Trace metals speciation in coastal particulate matter for marine environmental studies in Antarctica

Solid speciation of some trace metals (Pb, Cd, Fe, Mn, Cu) having environmental relevance was studied in coastal particulate sampled during the Austral Spring 2000/2001. A nearshore station situated in the Gerlache Inlet of Terra Nova Bay (Ross Sea, Antarctica) was sampled from November to February. Samples were collected using the in situ filtration system FIS500, equipped with polycarbonate membrane filters having different pore sizes (10 microm, 2 microm and 0.4 microm) for the size fraction analysis of particles. The total concentration of metals was determined both in dissolved and particulate fractions, while speciation was determined on particulate by applying a sequential extraction procedure. Concerning the surface and sub-surface layers, it has been observed that concentration of elements is mainly affected by the dynamic of the pack ice melting and by phytoplankton activity.The solid speciation in November and December is similar for all the studied elements, while some differences can be noted in February, when the pack has completely melted and phytoplankton bloom occurs. With the exception of iron, during this sampling period the quantity of metal associated to the labile fraction increases.     

Uranium series radionuclides in surface waters from the Shu river (Kazakhstan)

The concentrations of (238)U, (234)U, (226)Ra, (210)Po and (210)Pb have been determined in surface waters collected along the course of the Shu River, lying on the border between Kazakhstan and Kyrgyzstan. In the study area, the river runs through some of the largest uranium deposits worldwide, which were actively exploited during the nuclear weapons and nuclear energy programmes of the former Soviet Union. The data show an increasing trend in uranium concentrations downstream the river from the city of Tokmak to the city of Shu, with good correlation between total uranium concentrations and total dissolved solids. Data on uranium isotopes disequilibrium show the presence of technogenic uranium inputs into the Shu River downstream from the city of Karasu, evidenced by a decrease in the measured (234)U/(238)U isotopic ratio from 1.63 in uncontaminated sites to 1.29 in sites affected by past mining activities.     

Characterization of microbial communities from coastal waters using microarrays

Molecular methods, including DNA probes, were used to identify and enumerate pathogenic Vibrio species in the Chesapeake Bay; our data indicated that Vibrio vulnificus exhibits seasonal fluctuations in number. Our work included a characterization of total microbial communities from the Bay; development of microarrays that identify and quantify the diversity of those communities; and observation of temporal changes in those communities. To identify members of the microbial community, we amplified the 16S rDNA gene from community DNA isolated from a biofilm sample collected from the Chesapeake Bay in February, 2000. The resultant 75 sequences were 95% or more similar to 7 species including two recently described Shewanella species, baltica and frigidimarina, that have not been previously isolated from the Chesapeake. When the genera of bacteria from biofilm after culturing are compared to those detected by subcloning amplified 16S fragments from community DNA, the cultured sample exhibited a strong bias. In oysters collected in February, the most common bacteria were previously unknown. Based on our 16S findings, we are developing microarrays to detect these and other microbial species in these estuarine communities. The microarrays will detect each species using four distinct loci, with the multiple loci serving as an internal control. The accuracy of the microarray will be measured using sentinel species such as Aeromonas species, Escherichia coli, and Vibrio vulnificus. Using microarrays, it should be possible to determine the annual fluctuations of bacterial species (culturable and non-culturable, pathogenic and non-pathogenic). The data may be applied to understanding patterns of environmental change; assessing the health of the Bay; and evaluating the risk of human illness associated with exposure to and ingestion of water and shellfish.     

Macroalgae and DGT as indicators of available trace metals in marine coastal waters near a lead–zinc smelter

The levels of Cd, Cu, Pb, and Zn were determined in the commonest species of green, red, and brown algae collected from five coastal sites in south-western Sardinia (Italy), an area with a long history of mining and smelting. The usefulness of employing Enteromorpha sp. and Padina pavonica (L.) Thivy to monitor metal pollution was evaluated, while diffusive gradients in thin films (DGT) devices were used to measure dissolved metals in seawater. Levels of Cd and Pb were high enough to be of environmental concern in the whole study area. A significant relationship was found between the content of Pb in P. pavonica and DGT-labile Pb in seawater, suggesting that gross elemental concentrations of nonessential metals such as Pb in algal tissues are apparently controlled by the abundance of dissolved metal species in the ambient seawater. The results pointed out the usefulness of using both DGT and algal methods for a better understanding of trace metal availability in coastal waters.     

TBT in California coastal waters: Monitoring and assessment

Butyltins were monitored at over eighty sites, primarily marinas, in surface waters and sediments of the California coast. Values of tributyltin (TBT) in marina waters ranged from 20 to 600 ppt while lower values were usually found in harbors and on the coast. The origin of the tributyltin is in its use as an antifouling agent in marine paints. In those marinas where the concentrations are greater than about 100 ppt, there is usually a conspicuous absence of native organisms, especially molluscs, which are among the most sensitive animals to the highly toxic TBT. The impact of TBT upon not-target organisms recalls the DDT episode of the 1970s. Increasing uses of TBT-containing antifouling paints in the future may have even more drastic effects on coastal organisms than those observed today. The conclusion is inescapable that TBT should be banned for use in commercially available marine paints.     

Dose equivalent commitments from fallout radionuclides in the open waters of the Great Lakes. 1973–1981

The levels of ¹⁴⁴Ce, ¹³⁷Cs, ¹²⁵Sb, and ⁹⁰Sr in the open waters of the Great Lakes were measured over the period 1973–81. The levels were found to be very low. ¹⁴⁴Ce was detected only up to 1975 after which it dropped below the detection limit. The data indicate that the concentrations of the remaining three radionuclides have decreased with time. ⁹⁰Sr and ¹³⁷Cs provide essentially all of the radiological dose from drinking Great Lakes water. The dose equivalant commitments have been calculated from these measurements and found to be well within the Great Lakes Water Quality Agreement's water quality objective for radioactivity.     

Trace metal bioaccumulation in eight common coastal Australian polychaeta

Whole tissue trace metal concentrations of ten metals in eight common coastal Australian polychaete species collected from uncontaminated locations were measured. The mean concentration range for each trace metal was: Mn: 2.6-13 microg g(-1); Co: 0.8-4.6 microg g(-1); Cu: 3.4-26 microg g(-1); Zn: 47-225 microg g(-1); As: 18-101 microg g(-1); Se: 2.2-20.4 microg g(-1); Ag: 0.03-2.5 microg g(-1); Cd: 0.07-17 microg g(-1); Hg: 0.08-0.88 microg g(-1) and Pb: 0.09-3.2 microg g(-1)dry mass. Principal components analysis of trace metal signatures revealed that the habitat, i.e. exposed coast sand or rock, estuarine sand or estuarine mud substrate in which a polychaete species was found, had a significant influence on the bioaccumulation of six trace metals (Mn, Cu, Zn, Ag, Cd and Pb). However, there is no clear relationship between trace metal concentrations in substrates and polychaetes. The results of the current study contribute to a reference dataset of polychaete species-specific natural background trace metal concentrations for use in determining the extent of trace metal contamination by urban and industrial sources.     

Trace metals in soil and vegetables and associated health risk assessment

The objective of this study was to assess the contamination level of trace metals in soil and vegetables and health risk to the urban population in Bangladesh. The range of Cr, Ni, Cu, As, Cd, and Pb in agricultural soils was 158–1160, 104–443, 157–519, 41–93, 3.9–13, and 84–574 mg/kg, respectively. Sequential extraction tests revealed that the studied metals were predominantly associated with the residual fraction, followed by the organically bound phase. Concerning Cu, Ni, Cd, and Pb in vegetables, more than 50 % samples exceeded the FAO/WHO recommended permissible limits. Considering the transfer of metals from soil to vegetables, Cu and Cd exhibited higher transfer factor (TF) values than the other metals. Target hazard quotient (THQ) for individual metal was below 1, suggesting that people would not experience significant health hazards if they ingest a single metal from vegetables. However, total metal THQ signifies the potential non-carcinogenic health hazard to the highly exposed consumers. The carcinogenic risk (TR) of As (1.9?×?10^?4) and Pb (2.3?×?10^?5) through consumption of vegetables were higher than the USEPA threshold level (10^?6), indicating potential cancer risks.     

Heavy metals in cooler waters in Riyadh, Saudi Arabia

Water samples were collected from 400 coolers in Riyadh area. From each cooler, one feed and one cooled water samples were collected. These samples were analyzed for trace metals like Al, Cr, Cu, Fe, Mn, Ni, Pb, and Zn by Inductively Coupled Plasma (ICP) Spectrophotometer equipped with ultrasonic nebulizer. Out of 400 coolers, water from 382 (95.50%) were found to meet World Health Organization (WHO), Saudi Arabian Standards Organization (SASO), and United States Environmental Protection Agency (USEPA) drinking water standards whereas water from 18 coolers (4.50%) were found to have elevated levels of Fe, Pb, and Ni metals. In one cooler, water was allowed to stand for 12 h and a 1 L sample collected every 2 h. All the metals mentioned above with the exception of Pb were found to increase due to standing time.     

舟山近岸海域赤潮优势种中肋骨条藻的生长模型

中肋骨条藻是舟山近岸海域的赤潮优势种,常有大小不等的中肋骨条藻赤潮发生.本文采用多元线性回归模拟春秋两季非赤潮期中肋骨条藻的生长趋势,以探讨影响此种藻类生长的重要因子.结果表明,春季影响中肋骨条藻生长的重要因子包括盐度、无机氮、悬浮物、水温和pH;秋季影响中肋骨条藻生长的重要因子包括溶解氧、活性磷酸盐、悬浮物、硅酸盐、COD和盐度.并与前人的研究结果相比较,从而发现赤潮期和非赤潮期共同的或不同的影响骨条藻生长的因素.     

The polycyclic aromatic hydrocarbon composition of mussels (Mytilus edulis) from Scottish coastal waters

Blue mussels (Mytilus edulis) were collected from coastal areas and voes in Shetland and Orkney during March and April 1998 and from various coastal locations around mainland Scotland and from the Islands during October and December 1999. The polycyclic aromatic hydrocarbon concentration and composition (2- to 6-ring parent and branched) were determined for all samples. Additional analysis, including sensory assessment and the determination of n-alkanes and geochemical biomarkers, was also undertaken on the Shetland and Orkney mussels collected in 1998. Mussels from Shetland and Orkney exhibited a wide range of total PAH concentration (14.7 to 7,177 ng g(-1) wet weight). Those mussels collected in 1999 exhibited a narrower concentration range. The lowest value (mussels from Loch Kentra) was 8.4 ng g(-1) wet weight while the maximum concentration was 344.1 ng g(-1) wet weight and was determined in mussels from Granton East in the Firth of Forth. The PAH concentration ratios in mussels from Dury Voe (Grunna), Long Hope and Kirkwall Bay were consistent with a predominately petrogenic source for these contaminants. This was supported by both the sensory assessment and the n-alkane and triterpane profiles. Comparisons of the PAH concentrations in mussels with sediments collected from the same locations around Shetland and Orkney showed that in areas of high sediment PAH concentration the bioavailability of these contaminants was limited.     

Estimation of underwater visibility in coastal and inland waters using remote sensing data

An optical method is developed to estimate water transparency (or underwater visibility) in terms of Secchi depth (Z _sd ), which follows the remote sensing and contrast transmittance theory. The major factors governing the variation in Z _sd , namely, turbidity and length attenuation coefficient (1/(c + K _d ), c = beam attenuation coefficient; K _d  = diffuse attenuation coefficient at 531 nm), are obtained based on band rationing techniques. It was found that the band ratio of remote sensing reflectance (expressed as (R _rs (443) + R _rs (490))/(R _rs (555) + R _rs (670)) contains essential information about the water column optical properties and thereby positively correlates to turbidity. The beam attenuation coefficient (c) at 531 nm is obtained by a linear relationship with turbidity. To derive the vertical diffuse attenuation coefficient (K _d ) at 531 nm, K _d (490) is estimated as a function of reflectance ratio (R _rs (670)/R _rs (490)), which provides the bio-optical link between chlorophyll concentration and K _d (531). The present algorithm was applied to MODIS-Aqua images, and the results were evaluated by matchup comparisons between the remotely estimated Z _sd and in situ Z _sd in coastal waters off Point Calimere and its adjoining regions on the southeast coast of India. The results showed the pattern of increasing Z _sd from shallow turbid waters to deep clear waters. The statistical evaluation of the results showed that the percent mean relative error between the MODIS-Aqua-derived Z _sd and in situ Z _sd values was within ±25%. A close agreement achieved in spatial contours of MODIS-Aqua-derived Z _sd and in situ Z _sd for the month of January 2014 and August 2013 promises the model capability to yield accurate estimates of Z _sd in coastal, estuarine, and inland waters. The spatial contours have been included to provide the best data visualization of the measured, modeled (in situ), and satellite-derived Z _sd products. The modeled and satellite-derived Z _sd values were compared with measurement data which yielded RMSE = 0.079, MRE = ?0.016, and R ²  = 0.95 for the modeled Z _sd and RMSE = 0.075, MRE = 0.020, and R ²  = 0.95 for the satellite-derived Z _sd products.     

Comparison of trace metal bioavailabilities in European coastal waters using mussels from Mytilus edulis complex as biomonitors

Mussels from Mytilus edulis complex were used as biomonitors of the trace metals Fe, Mn, Pb, Zn, and Cu at 17 sampling sites to assess the relative bioavailability of metals in coastal waters around the European continent. Because accumulated metal concentrations in a given area can differ temporally, data were corrected for the effect of season before large-scale spatial comparisons were made. The highest concentration of Fe was noted in the North Sea and of Mn in the Baltic. Increased tissue concentrations of Pb were recorded in the mussels from the Bay of Biscay and the Baltic Sea. Low concentrations of metals were determined in the mussels from the Mediterranean Sea and the Northern Baltic. Relatively low geographic variations of Cu and Zn indicate that mussels are able to partially regulate accumulated body concentrations, which means Cu and Zn are, to some extent, independent of environmental concentrations.     

Monitoring of ocean surface algal blooms in coastal and oceanic waters around India

The National Aeronautics and Space Administration’s (NASA) sensor MODIS-Aqua provides an important tool for reliable observations of the changing ocean surface algal bloom paradigms in coastal and oceanic waters around India. A time series of the MODIS-Aqua-derived OSABI (ocean surface algal bloom index) and its seasonal composite images report new information and comprehensive pictures of these blooms and their evolution stages in a wide variety of events occurred at different times of the years from 2003 to 2011, providing the first large area survey of such phenomena around India. For most of the years, the results show a strong seasonal pattern of surface algal blooms elucidated by certain physical and meteorological conditions. The extent of these blooms reaches a maximum in winter (November–February) and a minimum in summer (June–September), especially in the northern Arabian Sea. Their spatial distribution and retention period are also significantly increased in the recent years. The increased spatial distribution and intensity of these blooms in the northern Arabian Sea in winter are likely caused by enhanced cooling, increased convective mixing, favorable winds, and atmospheric deposition of the mineral aerosols (from surrounding deserts) of the post-southwest monsoon period. The southward Oman coastal current and southwestward winds become apparently responsible for their extension up to the central Arabian Sea. Strong upwelling along this coast further triggers their initiation and growth. Though there is a warming condition associated with increased sea surface height anomalies along the coasts of India and Sri Lanka in winter, surface algal bloom patches are still persistent along these coasts due to northeast monsoonal winds, enhanced precipitation, and subsequent nutrient enrichment in these areas. The occurrence of the surface algal blooms in the northern Bay of Bengal coincides with a region of the well-known Ganges–Brahmaputra Estuarine Frontal (GBEF) system, which increases supply of nutrients in addition to the land-derived inputs triggering surface algal blooms in this region. Low density (initiation stage) of such blooms observed in clear oceanic waters southeast and northeast of Sri Lanka may be caused by the vertical mixing processes (strong monsoonal winds) and the occurrence of Indian Ocean Dipole events. Findings based on the analyses of time series satellite data indicate that the new information on surface algal blooms will have important bearing on regional fisheries, ecosystem and environmental studies, and implications of climate change scenarios.     

Trace metals in aerosol at Terra Nova Bay, Antarctica

Atmospheric particulate with an aerodynamic diameter <10 microm (PM10) was sampled continuously during the austral summers of 2000-2001 and 2001-2002 at a coastal site near to the Italian base of Terra Nova, Antarctica. Li, Pb, Cd, U, Ba, Bi, Cs, Rb, Tl, Sr, Al, V, Fe, Cu, Mn, Zn, Co, Ag were determined by inductively coupled sector field mass spectroscopy (ICP-SFMS) after sample digestion by a combination of HF, HNO3, and H2O2 in ultraclean conditions. Quality control of the analytical procedure was carried out by blank control, by evaluating the limits of detection, recoveries and repeatability. Concentrations found are extremely low for most metals, confirming the high purity of Antarctic aerosol. Principal Component Analysis (PCA) highlights high correlations among Pb, Cr, Bi, Cu and Zn concentration values and among Li, U, Ba, Cs, Rb, Al, V, Fe, Mn, Co concentration values permitting the identification of two principal source groups, namely crustal dust and human emission activities. Elements of anthropogenic origins (Pb, Cr, Cu, Zn) were highly enriched with respect to their crustal composition.     

Heavy metals concentration in edible fishes from coastal region of Kalpakkam, southeastern part of India

Concentrations of Cu, Mn, Zn, Fe, Cr, and Pb were estimated using ICP-MS in nine commercially important and locally consumed fish species (Sarda orientalis, Scomberomorus commerson, Rastrelliger kanagurta, Sardinella longiceps, Paraplagusia bilineata, Cynoglossus lida, Cynoglossus macrostomus, Lepturacanthus savala, and Siganus javus) collected from coastal waters of Kalpakkam, eastern part of India. Their concentration (μg g(-1)) in the examined fish species ranged as follows: Cu (0.8-6.5), Zn (14.3-27.9), Mn (0.5-8.8), Fe (17.6-117.0), Cr (0.24-1.78), and Pb (0.18-2.29). Concentrations of most of the metals in the fish species studied were found to be safe for human consumption barring Mn.     

Development of MODIS data-based algorithm for retrieving sea surface temperature in coastal waters

A new algorithm was developed for retrieving sea surface temperature (SST) in coastal waters using satellite remote sensing data from Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua platform. The new SST algorithm was trained using the Artificial Neural Network (ANN) method and tested using 8 years of remote sensing data from MODIS Aqua sensor and in situ sensing data from the US coastal waters in Louisiana, Texas, Florida, California, and New Jersey. The ANN algorithm could be utilized to map SST in both deep offshore and particularly shallow nearshore waters at the high spatial resolution of 1 km, greatly expanding the coverage of remote sensing-based SST data from offshore waters to nearshore waters. Applications of the ANN algorithm require only the remotely sensed reflectance values from the two MODIS Aqua thermal bands 31 and 32 as input data. Application results indicated that the ANN algorithm was able to explaining 82–90% variations in observed SST in US coastal waters. While the algorithm is generally applicable to the retrieval of SST, it works best for nearshore waters where important coastal resources are located and existing algorithms are either not applicable or do not work well, making the new ANN-based SST algorithm unique and particularly useful to coastal resource management.     

The role and distribution of total suspended solids in the macrotidal coastal waters of Korea

Spatial and temporal distribution patterns of total suspended solids (TSS) in the shallow and macrotidal regions of the Korean peninsula indicated there were significant changes in TSS concentrations. These were seasonally influenced by the wind, river input and tidal cycle. There were high TSS values at estuarine and river mouth stations and during low tide due to the re-suspension of bottom sediment by strong wind action during winter months, in addition the land input through rivers and strong tidal current during ebbing. Monthly mean values of TSS significantly correlated with wind speed and nitrate concentration (p < 0.01). This indicated that the resuspension of surface sediment was a more important source of TSS than the river input, and that nitrate was introduced into the water column during the resuspension process. TSS were seven times higher at low tide than in high tide. Light penetration was significantly inhibited by TSS; as >98% of incident light was absorbed within 2 m and zero photosynthetically active radiation (PAR) under 2 m in the estuarine stations during winter. Removal of heavy metals and nutrients by TSS in the water column was evident. Over 80% of the initial concentration of nutrients was removed within 10 min under various concentrations of TSS and also TSS contained significantly higher concentration of heavy metals than surface sediment. The concentration levels of nutrients and chemical oxygen demand in the west coast were comparable with the East and South Sea, even the major rivers in the Korean peninsula flow into the West Sea with major pollutant loadings into the coastal areas. High concentration of TSS is likely to contribute to the removal process of these pollutants, resulting in relatively lower levels of nutrients and organic materials in these coastal waters.     

Monitoring of labile metals in turbid coastal seawater using diffusive gradients in thin-films

Diffusive gradients in thin-films (DGT) have been investigated for in situ monitoring of labile metals in north Australian coastal seawater. Field and experimental data showed that DGT devices provided adequate detection limits, accuracy and precision for monitoring of near-pristine levels of labile Mn, Co, Cu, Cd and Pb when deployed for periods of 3 days. However, Zn could not be adequately determined due to high blank levels. The ratio of DGT-labile to 0.45 microm-filtered metal levels in natural seawater ranged from 0.44-0.63 for Cu but was close to unity for Co and Cd. Elevated levels of suspended particulate matter up to 57.3 mg l(-1) did not have an adverse effect on the performance of DGT.