Concentrations In Surface Sediments Research Articles

Study on spatial distribution, potential sources and ecological risk of heavy metals in the surface water and sediments at Shanghai Port, China

Heavy metal concentrations in surface waters and sediments of Shanghai port were measured to analyze the spatial distribution characteristics, sources and pollution degrees. The southern Shanghai port was heavily polluted by Cd, Pb, Cr and Cu in water, and the concentrations of Pb, Hg and Zn in sediments exceeded Effects Range Low. Cu, Pb, Cd and Cr in water were positively correlated in group, and they probably derived from industrial and domestic sewage, fossil fuel burning and vehicular pollution and represented 82.47 % of the contribution. Zn, Hg and As contaminations represented industrial and agricultural effluent sources and accounted for the remaining 17.53 %. Heavy metal pollution of Yangshan Port water was at high pollution, and the remaining sites were at low pollution. Most of the sampling sites were at moderate ecological risk in sediments, and the pollution of Cd, Hg and Zn were serious.

Evaluating soil-water conserving performance of land management strategies for spoil tips on the Chinese Loess Plateau

Surface runoff decrease (SRD) and sediment concentration change (SCC) are accountable for sediment reduction by anti-erosion strategies. Using a design of horizontal stages, contour trenches, fish-scale pits, as well as their combinations, this study evaluated the two components for sediment reduction after the implementation of various land management strategies on steep spoil tips. The study highlighted the interactions between SRD and SCC in reducing sediment, and characterized the temporal variations of sediment-reducing capacity by SRD and SCC. Results showed that slope erosion was well controlled with control ratios of sediment yield ranging from 0.4 to 0.59, 0.2 to 0.22, for horizontal stage- and contour trench-based strategies, respectively. Sediment-reducing benefit by SRD accounted for 52%–77% of the total sediment reduction and highly determined the performance of SCC. Quadratic relationships between sediment-reducing capacity by SCC and that by SRD were observed. The function of SCC only operated when the sediment-reducing capacity by SRD reached a certain threshold. These thresholds varied greatly in the range of 0.75 kg m−3–0.91 kg m−3 and 0.61 kg m−3–0.66 kg m−3 for horizontal stage- and contour trench-based strategies, respectively. The upper limits for sediment-reducing capacity by SCC varied in the range of 0.32 kg m−3–0.44 kg m−3 and 0.63 kg m−3–0.76 kg m−3 for horizontal stage- and contour trench-based strategies, respectively. An efficiency coefficient of 55% and an M-N ratio of 1:1 indicated that sediment-reducing benefits by SRD and SCC were effectively exerted by combining contour trenches and fish-scale pits. The findings emphasized that the application of land management strategies must be considered based on particular goals to restore spoil tips. In practice, if targeted to enhancing sediment-reducing efficiency, contour trenches and fish-scale pits should be primarily considered. However, if the aim is to decrease water consumed for sediment control, then horizontal stages should be principally considered.

DISTRIBUTION OF POLYNUCLEAR AROMATIC AND TOTAL ALIPHATIC HYDROCARBON CONTENTS IN SURFACE WATER AND SEDIMENTS OF SOMBRIERO RIVER IN RIVERS STATE, NIGERIA

Variations in Polynuclear Aromatic Hydrocarbons (PAH) and Total Aliphatic Hydrocarbon (TAH) concentrations in surface water and sediments of Sombriero River during wet and dry climatic conditions and their implications to human health and the environment were investigated. The sediments and water samples were collected from seven selected stations at Sombriero river banks and within Sombriero River. The dry season sampling was carried out in December, 2020 while the wet season sampling took place in May, 2021. The samples were analyzed in the laboratory for Polynuclear Aromatic Hydrocarbons (PAH’s), and Total aliphatic Hydrocarbons (TAHs) following the standard operational procedures. The results indicated that the summation of the Polynuclear Aromatic Hydrocarbon (\(\Sigma\)PAH’s) exceeded 0 – 50ng/l background value signifying contamination by polynuclear aromatic hydrocarbon with congeners such as benzo(a) pyrene; benzoflouranthenes; benzo(a) anthracene; indeno(1,2,3-cd) pyrene and dibenzo(a,h) anthracene which are carcinogenic. The aliphatic fraction of the total petroleum hydrocarbons (TPH) results indicated ranges within DPR target and intervention limits, but the aromatic fraction indicated presence of chemical compounds that are carcinogenic to human health and at concentrations that exceeded their tolerable limits. The potential health effect of concentrations of total petroleum hydrocarbons to human exposure in the study area lies on the carcinogenic Polynuclear Aromatic Hydrocarbons (PAHs) fractions constituent chemical compounds such as Benz[a]anthracene, Benzo[b]fluoranthene, Benzo[k]fluoranthene, Benzo[a]pyrene, Dibenz [a,h] anthracene, Indeno[1,2,3-cd]pyrene, whose concentrations portends human health hazard.

Trace elements V, Ni, Mo and U: A geochemical tool to quantify dissolved oxygen concentration in the oxygen minimum zone of the north-eastern Pacific

Deoxygenation of the water column in the oceans and in the oxygen minimum zone (OMZ) has become relevant due to its connection with global climate change. The variability of the OMZ has been inferred by in situ measurements for the last 70 years and qualitatively assessed through the monitoring of trace elements and the nitrogen stable isotope ratio (δ 15 N) of organic matter on several time scales. The V, Ni, Mo and U concentrations in surface sediments and the dissolved oxygen concentration in the water column of La Paz Bay and the Mazatlán margin were used to propose an exponential regression model. This model will allow the inference of the dissolved oxygen concentration in the sedimentary records from the Alfonso Basin in La Paz Bay and in the Mazatlán margin over the last 250 years. Based on this exponential regression model, the dissolved oxygen concentration increased by 6.4 μM in the Alfonso Basin and 4.1 μM in the Mazatlán margin, in the period between 1800 CE and the present day. This suggests a reoxygenation of the OMZ at the mouth of the Gulf of California. This finding is consistent with previous studies (Deutsch et al., 2014; Tems et al., 2016), which suggest a reduction in the deoxygenation of the water column throughout most of the 20th century. • Deoxygenation in the oceans and its connection with global climate change. • V, Ni, Mo and U concentrations proxies of dissolved oxygen in the water column. • Re‑oxygenation of the OMZ at the mouth of the Gulf of California.

Rare earth elements in surface lake sediments of Russian arctic: Natural and potential anthropogenic impact to their accumulation

Investigations of the rare earth elements (REEs) concentrations in surface sediments of small lakes in the Arctic zone of the Russian Federation are presented. The territories of Murmansk Region and the Republic of Karelia were used as key study areas. The sampling of 9 lake sediments was carried out. Inductively coupled plasma mass spectrometry (ICP-MS) method was used as a main approach to estimate total concentrations of REEs and heavy metals and content of their elements in different fractions, using sequential extraction method. The role of the natural landscapes factor (tundra, forest-tundra, taiga) in the process of REEs accumulation in lake sediments was evaluated in the course of the work. It was revealed that the highest median accumulation of REEs occurred in the sediments of lakes in the tundra zone, and the lowest median accumulation of REEs occurred in the lakes in the forest zone (taiga). The dynamics of the REEs accumulation in the lakes of the background (pristine) regions of the Arctic, as well as in the lakes of urbanized territories, is shown on the example of the cities of Murmansk Region. The analysis of the vertical distribution of REEs and heavy metals in the cores of sediments of the studied lakes showed that the anthropogenic factor plays an important role in the accumulation of REEs in urban water bodies. First of all, this is due to dust from construction, wear and tear of houses and road structures, and weathering of soils and quaternary deposits in urban areas. All urban lakes showed similarity between distribution of REEs and heavy metals in the sediments. The main fractions of REEs in the sediments of the lakes of the Arctic zone of Russia were determined. It was revealed that the residual phase of sediments and organic matter plays a significant role in the accumulation of REEs in surface sediments of the North of Russia. At the same time, mobile forms and phases of REEs associated with Fe and Mn oxides also did not play a large role in the accumulation of REEs in the sediments of lakes in Northwest Russia.

Long-Term Monitoring of an In Situ Activated Carbon Treatment to Reduce Polychlorinated Biphenyl Availability in an Active Harbor.

Activated carbon-based amendments have been demonstrated as a means of sequestering sediment-associated organic compounds such as polychlorinated biphenyls (PCBs). In a 2012 effort, an activated carbon amendment was placed at a 0.5-acre amendment area adjacent to and underneath Pier 7 at the Puget Sound Naval Shipyard and Intermediate Maintenance Facility, Bremerton, Washington, USA to reduce PCB availability. Multiple postplacement monitoring events over a 3-year period showed an 80%-90% reduction in PCBs, stability of activated carbon, and no significant negative impacts to the benthic community. To further evaluate the long-term performance, a follow-on to the approximately 7-year (82-month) postplacement monitoring event was conducted in 2019. The results of in situ porewater and bioaccumulation evaluations were consistent with previous observations, indicating overall PCB availability reductions of approximately 80%-90% from preamendment conditions. Multiple measurement approaches for quantifying activated carbon and amendment presence indicated that the amendment was present and stable in the amendment area and that the activated carbon content was similar to levels observed previously. As in the previous investigation, benthic invertebrate community metrics indicated that the amendment did not significantly impair benthic health. An application of carbon petrography to quantify activated carbon content in surface sediments was also explored. The results were found to correspond within a factor of 1.3 (on average) with those of data for the black carbon content via a black carbon chemical oxidation method, an approach that quantifies all forms of black carbon (including activated carbon). The results suggest that at sites with low soot-derived black carbon content in sediment (relative to the targeted activated carbon dose), the black carbon chemical oxidation method would be a reasonable method for measurement of activated carbon dosage in sediment at sites amended with activated carbon. Environ Toxicol Chem 2022;41:1568-1574. © 2022 SETAC.

Heavy metals pollution characteristics and risk assessment in sediments and waters: The case of Tianjin, China

Potential health and ecological risks due to heavy metal pollution in surface waters and sediments were evaluated based on a health risk assessment model and a potential ecological risk index method. Combined with the reclamation progress of Tianjin Nangang Industrial Zone, in China, a survey was carried out in the area dealing with heavy metals concentrations in surface waters and sediments, covering from 2008 to 2018. Specifically, concentrations were determined for As, Cd, Hg, Cu, Pb, and Zn. The results show that As、Cd、Hg、Cu 、Pb、Zn average concentrations in surface water were 0.99 μg/L∼1.27 μg/L, 0.13 μg/L∼0.63 μg/L, 0.03 μg/L∼0.13 μg/L, 1.5 μg/L∼4.65 μg/L, 1.25 μg/L∼4.7 μg/L, 13.5 μg/L∼20.99 μg/L and which average concentrations in sediment were 5.12 mg/kg∼12.34 mg/kg, 0.12 mg/kg∼0.18 mg/kg, 0.04 mg/kg ∼0.087 mg/kg, 13.45 mg/kg∼31.92 mg/kg, 13.2 mg/kg ∼21.26 mg/kg, 21.58 mg/kg ∼77.21 mg/kg, respectively. The background values of the Hailuan River basin near the study area were taken as the reference and compared with the national sediment quality standards a tell us the quality of the sediments in Tianjin Nangang coastal area being good. As regards the characteristics of pollution, heavy metals showed a high concentration in 2008 and then decreased significantly, which related to the dredging of large amounts of contaminated surface sediment during port construction. According to the phase equilibrium partition coefficient (Kp) and temporal and spatial distribution characteristics of heavy metals, sediments can be seen as an obvious sink for lead, with this element being mainly affected by exogenous input in coastal seawater. Zn, As, Cd, and Hg contents in surface water were greatly affected by the endogenous release from sediments. The results of the environmental risk assessment showed that the main environmental health risk of Tianjin coastal waters was carcinogenic, and specifically due to As. The potential heavy metals ecological risk assessment results of surface sediments were mild for the affected areas.

Effects of river inputs on particulate organic matter composition and distributions in surface waters and sediments of the Mersin Bay, Northeastern Mediterranean Sea

Terrestrial inputs-induced eutrophication in the P-depleted Northeastern (NE) Mediterranean shelf waters has led to changes in particulate organic matter (POM) composition and distributions in the water column and surface sediments. The present study aimed to understand the impacts of terrestrial nutrient and POM inputs on coastal eutrophication, bulk POM composition and concentrations in surface waters and sediments of the Mersin Bay, located at the Cilician Basin of NE Mediterranean Sea. The present results showed that the regional rivers and wastewater discharges markedly increased nutrient concentrations, leading to enhanced eutrophication and POM concentrations surface waters of the Mersin inner bay. The C/N and C/P molar ratios derived from the regressions of POM data in surface waters were 6.92 and 129, respectively. The higher C/N and C/P molar ratios in the surface sediments of productive Mersin Bay indicated selective decay of N, P-containing organic matter buried in muddy sediments. Close positive correlations were found in sediment organic matter and mud contents, indicating the crucial role of fine particles in transport and enrichment of organic matter in the muddy shelf sediments of NE Mediterranean Sea.

Chemistry of surface water, precipitation, throughfall, leaves, sediment, soil, and air near a gold mining region in Peru.

Artisanal and small-scale gold mining (ASGM) is the primary global source of anthropogenic mercury (Hg) emissions and a large source of landscape change. ASGM occurs throughout the world, including in the Peruvian Amazon. This data set contains measurements of surface water, precipitation, throughfall, leaves, sediment, soil, and air samples from across the Madre de Dios region of Peru, in locations near and remote from ASGM. These data were collected to determine the fate and transport of Hg across the landscape. Samples were collected in 2018 and 2019. Data predominantly included total Hg and methyl Hg concentrations in surface water, precipitation, throughfall, leaves, sediment, soil, and air. Additional water and soil parameters were also measured to better characterize their chemistry. There are no copyright restrictions; please cite this data paper when the data are used in publication.

Benthic food web structures as an explanation for prolonged ecological half-life of 137Cs in flatfish species in the Fukushima coastal area

After the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP), Japan, in March 2011, 137Cs in demersal fish had, between 2011 and 2015, a prolonged ecological half-life when compared to pelagic fish. Using stable isotope mixing models combined with gut content analysis and 137Cs activity concentrations, this study investigated the hypothesis that an unexplored food web structure could be a contributing factor explaining the ecological half-life of 137Cs in benthic flatfish. Benthic invertebrates and demersal fish species sampled in 2015 still showed 137Cs activity concentrations higher than pre-accident. The mixing models of stable N and C isotopes and gut content analysis identified deposit, suspension and filter feeders to be the main flatfish food items in the benthos. There was a significant correlation between 137Cs activity concentrations in specific flatfish species and benthos, and between 137Cs activity concentrations in benthos and surface sediment. The results of this study partially explained the 137Cs activity concentrations found in the analysed demersal fish, suggesting that the benthos can be a continuous source of 137Cs for the demersal fish during this period of time. Extending monitoring programmes to include invertebrates that are not food species for humans would greatly improve our ability to understand the role of trophic transfer pathways and take appropriate management actions.

Spatio-temporal distribution of heavy metals in sediments of Biyyam Backwater, Kerala, Southwest India; its environmental implications

Biyyam backwater is a developing eco-tourism hub and prone to increased pollution due to urbanization and agricultural waste disposal. This study investigates the distribution, temporal variation, enrichment and accumulation of heavy metals in the surface sediments from Biyyam backwaters. Samples were collected from four locations during post-monsoon (December 2017), pre-monsoon (March 2018) and monsoon (July 2018) seasons. Sediment texture, organic matter and heavy metals such as Mn, Co, Zn, Ni, Cr, Pb, Sc, Cd, and As were analyzed. The metal concentration in surface sediments decreased in the following order, i.e., Mn > Cr > Zn > Ni > Pb > As > Co > Sc > Cd. Spatio-temporal variability in distribution pattern of heavy metals show higher concentrations in upstream region. Heavy metal concentrations in surface sediments show relatively higher Igeo factors indicating contribution of heavy metals from agricultural and urban waste disposal. These relatively high values indicate that the Biyyam backwater is threatened by metal contamination, specifically by As, Cd, Cr and Ni. Biyyam backwater is an eco-tourism hub and a beautiful aquatic ecosystem, thus our results would help the local environmental managers to develop strategies to conserve the natural state of the kayal via managing the sources of pollution and sediment remediation in the area.

Assessment of zinc concentrations in surface sediment from urban and industrial sites of Umeda River, Japan

Abstract Heavy metal contamination in the urban river has become the most severe problem in the urban environment, especially the zinc (Zn) compound is harmful to the environment at current levels of exposure. This study aims to assess the impact of urbanization and industrialization on Zn pollution in surface sediment at the Umeda River. Triplicate surface sediment samples were collected at nine sample points. An atomic absorption spectrophotometer was used for analyzing the Zn and Fe concentrations. The surface sediments in the Umeda River contained 48–159 mg/kg of Zn. The results indicated that Zn concentrations were abundant in the ascending order of 600–1,000 μm, 300–600 μm, and smaller than 300 μm. The higher the grain size, the higher the particulate organic carbon which might contribute to the higher Zn and Fe concentrations. In addition, the sediment quality guidelines indicated that the Zn levels in the study area did not constitute a major threat to biota. Normalization with Fe showed that the Zn pollution in surface sediment had been influenced by anthropogenic activities such as industrialization and urbanization.

Monitored Natural Recovery of Contaminated Sediment in Cottonwood Bay, Texas

ABSTRACT Monitored natural recovery (MNR) is a response action for contaminated sediment that relies on natural processes to reduce ecological and human health risks to acceptable levels over time. Multi-media long-term monitoring is necessary to verify remedy effectiveness and success. Whereas MNR has most often been employed together with other engineered remedies to address contaminated sediment, this case study describes an evaluation demonstrating the suitability of MNR with adaptive management as a stand-alone sediment remedial strategy for Cottonwood Bay, located in Dallas, Texas. Current risks at the Cottonwood Bay site are associated with human consumption of fish contaminated with polychlorinated biphenyls (PCBs). The lines of evidence used to evaluate MNR included documentation of source control; review of PCB burial/isolation and surface sediment recovery; evaluation of sediment deposition and sediment stability; and demonstration of decreasing temporal trends in fish tissue PCB concentrations. The multiple lines of evidence demonstrated that source control and natural recovery processes have contributed substantially to reduced concentrations of PCBs and metals in surface sediments and PCBs in fish. MNR has been approved by the Texas Commission on Environmental Quality (TCEQ) and is incorporated as a stand-alone remedy in the revised Remedial Action Plan (RAP) for Cottonwood Bay. A long-term monitoring plan is being implemented as part of an MNR response action to confirm decreasing trends in surface sediment and fish fillet PCB concentrations over time and to demonstrate the continued effectiveness of natural recovery processes.

Plutonium isotopes in the northwestern South China Sea: Level, distribution, source and deposition

The spatial distribution of plutonium isotopes (239Pu, 240Pu) in the surface sediments collected from the northwestern South China Sea (SCS) in 2018 was investigated. The 239,240Pu concentrations in surface sediments vary from 0.048 to 0.960 mBq/g (with mean of 0.282 ± 0.242 mBq/g) depending on the geographical feature of the sampling location such as the river estuary, continental shelf, slope and deep basin. Higher 240Pu/239Pu atomic ratios (0.24–0.31) in the surface sediment of the SCS compared to the global fallout value of 0.18 were observed, this is attributed to the input of close-in fallout of the Pacific Proving Ground (PPG) transported by the North Equatorial Current and Kuroshio Current to the northern SCS. The contribution of the PPG derived plutonium in the SCS sediment was estimated to be 39%–78% using a simple two-end member mixing model based on the measured 240Pu/239Pu atomic ratios in the sediment. Besides the soluble 239,240Pu level in seawater, load of suspended particulate matter from the river runoff and biological debris, hydrographic and hydrodynamic conditions are key parameters influencing the deposition process of plutonium to the sediment.

Risk Assessment and Source Identification of Arsenic in Surface Sediments from Caohai Lake, China.

Urban freshwaters containing arsenic are facing an increasing problem of eutrophication. This study evaluated the spatial distribution, ecological risk, and origin of As in surface sediments obtained from Caohai Lake, a typical hypertrophic urban lake in China. It revealed that the total As concentration in surface sediments decreased gradually from north to south, consisted with the lake eutrophication status. The average As level was 161mg/kg, dominated by reducible and oxidisable fractions. The analyses of geoaccumulation index and enrichment factor indicated that As ranged between moderately-to-heavily and heavily contamination, was severely influenced by anthropogenic factors, i.e. industrial discharges and agricultural activities. Risk assessment code and potential ecological risk index results showed moderate to high potential ecological risk could be observed although the current As risk was low, supporting by the experimentally quantified As release data.

Modeling of the Surface Sediment Concentration in the Doce River Basin Using Orbital Remote Sensing

Modeling of the Surface Sediment Concentration in the Doce River Basin Using Orbital Remote Sensing

Impact of Enclosure Culture on Heavy Metal Content in Surface Sediments of Hongze Lake and Ecological Risk Assessment

In order to explore the concentrations of heavy metals and the influence of fencing on Hongze lake, the content, source, and spatial distribution characteristics of heavy metals in surface sediments and ecological risks were analyzed in 2018 after part of the fence around Hongze Lake was removed. The results showed that the average contents of Cr, Ni, Cu, Zn, As, Cd, and Pb in the surface sediments in Hongze Lake were 66.78, 33.89, 25.35, 74.77, 16.55, 0.23, and 27.20 mg·kg-1, respectively. Cr, Ni, Cu, Zn, and Pb contents were at non-polluting levels, with As and Cd at the lowest level, based on the accumulation index evaluation. Except for Cd, all the elements showed low potential ecological risk. The results showed that the heavy metal content in the fenced, dismantled, and peripheral areas increased and accumulated towards the center of the lake. The removal of the fence did not significantly reduce the heavy metal content in the short-term. Overall, Hongze Lake presented a state of low ecological risk. In the future, environmental policies should include surface sediment accumulation areas and fencing culture in the north and northeast of Hongze Lake.

Elevated levels of per- and polyfluoroalkyl substances (PFAS) in freshwater benthic macroinvertebrates from the Hudson River Watershed

Per- and polyfluoroalkyl substances (PFAS) are contaminants of global concern due to their persistence and associated negative health effects. Considerable attention has been given to monitoring PFAS in the aquatic environment, however, few investigations have done so using freshwater benthic macroinvertebrates (BMIs). As these bottom-dwelling animals are known to bioconcentrate exogenous pollutants to a high degree, studying their PFAS levels may provide a more integrated view of PFAS contamination in the aquatic environment. In this study, BMIs, sediment, and surface water were collected from two streams in the Hudson River Watershed (one historically-impacted by PFAS) and analyzed for 44 PFAS using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Orbitrap high-resolution mass spectrometry (HRMS) was used to confirm the identities of quantitated analytes. Across all matrices, 17 analytes were detected with PFOA dominating in surface water and PFOS in sediment/BMIs. PFOS bioaccumulation factors (BAFs) were approximately one order of magnitude higher than those of PFOA and ranged from 857 to 5151 L kg−1 across different BMI taxa. While PFAS concentrations in surface water and sediment were not excessively high, elevated levels were still measured in most BMI taxa. This observation suggests that the extent of PFAS contamination in a local system may be severely underestimated if only surface water and sediment are used for monitoring. Moreover, these findings have relevance for human exposure assessment considering BMIs are the primary food source of many fish.

Variability of Microbial Community Structure Distribution in Marine Shallow Surface Sediments in Shenhu Area

Due to the frequent exchange of matter and energy between living and non-living matter in seawater, the surface layer, particularly the distribution of microorganisms in centimeter-scale and element concentrations in surface sediments, demonstrates the important message of the local biogeochemical environment. This work probed the differences in microbial communities between two sampling cores obtained from the same area and the possible environmental factors, e.g., in situ component and concentration in porewater. Here, high-throughput sequencing (16S rRNA, Illumina sequencing) and quantitative PCR analysis were used to investigate the diversity of microorganisms in sediments of two push cores of L1 and S8 from Shenhu Area, South China Sea. Porewater concentration of components and isotopic fractionation were also obtained to explore the possible correlation between the microbial community and the chemical compositions of porewater. Q-PCR revealed bacteria play an important role in the geochemical cycle in the surface sediments, and archaea may be the main community in response to environmental changes and maintain the local marine ecosystem. The total gene copies of microorganisms in the study area were lower than nearby marine sediments. Microbial community compositions showed the dominant microbial phyla were similar on Phylum level in L1 and S8, with only different abundances. Firmicutes and Proteobacter were the main bacterial phyla, while Thaumarchaeota, Lokiarchaeota and Bathyarchaeota dominated the archaeal community. The abundance of the dominant class varied significantly between L1 and S8. Bacilli in Firmicutes and Gammaproteobacteria in Proteobacter were prevalent bacterial class, MGI in Thaumarchaeota was the predominant archaeal class in L1, while Thermoplasmata and Group-C3 dominated in S8. PCoA results showed a clear diversity of bacterial and archaeal communities between these two sites, as well as significant geographic variation in microbial communities. RDA results revealed that a complex combination of environmental factors might correlate to microbial communities in a marine dynamic environment. Here, δ13CDIC, DIC and SO4 2– were strongly correlated to the bacterial communities, whereas δ13CDIC, Fe2+ and SO4 2– concentration linked to archaeal communities. Microbial communities and RDA results suggested carbon may be the main factor related to the microbial community in L1, while Fe2+ correlated with microbial community composition in S8. SO4 2– concentration and the distribution of Gammaproteobacteria indicated that the sulfur cycle is probably active in this area.

Trends of Nitrogen and Phosphorus in Surface Sediments of the Lagoons of the Northern Adriatic Sea

The analysis of nutrient concentrations in surface sediments is a reliable tool for assessing the trophic status of a water body. Nitrogen and phosphorus concentrations are strongly related to the sediment characteristics but are mainly driven by anthropogenic impacts. The results of the determination of total nitrogen and total inorganic and organic phosphorus in surface sediments of the lagoons and ponds of the northwestern Adriatic Sea (Marano-Grado, Venice, Po Delta, Comacchio Valleys, Pialassa della Baiona) show the merit of this approach. Indeed, when previous data are available, the ratio between the actual and background values can provide useful information on the trophic changes that have occurred in the most recent times, and the results can also explain the conditions present in less studied environments. In this context, numerous studies performed in the Venice lagoon since the second half of the 20th century during different environmental scenarios provide mean concentration ranges and propose the main causes of changes. The results of single datasets available for the other lagoons fall into scenarios that occurred in the Venice lagoon. At present, the most eutrophic basins are Pialassa della Baiona, the Po Delta lagoons and ponds and the Comacchio valleys due to industrial effluents, fish farming and clam harvesting, respectively, whereas the Venice lagoon is now experiencing environmental recovery.