Spatiotemporal evolution of nutrients and the influencing factors in Laizhou Bay over the past 40 years.

The nutrient status in Laizhou Bay has changed in composition and structure as a result of anthropogenic activities and climate change, which has led to several environmental problems (e.g., eutrophication, organic pollution and red tides). To better understand the spatiotemporal variations in dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and eutrophication in the Laizhou Bay, we collected historical research data and conducted four cruises in 2021. The highest surface DIN was found to occur in autumn and predominantly concentrated in the southwestern bay. The highest surface DIP content was found in winter and distributed in the northwestern bay. Surface organic pollution showed estuaries as the most polluted areas. In the past 40-60 years, the DIN, DIP, and eutrophication have shown an inverted U-shaped trend, and the bay has changed from N limitation to P limitation. Economic development, phytoplankton absorption, and bottom mineral release are factors influencing the content and distribution of nutrient in the bay.

Compound effect of land reclamation and land-based pollutant input on water quality in Qinzhou Bay, China.

Based on a three-dimensional hydro-biogeochemical model, the compound and individual impacts of two types of human activities, i.e., land reclamation and land-based pollutant input, on coastal water quality were studied. In Qinzhou Bay (QZB), China, a total of 38.90 km2 of tidal flat was reclaimed between 2004 and 2019, and the Chemical Oxygen Demand (COD) in the wastewater was reduced by over 40%. However, the Dissolved Inorganic Nitrogen (DIN) was increased by above 40%, and the Dissolved Inorganic Phosphorus (DIP) was increased by about 17%, leading to the continuous deterioration of water quality in QZB. Correspondingly, the model results show that the bay's average COD decreased by 6.86%, but the DIN and DIP increased by 57.53% and 17.39%, respectively. Considering the individual effects, land reclamation contributed 72.73%, 75.38%, and 25.01% to the changes in the COD, DIN, and DIP concentrations in QZB, respectively; and the remainder was caused by the variations in the land-based pollutant input. By considering the compound effect of these two types of human activities, it was found that land reclamation can hinder the water quality improvement induced by the decrease in land-based pollutant input; and it can intensify the water quality deterioration induced by the increase in land-based pollutant input. These results indicate that the impact of land-based pollutant input on coastal water quality was modulated by land reclamation. However, the modulation did not affect the DIP since the phosphorus was the restrictive element in QZB. The comparison of different experimental results revealed that restoring hydrodynamics to enhance the bay-shelf exchange would be a more effective method of ecological restoration than solely reducing the pollutant input.

Lead contamination from gold mining in Yellowknife Bay (Northwest Territories), reconstructed using stable lead isotopes.

The contributions of contaminant sources are difficult to resolve in the sediment record using concentration gradients and flux reconstruction alone. In this study, we demonstrate that source partitioning using lead isotopes provide complementary and unique information to concentration gradients to evaluate point-source releases, transport, and recovery of metal mining pollution in the environment. We analyzed eight sediment cores, collected within 24 km of two gold mines, for Pb stable isotopes, Pb concentration, and sediment chronology. Stable Pb isotope ratios (206Pb/207Pb, 208Pb/204Pb) of mining ore were different from those of background (pre-disturbance) sediment, allowing the use of a quantitative mixing model. As previously reported for some Arctic lakes, Pb isotope ratios indicated negligible aerosol inputs to sediment from regional or long-range pollution sources, possibly related to low annual precipitation. Maximum recorded Pb flux at each site reached up to 63 mg m-2 yr-1 in the period corresponding to early years of mining when pollution mitigation measures were at a minimum (1950s-1960s). The maximum contribution of mining-derived Pb to these fluxes declined with distance from the mines from 92 ± 8% to 8 ± 4% at the farthest site. Mining-derived Pb was still present at the sediment surface within 9 km of Giant Mine more than ten years after mine closure (5-26 km, 95% confidence interval) and model estimates suggest it could be present for another ∼50-100 years. These results highlight the persistence of Pb pollution in freshwater sediment and the usefulness of Pb stable isotopes to quantify spatial and temporal trends of contamination from mining pollution, particularly as concentrations approach background.

Sedimentary record of hydrocarbons and sewage inputs from a highly populated region in South-Eastern Brazil.

The environmental impacts of the urban expansion in Rio de Janeiro was evaluated based on the historical accumulation of black carbon (BC), aliphatic (AHs) and aromatic hydrocarbons (PAHs) and sterols in a sediment core retrieved from Botafogo Cove. BC related to oil combustion sources increased significantly since the 1990s. AHs were associated with petroleum inputs and revealed a high level of contamination. Multivariate statistical methods (a Principal Component Analysis associated with a linear multiple regression - PCA/LMR) applied to PAHs suggests changes in the sources in recent years. This can be ascribed to a reduction in pyrogenic emissions over the last four decades and to an increase in petrogenic inputs since the 1990s. The sterol dinosterol registered the increased eutrophication over the last three decades, but the sewage marker coprostanol was present at relatively low concentrations (0.40 to 1.16 µg g-1) probably caused by enhanced bacterial activity in the sediment.

Oiling of the continental shelf and coastal marshes over eight years after the 2010 Deepwater Horizon oil spill.

We measured the temporal and spatial trajectory of oiling from the April, 2010, Deepwater Horizon oil spill in water from Louisiana's continental shelf, the estuarine waters of Barataria Bay, and in coastal marsh sediments. The concentrations of 28 target alkanes and 43 target polycyclic aromatic hydrocarbons were determined in water samples collected on 10 offshore cruises, in 19 water samples collected monthly one km offshore at 13 inshore stations in 2010 and 2013, and in 16-60 surficial marsh sediment samples collected on each of 26 trips. The concentration of total aromatics in offshore waters peaked in late summer, 2010, at 100 times above the May, 2010 values, which were already slightly contaminated. There were no differences in surface or bottom water samples. The concentration of total aromatics declined at a rate of 73% y-1 to 1/1000th of the May 2010 values by summer 2016. The concentrations inside the estuary were proportional to those one km offshore, but were 10-30% lower. The oil concentrations in sediments were initially different at 1 and 10 m distance into the marsh, but became equal after 2 years. Thus, the distinction between oiled and unoiled sites became blurred, if not non-existent then, and oiling had spread over an area wider than was visible initially. The concentrations of oil in sediments were 100-1000 times above the May 2010 values, and dropped to 10 times higher after 8 years, thereafter, demonstrating a long-term contamination by oil or oil residues that will remain for decades. The chemical signature of the oil residues offshore compared to in the marsh reflects the more aerobic offshore conditions and water-soluble tendencies of the dissolved components, whereas the anaerobic marsh sediments will retain the heavier molecular components for a long time, and have a consequential effect on the ecosystems.

Phototoxicity Assessments of Field Sites in Barataria Bay, Louisiana, USA, and Heavily Weathered Macondo Crude Oil: 4 Years after the Deepwater Horizon Oil Spill.

The Deepwater Horizon oil spill resulted in the release of large amounts of crude oil into waters of the Gulf of Mexico (USA). A significant portion of the oil reached coastal waters and shorelines where aquatic organisms reside. Four years after the spill, oil remains in small quantities along the coast. Given the high volume of oil coupled with the high ultraviolet light intensities of the Gulf of Mexico, continued polycyclic aromatic hydrocarbon phototoxicity may be occurring in the Gulf region. The objective of the present study was to determine the potential for phototoxicity at 5 field sites (oiled, remediated, and unoiled) in Barataria Bay (LA, USA) to caged mysid shrimp and sheepshead minnows and to evaluate the phototoxic potential of field-collected oil water accommodated fractions (WAFs). Water chemistries were similar between field-collected oil WAFs and ambient waters, excluding the most oiled field site. Field bioassays indicated no phototoxic risk of heavily weathered crude oil under the highly turbid conditions present during the study. Laboratory WAFs of field-collected oil resulted in phototoxicity to mysid shrimp, suggesting a potential for phototoxicity of heavily weathered crude oil remaining in the Gulf of Mexico. Environ Toxicol Chem 2019;38:1811-1819. © 2019 SETAC.

Temporal and spatial variations and impact factors of nutrients in Bohai Bay, China.

The temporal and spatial distributions of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved silicate (DSi), and their long-term changes were investigated in Bohai Bay (BHB) in spring, summer, and autumn (2013-2014). The high DIN values were consistently distributed in the western inshore waters, mainly determined by terrestrial factors, e.g., riverine input, while DIP and DSi were mostly distributed in the southern coastal waters, the central BHB, or near the sea port Caofeidian in northern BHB, largely related to non-terrestrial factors, e.g., sediment release. Based on the nutrient distribution, BHB could be partitioned into western and eastern parts, with -15 m depth as the separation. The long-term variations of nutrients since 2000 showed an increase in DIN and decreases in DIP and DSi. Relatively slow changes in DIN and DIP and a rapid decrease in DSi were exhibited in summer, which was associated with precipitation and sediment release.

Using multivariate statistical analyses to identify and evaluate the main sources of contamination in a polluted river near to the Liaodong Bay in Northeast China.

Using multivariate statistical analysis, the study evaluated anthropogenic sources of river water contamination and their relationships with river water quality in the Haicheng River basin near to the Liaodong Bay in Northeast China. The results showed that nitrogen (N) and phosphorous (P) were identified as the main pollutants in the river water by factor analysis. Human population and elevational gradient were all significantly correlated with N, P, and other water quality variables in correlation analysis and explained chemical oxygen demand (COD), N, and P variables from 23.9% (TN) to 53.1% (NH3+-N) of the total variances in regression analysis, indicating that population and its distribution were all responsible for river contaminations, especially for COD, N, and P contaminations. The excessive applications of fertilizers and pesticides were all positively correlated with nitrogen variables and nitrogen pollution factor in correlation analysis, suggesting that agricultural activities were contributed to the river nitrogen pollution. Due to inadequate or lack wastewater treatment facilities, huge amounts of domestic sewage and industrial effluents were released into the river, becoming the predominant anthropogenic sources for the river water deterioration of COD, N, and P. Multivariate statistical analysis provided useful tools to correlate sources of contamination with water quality data. This approach will provide a better management for river pollution control in a human-driven river ecosystem.

Phosphorus sorption behavior on sediments in Sanggou Bay related with their compositions by sequential fractionation.

The surficial sediment samples collected from the Sanggou Bay in China were treated by a sequential extraction procedure. After removal of calcite, organic matter and Fe/Mn oxides, P adsorption onto the sediment residues was then evaluated through kinetic and thermodynamic characteristics. The sorption kinetic curves could be described by a two-compartment first order equation. The sorption isotherms fit well with the Langmuir and Freundlich equations. The HCl-treated sediments with calcite removed showed a rising fraction of the rapid step and a higher P adsorption potential compared with the un-extracted samples. For the clay minerals and silicate residue after NH2OH·HCl treatment, the rapid step fraction was dominant, the sorption capability was prohibited, and the process was much more reversible than the original and previously-generated samples. An increase of temperature was favorable for the sorption. Estimation of thermodynamic parameters showed that the process was spontaneous and endothermic, with an increased randomness at the solid-liquid interface. Compared with the un-extracted sediment, the thermodynamic parameters in our case changed slightly after HCl treatment and NH2OH·HCl treatment.

Occurrence, source and ecological assessment of petroleum related hydrocarbons in intertidal marine sediments of the Bay of Fundy, New Brunswick, Canada.

Total petroleum hydrocarbons (TPH), n-alkanes, petroleum-related biomarkers of terpanes and steranes, and polycyclic aromatic hydrocarbons (PAHs) were analyzed in the intertidal sediments in the Bay of Fundy, Nova Scotia/New Brunswick, Canada. Sites close to the harbour and more densely populated areas had higher TPH levels than other pristine areas. n-Alkanes presented a typical single bell-shape in n-C16 to n-C35 range and an obvious odd to even carbon preference. Most sites had trace amounts of petroleum biomarkers. Abundant non-alkylated PAHs and lower amounts of alkylated PAHs represented the major input of the incomplete combustion of solid (e.g., coal, coke, biomass, and coal tar) and liquid fuels. The toxicity estimation for PAHs indicates that they did not have potential toxicity to benthic organisms at most sampling sites. However, possible to probable negative effects from the measured PAH concentrations were found for the two samples from Courtenay Bay and Saint Andrews.

Sediment bacterial community structures and their predicted functions implied the impacts from natural processes and anthropogenic activities in coastal area.

Coastal ecosystem structures and functions are changing under natural and anthropogenic influences. In this study, surface sediment samples were collected from disturbed zone (DZ), near estuary zone (NEZ), and far estuary zone (FEZ) of Hangzhou Bay, one of the most seriously polluted bays in China. The bacterial community structures and predicted functions varied significantly in different zones. Firmicutes were found most abundantly in DZ, highlighting the impacts of anthropogenic activities. Sediment total phosphorus was most influential on the bacterial community structures. Predicted by PICRUSt analysis, DZ significantly exceeded FEZ and NEZ in the subcategory of Xenobiotics Biodegradation and Metabolism; and DZ enriched all the nitrate reduction related genes, except nrfA gene. Seawater salinity and inorganic nitrogen, respectively as the representative natural and anthropogenic factor, performed exact-oppositely in nitrogen metabolism functions. The changes of bacterial community compositions and predicted functions provide a new insight into human-induced pollution impacts on coastal ecosystem.

Stable isotopes in water indicate sources of nutrients that drive algal blooms in the tributary bay of a subtropical reservoir.

Eutrophication has become a severe environmental problem in some tributaries of the Three Gorges Reservoir (TGR) in China. A two-year field investigation of nutrients, oxygen stable isotopes (δ18O), and hydrogen stable isotopes (δD) was performed from January 2010 to December 2011 to determine the sources of nutrients in Xiangxi Bay (XXB). The results showed that nitrogen, phosphorus and silicon varied seasonally depending on hydrodynamic changes. The bottom-layer intrusive density current decreased nitrogen and silicon concentrations and increase phosphorus concentrations in XXB, while the middle-layer intrusive density current increased nitrogen and silicon concentrations and decrease phosphorus concentrations. The differences in δ18O and δD among the Yangtze River (YR), XXB and the region upstream of XXB were significant, and according to the tracer method, the estimated contribution ratios of nitrogen, phosphorus and silicon from the YR to XXB were much larger than those from the region upstream of XXB. These findings suggest that water quality in the TGR can be improved by reducing the pollution load throughout the upstream basin of the YR but not through decentralized efforts in only one or two tributary basins.

Aerosol concentrations and atmospheric dry deposition fluxes of nutrients over Daya Bay, South China Sea.

Based on one and a half years of observations (September 2015 to March 2017) in Daya Bay, we analysed the nutrient concentrations in aerosols and calculated dry deposition fluxes of nutrients. DON was the dominant species of TDN in aerosol particles, accounting for 63.3%. The mean values of DIP, DOP and DSi were 0.78, 0.61 and 2.6 nmol·m-3, respectively. The mean fluxes of nutrients (TDN, TDP and DSi) from dry deposition during the field observation were 2150, 7.4 and 28.2 µmol·m-2·month-1, respectively. The fluxes of nitrogen species show a seasonal pattern with higher input in spring and winter. The dry deposition of nutrients accounted for approximately 20% of the total deposition budget. The molar ratios of DIN/DIP in the dry deposition (mean value 167) suggest that atmospheric dry deposition of nutrients may increase the risk of the unbalanced nutrient condition in the seawater column of Daya Bay.

Distribution of hydrocarbons in seabed sediments derived from tsunami-spilled oil in Kesennuma Bay, Japan.

As a result of the 2011 Great East Japan earthquake, about 11,000kL of fuel oil was spilled into Kesennuma Bay, Miyagi Prefecture. This oil either accumulated in seabed sediments or was burned in a marine fire on the sea surface. We investigated spatial and temporal variations in the concentrations of oil and hydrocarbons. The maximum concentrations of n-hexane extract (NHE), total petroleum hydrocarbon (TPH), and polycyclic aromatic hydrocarbons (PAHs) in the sediments in 2012 were 8000, 1200, and 16.2mg/kg (DW), respectively. NHE and TPH concentrations were high in the inner and west bay, and PAHs concentrations were high in the east bay. NHE and PAH concentrations didn't change; however, TPH concentrations decreased significantly with time. The total NHE in the sediment across the whole bay was estimated at 1685kL and there was still about 13% of the original amount in the sediment in December 2014.

Semivariance analysis and transinformation entropy for optimal redesigning of nutrients monitoring network in San Francisco bay.

This paper introduces a Semivariance-Transinformation (S-T) based method for designing an optimum bay water nutrients monitoring network in San Francisco bay (S.F. bay), USA. Phosphorus and nitrogen are the most important nutrients that lead to eutrophic condition. The monthly phosphate and nitrate+nitrite data recorded during September 2006 to August 2015 was obtained over 14 active stations located at S.F. bay and was used in the research. Semivariance and discrete transinformation entropy have been applied to calculate the optimum range of the monitoring distance. The study indicated the ranges of 28 to 82 and 37 to 50km for the phosphate and nitrate+nitrite respectively. Useful information can be obtained from the monitoring network, if the monitoring distance is included in the mentioned intervals. The findings of the research introduce a new approach in the field of water quality monitoring networks design.

Use of the sea hare (Aplysia fasciata) in marine pollution biomonitoring of harbors and bays.

Our study evaluated heavy metal concentrations in soft tissues of sea hare, Aplysia fasciata, from the Lower Laguna Madre, Texas. Heavy metals in tissues followed Se>As>Pb>Cd. Concentrations ranged As (BDL-28.08), Cd (BDL-5.50), Pb (BDL-12.85) and Se (4.25-93.43ppm). Median As, Cd, Pb, and Se tissue levels exceeded exposure levels. Significant relationships occurred in metal-metal (AsCd, AsPb, CdPb, CdSe, and PbSe), metal-tissue (significant Se uptake by inhalant and exhalant siphons and As in the hepatopancreas), and metal-metal within tissue (AsPb in the hepatopancreas and CdPb in the digestive cecum) analyses (p<0.05). Bioaccumulation factors (BAF) suggested the inhalant siphon, hepatopancreas, and digestive cecum function as macroconcentrators of Cd, hepatopancreas and digestive cecum as macroconcentrators of Pb, and all tissues were deconcentrators for As and Se. As a bioaccumulator of heavy metals, Aplysia was evaluated as a bioindicator of marine pollution in harbors and bays.

Quantitative model of carbon and nitrogen isotope composition to highlight phosphorus cycling and sources in coastal sediments (Toulon Bay, France).

Nutrient loadings from either point or non-point sources to the environment are related to the growing global population. Subsequent negative impacts of nutrient loading to aquatic environments requires a better understanding of the biogeochemical cycling and better tools to track their sources. This study examines the carbon (C), nitrogen (N) and phosphorus (P) discharge and cycling in a Mediterranean coastal area from rivers to marine sediments and assesses the anthropogenic contributions. Carbon and N concentrations and isotope compositions in rivers particles, surface sediments, and sediment cores were investigated to build up a quantitative multiple-end-member mixing model for C and N isotopes. This model predicts the contribution of four natural and one anthropogenic sources to the sediments and highlighted the anthropogenic fraction of P based on the relationship with anthropogenic δ15N. Although P is a monoisotopic element and total P concentration has been the sole index to study P loading, this study suggests an alternative approach to differentiate anthropogenic and non-anthropogenic (diagenetic) P, revealed point and non-point sources of P, and the corresponding P loading. Also, the diagenetic P background has been calculated for the 50-cm sediment layer of the whole Bay.

Petroleum Hydrocarbon Profiles of Water and Sediment of Algoa Bay, Eastern Cape, South Africa.

Petroleum hydrocarbon profiles of water and sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed using standard analytical procedures. Water (from surface and bottom levels) and sediment samples were collected from five locations in the bay from February to June 2016. Extraction of the petroleum hydrocarbons from the water and sediment samples collected was achieved using liquid-liquid and Soxhlet extraction techniques, respectively, followed by column clean up. Target compounds were analytically determined with gas chromatography-flame ionization detector (GC-FID) and quantified by integrating the areas of both the resolved and unresolved components. Physicochemical properties of the water samples were also determined on site using a SeaBird 19plusV2 CTD SBE 55 device. Estimated limit of detection, limit of quantitation and relative standard deviation for the 35 n-alkane standards ranged from 0.06 to 0.13 µg/L, 0.30 to 0.69 µg/L and 3.61 to 8.32%, respectively. Results showed that total petroleum hydrocarbon (TPH) varied from 45.07 to 307 µg/L in the water and 0.72 to 27.03 mg/kg in the sediments. The mean concentrations of TPH in both the water and sediment samples from Algoa Bay revealed a slight level of pollution. The diagnostic indices used showed that the hydrocarbons in the area were from both biogenic and anthropogenic sources. Hence, there is need for adequate regulation and control of all activities contributing to the levels of petroleum hydrocarbon in the marine environment for the safety of human, aquatic and wild lives in the area.

Body burdens, sources and interrelations of selected toxic and essential elements among the nine Cree First Nations of Eeyou Istchee, James Bay region of northern Quebec, Canada.

BACKGROUND: this article constitutes a report on the comprehensive Nituuchischaayihtitaau Aschii multi-community environment-and-health study conducted among the Cree peoples (Eeyouch) of northern Quebec, Canada. OBJECTIVES: to interpret observed concentrations of a suite of chemical elements in a multi-media biological monitoring study in terms of sources and predictors. METHODS: the concentrations of 5 essential and 6 toxic chemical elements were measured in whole blood, and/or in urine or hair by ICP-MS. Concentrations of essential elements are compared to those considered normal (i.e., required for good health) and, when toxic, deemed acceptable at specified concentrations in public health guidelines. Their dependence on age, sex, the specific community lived-in and diet were explored employing multivariate analysis of variance (MANOVA) involving new variables generated by principle component analysis (PCA) and correspondence analysis (CA). RESULTS: the 5 most prominent PCA axes explained 67.7% of the variation, compared to 93.0% by 6 main CA factors. Concentrations of the essential elements in whole blood (WB) and iodine(i) and arsenic (As) in urine were comparable to those reported in the recent Canadian Health Measures survey and are assigned to dietary sources. By contrast, WB cadmium (Cd) was elevated even when smoking was considered. Mercury (Hg) concentrations in WB and hair were also higher in adults, although comparable to those observed for other indigenous populations living at northern latitudes. Fish consumption was identified as the prominent source. Of the 5 coastal communities, all but one had lower Hg exposures than the four inland communities, presumably reflecting the type of fish consumed. Use of firearms and smoking were correlated with WB-lead (Pb). The concentrations of both Hg and Pb increased with age and were higher in men, while WB-Cd and smoking prevalence were higher in women when considering all communities. Hg and Pb were low in children and women of reproductive age, with few exceedances of health guidelines. Although individuals with T2D had somewhat lower WB-Cd, there is some indication that Cd may potentiate renal dysfunction in this subgroup. Plots of selected CA axes grouped those elements expected to be in a normal diet and distinguished them from those with well-known unique sources (especially Hg and As in hair; and Hg, Pb and Cd in WB). CONCLUSIONS: the use of multiple biological media in conjunction with the complementary PCA and CA approaches for constructing composite variables allowed a more detailed understanding of both the sources of the essential and toxic elements in body fluids and the dependencies of their observed concentrations on age, sex, community and diet.

Capability of Paraguaçu estuary (Todos os Santos Bay, Brazil) to form oil-SPM aggregates (OSA) and their ecotoxicological effects on pelagic and benthic organisms.

For experiments concerning the formation of oil-suspended particulate matter (SPM) aggregates (OSA), oil and sediment samples were collected from Campos Basin and six stations of Paraguaçu estuary, Todos os Santos Bay, Brazil, respectively. The sediments samples were analyzed for organic matter determined by the EMBRAPA method, nitrogen determined by the Kjeldahl method, and phosphorus determined by the method described by Aspila. The oil trapped in OSA was extracted following the method described by Moreira. The experiment showed a relationship between the amount of organic matter and OSA formation and consequently the dispersion of the studied oil. On the basis of the buoyancy of OSA and the ecotoxicological effects on pelagic and benthic community, the priority areas for application of remediation techniques are Cachoeira, Maragogipe, and Salinas da Margarida because of the large amount of oil that accumulated at the bottom of the experiment flask (5.85%, 27.95%, and 38,98%; 4.2%, 17.66%, and 32.64%; and 11.82%, 8.07%, and 10.91% respectively).