Trace element distributions in coastal waters along the US-Mexican boundary: relative contributions of natural processes vs. anthropogenic inputs

Trace element concentrations (Pb, Cd, Mn, Fe, and Zn) were measured along four surface water transects across the continental shelf off Baja California, to evaluate the magnitude of heavy metal contamination in the coastal waters along the US-Mexican boundary. These initial measurements of trace elements in Mexican neritic waters revealed offshore concentration gradients, with the highest levels in coastal waters with high salinities and nutrient concentrations. There were also longshore gradients, with lower concentrations in the southern locations. Although the relative enrichment of metals detected at nearshore stations along the US-Mexican border appeared to correspond to wastewater discharges in that area, these trace metal enhancements were found to be primarily associated with physical oceanographic processes (upwelling and advection), rather than anthropogenic inputs. This was demonstrated both by metal-nutrient correlations and multivariate statistical analyses. Mass balance calculations also indicated that about 1% of Cd, 9% of Zn, and 29% of Pb were from urban discharges within the area.     

Techniques for determination of trace metals in small samples of size-fractionated particulate matter: phytoplankton metals off central California

The oceanic biogeochemical cycles of many trace elements are dominated by their association with the growth, death, consumption and sinking of phytoplankton. The trace element content of marine phytoplankton reflects nutritional status, species composition, surface area to volume ratios, and interactions with bioactive and toxic elements in the ambient seawater. Despite the ecological and environmental importance of trace element assimilation by autotrophs, there are few modern measurements of trace elements in phytoplankton assemblages from the natural environment. Here we introduce a new method for collection and analysis of size-fractionated particulate samples from practical seawater volumes. We pay particular attention to accurate determination of trace element filter blanks which are typically the limiting factor for analysis of such samples. Metals were determined at very low detection limits by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for 11 elements (Ag, Al, Cd, Co, Cr, Cu, Fe, Mn, U, Zn and P, which is used as a biomass normalizer) in three types of polymer filters (0.45, 5.0, and 53 μm pore size) and a quartz fiber filter (0.8 μm pore size). To place these new determinations in a practical context, results are presented for a vertical profile of samples filtered from 1–4 l of coastal seawater (0.3–1.0 mg total solid dry weight) at a station off central California. The results demonstrate that the blanks of the evaluated filter types, precleaned appropriately, are sufficiently low to allow accurate determination of the trace metal content of three size-classes of phytoplankton. At the Pacific station, measured phytoplankton Zn content (as Zn/P) agrees with values predicted from single-species culture studies growing at seawater Zn concentrations expected for coastal waters. The new method has utility as a generally applicable and simple size fractionation technique, and allows determination of natural and pollutant elements in small samples of phytoplankton and particles in coastal, estuarine and offshore marine regimes.     

Statistical Study of Trace Elemental Concentrations in Major Types of Organisms from Typical Chinese Coastal Waters

Frequency distribution characteristics of trace elements Fe. Mn, Zn, Cu. Sr and Ba are studied for the marine organisms collected from typical Chinese coastal waters and compared with those of major elements Ca and Mg. Nearly all the distributions for trace elements in macroalgae, benthic molluscs, crustaceans, cephalopods and different tissues of fish (muscle, liver and bone ) are found to show some degree of positive skewness, indicating a relatively large number of marine organisms with low concentrations for a particular element and only a few organisms with disproportionately high concentrations. Their distribution types are generally logarithmic normal distribution or nearly logarithmic normal distribution. Distribution of Ca is similar to that of trace elements, while Mg shows normal distribution. Average elemental concentrations of major types of organisms are calculated based on their frequency distributions.     

The distribution of zinc,nickel, manganese,cadmium, copper,and iron in some surface waters from the world ocean

Determinations of Zn, Ni, Mn, Cd, Cu, and Fe have been carried out on 51 near-shore and 38 open-ocean surface seawaters from various regions of the World Ocean.The concentrations of the trace metals have been established in the open-ocean waters, and have been used as “baselines” to evaluate trace-metal enhancement in near-shore regions. The factors by which the trace metals are enriched in near-shore regions vary from one element to another and, according to the highest concentration factors found, decrease in the order Zn = Mn > Cd = Cu = Ni.These elements exhibit differences in their distributions between near-shore and open-ocean waters, and they have been divided into two types on this basis: Type I, in which the largest number of samples in both shelf and open-ocean waters lie in the same concentration range. Zinc, cadmium, and copper are Type I elements. Type 2, in which the largest number of samples of near-shore waters lie in a higher concentration range than the largest number of samples of open-ocean waters. Nickel and manganese are Type 2 elements.The concentrations of Mn, Cd and Zn are similar in open-ocean surface waters from the South Atlantic and Indian Ocean, but Cu and Ni have higher concentrations in the former ocean.There is considerable variation in the concentrations of the trace metals in near-shore surface waters from various regions of the World Ocean. These variations are discussed in detail.     

西藏盐湖及其水系中的痕量金属

于1978年采集了西藏高原26个盐湖、6条河流、10处泉水及3地盐湖区的大气降水的水样,以ZCP等离子光谱仪测定所采水样中Fe,Mn,Al,Cu,Pb,Zn,Ni,Cr等痕量金属含量,结果表明,1.盐湖水及河流、泉水和大气降水等水系中的痕量金属均高度富集,但以盐湖水的最大;盐湖水中各痕量金属富集程度不一,其顺序:Pb>Mn>Cr>Fe>Zn>Cu>Al>Ni。2.区域出露的岩性、气候、湖盆及水文等为盐湖水中富集痕量金属创造了有利条件。3.高痕量金属浓度的河流、泉水及大气降水是控制和影响盐湖水中痕量金属富集的主要的直接因素。4.盐湖水的矿化度、pH及水化学类型也影响着水中痕量金属的富集。     

Distribution of trace elements in Callichirus laurae burrows and nearby sediments in the gulf of Aqaba, Jordan (Red Sea)

In nearshore waters of the Jordanian sector of the Gulf of Aqaba, the distributions of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, as well as Ca and Mg, were determined in the mucus-rich burrow lining made by the locally abundant Crustacea Callichirus laurae (Thalassinidea: Callianassideae), and compared with concentrations obtained in surface sediments surrounding the burrows. The highest concentrations of trace elements were observed in a sewage affected area. At uncontaminated stations, a marked increase from surface sand values was observed in the burrow lining. The correlations between the concentration of trace elements in this biogenic micro-environment and both the concentration of organic carbon and the mean granulometric diameter were highly significant.This study shows that the C. laurae burrow acts as a chemical reservoir that may reach several meters deep into the sediment. This special reservoir is created as an indirect consequence of the building of a mucus-rich, metal-reacting lining. It is demonstrated that the absolute quantity of trace elements incorporated in the lining is much higher (c. 85 to 250 times more, depending on the element) than in the dense and healthy Halophila stipulacea seagrass bed covering the surface.The environmental significance of large lined burrows for the distribution of trace elements is discussed.     

Trace metals in seawater and copepods in the ocean outfall area off the northern Taiwan coast

The distribution, partitioning and concentrations of trace metals (Cd, Cr, Cu, Fe, Mn, Pb and Zn) in seawater, including dissolved and particulate phases, and in copepods in the ocean outfall area off the northern coast of Taiwan were investigated. Normalization of metal concentrations to the background metal concentration to yield relative enrichment factors (EF), which were used to evaluate the contamination of dissolved and particulate trace metals in seawater around the ocean outfall. The EF results indicated that the outfall area was significantly contaminated by dissolved Fe and Zn, and by particulate Fe, Cr, Cu, Pb and Zn. In addition, most trace metals were chiefly in the particulate phase. The average percentage of total metal concentrations (dissolved plus particulate phases) bound by suspended particulate matter followed the sequence Al(95%) = Mn(95%) > Pb(88%) > Cu(86%) > Fe(72%) > Zn(32%) > Cr(17.5%) > Cd(3.4%). Therefore, metal contamination is better evaluated in solid phase than in the dissolved phase. The concentration ranges of trace metals in the copepods, Temora turbinata, Oncaea venusta and Euchaeta rimana, near the outfall were: Cd, 0.23-1.81 microg g(-1); Cr, 16.5-195 microg g(-1); Cu, 14-160 microg g(-1); Fe, 256-7255 microg g(-1); Mn, 5.5-80.8 microg g(-1); Pb, 2.6-56.2 microg g(-1); Zn, 132-3891 microg g(-1); and Al, 0.21-1.13%. Aluminum, and probably Fe, seemed to be the major elements in copepods. The concentrations of trace metals in copepods, especially Temora turbinata, near the outfall were generally higher than those obtained in the background station. The mean increase in bioconcentration factor of metals in copepods ranged from 4 to 7 and followed the sequence Al(6.4) > Cu(6.2) > Fe(6.0) > Zn(5.7) > Pb(5.6) > Cr(5.5) > Cd(5.1) > Mn(4.7). Therefore, marine copepods in the waters of northern Taiwan can accumulate trace metals over background concentrations and act as contamination indicators.     

Submarine groundwater discharge: A large, previously unrecognized source of dissolved iron to the South Atlantic Ocean

This paper reports the initial results of a study of groundwater and coastal waters of southern Brazil adjacent to a 240 km barrier spit separating the Patos Lagoon, the largest coastal lagoon in South America, from the South Atlantic Ocean. The objective of this research is to assess the chemical alteration of freshwater and freshwater–seawater mixtures advecting through coastal permeable sands, and the influence of the submarine discharge of these fluids (SGD) on the chemistry of coastal waters. Here we focus on dissolved iron in this system and use radium isotopic tracers to quantify SGD and cross-shelf fluxes. Iron concentrations in groundwaters vary between 0.6 and 180 μM. The influence of the submarine discharge of these fluids into the surf zone produces dissolved Fe concentrations as high as several micromolar in coastal surface waters. The offshore gradient of dissolved Fe, coupled with results for Ra isotopes, is used to quantify the SGD flux of dissolved Fe from this coastline. We estimate the SGD flux to be 2 × 10⁶ mol day^− 1 and the cross-shelf flux to be 3.2 × 10⁵ mol day^− 1. This latter flux is equal to about 10% of the soluble atmospheric Fe flux to the entire South Atlantic Ocean. We speculate on the importance of this previously unrecognized iron input to regional ocean production and on the potential significance of this source to understanding variations in glacial–interglacial ocean production.     

Evidence for enhanced bioavailability of trace elements in the marine ecosystem of Deception Island, a volcano in Antarctica

This study assessed whether trace elements present at Deception Island, an active submarine volcano in the Antarctic Peninsula, show enhanced biological availability to the local marine community. Using a weak acid extraction method to dissolve organic material and leach associated but not constitutive trace elements of sediments, fifteen elements were measured from seafloor sediment, seawater particulates, and tissues of benthic (bivalves, brittlestars, sea urchins) and pelagic (demersal and pelagic fishes, krill) organisms collected in the flooded caldera. The highest element concentrations were associated with seafloor sediment, the lowest with seawater particulates and organism tissues. In the case of Ag and Se, concentrations were highest in organism tissue, indicating contamination through the food chain and biomagnification of those elements. The elements Al, Fe, Mn, Sr, Ti, and to a lesser extent Zn, were the most concentrated of the trace elements for all sample types. This indicates that the whole ecosystem of Deception Island is contaminated with trace elements from local geothermal activity, which is also reflected in the pattern of element contamination in organisms. Accordingly, element concentrations were higher in organisms collected at Deception Island compared to those from the neighboring non-active volcanic King George Island, suggesting that volcanic activity enhances bioavailability of trace elements to marine organisms. Trace element concentrations were highest in digestive tissue of organisms, suggesting that elements at Deception Island are incorporated into the marine food web mainly through a dietary route.     

青岛市奥帆赛区海域表层海水中微量元素的研究

通过离子色谱离线螯舍和ICP—MS对青岛市汇泉湾、太平湾、浮山湾采集的海水样品进行分析，得到了该海域表层海水中微量元素质量比的可靠数据，并对表层海水中微量元素的分布特征及其影响因素进行了探讨。将分析结果与国家海水标准进行比较表明，该海域海水中微量元素质量比符合国家一级海水标准。对该海域表层海水微量元素的分布特征的研究表明，近岸和远岸表层海水中微量元素的质量比差别很小，而不同于沿岸海区质量比高，离岸远处质量比较低的一般规律。其主要原因是该海域的人为污染程度小，再加上其特殊的海岸地形以及水动力条件，有利于溶解物质的扩散、迁移和稀释。     

Submarine groundwater discharge of nutrients to the ocean along a coastal lagoon barrier, Southern Brazil

The Patos–Mirim Lagoon system along the southern coast of Brazil is linked to the coastal ocean by a narrow mouth and by groundwater transport through a Holocene barrier. Although other groundwater systems are apparently active in this region, the hydraulic head of the lagoon, the largest in South America, drives groundwater transport to the coast. Water levels in wells placed in the barrier respond to changing water level in the lagoon. The wells also provide a measure of the nutrient concentrations of groundwater flowing toward the ocean. Additionally, temporary well points were used to obtain nutrient samples in groundwater on the beach face of the barrier. These samples revealed a subterranean freshwater–seawater mixing zone over a ca. 240 km shoreline. Previously published results of radium isotopic analyses of groundwater and of surface water from cross-shelf transects were used to estimate a water flux of submarine groundwater discharge (SGD) to nearshore surface waters of 8.5 × 10⁷ m³/day. Using this SGD and the nutrient concentrations in different compartments, nutrient fluxes between groundwater and surface water were estimated. Fluxes were computed using both average and median reservoir (i.e. groundwater and surface water) nutrient concentrations. The SGD total dissolved inorganic nitrogen, phosphate and silicate fluxes (2.42, 0.52, 5.92 × 10⁶ mol day^− 1, respectively) may represent as much as 55% (total N) to 10% (Si) of the nutrient fluxes to the adjacent shelf environment. Assuming nitrogen limitation, SGD may be capable of supporting a production rate of ca. 3000 g C m² year^− 1in the nearshore surf zone in this region.     

Metal and metalloid concentrations in the giant squid Architeuthis dux from Iberian waters

This study investigated 14 trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V and Zn) in the tissues of the giant squid Architeuthis dux from the Mediterranean and Atlantic Spanish waters. As for other families of cephalopods, the digestive gland and the branchial hearts of Architeuthis showed the highest concentrations of Ag, Cd, Co, Cu, Fe, Ni, Se, V and Zn, highlighting their major role in the bioaccumulation and detoxification processes. With the exception of Hg, the muscles showed relatively low trace element concentrations. Nevertheless, this tissue contained the main proportion of the total As, Cr, Hg, Mn, Ni, and Zn body burden because muscles represent the main proportion of the squid mass. These findings suggest that the metal metabolism is overall the same as other cephalopod families from neritic waters. In females, Zn concentrations increased in the digestive gland with the squid's weight likely reflecting physiological changes during sexual maturation. Comparing the trace element concentrations in the tissues of Architeuthis, higher Ag, Cu, Hg and Zn concentrations in the squid from the Mediterranean reflected different exposure conditions. In comparison to other meso-pelagic squids from the Bay of Biscay, Cd concentrations recorded in the digestive gland suggest that Architeuthis might feed on more contaminated prey or that it displays a longer life span that other cephalopods.     

A study of the geochemistry of suspended particulate matter in coastal waters

The concentrations of Si, Al, Ti, Fe, K, Ca, Mg, P and Mn, before and after chemical leaching, in particulate matter from waters off the west coast of Scotland have been measured in vertical profiles at two seasons. The distribution of Si and Ca are shown partly to reflect temporal changes in biological production in different waters. The distributions of Al, Ti, Fe, K and Mg have been used to distinguish different sources and types of suspended alumino-silicates, and to trace probable circulation patterns in the water mass.While Si and Ti contents of the particulate matter are unaffected by mild chemical leaching, large amounts of other elements, notably Mg, K and Al, can be removed by this treatment. Presumably, these losses indicate preferential release of these elements from octahedral and interlayer sites in clay mineral lattices.The distribution of particulate P covaries with non-silicate Fe in the surface waters, while in bottom waters, high concentrations of particulate Fe and Mn are associated. The relationship of Fe and P is considered to be due to the presence of particulate ferriphosphates derived from runoff. The particulate Mn and Fe in deep waters is produced by the precipitation of dissolved metals released from bottom sediments by diagenesis.     

The influence of shelf processes in delivering dissolved iron to the HNLC waters of the Drake Passage,Antarctica

Dissolved trace element distributions near Elephant Island in the Drake Passage show extremely high levels of dissolved Fe and Mn in waters above the shelf. The entrainment of this enriched shelf water by the Fe-poor Antarctic Circumpolar Current (ACC) as it passes through the Shackleton Gap delivers an estimated 2.8×10⁶ mol yr⁻¹ dissolved Fe to the offshore waters of the Drake Passage. The magnitude and spatial distribution of dissolved Fe, Mn and Al over the shelf are consistent with a diagenetically produced sedimentary source, but are inconsistent with eolian or upwelling sources. The systematics of the Mn and Fe concentrations suggest that there are two distinct sources of dissolved Fe to the surface waters of this region. The highest Fe concentrations are associated with Bransfield Strait water, which can be identified by its characteristic temperature and salinity (T/S) properties both inside the Bransfield Strait and in the Bransfield Current outflow between Elephant and Clarence Islands. Most of the shelf area is dominated by a second water type with T/S properties that are typical of modified Antarctic Surface Water, which while also enriched has a lower Fe:Mn ratio.The predominantly linear relationships between the Fe and Mn concentrations at the stations in each of these water mass types suggest that the distribution of these elements is largely controlled by physical mixing processes and that biological removal of Fe on the shelf, while certainly occurring, is limited, perhaps as a result of rapid physical flushing processes and relatively slow biological growth rates. The consequent export of large quantities of this shelf-derived Fe into the ACC is likely responsible for the extensive regions of enhanced primary production seen in satellite imagery downstream of the Drake Passage.     

紫海胆生殖腺和棘壳中的金属元素

在生殖季节从大亚湾采集紫海胆Anthocidariscrassispina ,分离出生殖腺和棘壳 ,用ICP AES法测定其金属元素含量。结果表明 ,紫海胆生殖腺中含有Ca ,Mg ,Sr,Fe ,Mn等1 8种金属元素。这些元素几乎都同样在棘壳中存在 ,而且棘壳中的浓度比生殖腺的高出几十倍到几百倍。同时发现棘壳中金属元素的浓度比海水中的高很多 ,如Fe的浓度为海水的34万倍 ,Mn为 1 4.5万倍 ,说明紫海胆对海水中金属元素有很强的富集作用。结果还表明紫海胆生殖腺中金属元素的含量存在性别差异 ,雌性生殖腺中Zn含量是雄性生殖腺的 4倍 ,而雄性生殖腺中Mg的含量比雌性生殖腺高。以食品卫生标准来衡量 ,大亚湾紫海胆生殖腺金属元素含量完全符合国家标准GBn 2 38 84。如何开发和利用这一海产资源 ,值得深入研究。     

Trace metal concentrations in the Ross Sea and their relationship with nutrients and phytoplankton growth

Dissolved and particulate trace metal concentrations (dissolved Fe, Zn, Cd, Co, Cu and Ni; particulate Fe, Mn and Al) were measured along two transects in the Ross Sea during austral summer of 1990. Total Fe concentrations in southern Ross Sea and inshore waters were elevated >3.5 times that of northern waters. Dissolved Zn, Cd and Co concentrations were lower by factors of 4.5, 3.5 and 1.6 in southern surface waters relative to northern waters. Dissolved Cu and Ni concentrations were similar in both areas. Elevated Fe concentrations coincided with areas of increased productivity, phytoplankton biomass and nutrient drawdown, indicating that Fe is an important factor controlling the location of phytoplankton blooms in the Ross Sea. Particulate concentrations of Fe, Mn and Al indicate two possible sources of iron to the Ross Sea, resuspension of continental shelf sediments and iron incorporated in annual sea ice and released with meltwaters.     

Processes influencing dissolved iron distributions below the surface at the Atlantic Ocean–Celtic Sea shelf edge

Shelf break systems are highly dynamic environments. However little is known about the influence that benthic interactions and water mass mixing may have on vertical distributions of iron in these systems. Dissolved Fe (< 0.4 μm) concentrations were measured in samples from nine vertical profiles across the upper slope (150–2950 m water depth) at the Atlantic Ocean–Celtic Sea shelf break. Dissolved iron concentrations varied between less than 0.2 and 5.4 nM, and the resulting detailed section showed evidence of a range of processes influencing the Fe distributions. The near sea floor data were interpreted in terms of release and removal processes. The concentrations of dissolved Fe present in near seabed waters were consistent with release of Fe from in situ remineralisation of particulate organic matter at two upper slope stations, and possibly release from pore water upon resuspension on shelf. Lateral transport of dissolved iron was evident from elevated Fe concentrations in an intermediate nepheloid layer and its advection along isopycnals. Surface waters at the shelf break also showed evidence of vertical mixing of deeper iron-rich waters. These waters contained macronutrients that sustained primary productivity in these otherwise nutrient-depleted surface waters. The data also suggest some degree of stabilisation of relatively high concentrations of iron, presumably through ligand association or as colloids. This study supports the view that lateral export of dissolved iron to the interior of the ocean from shelf and coastal zones and may have important implications for the global budget of oceanic iron.     

Aspects of rhodium marine chemistry

Rhodium, one of the least abundant of the Pt-group elements in the earth's crust, has the second highest concentration in seawater. This may be a consequence of strong complexing, perhaps kinetically restrained with time constants of the order of centuries to millenia. The element shows a nutrient-like distribution in waters of the Pacific Ocean. Pelagic and coastal sediments have Rh concentrations close to crustal values. There is a remarkable enrichment of Rh in ferromanganese minerals that cannot be explained by oxidative capture. Unlike the other Pt-group elements, Rh is enriched in the high temperature hydrothermal sulfide deposits as well as phosphorites.     

Composition of the inorganic fraction of the particulate organic matter in seawater

Na, K, Mg, Ca, Fe, and Mn have been measured in both naturally occurring particulate matter and artificially created aggregates taken from water from the Nova Scotian coastal region and from the North Atlantic Ocean. The order of concentration of these elements is the same in both the aggregates and the natural particulate matter as it is in seawater. There is an inverse relationship between depth of the water and the amount of inorganic matter in artificially created aggregates, while a direct relationship is found with the naturally occurring particles. This direct relationship may reflect the utilization of organic material in the surface waters. Iron and manganese are enriched in both kinds of particles.