲基汞含量增加。有机肥施用后,水稻不同部位总汞累积差异显著,根部最高(2 812.83μg/kg),其次是糙米(336.78μg/kg)和茎叶(300.44μg/kg)。有机肥施用后,水稻不同部位累积甲基汞的能力不同,表现为糙米(180.06μg/kg)根(59.71μg/kg)茎叶(38.97μg/kg)。不同有机肥的施用均增加籽粒中甲基汞的含量,与对照相比,各处理增加量表现为1%豆饼粉肥(16.1%)1%鱼粉肥(19.3%)2%豆饼粉肥(41.5%)2%鱼粉肥(57.9%)。同时稻米中甲基汞含量与水稻土中甲基汞含量呈正相关关系。有机肥施用增加汞污染土壤水稻中汞与甲基汞累积,其可为合理施肥提供科学依据和理论指导。     

Distribution of Mercury and Monomethylmercury in Sediments of Vigo Ria, NW Iberian Peninsula

Fifty four samples of surface sediments (1-cm of thickness) and a gravity core of 154-cm long were collected in the Vigo Ria, NW of Iberian Peninsula. In the laboratory the sediments were oven dried at 40°C, desegregated, homogenised and analyzed for total Hg, monomethylmercury (MMHg), Al, and particulate organic carbon (POC). Mercury in sediments varied within a broad range: 0.09 to 8.9 nmol g^?1 the higher concentrations being found in the shipyards and docks areas of Vigo port (southern–middle Ria zone). No correlation was found between Hg and POC. The good exponential correlation between total Hg and Al levels suggests that Hg is closely associated with the fine fraction of sediments. Monomethylmercury concentrations in surface sediments ranged between <1.4 (DL) and 8.5 pmol g^?1 being the spatial distribution similar to that observed for total Hg. The lack of correlations MMHg–Al and MMHg–POC suggests that in situ processes of methylation/demethylation are responsible for MMHg distribution rather than the sediment characteristics. Additionally, these processes appear mercury-dependent only for Hg concentrations above 2.5 nmol g^?1. On the basis of these results it was estimated that 155 kg of Hg (0.1% MMHg) are present in the surface sediments of Vigo Ria, being 61% of anthropogenic origin.     

Risk Assessment of Mercury in Alta Floresta. Amazon Basin - Brazil

In the last 15 years gold mining activity has been the main source of the mercury (Hg) emissions into the atmosphere in the Amazon Basin. The first phase of gold production takes place in remote areas. In general the second one happens in the local urban area, where the gold is commercialized and sent to the great economic centers. In the last 3 years, this activity started to decline as a consequence of the high cost of the gold production but in the Municipality of Alta Floresta, the gold trade still plays an important role in the local economy. This paper addresses the assessment of the Hg exposure scenarios and their quantitative risk for inhalation of metallic Hg vapor and for ingestion of total Hg, using indirect exposure measurements, for different age groups of the urban area of Alta Floresta. This work took into account the field study which provided background information, such as characteristics of local and regional environment, Hg concentrations in different environmental media, and the character of the local urban population. The mean levels of Hg in the atmosphere of the urban area ranged from 210 ng/m³ to 880 ng/m³. Alta Floresta has no riverside population and there is a low fish consumption rate of 8 g/d among the general population. However, mercury levels in locally consumed carnivorous fish, ranged from 0.3 to 3.6 mg/kg, depending on the species and on the period of the year. The levels of mercury in soil surrounding the residential areas near the Hg emissions sources, ranged from 0.05 to 4.10 mg/kg. Hg in soil may represent an important source of mercury ingestion for local children up to 4 years of age. The mean Hazard Index estimated for the general adult population was 1.4. For the general population, regarding the number of persons exposed in the urban area, inhalation of metallic Hg vapor is the main route of exposure. The results for water ingestion for all groups are negligible. For families of fishermen the Hazard Index was estimated to be 9.3, with a contribution of 92% from fish ingestion.     

Mercury Accumulation in Transplanted Hypogymnia Physodes Lichens Downwind of Wisconsin Chlor-Alkali Plant

Emissions of mercury from a chlor-alkali plant in central Wisconsin have raised concern about possible effects on biota in the area. Samples of the lichen Hypogymnia physodes, which no longer grows in the area, were transplanted from a site in northeastern Wisconsin and positioned on plastic stands at varying distances up to 1250 m from the plant and sampled for Hg quarterly for one year to test the hypothesis that Hg would be taken up by the lichens and would decline with distance. Average tissue concentrations were elevated when first sampled at three months and continued to increase at the nearest sites until the study ended after one year. Average concentrations after a year of exposure ranged from 4418 ppb at 250 m from the plant to 403 ppb at 1250 m from the plant. The decrease over distance followed a negative exponential pattern. Background concentrations at a control site in northern Wisconsin averaged 155 ppb.     

Determination of Organic Mercury in Biota, Plants and Contaminated Sediments Using a Thermal Atomic Absorption Spectrometry Technique

A simple, rapid procedure for the determination of organic mercury in sediments, plants and fish tissues has been developed and validated. Extraction and separation of organic mercury compounds from the sample matrix was achieved by an established procedure based on an acid leaching of the sample (H₂SO₄/KBr/CuSO₄), followed by extraction of the organic mercury halide with toluene and back-extraction with an aqueous solution of thiosulphate. Detection and quantification of mercury, in the liquid extracts, was made by atomic absorption spectrometry (AAS), following thermal decomposition of the sample. The method was evaluated using Certified Reference Material (CRM) BCR 463 (tuna fish), BCR 580 (estuarine sediment), IAEA-140TM (sea plant homogenate) and NRCC TORT-2 (lobster hepathopancreas). The recovery factors for organic mercury in all tested CRM were between 81–107%. The precision of the method has relative standard deviations of less than 10% for sediments and fish tissues and of less than 16% for plant material. The method was successfully applied to natural samples of sediments, plants, macroalgae and fish tissues collected from an estuarine ecosystem and could, therefore, be used for routine analyses.     

Mercury Levels of Soils,Sediments and Fish in French Guiana,South America

This study examines the level of mercury contamination for different components of the biosphere in French Guiana. The spatial variability of the contamination of the waters, soils and sediments in the catchment area of the Sinnamary River is studied. The contamination of the trophic chain isdiscussed by analysis of the flesh of fish for the principal species represented in nine Guianese rivers, especially species consumed by human populations. The mercury contamination of sediments and soils, is extremely heterogeneous and that of fish is generalised. For carnivorous fish, the average mercury content is 0.48 μg g^-1 (±0.28) (fresh weight) and for non-carnivorous species, 0.05 μg g^-1 (±0.07). The concentrationsmeasured are greater than the European standards forconsumption for 4.7% of the carnivorous individuals.     

长期施肥对汞在典型壤质潮土及作物中累积影响的研究

研究了长期(1989~2009年)不同施肥条件下,汞在典型壤质潮土中的累积趋势、形态变化,及其在冬小麦/夏玉米体系作物体内的富集与转移。田间试验设置7个不同施肥处理,有机肥(OM)、OM+化肥氮磷钾(NPK)、NPK、NP、PK、NK、和不施肥(CK),其中OM+NPK处理有机肥和化肥氮磷钾各占50%。每个处理4个重复。结果显示,经过20年的不同施肥处理,汞在表层土壤(0～20 cm)中的含量呈现先增加后减少的趋势。磷肥的长期施用是土壤中汞的重要来源,但对其在土壤中的累积趋势影响较小。弱酸溶解态和有机结合态汞的生物毒性较强,但在供试土壤中的含量较低,均约占其全量的6%;而铁锰结合态(18%)和残渣态(70%)是该土壤中汞的主要形态。汞在小麦茎叶和籽粒中的含量差异较小,显著的低于其在根系中的含量;汞在玉米根系和茎叶中的含量相似,明显高于其在籽粒中的含量。经过长期不同的施肥处理,汞在土壤中的含量表现为NPK≈OM+NPK≈NP≈PK>OM>NK≈CK,与其在作物根系及茎叶中含量的趋势总体一致;汞在两种作物籽粒中的含量表现为NPK≈CK>OM≈OM+NPK>NK>PK>NP,在作物产量较高及较低的情况下均容易导致汞在籽粒中的富集。在OM、OM+NPK、NK和CK几种施肥处理下,汞在土壤及作物根系中的含量与其余处理相比均较低,但作物通过加强对汞的转移能力,提高了其在作物茎叶及籽粒中的含量,尤其CK处理汞在两种作物籽粒中的含量。