Natural heavy metal and metalloid concentrations in sediments of the Minho River estuary (Portugal): baseline values for environmental studies

Forty-nine surface sediment samples from the Minho estuary sector between Tui and Caminha were analyzed for grain-size contents, Al, As, Cr, Cu, Hg, Li, Pb, Sn, and Zn concentrations. Selected heavy metal (Cu, Cr, Hg, and Zn) and metalloid (As and Sn) distributions were normalized against Al and Li with the main goal of compensating for natural grain-size variability and to separate natural from anthropogenic contributions, by using a combination of normalization techniques (definition of regional geochemical baselines (RGB) and determination of enrichment factors (EF)). Lead did not reveal a significant relationship with Al and Li. Aluminum explained more variance than Li for As, Cu, Hg, and Zn. Assuming the general non-impacted metal character of the Minho River estuary sediments, RGBs are defined for differentiating between natural and anthropogenic contributions. Based on RGB defined for each heavy metal/metalloid, the degree of enrichment is estimated through the determination of EF. Despite the relatively low total heavy metal and metalloid concentrations, the defined RGB identifies a set of samples characterized by presenting As, Cu, Cr, Hg, and Zn enrichments relatively to expected natural levels. Mercury is the element showing the highest level of enrichment relative to the baseline values being spread through all the study area. Tin present enrichments relatively to Al and or Li always lower than 1.5 suggesting natural contributions.     

Tidally driven N, P, Fe and Mn exchanges in salt marsh sediments of Tagus estuary (SW Europe)

Short-sediment cores and flooding water were collected at 0, 5, 15, 25 and 50?min of tidal inundation in the two sites colonised by pure stands of Spartina maritima (low marsh) and Sarcocornia fruticosa (high marsh) from the Rosário salt marsh (Tagus estuary, SW Europe). Concentrations of NH (4) (+) , NO (3) (-) +?NO (2) (-) and HPO (4) (2-) , Fe and Mn were measured in tidal flooding water and pore water. Flooding water is enriched in nutrients, particularly ammonium due to local discharge of untreated urban effluents. Nevertheless, NH (4) (+) and NO (3) (-) +?NO (2) (-) concentrations in flooding waters at t?=?5?min (NH (4) (+) =?246?±?7?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. fruticosa and NH (4) (+) =?256?±?8?μM, NO (3) (-) +?NO (2) (-) =?138?±?1?μM for S. maritima) rose sharply at both vegetated sites. An increase was also registered for HPO (4) (2-) and total dissolved Fe although the subsequent decrease was smoother. Advective transport induced by the two daily pulses of inundation is several orders of magnitude higher than the diffusive fluxes during submerged periods. In addition, solutes are exported from the sediment with the inundation and imported in submerged periods. The exported amount of inorganic nitrogen during tidal inundation (export of 3,200?μmol?N?m(-2)?day(-1)to the water column), is not counterbalanced by the sink of -290?μmol?N?m(-2)?day(-1) occurred during the submerged period.     

Linear alkylbenzenesulfonates (LAS) of an urban stream in Korea

Profiles of alkyl homologues and isomers of LAS were monitored for an urban stream polluted with municipal wastewaters in Korea. Alkylchains of the stream LAS were shorter than commercial standards and higher I/E ratios were associated with lower LAS concentrations. These suggested a partial biodegradation of LAS in the stream. Higher LAS concentrations were observed in the upper stream. LAS levels were at their lowest during summer probably due to high precipitation and faster biodegradation rates. LAS contributed to about 29% of MBAS and could be used to roughly estimate BOD concentration of the stream.     

Distribution of endocrine disruptors in the Mondego River estuary, Portugal

Recent studies in the Mondego River estuary demonstrated signs of pollution in the area, but the nature of the contamination remains unexplored. Because there seems to be any studies in that zone checking for the simultaneous presence of xenoestrogenic endocrine disrupting compounds, either of animal (estradiol and estrone), vegetal (daidzein, genistein and biochanin A), pharmaceutical (17alpha-ethynylestradiol) or industrial (bisphenol A, 4-octylphenol, 4-nonylphenol) origins, the main objective of this study was to investigate their presence, in every year season and at eight points along the estuarine gradient. For this propose, water samples (2 L) were collected in high and low tides, preconcentrated in the Oasis HLB cartridges and cleaned in silica cartridges before their analysis by HPLC-DAD and GC-MS. The current data showed the absence of contamination by animal or pharmaceutical estrogens and by alkylphenols, but demonstrated the presence of high levels of phytoestrogens (up to 1.1 mug/L) and of bisphenol A (up to 880.0 ng/L). Because these two chemicals existed in high environmental concentrations in the most upstream sampling station, and taking in account that these pollutants may additively contribute to endocrine disruption, namely on fish, it was concluded that at least this particularly area of the Mondego estuary deserves continuous monitoring programmes.     

Phosphorous speciation in surface sediments of the Cochin estuary

Sequential chemical extraction using chelating agents were used to study the P dynamics and its bioavailability along the surface sediments of the Cochin estuary (southwest coast of India). Sediments were analyzed for major P species (iron bound P, calcium bound P, acid soluble organic P, alkali soluble organic P and residual organic P), Fe, Ca, total carbon, organic carbon, total nitrogen and total sulfur contents. An abrupt increase in the concentration of dissolved inorganic P with increasing salinity was observed in the study region. Iron-bound P exhibited a distinct seasonal pattern with maximum values in the monsoon season when fresh water condition was prevailed in the estuary. As salinity increased, the percentage of iron-bound P decreased, while that of calcium-bound P and total sedimentary sulfur increased. C/P and N/P ratios were low which indicate that large amounts of organic matter enriched with P tend to accumulate in surface sediments. The high organic P contribution in the sedimentary P pool may indicate high organic matter load with incomplete mineralization, as well as comparatively greater percentage of humic substance and resistant organic compounds. Principal component analysis is employed to find the possible processes influencing the speciation of P in the study region and indicate the following processes: (1) the spatial and seasonal variations of calcium bound P and acid soluble organic P was mainly controlled by sediment texture and organic carbon content, (2) sediment redox conditions control the distribution of iron bound P and (3) the terrigenous input of organic P is a significant processes controlling total P content in surface sediments. The bioavailable P was very high in the surface sediments which on an average accounts for 59 % in the pre-monsoon, 65 % in the monsoon and 53 % in the post-monsoon seasons. The surface sediments act as a potential internal source of P in the Cochin estuary.     

Environmental monitoring of linear alkylbenzene sulfonates and physicochemical characteristics of seawater in El-Mex Bay (Alexandria, Egypt)

In the present work, the influence of different physicochemical characteristics on the distribution of anionic detergents, linear alkylbenzene sulfonates (LAS), was studied. Surface and bottom water samples were collected from eight different sites from a small bay near the main sewage discharge of Alexandria City (El-Max Bay). The results showed great variations in the concentrations, as a function of the regional and seasonal variations. The study revealed that the pH values lie in the normal side, with a range of 8.0–8.5 inside the bay and 7.5–7.7 at El-Umum Drain effluent. Wide variations, observed between the surface and the bottom water of the bay, salinity, dissolved oxygen, oxidizable organic matter, total hardness, and total alkalinity, were scattered in the ranges (3.33–42.73 practical salinity unit), (0.42–8.27 mg O₂/l), (0.12–10.49 mg/l), (1.39–8.99 mg/l), and (0.23–0.48 mg/l), respectively. The regional variations of LAS concentrations in the bay waters showed that the concentration decreased as the distance from the source of drainage water (El-Umum Drain). The seasonal average variations of LAS cleared out that summer and spring periods had the highest concentrations at surface (0.13?±?0.04 mg LAS/l) and bottom (0.12?±?0.10 mg LAS/l) layer, which is attributed to increase in population density and human activities. The inverse relationships between total LAS concentration and salinity, dissolved oxygen, and calcium ions concentration are r?=??0.78, 0.50, and 0.67, respectively. This is related to the occurrence of the untreated wastewater containing detergents, the biodegradation rate of surfactants, and strong precipitation of LAS as Ca.     

Perfluoroalkyl compounds (PFCs) in wildlife from an urban estuary

Previous research has documented the bioaccumulation of perfluoroalkyl compounds (PFCs) in apex predators in remote locations but few studies have evaluated urban estuaries. To assess the importance of PFCs in San Francisco Bay, two apex predators in the San Francisco Bay, double-crested cormorants (Phalacrocorax auritus) and Pacific harbor seals (Phoca vitulina richardii), were sampled. Prey fish (Atherinops affinis and Menidia audens) were also evaluated to better understand potential sources of PFCs to the foodweb. Perfluorooctane sulfonate (PFOS) was the primary PFC detected in cormorant eggs, small fish and harbor seal serum. PFOS detected in San Francisco Bay seal serum was typically an order of magnitude higher than those at the reference site. PFOS concentrations were highest in seals and cormorant eggs from the highly urbanized southern portion of the Bay. PFOS in eggs from the southern part of the Bay remained relatively constant between 2006 and 2009 despite the phase-out of perfluorosulfonyl-based compounds nationally. In addition, these levels exceed the avian predicted no effects concentration of 1.0 μg mL(-1). Concentrations of the remaining PFCs measured were substantially lower than those of PFOS.     

Polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Bizerte Lagoon,Tunisia: levels,sources, and toxicological significance

To assess the status of polycyclic aromatic hydrocarbon (PAH) contamination in sediments from the Bizerte Lagoon (northern Tunisia), 18 surface sediment samples were collected in March 2011 and analyzed for 14 US Environmental Protection Agency priority PAHs by high-performance liquid chromatography. The total concentrations of the 14 PAHs (ΣPAHs) ranged from 16.9 to 394.1 ng g^?1 dry weight (dw) with a mean concentration of 85.5 ng g^?1 dw. Compared with other lagoons, coasts, and bays in the world, the concentrations of PAHs in surface sediments of the Bizerte Lagoon are low to moderate. The PAHs’ composition pattern was dominated by the presence of four-ring PAHs (45.8 %) followed by five-ring (26.8 %) and three-ring PAHs (12.7 %). The PAH source analysis suggested that the main origin of PAHs in the sediments of the lagoon was mainly from pyrolytic sources. According to the numerical effect-based sediment quality guidelines of the USA, the levels of PAHs in the Bizerte Lagoon should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent values calculated for the samples varied from 3.1 to 53.7 ng g^?1 dw with an average of 10.6 ng g^?1 dw.     

Spatial and seasonal distribution of 17 endocrine disruptor compounds in an urban estuary (Mondego River,Portugal): evaluation of the estrogenic load of the area

The Mondego River estuary demonstrates signs of pollution, but the levels of endocrine disrupting compounds (EDCs), such as the natural (17β-estradiol and estrone) and pharmaceutical (17α-ethynylestradiol) estrogens, xenoestrogenic industrial pollutants (4-octylphenol, 4-nonylphenol, and their mono- and diethoxylates and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, and genistein), and sitosterol were either poorly or never measured in this area. Thus, to conclude about the influx of EDCs in this estuary, water samples were taken every 2 months, during 1 year (2010) in low tide, at eight sites distributed along the estuary. Water samples (1 L) were preconcentrated in the Oasis HLB cartridges and cleaned in silica cartridges before their analysis by GC-MS. In summer, potentially hazardous amounts of estrogens (≈26 ng L^?1), alkylphenols (≈11.5 μg L^?1), alkylphenolethoxylates (≈13 μg L^?1), and phytoestrogens (≈5.6 μg L^?1) were measured. These data suggest that changes in the hydrodynamics of the estuary coupled with the increase of water temperatures interfere with the amount of EDCs in the water. Complementary physicochemical parameters also point to high levels of anthropogenic pollution in this area. Globally, the estrogenic load, expressed in ethynylestradiol equivalents, attained 71.8 ng L^?1 demonstrating that, all together, the measured EDCs pose important health risks for both biota and humans.     

The chemical oceanographic consequences of environmental restoration projects in the Golden Horn estuary (Marmara Sea, Turkey)

This paper deals with the diversity and seasonal variations of macro-benthic infauna and associated environmental factors influencing the benthic community in the inshore waters of southern Indian coast. Four seasonal collections (2006–2007) were made at three different depths (5, 15 and 25 m) in the inshore waters of Pazhayar, Parangipettai and Cuddalore and at 5 m near State Industrial Promotion Council of Tamilnadu (SIPCOT), covering 10 stations in Bay of Bengal. Altogether, 80 infaunal samples (Van-veen grab 0.1 m²) were collected which revealed the occurrence of 132 species representing five diverse groups. Polychaetes were the dominant group (45%), followed by bivalves (31%) and gastropods (16%). Diversity (H’log2) was maximum (4.601) at Parangipettai 25 m during the pre-monsoon season, and the minimum (0.954) was in SIPCOT during monsoon. Multivariate analyses were used to define assemblages.     

Nitrate levels modulate denitrification activity in tropical mangrove sediments (Goa, India)

A study to examine the short-term effect of nitrate and organic carbon addition on denitrification activity was carried out on sediments from a mangrove ecosystem prone to anthropogenic activities (Divar, Goa, India). Laboratory microcosms were prepared using sediment sectioned at every 2-cm-depth interval from the surface to 10 cm. The incubations were subjected to varying nitrate amendments at concentrations ranging from 0, 5, 10, 20, 40 to 60 ??mol l^???1 (up to three times more than measured in field). Nitrous oxide production rates increased significantly (n?=?15; p?<?0.001) on addition of the nutrient at all depths investigated indicating that denitrification in mangrove sediments was NO $_{3}^{-}$ limited. Incubations amended with organic carbon were prepared using glucose as a substrate with concentrations ranging from 0%, 0.1%, 0.3%, 0.5%, 0.75% to 1%. No significant increase in N₂O production was observed on organic C addition. When both the substrates were in excess (1 mmol KNO₃ + 1 mmol glucose), potential denitrification rates decreased with depth and were up to 38 times higher than the in situ denitrification activity varying from 81.26 to 304.09 ??mol N₂O-N m^???2 h^???1. These results reveal that mangrove sediments could act as a sink for nitrate and microbially mediated denitrification could effectively reduce N load controlling any adverse environmental impact in the adjoining estuarine system.     

Distribution and ecotoxicological significance of polycyclic aromatic hydrocarbons in sediments from Iko River estuary mangrove ecosystem

The distribution of polycyclic aromatic hydrocarbons (PAHs) in epipelic and benthic sediments from Iko River estuary mangrove ecosystem has been investigated. Total PAHs ranged from 6.10 to 35.27 mg/kg dry weight. Quantitative difference between the total PAHs in epipelic and benthic sediments showed that the benthic sediment known for higher capability to serve as sink for chemical pollutants accumulated less PAHs. This implies that PAHs in the epipelic sediment may plausibly be from industrial sources via runoff and/or of biogenic origin. A strong pyrolytic source fingerprint has been detected with slight influence of petrogenic sources. Total organic carbon normalized PAHs (sum of 16 PAHs, 59.7 to 372.4 mg/kg OC) were under (except for ES3 and BS3) the threshold effects concentrations (TEC, 290 mg/kg OC). Total PAHs in Iko River estuary sediments were in the range between ERL and ERM.     

Chemical monitoring of river water bodies in an EU outermost region: examples from the Azores archipelago (Portugal)

Chemical monitoring of water quality on a total of 16 rivers in the Azores archipelago (Portugal), since 2003, made it possible to identify the major pressures and spatial geochemical variations along main course of the rivers. River water pollution is to a large extent associated to point sources, namely domestic wastewater discharges, especially in urban areas, and diffuse sources, associated with pasture land, and explain the high values on BOD(5) and nutrients (P and N). Heavy metals and metalloids, as well as hydrocarbons and pesticides, are generally under the detection limits of the analytical methods. Generally, river water reflects pollution loads according to a simple model, derived from land use in the watershed: in the upper part conditions are pristine, in the intermediate portion of the basin pasture land dominates and near the coast urban discharges are increasingly important. Results stress the role that an approach based on the watershed scale, coupled with land use management measures, are crucial to water management procedures and a successful WFD implementation in small river basin districts like the Azores. The paper also shows the need for full compliance regarding EU directives on urban wastewater and nitrate pollution due to agriculture.     

Bioaccumulation of HCH isomers in selected macroinvertebrates from the Elbe River: sources and environmental implications

Sediments of the Elbe River have been extremely polluted by contaminants originating from previous large-scale hexachlorocyclohexane (HCH) production and the application of γ-HCH (lindane) in its catchment in the second half of the twentieth century. In order to gain knowledge on bioaccumulation processes at lower trophic levels, field investigations of HCHs in macroinvertebrates were carried out along the longitudinal profile of the Elbe and tributary. Among the sites studied, concentrations in macroinvertebrates ranged within five orders of magnitude (0.01–100 μg/kg). In general, lower values of HCH isomers were observed at all Czech sites (mostly <1 μg/kg) compared with those in Germany. At the most contaminated site, Spittelwasser brook (a tributary of the Mulde), extremely high concentrations were measured (up to 234 μg/kg α-HCH and 587 μg/kg β-HCH in Hydropsychidae). In contrast, the Ob?íství site, though also influenced by HCH production facilities, showed only negligibly elevated values (mostly <1 μg/kg). Results showed that fairly high levels of α-HCH and β-HCH compared to γ-HCH can still be detected in aquatic environments of the Elbe catchment, and these concentrations are decreasing over time to a lesser extent than γ-HCH. Higher HCH concentrations in sediments in the springtime are considered to be the result of erosion and transport processes during and after spring floods, and lower concentrations at sites downstream are thought to be caused by the time lapse involved in the transportation of contaminated particles from upstream. In addition, comparison with fish (bream) data from the literature revealed no increase in tissue concentrations between invertebrates and fish.     

Environmental impact from agrochemicals in Bali (Indonesia)

Irrigation of paddy has been practised for centuries in Bali, based on the use of upland weirs for diverting river waters to irrigate downstreams lands ranging from upland terraces to flat coastal plains. While in earlier times, traditional irrigation practices have met the island's food needs, in recent decades an increasing population has increased food requirements to levels surpassing the productivity of traditional methods. Government assistance programs were initiated beginning in about 1960, and a major new program, called the Bali Irrigation Project, is now being implemented. These programs recognize that little additional farm lands will be available, hence their objective is to increase productivity through intensified agriculture, including the use of high-yield rice varieties and increasing amounts of agricultural chemicals, including both fertilizers and pesticides. The feasibility study for the Bali Irrigation Project included an evaluation of the pollutional effects of agricultural chemicals used in Bali. The study showed that past use of hard organochlorides has pervasively polluted the island's soil and water resources and, while the Government's programs now use only relatively degradable chemicals, considerable environmental damage has already occurred and much care will be needed in avoiding the use of hard toxics in the future. The study also indicated no adverse effects from increased use of fertilizers.     

Natural radioactivity in groundwater from the south-eastern Arabian Peninsula and environmental implications

Groundwater is the most valuable resource in arid regions, and recognizing radiological criteria among other water quality parameters is essential for sustainable use. In the investigation presented here, gross-α and gross-β were measured in groundwater samples collected in the south-eastern Arabian Peninsula, 67 wells in Unite Arab Emirates (UAE), as well as two wells and one spring in Oman. The results show a wide gross-α and gross-β activities range in the groundwater samples that vary at 0.01～19.5 Bq/l and 0.13～6.6 Bq/l, respectively. The data show gross-β and gross-α values below the WHO permissible limits for drinking water in the majority of the investigated samples except those in region 4 (Jabel Hafit and surroundings). No correlation between groundwater pH and the gross-α and gross-β, while high temperatures probably enhance leaching of radionuclides from the aquifer body and thereby increase the radioactivity in the groundwater. This conclusion is also supported by the positive correlation between radioactivity and amount of total dissolved solid. Particular water purification technology and environmental impact assessments are essential for sustainable and secure use of the groundwater in regions that show radioactivity values far above the WHO permissible limit for drinking water.     

Trace elements as tracers of environmental pollution in the canal sediments (alluvial formation of the Danube River, Serbia)

The purpose of this study was to examine the levels of trace elements and to discuss the origin and mobility of these contaminants in the canal sediments (alluvial formation of the Danube River). The most significant fractions binding all of the studied elements were oxides and silicates. The high proportion of elements in the residual fraction and the generally low contents of extractable elements reflected the background geochemical conditions. The contents of trace elements (except Hg and As) were dominantly controlled by the presence of Fe and Mn oxides as well as by the grain size and the geochemical composition of the sediment. The studied alluvial sediments were not heavily contaminated; there were only few sites where an anthropogenic influence on the concentrations of some metals (Cu, Cd, Zn, and Pb) was noticed. The results from this study show that impact of Pan?evo industrial zone on the quality of the Danube River and its contamination with trace element is minor.     

Mercury pollution in Ria de Aveiro (Portugal): a review of the system assessment

The Ria de Aveiro (Portugal) is a coast al lagoon adjacent to the Atlantic Ocean and it has an inner bay (Laranjo bay) that received a highly contaminated effluent discharged by a mercury cell chlor-alkali plant from the 1950s until 1994. The aim of this study is to review in a holistic way several research studies that have been carried out in the Ria de Aveiro, in order to evaluate the remobilization of the mercury accumulated within the system and the recovery of the lagoon. The spatial distribution of the total mercury in the surrounding terrestrial environment has also been considered. Results indicate that the main mercury contamination problems in the Ria de Aveiro are confined to the Laranjo bay. Mercury export to the coastal waters and its impact on the nearshore compartments (water column, sediment and biota) are low. No direct effects of the mercury from nearby industrial activities were detected in Aveiro's urban soils, although historical mercury contamination is still affecting soil quality in the immediate vicinity of the chlor-alkali plant, located in Estarreja. Moreover, macrophyte harvesting for human direct or indirect use and the consumption of mussels, crabs and the sea bass from the Laranjo bay may constitute a health risk. Further studies focusing on developing skills for the restoration of the ecosystem are presently underway.     

Metal levels in sediments and transplanted mussels in Pagassitikos Gulf (Aegean Sea, Eastern Mediterranean)

Metal concentrations were determined in surface sediments and transplanted mussels in a shallow semi-enclosed bay, Pagassitikos Gulf, Aegean Sea. Cu, Zn, Pb, Hg, and As levels in sediments were enriched close to point sources of pollution, i.e., Volos Port and cement plant. Fe, Mn, Cr, and Ni spatial distributions in sediments were rather uniform with increasing concentrations towards deeper sites, suggesting natural enrichment, whereas levels found in the port, although elevated, were not the highest in the study area. Spatial variations in concentrations of most metals in mussels transplanted nearshore were generally in accordance to those in sediments, with the highest Fe, Mn, Cr, Ni, and Cu levels in the port and the highest Hg levels close to the cement plant. Concentrations of metals in sediments and transplanted mussels were comparable to those reported in Mediterranean areas. Results indicate that pollution point sources contribute to anthropogenic metal enrichment in the study area.