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1.
This article presents results of mercury in surface waters from Hunza River basin, Northern Areas, Pakistan. Small‐scale gold mining activities along the Hunza and Gilgit rivers are long known to be discharging mercury in the amalgamation and roasting processes. Previous studies reported high mercury concentrations in soils close to mining operations as well as serious health problems for miners. However, none of the studies have focused on the level of contamination in aqueous environments. This is the first study on the investigation of source and fate of sediment and river‐borne mercury in the Hunza River. The samples collected near gold panning sites showed higher mercury concentrations than critical levels established by the U.S. Environmental Protection Agency. The observed dissolved mercury concentrations ranged from 5.10 to 25.25 ng/l, whereas particulate‐bound mercury ranged from 4.85 to 154.62 ng/l. Particulate‐phase mercury corresponded to more than 75% of the total observed mercury concentrations for all of the sampled rivers. Thus, suspended sediments represented the major pathway of the riverine mercury transport. A mass balance calculation suggested an annual mercury flux of 48.6 g/km2 into the Hunza River basin. The samples collected from the most affected river, the Shimsal River, averaged to have 108 ng/l total mercury. This amount was close to the average soil mercury data of 151 ng/l as reported by the Pakistan Mineral Development Corporation in 2001. The dominant source of contamination was shown to be the leaching of large quantities of mercury from the mercury‐rich sediment and flood plain soil into the rivers, rather than the direct release from mining activities. Significant decrease in both dissolved and particulate‐bound mercury concentration downstream of Attabad Lake suggested that mercury is being accumulated or consumed in the lake. Although minimization or elimination of mercury loses from the mining process seems important for the well‐being of the miners, preventing the remobilization of accumulated mercury is equally important in mercury control in this region. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
2.
Alain Abarnou Jacques Avoine Jean Paul Dupont Robert Lafite Serge Simon 《Continental Shelf Research》1987,7(11-12)
PCB (polychlorinated biphenyls) contamination and its relationship to SPM (suspended particulate material) have been studied in the Seine Estuary, which is heavily polluted by these persistent and hydrophobic man-made chemicals. Two sampling cruises have been performed during different freshwater discharge conditions. PCB and SPM concentrations, as well as grain-size distributions in the particulate material have been determined. Water samples have been collected at fixed positions during a tidal cycle, and along transects within the estuary.PCB concentrations vary from 2 ng 1−1 in the marine zone to 250 ng 1−1 within the estuary, and reach 1.3 × 103 ng 1−1 in the turbidity maximum zone. During a tidal cycle, low PCB concentrations are observed at high water, and are in the same range in February as in July. High PCB contamination is observed at low water, but PCB concentrations are about five times higher in February. SPM and PCB variations are well correlated in both periods of observations. Higher PCB contamination during February is explained by higher SPM inputs, mainly due to particles of riverine origin. The transport of PCB within the estuary depends on the quantity and the grainsize composition of suspended material, which varies according to freshwater discharge and tidal amplitude. 相似文献
3.
P. Pato M. Otero M. Válega C.B. Lopes M.E. Pereira A.C. Duarte 《Marine pollution bulletin》2010,60(10):1658-1666
After having estimated the patterns of flow to the ocean and found some seasonal and tidal differences, mainly with regard to the relative importance of dissolved and particulate fractions, mercury partitioning at the interface between a contaminated lagoon and the Atlantic Ocean was investigated during four tidal cycles in contrasting season and tidal regimes. Mercury was found to be located predominantely in the particulate fraction throughout the year, contributing to its retention within the system. Seasonal conditions, variations in marine and fluvial signals and processes affecting bed sediment resuspension influenced the character and concentration of suspended particulate matter in the water column. Variation in the nature, levels and partitioning of organic carbon in the particulate fraction affected levels of particulate mercury as well as mercury partitioning. These results highlight the dominant role of suspended particulate matter in the distribution of anthropogenic mercury and reinforce the importance of competitive behavior related to organic carbon in mercury scavenging. 相似文献
4.
Ramalhosa E Pereira E Vale C Válega M Monterroso P Duarte AC 《Marine pollution bulletin》2005,50(11):1218-1222
Determinations of dissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary of river Douro, in northern Portugal. The estuary was stratified by salinity along most of its length, it had low concentrations of SPM, typically <20 mg dm(-3), and concentrations of DOC in the range <1.0-1.8 mg dm(-3). The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm(-3), whereas for the more saline bottom waters it was about 65 ng dm(-3). The surface waters had maximum concentrations of total suspended particulate mercury of approximately 7 microg g(-1) and the bottom waters were always <1 microg g(-1). Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 microg g(-1). The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport of mercury is more important. Lower particulate organic matter, formation of chlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters. 相似文献
5.
Total mercury (Hg) and methylmercury (MeHg) were analyzed in near surface sediments (0-2 cm) and biota (zooplankton, macro-invertebrates, finfish) collected from Narragansett Bay (Rhode Island/Massachusetts, USA) and adjacent embayments and tidal rivers. Spatial patterns in sediment contamination were governed by the high affinity of Hg for total organic carbon (TOC). Sediment MeHg and percent MeHg were also inversely related to summer bottom water dissolved oxygen (DO) concentrations, presumably due to the increased activity of methylating bacteria. For biota, Hg accumulation was influenced by inter-specific habitat preferences and trophic structure, and sediments with high TOC and percent silt-clay composition limited mercury bioavailability. Moreover, hypoxic bottom water limited Hg bioaccumulation, which is possibly mediated by a reduction in biotic foraging, and thus, dietary uptake of mercury. Finally, most biota demonstrated a significant positive relationship between tissue and TOC-normalized sediment Hg, but relationships were much weaker or absent for sediment MeHg. These results have important implications for the utility of estuarine biota as subjects for mercury monitoring programs. 相似文献
6.
Coelho JP Reis AT Ventura S Pereira ME Duarte AC Pardal MA 《Marine pollution bulletin》2008,56(6):1104-1110
Carcinus maenas is an important and exploited natural resource in temperate estuaries, being consumed by local populations and also used as fish bait. Through bioaccumulation and bioamplification processes occurring in polluted estuarine ecosystems, this species may directly or indirectly represent a major pathway for Human contamination. No information is available on the overall lifespan bioaccumulation pattern of mercury for this species, which would be an invaluable tool for assessing the risks associated with C. maenas harvest in contaminated areas. Taking that in mind, the main objectives of this work were to clarify the lifespan bioaccumulation pattern of mercury for this species. A consistent lifespan accumulation pattern was found for this species, both for total and organic mercury, and coherent differences were found between genders, suggesting different physiological responses to contamination. From our results two scenarios emerge: (a) for low mercury contamination areas where the diet is the major pathway for metal uptake, with higher levels in muscle and hepatopancreas (twice as high as in gills) and higher organic mercury fractions (as high as 80-90% in muscle), crabs bioaccumulate with age and (b) on high contaminated areas, environmental exposure is predominant, with higher levels found in gills (reaching 0.8 mg kg(-1)), lower organic fractions and no mercury increment with age. Detoxification strategies, dietary differences and species mobility may account for these two accumulation patterns. 相似文献
7.
This paper deals with the performances of non-permanent environmental monitoring stations when recording at high-sampling interval (hour) over a long term (months, years) within estuarine waters. Information about data quality and system maintenance requirements are provided based on the experience gained with an autonomous station deployed during 2?years at the Guadiana Estuary (southern Portugal–Spain border). The station includes (1) a multi-parameter probe for water quality (temperature, conductivity, dissolved oxygen, turbidity, chlorophyll and pH) inserted in a tube through a surface-floating buoy; and, (2) a bottom-mounted current meter. The main issues for the continuous acquisition of valid data were biofouling on the optical (chlorophyll, turbidity, dissolved oxygen), conductivity sensors of the probe and high sediment dynamics at the bed. The definition of a detailed maintenance programme is required for the lengthening of (valid) data time series. The typical variability of the parameters is described at seasonal and tidal time scales and episodic events are identified (coastal upwelling and high freshwater inputs). These examples illustrate how integrated data analysis is fundamental to define and understand the changes induced by specific events on several interrelated parameters, and, more generally, how these systems can contribute to a better understanding of the hydro-ecological processes operating in estuaries. 相似文献
8.
Cardoso PG Lillebø AI Lopes CB Pereira E Duarte AC Pardal MA 《Marine pollution bulletin》2008,56(2):325-334
Mercury, with its reactive forms being the most deleterious for the trophic chains, has been identified as a major pollutant in a few confined bodies of the coastal zone. Due to feeding, burrowing, and bioirrigation activities, infauna are known to play a crucial role in the biogeochemical processes of contaminants. The main goal of the present study is to evaluate the effects of Hediste diversicolor bioturbation on mercury fluxes from estuarine sediments in a mesocosms laboratory experiment. Additionally, an attempt was made to establish a relationship between the amount of remobilised mercury to the water column and the degree of contamination of the sediments using a mercury contamination gradient. The present experiment demonstrated that the bioturbation activity caused by the gallery-diffuser H. diversicolor did not influence the remobilisation of mercury (in dissolved reactive forms) from the sediment to the water column. The concentration of dissolved reactive mercury in the water column also did not reflect the degree of contamination in the sediments. The results obtained were in accordance with the sediment characteristics of the Mondego Estuary and Ria de Aveiro (Portugal), since they are very rich in organic matter content, iron/manganese total and hydrous oxides. These physicochemical characteristics of the sediments may partially justify the retention of mercury by these systems, even when they are subjected to bioturbation. In conclusion, sediments with high organic matter content and a high concentration of iron/manganese hydrous oxides allowed for efficient retention of mercury, and the bioturbation process did not seem to affect the system. Another conclusion from this study is that the remobilisation of mercury by bioturbation to the water column is not a fast process, requiring more than 24h. This study constitutes an important work in the area of the effects of bioturbation on mercury remobilisation. Considering the toxicity of mercury for the biota, it is essential to evaluate the real magnitude of mercury processes occurring in estuarine systems in order to obtain essential information on metal behaviour. 相似文献
9.
贵州省草海表层水体和沉积物间隙水中汞的含量和形态分布初步研究 总被引：10，自引：1，他引：9
运用金汞齐-冷原子荧光光谱法(CVAFS)和气相色谱技术(GC),对贵州省草海不同水文季节(枯水期和丰水期)表层水中汞的各种赋存形态,包括总汞(HgT)、溶解态汞(HgD)、活性汞(HgR)、颗粒态汞(HgP)、总甲基汞(MeHgT)、溶解态甲基汞(MeHgD)和颗粒态甲基汞(MeHgP)以及沉积物间隙水剖面中的溶解态总汞和甲基汞含量进行了测定.结果显示:草海表层水体总汞浓度为1.7-9.0ng/L,活性汞浓度为0.06-1.4ng/L,总甲基汞浓度为0.11-0.67ng/L.沉积物间隙水中溶解态汞浓度为8.6-39.6ng/L,溶解态甲基汞浓度为0.11-4.9ng/L.实验数据表明,草海湖水以溶解态汞为主,其占总汞的比例为枯水期87%,丰水期51%,溶解态汞与总汞呈显著相关(丰水期P<0.01;枯水期P<0.05),颗粒态汞与总汞也呈显著相关(丰水期P<0.01;枯水期P<0.05).溶解态甲基汞与总甲基汞呈显著相关(丰水期P<0.01;枯水期P<0.05),表明溶解态甲基汞控制总甲基汞的分布.沉积物间隙水溶解态汞与溶解态甲基汞浓度明显高于上覆水体,表明沉积物为草海湖水中汞的一个重要来源. 相似文献
10.
Back-barrier tidal flat systems are characterized by basins and inlets through which water is exchanged with the coastal sea
by tidal water movements. The hydrographic and morphometric properties at the inlets and in the basins vary considerably,
but there is little information available how biogeochemical properties in the water column at these different sites respond
to these differences. Therefore, we investigated tidal dynamics of suspended particulate matter (SPM), particulate and dissolved
organic carbon (DOC), chlorophyll a, phaeopigments, numbers of particle-associated (PA) and free-living bacteria (FL), bacterial biomass production, and concentrations
of dissolved manganese (Mn). Samples were taken at the surface, a mid-depth and 1 m above the bottom at a fixed station at
the inlet and in the basin of the Spiekeroog back-barrier tidal flat system in the German Wadden Sea. Five tidal cycles representative
for typical seasonal situations, January (winter), April and May (late spring bloom), July (summer), and November (late fall)
were studied in 2005 and 2006. In July, processes related to phytoplankton dynamics and bacterial decomposition were much
more enhanced in the basin, whereas in April, these processes were enhanced at the inlet but were particularly low within
the basin itself. The low values within the basin were a result of the settled phytoplankton spring bloom and represent a
rather short period at the decline of this bloom. In November and January, differences were much less pronounced than during
the growing season and restricted mainly to SPM and PA bacteria, exhibiting higher values in the basin. FL bacteria, DOC,
and dissolved Mn exhibited different patterns and much less differences between the two stations, indicating that biogeochemical
processes in the dissolved phase were controlled by different factors than PA biogeochemical processes. These differences
reflect the retentive properties of the basin for particles and PA biogeochemical processes, particularly during the growing
season, and in general emphasize the high productivity of back-barrier tidal flat systems. 相似文献
11.
Matthew Robert Palmer 《Ocean Dynamics》2010,60(2):219-226
Understanding the fate of freshwater runoff and corresponding nutrient and pollution loads is of critical importance for the
development of accurate predictive models and coastal management tools. A key element of such studies is the identification
and understanding of the interaction between stratification and current structure. This paper presents a new series of measurements
made in the Liverpool Bay region of freshwater influence (ROFI) during spring 2004 where freshwater-maintained horizontal
density gradients and strong tidal currents interact to produce strain-induced periodic stratification (SIPS). During stratification,
tidal current profiles are significantly modified such that the tidal flow deviates from the otherwise rectilinear E–W axis
generating counter rotating upper and lower mixed layers. This feature has often been reported for the Rhine ROFI but not
previously identified in Liverpool Bay despite previous investigation at this site. Investigation of an ongoing long-term
dataset collected nearby reveals this process to be a common feature throughout the year. Liverpool Bay is shown to maintain
three different regimes, long term mixed, long term stratified, and a transitional state when SIPS occurs. The phase of SIPS
relative to the tide results in a residual flow away from the Welsh coastline in the upper water column of 2.3–3.6 cm s−1 with a counterflow in the lower layer of 2.8–3.1 cm s−1 towards the coast. 相似文献
12.
《Continental Shelf Research》2007,27(10-11):1568-1583
A study is presented where satellite images (SeaWiFS), in situ measurements (tidal cycle and snapshot) and a 2D hydrodynamic numerical model have been combined to calculate the long term SPM (Suspended Particulate Matter) transport through the Dover Strait and in the southern North Sea. The total amount of SPM supplied to the North Sea through the Dover Strait is estimated to be 31.74×106 t. The satellite images provide synoptic views of SPM concentration distribution but do not take away the uncertainty of SPM transport calculation. This is due to the fact that SPM concentration varies as a function of tide, wind, spring-neap tidal cycles and seasons. The short term variations (tidal, spring-neap tidal cycle) have not been found in the satellite images, however seasonal variations are clearly visible. Furthermore the SPM concentration in the satellite images is generally lower than in the in situ measurements. The representativness of SPM concentration maps derived from satellites for calculating long term transports has therefore been investigated by comparing the SPM concentration variability from the in situ measurements with those of the remote sensing data. The most important constraints of satellite images are related to the fact that satellite data is evidence of clear sky conditions, whereas in situ measurements from a vessel can be carried out also during rougher meteorological conditions and that due to the too low time resolution of the satellite images the SPM concentration peaks are often missed. It is underlined that SPM concentration measurements should be carried out during at least one tidal cycle in high turbidity areas to obtain representative values of SPM concentration. 相似文献
13.
There is an ongoing eutrophication process in the Ria de Aveiro coastal lagoon (Portugal), with progressive replacement of rooted primary producers for macroalgae. Taking advantage of a well-defined environmental contamination gradient, we studied mercury accumulation and distribution in the aboveground and the belowground biomass of several salt marsh plants, including the seagrass species Zostera noltii and the dominant green macroalgal species Enteromorpha sp. The results of these experiments were then placed into the context of the estuarine mercury cycle and transport from the contaminated area.All salt marsh plants accumulated mercury in the root system, with Halimione portulacoides showing the highest levels, with up to 1.3 mg kg−1 observed in the most contaminated area. Belowground/aboveground ratios were generally below 0.4, suggesting that salt marsh plants are efficient immobilizers and retainers of mercury agents. Moreover, due to their sediment accretion capacities, salt marsh plants seem to play an important role in the sequestration of mercury in estuarine sediments.Seagrasses, on the other hand, accumulated considerable amounts of mercury in the aboveground biomass with belowground/aboveground ratios reaching as high as 1.4. These results may be due to their different routes of uptake (roots and foliar uptake) which suggests that seagrass meadows can be an important agent in the export of mercury from contaminated areas, considering the high aboveground biomass replacement rates.Rooted macrophytes accumulate less mercury in their aboveground biomass than macroalgae. The change of primary producer dominance due to eutrophication can originate a 4- to 5-fold increase in primary producer associated mercury. This mercury would be available for export, making it bioavailable to estuarine food webs, which stresses the need to reverse the current eutrophic status of estuarine systems. 相似文献
14.
The flux of suspended particulate material across the mouth of a well-mixed estuary was measured over 12 months. Samples were taken over one neap and one spring tidal cycle each month and analysed for total suspended particulate material, inorganic and organic particulates, particulate organic carbon and particulate organic nitrogen. Water volume transport at discrete time-steps were determined by means of a one-dimensional hydrodynamic model, calibrated for each tidal cycle sampled. Net transport varied between tidal cycles with regard to direction (import or export) and magnitude. Annual budgets revealed a net export of 5306 tonne of total suspended particulate material (3900 tonne of inorganic particulates, 1286 tonne of particulate organic carbon and 120 tonne of particulate organic nitrogen). The sources of particulate organic carbon are mainly from saltmarshes (194 g POC m2y1) and from intertidal invertebrate production (586 g POC m−2y−1). 相似文献
15.
A two-part study conducted in Elimbah Creek, a shallow estuarine waterway in south-east Queensland, Australia, examined the variations in physico-chemical parameters of water quality, chlorophyll a, and faecal indicator bacteria abundances of total coliform, Escherichia coli and enterococci, spatially at high and low tide and also over a 12h tidal cycle. Gradients of increasing faecal indicator bacteria from the mouth to the upper, tidal freshwater reaches were observed, despite isolated peaks during either tidal phase. Phytoplankton biomass (measured as chlorophyll a) did not noticeably increase during the study. Variations in the abundances of all three faecal indicator bacteria and their correlations with physico-chemical parameters indicated that although the creek was likely subject to some level of faecal contamination, tidal movement serves to limit faecal indicator and phytoplankton levels in the creek through physico-chemical stress and dilution. However, each faecal indicator bacteria investigated provided different estimations of faecal contamination, which challenges the effectiveness of employing a single type of faecal indicator bacteria when investigating the level of faecal contamination in waterways. 相似文献
16.
17.
季节性缺氧水库甲基汞的产生及其对下游水体的影响 总被引：14，自引：0，他引：14
本文采用蒸馏-乙基化结合GC-CVAFS法对贵州红枫湖水库及其各入库和出库河流中的甲基汞时空分布和控制因素进行了研究.在春、秋、冬季节总甲基汞浓度和分布无明显时空变化,在0．053-0．333 ng／L之间.春季河流是水库甲基汞一个重要的输入源．夏季水库下层甲基汞显著升高,缺氧层最高值达0．923 ng／L.同时发现．缺氧层升高的甲基汞主要来自于水体自己产生或上层水体甲基汞的沉降,而不是来自于沉积物的释放．各季节湖水和河流样品的总甲基汞和溶解氧存在显著的负相关关系,Personal相关系数r为-0．81(n=78).在春、秋、冬季节溶解态甲基汞比例略低于颗粒态甲基汞,但在夏季,特别是缺氧层,甲基汞主要以溶解态存在．夏季河流入水经水库蓄水后,到再流出时已经富含甲基汞,出库河流中总甲基汞浓度已达到各入湖河流总甲基汞平均值的5.5倍,很明显在复季红枫湖已成为下游水体甲基汞的输入源,必将会对下游生态系统产生一定影响． 相似文献
18.
Exchange flux of total gaseous mercury between air and natural water surfaces in summer season 总被引：5，自引：0，他引：5
The exchanges of mercury between surface and air are of significance in the biogeochemical cycling of Hg in the environment,
but there are still few reliable data on air/surface exchange in aquatic systems. Field measurement campaigns over seawater
surface at Kristineberg Marine Research Station (KMRS) and over Hovg?rds?n River surface at Knobesholm in southwestern Sweden
were conducted to measure mercury flux using a dynamic flux chamber technique coupled with automatic mercury vapor-phase analyzers.
Both sites show net emissions during summer time. Mercury fluxes measured over both river and seawater surfaces exhibit a
consistently diurnal pattern with maximum fluxes during the daytime period and minimum fluxes during the nighttime period.
At freshwater site, mercury flux is strongly correlated with the intensity of net solar radiation, and negatively correlated
with relative humidity. A typical exponential relationship between mercury flux and water temperature was observed at freshwater
measurement site. At seawater site, a strong correlation between mercury flux and intensity of solar radiation was obtained.
The driving force of mercury emission from water surface to air is the super-saturation of dissolved gaseous mercury in aqueous
phase. 相似文献
19.
The Seine’s estuary (France) waters are the receptacle of effluents originating from wastewater treatment plants (WWTP). In this estuary, mudflats are deposition zones for sediments and their associated contaminants, and play an essential role in the mercury (Hg) biogeochemical cycle mainly due to indigenous microorganisms. Microcosms were used to assess the impact of WWTP-effluents on mercury methylation by monitoring Hg species (total dissolved Hg in porewater, methylmercury and total mercury) and on microbial communities in sediments. After effluent amendment, methylmercury (MeHg) concentrations increased in relation with the total Hg and organic matter content of the WWTP-effluents. A correlation was observed between MeHg and acid-volatile-sulfides concentrations. Quantification of sulfate-reducing microorganisms involved in Hg methylation showed no increase of their abundance but their activity was probably enhanced by the organic matter supplied with the effluents. WWTP-effluent spiking modified the bacterial community fingerprint, mainly influenced by Hg contamination and the organic matter amendment. 相似文献
20.
A sampling and measuring device which enables the assessment of atmospheric particulate and gaseous mercury concentrations has been tested on Mount Etna Volcano. Particulate matter is collected on a Whatman GF/C of 1.0 µm pore-size, gaseous mercury species on a Au-column. The analysis is carried out in two steps: (1) the mercury species collected on the filter or the Au-column are transferred to a fixed analytical Au-column; (2) mercury liberated from this column during the second step is detected with a Mercury Vapour Monitor. Average concentrations of gaseous and particulate mercury in ambient sampling sites on Mount Etna are 3.8 ng m?3 and 0.49 ng m?3 respectively. Average concentrations of gaseous and particulate mercury in the plume of Bocca Nuova on Mount Etna are 15 ng m?3 and 24 ng m?3 respectively. An estimation of the total mercury discharge from Mount Etna amounts to 2.5 10?2 tons day?1. 相似文献