Characteristics and risk assessment of potentially toxic elements pollution in river water and sediment in typical gold mining areas of Northwest China.

To assess the concentration characteristics and ecological risks of potential toxic elements (PTEs) in water and sediment, 17 water samples and 17 sediment samples were collected in the Xiyu River to analyze the content of Cr, Ni, As, Cu, Zn, Pb, Cd and Hg, and the environmental risks of PTEs was evaluated by single-factor pollution index, Nemerow comprehensive pollution index, potential ecological risk, and human health risk assessment. The results indicated that Hg in water and Pb, Cu, Cd in sediments exceeded the corresponding environmental quality standards. In the gold mining factories distribution river section (X8-X10), there was a significant increase in PTEs in water and sediments, indicating that the arbitrary discharge of tailings during gold mining flotation is the main cause of PTEs pollution. The increase in PTEs concentration at the end of the Xiyu River may be related to the increased sedimentation rate, caused by the slowing of the riverbed, and the active chemical reactions at the estuary. The single-factor pollution index and Nemerow pollution index indicated that the river water was severely polluted by Hg. Potential ecological risk index indicated that the risk of Hg in sediments was extremely high, the risk of Cd was high, and the risk of Pb and Cu was moderate. The human health risk assessment indicated that As in water at point X10 and Hg in water at point X9 may pose non-carcinogenic risk to children through ingestion, and As at X8-X10 and Cd at X14 may pose carcinogenic risk to adults through ingestion. The average HQingestion value of Pb in sediments was 1.96, indicating that the ingestion of the sediments may poses a non-carcinogenic risk to children, As in the sediments at X8-X10 and X15-X17 may pose non-carcinogenic risk to children through ingestion.

Utilization of metal and radionuclide concentrations to assess the influence of shrimp farming on the geochemical characteristics of sediments.

This article assesses the environmental impacts of aquatic biota cultivation, focusing on shrimp farming in Brazil's Northeast, as this practice has proven to be one of the main sources of economic growth in the region. For this purpose, sediment samples were collected from areas impacted and not directly impacted by shrimp farming, and concentrations of key geochemical parameters such as salinity, various elements (K, P, Cu, Mn, Pb, Zn, Al, Ca, Fe, Mg, and Na), and natural radionuclides (K-40, Ra-226 and Ra-228) were compared using statistical tools. Element concentrations were determined using ICP-OES, and naturally occurring radionuclide concentrations were obtained through gamma spectrometry. Statistical tests, such as ANOVA and/or Mann-Whitney, cluster analysis, and principal component analysis, were applied to the results. Additionally, the ERICA Tool software was employed to estimate deleterious effects on both human and non-human biota. Descriptive statistics reveal variability in sediment parameters around shrimp farming. ANOVA and Mann-Whitney tests compare concentrations of shrimp farm sediment and not directly impacted sediment, showing non-significant differences for most elements. pH and salinity, crucial for shrimp health, exhibit higher values in shrimp farm sediment. Alkali and alkaline earth metals, including K and Na, show no significant differences. Factor and cluster analyses suggest that certain elements, mainly radionuclides, are influenced by sediment variability. Hazard indices for naturally occurring radionuclides indicate negligible risk to both human and non-human biota, reinforcing the absence of adverse effects from shrimp farming activities. This study provides a comprehensive analysis of the environmental impacts of shrimp farming, emphasizing the importance of monitoring geochemical parameters for coastal environmental management.

Risk assessment of heavy metals and total petroleum hydrocarbons (TPHs) in coastal sediments of commercial and industrial areas of Hormozgan province, Iran.

The significant increase in the pollution of heavy metals and organic pollutants, their stable nature, and their high toxicity are gradually becoming a global crisis. In a recent study, a comprehensive assessment of the spatial distribution of heavy metals and total petroleum hydrocarbons (TPHs), as well as an assessment of their ecological risks in the sediments of 32 stations located in commercial and industrial areas (Mainly focusing on petrochemical and power industries, desalination plants and transit Ports) of Hormozgan province (East and West of Jask, Bandar Abbas, Qeshm, and Bandar Lengeh) was performed during 2021-2022. The sediment samples were digested with HNO3, HCl and HF solvents. The concentration of heavy metals was determined with furnace and flame systems of atomic absorption spectrometer. The concentration of heavy metals showed significant spatial changes between stations. The ecological assessment indices between the regions indicated that the stations located in Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan had a higher intensity of pollution than other places and significant risks of pollution, especially in terms of Cr and Ni. The average contamination degree (CD) (14.89), modified contamination degree (MCD) (2.48), pollution load index (PLI) (2.32), and potential ecological risk index (PERI) (100.30) showed the sediments in the area of Shahid Bahonar Port, Suru beach and Khor gorsouzuan, experience significant to high levels of pollution, especially Cr and Ni. Using contamination factor (CF) and Geoaccumulation index (Igeo), Cr was considered the most dangerous metal in the studied areas. Based on the global classification of marine sediment quality for the concentrations of TPHs, the sediments of the studied stations were classified as non-polluted to low pollution. In all regions, indices of the PELq (General toxicity) and CF (Contamination factor) were much lower than 0.1 and 1 respectively, showing the absence of adverse biological effects caused by TPHs in sediments. It is necessary to consider comprehensive and impressive strategies to control and reduce pollution of heavy metals, especially in the areas of Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan, so that the sources of this pollution are required to be identified and managed.

An extensive investigation on human risk associated with PAHs in fish and sediment in Bushehr, Northern of Persian Gulf.

Here, a comprehensive study was designed to estimate the human risk assessment attributed to exposure of polycyclic aromatic hydrocarbons (PAHs)in sediment and fish in most polluted shore area in north of Persian Gulf. To this end, a total of 20 sediment and inhabitual Fish, as one of most commercial fish, samples were randomly collected from 20 different stations along Bushehr Province coastline. The 16 different components of PAHs were extracted from sediment and edible parts of inhabitual fish and measured with high-performance liquid chromatography (HPLC) and gas chromatography (GC), respectively. In addition, dietary daily intake (DDI) values of PAHs via ingestion Indian halibut and the incremental lifetime cancer risk (ILCR) attributed to human exposure to sediments PAHs via (a) inhalation, (b) ingestion, and (c) dermal contact for two groups of ages: children (1-11 years) and adults (18-70 years) were estimated. The results indicated that all individual PAHs except for Benzo(b)flouranthene (BbF) and Benzo(ghi) perylene (BgP) were detected in different sediment sample throughout the study area with average concentration between 2.275 ± 4.993 mg.kg-1 dw. Furthermore, Naphthalene (Nap) with highest average concentration of 3.906 ± 3.039 mg.kg-1 dw was measured at the Indian halibut. In addition, the human risk analysis indicated that excess cancer risk (ECR) attributed to PAHs in sediment and fish in Asaluyeh with high industrial activities on oil and derivatives were higher the value recommended by USEPA (10-6). Therefore, a comprehensive analysis on spatial distribution and human risk assessment of PAHs in sediment and fish can improve the awareness on environmental threat in order to aid authorities and decision maker to find a sustainable solution.

Characteristics of inclusions in chang 7 member and shale oil accumulation stages in Zhijing-Ansai area, Ordos Basin.

In order to further clarify the shale oil accumulation period of the Chang 7 member of the Mesozoic Triassic Yanchang Formation in the Zhijing-Ansai area of the central Ordos Basin, Using fluid inclusion petrography analysis, microscopic temperature measurement, salinity analysis and fluorescence spectrum analysis methods, combined with the burial history-thermal history recovery in the area, the oil and gas accumulation period of the Chang 7 member of the Yanchang Formation in the Zhijing-Ansai area was comprehensively analyzed. Sixteen shale oil reservoir samples of the Mesozoic Triassic Yanchang Formation in seven typical wells in the study area were selected.The results show that the fluid inclusions in the Chang 7 member of Yanchang Formation can be divided into two stages. The first stage inclusions mainly develop liquid hydrocarbon inclusions and a large number of associated brine inclusions, which are mainly beaded in fracture-filled quartz and fracture-filled calcite. The fluorescence color is blue and blue-green, and the homogenization temperature of the associated brine inclusions is between 90-110°C. The second stage inclusions are mainly gas-liquid two-phase hydrocarbon inclusions, gas inclusions and asphalt inclusions. Most of them are distributed in the fracture-filled quartz, and the temperature of the associated brine inclusions is between 120-130°C. Fluid inclusions in Chang 7 member of the Yanchang Formation can be divided into two stages. The CO2 inclusions and high temperature inclusions in the Chang 7 member of the Yanchang Formation are mainly derived from deep volcanic activity in the crust.

Historical construction, quantitative source identification and risk assessment of heavy metals contamination in sediments from the Pearl River Estuary, South China.

Historical reconstruction of heavy metals (HMs) contamination in sediments is a key for understanding the effects of anthropogenic stresses on water bodies and predicting the variation trends of environmental state. In this work, eighteen sediment cores from the Pearl River Estuary (PRE) were collected to determine concentrations and geochemical fractions of HMs. Then, their potential sources and the relative contributions during different time periods were quantitatively identified by integrating lead-210 (210Pb) radioisotope dating technique into positive matrix factorisation (PMF) method. Pollution levels and potential ecological risks (PERs) caused by HMs were accurately assessed by enrichment factors (EF) based on establishment of their geochemical baselines (GCBs) and multiparameter evaluation index (MPE). HMs concentrations generally showed a particle size- and organic matter-dependent distribution pattern. During the period of 1958-1978, HMs concentrations remained at low levels with agricultural activities and natural processes being identified as the predominant sources and averagely contributing >60%. Since the reform and opening-up in 1978, industrial and traffic factors become the primary anthropogenic sources of HMs (such as Cu, Zn, Cd, Pb, Cr, and Ni), averagely increasing from 22.1% to 28.1% and from 11.6% to 23.4%, respectively. Conversely, the contributions of agricultural and natural factors decreased from 37.0% to 28.5% and from 29.3% to 20.0%, respectively. Subsequently, implementation of environmental preservation policies was mainly responsible for the declining trend of HMs after 2010. Little enrichment of sediment Cu, Zn, Pb, Cr and Ni with EFs (0.15-1.43) was found in the PRE, whereas EFs of Cd (1.16-2.70) demonstrated a slight to moderate enrichment. MPE indices of Cu (50.7-252), Pb (52.0-147), Zn (35.5-130), Ni (19.6-71.5), Cr (14.2-68.8) and Cd (0-9.90) highlighted their potential ecological hazards due to their non-residual fractions and anthropogenic sources.

Occurrence, source apportionment and ecological risk of bisphenol analogues in river sediments in areas with different land use patterns.

Bisphenol analogues (BPs) have gained increasing attention in recent years due to their ubiquitousness and potential endocrine disrupting properties in environments. However, little information is available on their spatiotemporal distribution, source apportionment and ecological risk in river sediments, especially the case in river basins with a high population density and those typical regions with agricultural-urban gradient, where land use patterns and intensity of human activity are varying. In this study, field investigations of BPs in the sediment of the entire Qinhuai River Basin, a typical agricultural-suburban agricultural-urban gradient area, were conducted before and after the flood period. Thirty-two sites were sampled for six types of BPs, resulted in no significant difference in the concentration of ΣBPs between the two periods, with ΣBPs ranging from 3.92 to 151 ng/g and 2.16-59.0 ng/g, respectively. Bisphenol A (BPA) was the main contributor. Whereas a multivariate analysis of variance (MANOVA) suggested that the composition structure of BPs had been influenced by water periods. The land use patterns had an impact on the distribution of ΣBPs in river sediments, which was more significant in after the flood period, with ΣBPs in urban rivers was 1.85 times, 3.44 times, and 3.08 times higher than the suburban rivers, agricultural rivers, and reservoirs, respectively. Yet land use types did not significantly alter the composition structure of BPs. The correlation analysis between BPs and the physicochemical properties of sediments showed a significant positive correlation between BPA and total organic carbon (TOC). The positive matrix factorization model (PMF) suggested that BPs in sediments of the basin might be influenced by industrial coatings, textiles, electronics and biopharmaceuticals, as well as urban wastewater or solid waste generated from daily life. The ecological risk assessment posed by BPA, based on the risk quotient, indicated that the ecological risk of BPA in sediments was low for three indicator benthic organisms: crustaceans, worms, and mollusks. However, the risk of BPA in river sediments varied among different land use patterns, with the risk ranking as follows: reservoirs < agricultural rivers < suburban rivers < urban rivers.

Spatial distribution and pollution assessment of metals in sediments along the industrialized coast of East Java, Indonesia.

The eastern coastline of Gresik, located in East Java, Indonesia, experienced significant industrialization, leading to the development of numerous diverse sectors. These diverse industrial activities, in addition to other human activities, result in the contamination of sediment across the eastern coast of Gresik with a variety of metals. Metals like arsenic (As), cadmium (Cd), copper (Cu), and zinc (Zn) have exceeded the international standards for sediment quality, potentially causing significant harm to the aquatic ecosystem in this coastal region. The results of the multivariate analysis indicate that the metals found in the sediment are related to a combination of anthropogenic inputs, specifically those originating from industrial effluents in the area under study. Based on the assessment of enrichment factor, contamination factor, geo-accumulation index, degree of contamination, ecological risk index, and pollution load index, it can be concluded that the metals examined displayed different degrees of sediment contamination, ranging from minimal to severely contaminated.

Revealing climatic and groundwater impacts on the spatiotemporal variations in vegetation coverage in marine sedimentary basins of the North China Plain, China.

The North China Plain (NCP) is one of the three great plains in China and also serves as a vital region for grain, cotton, and oil production. Under the influence of regional hydrothermal changes, groundwater overexploitation, and seawater intrusion, the vegetation coverage is undergoing continuous alterations. However, a comprehensive assessment of impacts of precipitation, temperature, and groundwater on vegetation in marine sedimentary regions of the NCP is lacking. Heilonggang Basin (HB) is located in the low-lying plain area in the east of NCP, which is part of the NCP. In this study, the HB was chosen as a typical area of interest. We collected a series of data, including the Normalized Difference Vegetation Index (NDVI), precipitation, temperature, groundwater depth, and Total Dissolved Solids (TDS) from 2001 to 2020. Then the spatiotemporal variation in vegetation was analyzed, and the underlying driving mechanisms of vegetation variation were explored in this paper. The results show that NDVI experiences a rapid increase from 2001 to 2004, followed by stable fluctuations from 2004 to 2020. The vegetation in the HB has achieved an overall improvement in the past two decades, with 76% showing improvement, mainly in the central and eastern areas, and 24% exhibiting deterioration in other areas. From 2001 to 2020, NDVI correlates positively with precipitation, whereas its relationship with temperature fluctuates between positive and negative, and is not statistically significant. There is a threshold for the synergistic change of NDVI and groundwater depth. When the groundwater depth is lower than 3.8 m, NDVI increases sharply with groundwater depth. However, beyond this threshold, NDVI tends to stabilize and fluctuate. In the eastern coastal areas, NDVI exhibits a strong positive correlation with groundwater depth, influenced by the surface soil TDS controlled by groundwater depth. In the central regions, a strong negative correlation is observed, where NDVI is primarily impacted by soil moisture under the control of groundwater. In the west and south, a strong positive correlation exists, with NDVI primarily influenced by the intensity of groundwater exploitation. Thus, precipitation and groundwater are the primary driving forces behind the spatiotemporal variability of vegetation in the HB, while in contrast, the influence of temperature is uncertain. This study has elucidated the mechanism of vegetation response, providing a theoretical basis for mitigating adverse factors affecting vegetation growth and formulating rational water usage regulations in the NCP.

Mobility, bioavailability and distribution of Fe and Cu in mangroves (Avicennia schaueriana and Rhizophora mangle) from a semiarid coast in NE Brazil.

Mangroves buffer metals transfer to coastal areas though strong accumulation in sediments making necessary to investigate metals' bioavailability to plants at the rhizosphere. This work evaluates the effect of mangrove root activity, through iron plaque formation, on the mobility of iron and copper its influence on metals' uptake, and translocation through simultaneous histochemical analysis. The Fe2+ and Fe3+ contents in porewaters ranged from 0.02 to 0.11 µM and 1.0 to 18.3 µg.l-1, respectively, whereas Cu concentrations were below the method's detection limit (<0.1 µM). In sediments, metal concentrations ranged from 12,800 to 39,500 µg.g-1 for total Fe and from 10 to 24 µg.g-1 for Cu. In iron plaques, Cu concentrations ranged from 1.0 to 160 µg.g-1, and from 19.4 to 316 µg.g-1 in roots. Fe concentrations were between 605 to 36,000 µg.g-1 in the iron plaques and from 2,100 to 62,400 µg.g-1 in roots. Histochemical characterization showed Fe3+ predominance at the tip of roots and Fe2+ in more internal tissues. A. schaueriana showed significant amounts of Fe in pneumatophores and evident translocation of this metal to leaves and excretion through salt glands. Iron plaques formation was essential to the Fe and Cu regulation and translocation in tissues of mangrove plants.

Predicting reservoir sedimentation using multilayer perceptron - Artificial neural network model with measured and forecasted hydrometeorological data in Gibe-III reservoir, Omo-Gibe River basin, Ethiopia.

The estimation and prediction of the amount of sediment accumulated in reservoirs are imperative for sustainable reservoir sedimentation planning and management and to minimize reservoir storage capacity loss. The main objective of this study was to estimate and predict reservoir sedimentation using multilayer perceptron-artificial neural network (MLP-ANN) and random forest regressor (RFR) models in the Gibe-III reservoir, Omo-Gibe River basin. The hydrological and meteorological parameters considered for the estimation and prediction of reservoir sedimentation include annual rainfall, annual water inflow, minimum reservoir level, and reservoir storage capacity. The MLP-ANN and RFR models were employed to estimate and predict the amount of sediment accumulated in the Gibe-III reservoir using time series data from 2014 to 2022. ANN-architecture N4-100-100-1 with a coefficient of determination (R2) of 0.97 for the (80, 20) train-test approach was chosen because it showed better performance both in training and testing (validation) the model. The MLP-ANN and RFR models' performance evaluation was conducted using MAE, MSE, RMSE, and R2. The models' evaluation result revealed that the MLP-ANN model outperformed the RFR model. Regarding the train data simulation of MLP-ANN and RFR shown R2 (0.99) and RMSE (0.77); and R2 (0.97) and RMSE (1.80), respectively. On the other hand, the test data simulation of MLP-ANN and RFR demonstrated R2 (0.98) and RMSE (1.32); and R2 (0.96) and RMSE (2.64), respectively. The MLP-ANN model simulation output indicates that the amount of sediment accumulation in the Gibe-III reservoir will increase in the future, reaching 110 MT in 2030-2031, 130 MT in 2050-2051, and above 137 MTin 2071-2072.

Individual and combined impacts of carbon dioxide enrichment, heatwaves, flow velocity variability, and fine sediment deposition on stream invertebrate communities.

Climate change and land-use change are widely altering freshwater ecosystem functioning and there is an urgent need to understand how these broad stressor categories may interact in future. While much research has focused on mean temperature increases, climate change also involves increasing variability of both water temperature and flow regimes and increasing concentrations of atmospheric CO2, all with potential to alter stream invertebrate communities. Deposited fine sediment is a pervasive land-use stressor with widespread impacts on stream invertebrates. Sedimentation may be managed at the catchment scale; thus, uncovering interactions with these three key climate stressors may assist mitigation of future threats. This is the first experiment to investigate the individual and combined effects of enriched CO2, heatwaves, flow velocity variability, and fine sediment on realistic stream invertebrate communities. Using 128 mesocosms simulating small stony-bottomed streams in a 7-week experiment, we manipulated dissolved CO2 (ambient; enriched), fine sediment (no sediment; 300 g dry sediment), temperature (ambient; two 7-day heatwaves), and flow velocity (constant; variable). All treatments changed community composition. CO2 enrichment reduced abundances of Orthocladiinae and Chironominae and increased Copepoda abundance. Variable flow velocity had only positive effects on invertebrate abundances (7 of 13 common taxa and total abundance), in contrast to previous experiments showing negative impacts of reduced velocity. CO2 was implicated in most stressor interactions found, with CO2 × sediment interactions being most common. Communities forming under enriched CO2 conditions in sediment-impacted mesocosms had ~20% fewer total invertebrates than those with either treatment alone. Copepoda abundances doubled in CO2-enriched mesocosms without sediment, whereas no CO2 effect occurred in mesocosms with sediment. Our findings provide new insights into potential future impacts of climate change and land use in running freshwaters, in particular highlighting the potential for elevated CO2 to interact with fine sediment deposition in unpredictable ways.

Dissolved organic matter quality in thermokarst lake water and sediments across a permafrost gradient, Western Siberia.

Thermokarst (thaw) lakes of permafrost peatlands are among the most important sentinels of climate change and sizable contributors of greenhouse gas emissions (GHG) in high latitudes. These lakes are humic, often acidic and exhibit fast growing/drainage depending on the local environmental and permafrost thaw. In contrast to good knowledge of the thermokarst lake water hydrochemistry and GHG fluxes, the sediments pore waters remain virtually unknown, despite the fact that these are hot spots of biogeochemical processes including GHG generation. Towards better understating of dissolved organic matter (DOM) quality at the lake water - sediment interface and in the sediments pore waters, here we studied concentration and optical (UV, visual) properties of DOM of 11 thermokarst lakes located in four permafrost zones of Western Siberia Lowland. We found systematic evaluation of DOM concentration, SUVA and various optical parameters along the vertical profile of lake sediments. The lake size and hence, the stage of lake development, had generally weak control on DOM quality. The permafrost zone exhibited clear impact on DOM porewater concentration, optical characteristics, aromaticity and weight average molecular weight (WAMW). The lowest quality of DOM, reflected in highest SUVA and WAMW, corresponding to the dominance of terrestrial sources, was observed at the southern boundary of the permafrost, in the sporadic/discontinuous zone. This suggests active mobilization of organic matter leachates from the interstitial peat and soil porewaters to the lake, presumably via subsurface or suprapermafrost influx. Applying a substitute space for time scenario for future evolution of OM characteristics in thermokarst lake sediments of Western Siberia, we foresee a decrease of DOM quality, molecular weight and potential bioavailability in lakes of continuous permafrost zone, and an increase in these parameters in the sporadic/discontinuous permafrost zone.

Heavy metal analysis of water and sediments of the Kaptai Lake in Bangladesh: Contamination and concomitant health risk assessment.

In this study, concentrations of 9 heavy metals (Cr, Fe, Co, Ni, Cu, Zn, As, Cd, and Pb) in water and sediments of the Kaptai Lake were determined by neutron activation analysis and atomic absorption spectrometry techniques to study their distribution and contamination in the lake. Average concentrations of Cr and Co in sediments, and Fe and Pb in water were higher than those of some international guideline values. Different environmental pollution indexes (individual and synergistic) suggested that the sediments of Kaptai Lake are minorly enriched by As and Zn, and have low severity of contamination at most of the sampling sites. For residential receptors exposed to the heavy metals in lake water, both non-carcinogenic and carcinogenic hazards were assessed which indicated that there is no carcinogenic risk for As while Cr shows a slightly carcinogenic risk. Moreover, estimated potential ecological risks and different SQGs suggested low ecotoxicological risks in the sediments of Kaptai Lake. Multivariate statistical analyses revealed the correlation among the studied heavy metals and indicated that the origin of most of the metals is mainly lithogenic and a small number of metals (Cu and Pb) from anthropogenic sources. The results of this study will be helpful in developing a pollution control strategy for the lake.

Resource partitioning of a Mexican clam in species-poor Baltic Sea sediments indicates the existence of a vacant trophic niche.

Invasive species are often generalists that can take advantage of formerly unexploited resources. The existence of such vacant niches is more likely in species-poor systems like the Baltic Sea. The suspension feeding wedge clam, Rangia cuneata, native to estuarine environments in the Gulf of Mexico, was sighted for the first time in the southeastern Baltic in 2010 and a few years later in the northern Baltic along the Swedish coast. To explore possible competition for food resources between R. cuneata and the three native clams inhabiting Baltic shallow soft bottoms, stable isotope and fatty acid analyses were conducted. There was no overlap between R. cuneata and any of the native species in either stable isotope or fatty acid niches. This suggests efficient partitioning of resources; multivariate analyses indicate that separation was driven mainly by δ13C and by fatty acids reflecting diatoms and cyanobacteria, respectively (e.g. 16:1ω7 and 18:3ω3). R. cuneata reflected seasonal variation in phytoplankton more than other clams reflecting higher trophic plasticity. In conclusion, the addition of R. cuneata to the Baltic shallow soft bottoms suggests the existence of a vacant trophic niche in these sediment habitats, however the long-term effects on other species and nutrient cycling requires further studies focusing on the population dynamics of R. cuneata and its impact on the Baltic Sea ecosystem.

NP, OP and Derivatives in Freshwater Sediment Downstream of Textile Associated Municipal Wastewater Discharges.

Alkylphenol ethoxylates comprise of many anthropogenic chemicals such as nonylphenol (NP), octylphenol (OP) and nonylphenol ethoxylates (NPEOs). The objectives of this study were to assess the frequency and magnitude of detections of 4-NP, OP and NPEOs in Canadian sediment downstream of textile associated municipal wastewater treatment plants (MWWTPs) to determine if regulatory actions have had a beneficial impact on the receiving environment. Surficial sediments were obtained in four locations in the province of Québec (Canada) and were analyzed for nonylphenol, nonylphenol monoethoxylates (NP1EO), nonylphenol diethoxylates (NP2EO) and octylphenol from 2015 to 2018. Individual concentrations of the compounds varied from non detect to 419 ng/g. Of the four compounds analyzed, NP was detected the most frequently with a 75% detection rate while OPs were not detected in any of the samples. Since the Canadian regulatory actions have drastically reduced NP/NPEOs usage in textile mill factories and manufactured products, the potential source of these compounds in sediment for this study could stem from the outfall from the MWWTPs but not related to textile mills as well as from the usage of these compounds as formulants in pesticide products. Lastly, there were no exceedances to the Canadian Sediment Quality guideline toxic equivalency approach (TEQ) of 1400 ng/g or the 1310 ng/g guideline for NP in freshwater sediment from the European Scientific Committee on Health, Environmental and Emerging Risks. We hypothesize that the significant concentrations of these compounds in sediment may be a relevant and continuous source of 4NP in surface waters due to resuspension of sediment in the water column.

Unrecognized extensive charge of microbial gas in the Junggar basin.

Different from the Qaidam basin with about 320 billion m3 microbial gas, only limited microbial gases were found from the Junggar basin with similarly abundant type III kerogen. To determine whether microbial gases have not yet identified, natural gas samples from the Carboniferous to Cretaceous in the Junggar basin have been analyzed for chemical and stable isotope compositions. The results reveal some of the gases from the Mahu sag, Zhongguai, Luliang and Wu-Xia areas in the basin may have mixed with microbial gas leading to straight ethane to butane trends with a "dogleg" light methane in the Chung's plot. Primary microbial gas from degradation of immature sedimentary organic matter is found to occur in the Mahu sag and secondary microbial gas from biodegradation of oils and propane occurred in the Zhongguai, Luliang and Beisantai areas where the associated oils were biodegraded to produce calcites with δ13C values from + 22.10‰ to + 22.16‰ or propane was biodegraded leading to its 13C enrichment. Microbial CH4 in the Mahu sag is most likely to have migrated up from the Lower Wuerhe Formation coal-bearing strata by the end of the Triassic, and secondary microbial gas in Zhongguai and Beisantan uplifts may have generated after the reservoirs were uplifted during the period of the Middle and Late Jurassic. This study suggests widespread distribution of microbial gas and shows the potential to find large microbial gas accumulation in the basin.

Passive biomonitoring for per- and polyfluoroalkyl substances using invasive clams, C. fluminea.

Per- and polyfluoroalkyl substances (PFAS) are a class of toxic manufactured chemicals in commercial and consumer products. They are resistant to environmental degradation and mobile in soil, air, and water. This study used the introduced bivalve Corbicula fluminea as a passive biomonitor at sampling locations in a primary drinking water source in Virginia, USA. Many potential PFAS sources were identified in the region. Perfluorohexane sulfonate (PFHxS) and 6:2 fluorotelomer sulfonic acid (6:2 FTS) levels were highest downstream of an airport. The highest levels of short-chain carboxylic acids were in locations downstream of a wastewater treatment plant. Measured PFAS concentrations varied by location in C. fluminea, sediment, and surface water samples. Two compounds were detected across all three mediums. Calculated partitioning coefficients confirm bioaccumulation of PFAS in C. fluminea and sorption to sediment. C. fluminea bioaccumulated two PFAS not found in the other mediums. Perfluoroalkyl carboxylic acids and short-chain compounds dominated in clam tissue, which contrasts with findings of accumulation of longer-chain and perfluorosulfonic acids in fish. These findings suggest the potential for using bivalves to complement other organisms to better understand the bioaccumulation of PFAS and their fate and transport in a freshwater ecosystem.

Severe flood modulates the sources and age of dissolved organic carbon in the Yangtze River Estuary.

Floods in global large rivers modulate the transport of dissolved organic carbon (DOC) and estuarine hydrological characteristics significantly. This study investigated the impact of a severe flood on the sources and age of DOC in the Yangtze River Estuary (YRE) in 2020. Comparing the flood period in 2020 to the non-flood period in 2017, we found that the flood enhanced the transport of young DOC to the East China Sea (ECS), resulting in significantly enriched Δ14C-DOC values. During the flood period, the proportion of modern terrestrial organic carbon (OC) was significantly higher compared to the non-flood period. Conversely, the proportion of pre-aged sediment OC was significantly lower during the flood period. The high turbidity associated with the flood facilitated rapid transformation and mineralization of sedimentary and fresh terrestrial OC, modifying the sources of DOC. The flux of modern terrestrial OC transported to the ECS during the flood period was 1.58 times higher than that of the non-flood period. These findings suggest that floods can modulate the sources and decrease the age of DOC, potentially leading to increased greenhouse gas emissions. Further research is needed to understand the long-term impacts of floods on DOC dynamics in global estuaries.

Residual loads from tilapia farming on the sediment of a Brazilian reservoir.

This study investigated the sediment geochemistry of a fish farming area in net cage tanks in the Rosário reservoir, Brazil. Three areas were investigated: reference (RA), fish farming (FFA), and dispersion (DA). The results were analyzed through correlation, similarity, principal component analysis, comparison with legislation, sediment quality guidelines, and sediment pollution indices. The mean concentrations for RA, FFA, and DA areas were respectively: Cu (mg.kg-1) 37.74, 62.23, and 71.83; Mn (mg.kg-1) 22.55, 66.48, and 55.90; Zn (mg.kg-1) 9.13, 114.83, and 94.27; Fe (%) 0.28, 0.40, and 0.43; OM (%) 15.84, 21.95, and 18.45; TOC (%) 1.86, 3.69, and 6.05; TN (mg.kg-1) 2365.00, 5015.00, and 3447.51; TP (mg.kg-1) 780.00, 6896.00, and 2585.50; ORP (mV) -95.50, -135.20, and -127.10; pH 6.60, 6.58, and 6.05; <63 µm 90.59, 78.68, and 87.30. Statistically, the influence of fish farming on sediment, organic matter, and pollutant sedimentation was demonstrated. Cu and Zn concentrations were below sediment quality guidelines. Regarding legal limits (resolution 454/2012/CONAMA), nutrients in the FFA area exceeded by 60% (TN) and 100% (TP), while in DA and RA areas they were 100% lower. TOC was 100% lower in all areas. Organic matter exceeded the limit by 100% in all areas. Pollution indices resulted in: low contamination factor 78%; unpolluted for 87% of pollution load and 83% of combined pollution; moderately polluted for 75% of the Nemerow index. The greatest impacts and influence of farming on pollutant sedimentation were more concentrated in the fish farming area. In terms of legal aspects and pollution indices, fish farming produced low levels of trace metal pollution and nutrient concentrations exceeded legal limits.