鄱阳湖西侧周边农村水塘夏季表层沉积物氮、磷、有机质分布特征及评价

水塘作为农村重要的水生态系统,其环境状况与人们生产生活和健康密切相关。为了解鄱阳湖西侧周边农村水塘沉积物的有机质和营养盐赋存状况,于2018—2019年对鄱阳湖流域西侧附近4个县的23个水塘进行沉积物营养盐的分析,同时通过相关分析和差异性分析对其来源进行解析,并采用综合污染指数评价法和主成分分析法对水塘沉积物的污染程度进行评价。结果表明：水塘沉积物污染物含量较高,其有机质、有机碳（TOC）、总氮（TN）和总磷（TP）含量分别为5.81%±2.16%、2.46%±1.02%、（6.48±2.35） mg/g和（1.89±0.80） mg/g。3种形态的无机氮中铵态氮含量最高,其次为硝态氮和亚硝态氮。沉积物TP受到洗涤废水的影响较大,清淤和活化显著减轻了沉积物TN和TOC污染。综合污染指数评价结果表明重度污染和中度污染的水塘占比分别为95.65%和4.35%,其平均评价结果为重度污染,表明水塘沉积物污染严重。而主成分分析结果表明P18水塘污染最重,而P6水塘污染最轻。综合污染指数与主成分分析总得分的相关系数为0.92,表明两者的评价结果较为一致。本研究通过分析鄱阳湖西侧农村水塘的沉积物营养...     

Heavy metal contamination in coastal sediments and soils near the Brazilian Antarctic Station, King George Island

This paper investigates the natural and anthropogenic processes controlling sediment chemistry in Admiralty Bay, King George Island, Antarctica, emphasizing the area affected by the Brazilian Antarctic Station Comandante Ferraz (Ferraz). Total and bioavailable concentrations of sixteen elements were determined in 32 sediment and 14 soils samples. Factor analysis allowed us to distinguish three groups of samples: (1) Ferraz sediments, with higher content of total trace metals and organic matter; (2) control sediments, with intermediate characteristics; (3) Ferraz soils, with higher bioavailability of most metals due to its oxidizing condition and low organic matter content. Major elements such as Fe, Al, Ca and Ti presented similar levels in all three groups. Enrichment factor calculations showed that paints, sewage and petroleum contamination enhanced metal concentrations in Ferraz surface sediments as follows: B, Mo, and Pb (>90%); V and Zn (70-80%); Ni, Cu, Mg, and Mn (30-40%). Despite evidence of contamination in these sediments, the low bioavailability, probably caused by iron-sulfide, indicates small environmental risks.     

Steroid markers to assess sewage and other sources of organic contaminants in surface sediments of Cienfuegos Bay,Cuba

Analyses of faecal steroids in coastal sediments from Cienfuegos Bay Cuba indicate chronic sewage contamination at the main outfalls from the city, where concentrations of coprostanol up to 5400 ng g⁻¹ (dry wt) were measured. In contrast, steroid concentrations and compositions from sites from the south part of the Bay are characteristic of uncontaminated sewage environments. The levels of coprostanol in the Cienfuegos sediments compares to the lower to mid-range of concentrations reported for coastal sediments on a world-wide basis, with sedimentary levels markedly below those previously reported for heavily impacted sites. This study delivers baseline data for further investigation of the effectiveness of the proposed sewerage plan promoted by the GEF project in Cienfuegos. Investigations on the correlations between faecal steroids and other organic contaminants confirmed that the major source of petroleum hydrocarbons within the bay was associated with the sewage effluents from the Cienfuegos city.     

Variations in different compounds in Volga water, suspension, and bottom sediments in the summer of 2009

Studies of water, suspension, and sediments of the Volga R. (from Konakovo Town to the delta) showed that at the confluence with tributaries, diffusion and dilution play the major role. Changes in conductivity, Biochemical oxygen demand (BOD₅), pH, suspension, chlorophyll a, dissolved and organic carbon, lipids, and hydrocarbons take place mostly under the effect of natural processes. Typical features in the case of summer low-water period are low chlorophyll a, suspension, and BOD₅. The accumulation of pollutants takes place in bottom sediments because of an increase in the share of C_org, and hydrocarbons have a petroleum and pyrogenic composition.     

Multi-residues of organic pollutants in surface sediments from littoral areas of the Yellow Sea, China

Concentrations of all studied organic pollutants, except for DDTs, were greatest at sites in Dalian Bay, where surface sediment concentrations of PHCs, PAHs, PCBs and DDTs exceeded the corresponding ERL values. The sum concentration of DDTs was greatest in Haizhou Bay exceeding the related ERM value. In terms of compositions of PAHs and PAEs, the predominant components were the MMW and HMW compounds, DBP and DEHP, respectively. The main degradation product of p,p'-DDT was p,p'-DDD at most sampling sites. The principal sources of PAHs and DDTs involved various pyrolytic processes (i.e., combustion of biomass and vehicle exhaust), and application of technical DDT (in the form of impurity or raw material), and a mixture of technical DDT and technical dicofol. Moreover, the coastal site with greatest potential ecological risk from total PAHs was located in Dalian Bay, while the littoral areas of Dalian Bay, two harbor cities (Yantai-Weihai), Jiaozhou Bay, and Haizhou Bay, had relatively high potential risk from DDTs, especially in Haizhou Bay.     

Terrestrial and marine biomarker estimates of organic matter sources and distributions in surface sediments from the East China Sea shelf

Revealing of the sources and distributions of sedimentary organic matter in the East China Sea (ECS) is important for understanding its carbon cycle, which has significant temporal and spatial variability due to the influences of recent climate changes and anthropogenic activities. In this study, we report the contents of both terrestrial and marine biomarkers including ∑C₂₇+C₂₉+C₃₁n-alkanes (38.6-580 ng/g), C₃₇ alkenones (5.6-124.6 ng/g), brassicasterol (98-913 ng/g) and dinosterol (125-1521 ng/g) from the surface sediments in the Changjiang River Estuary (CRE) and shelf areas of the ECS. Several indices based on biomarker contents and ratios are calculated to assess the spatial distributions of both terrestrial and marine organic matter in the ECS surface sediments, and these results are compared with organic matter distribution patterns revealed by the δ¹³C (−20.1‰ to −22.7‰) and C/N ratio (5-7.5) of total organic matter. The contents of terrestrial biomarkers in the ECS surface sediments decrease seaward, controlled mostly by Changjiang River (CR) inputs and surface currents; while higher contents of the two marine biomarkers (brassicasterol and dinosterol) occur in upwelling areas outside the CRE and in the Zhejiang-Fujian coastal zone, controlled mostly by marine productivity. Four proxies, f_Terr(δ¹³C) (the fraction of terrestrial organic matter in TOC estimated by TOC δ¹³C), odd-alkanes (∑C₂₇+C₂₉+C₃₁n-alkanes), 1/P_mar-aq ((C₂₃+C₂₅+C₂₉+C₃₁)/(C₂₃+C₂₅) n-alkanes) and TMBR (terrestrial and marine biomarker ratio) (C₂₇+C₂₉₊C₃₁n-alkanes)/((C₂₇+C₂₉+C₃₁) n-alkanes+(brassicasterol+dinosterol+alkenones)), reveal a consistent pattern showing the relative contribution of terrestrial organic matter (TOM) is higher in the CRE and along the Zhejiang-Fujian coastline, controlled mostly by CR inputs and currents, but the TOM contribution decreases seaward, as the influences of the CR discharge decrease.     

峡谷分层型水源水库表层沉积物溶解性有机物光谱特征

结合三维荧光光谱技术（EEMs）与紫外吸收光谱（UV-vis）,并利用平行因子分析（PARAFAC）的方法,对金盆水库表层沉积物中溶解性有机质（DOM）光谱的空间分布特征及来源进行分析,并探讨沉积物DOM的荧光组分与可溶性有机氮（SON）、可溶性无机氮（SIN）之间的相关性.结果表明,金盆水库表层沉积物DOM由3类荧光组分组成,分别是类富里酸C1（235 nm,315 nm/430 nm）、类色氨酸C2（220 nm,275 nm/330 nm）和类胡敏酸C3（265 nm/520 nm）,各组分荧光强度占总荧光强度百分比的平均值分别为43.15%、31.54%和25.31%.表层沉积物DOM浓度在空间上呈现从上游到主库区先减少后增加的趋势.光谱斜率S_275-295、S_350-400和光谱斜率比S_R反映出各采样点陆源与内源占比的差异性.荧光指数、自生源指标和腐殖化指标都表明金盆水库沉积物DOM的来源具有内源与陆源双重特征.相关性分析表明,表层沉积物DOM各组分与SON和SIN均呈显著正相关,说明DOM与氮元素的迁移转化密切相关.     

Sources of organic matter in surface sediments of the Louisiana Continental margin: Effects of major depositional/transport pathways and Hurricane Ivan

Lignin and pigment biomarkers were analyzed in surface sediments of the Louisiana Continental margin (LCM) to distinguish differences in the degradative state of sedimentary organic matter along and between two major depositional pathways (along shore and offshore to the Mississippi Canyon) from Southwest (SW) Pass in July 2003. Barataria Bay, an inter-distributary estuary, was also assessed as a potential source of terrestrial organic matter to the LCM. Sediment signatures taken along the same pathways after Hurricane Ivan (October 2004) were compared with the pre-Ivan signature to elucidate carbon dynamics after major hurricane events. Density fractions were investigated at key stages across the LCM. Mississippi Canyon sediments are a depocenter for labile and refractory organic matter derived from river and previously deposited shelf sediments. Barataria Bay material may be a contributing source of sedimentary organic matter in shallow shelf areas bordering the bay and is thus potentially important in carbon cycling in sediments of these shallow areas; however, our results show that organic matter inputs from the bay were likely rapidly decomposed and/or diluted. Hurricane Ivan mobilized sedimentary organic carbon (SOC) offshore and homogenized terrestrial sediment parameters and gradients. As observed through pigment concentrations sediments tended to equilibrate to a more steady-state condition within months of the disturbance. Insights from density fractions show that selective degradation and aggregation/flocculation processes were also very important processes during cross-shelf transport. Zooplankton grazing, largely on diatoms and other algae, was a shelf wide phenomenon, however, grazing products dominated the marine-derived SOC in margin sediments west of the birdsfoot delta indicated by the abundance of steryl chlorin esters (SCEs).     

Seasonal dynamics of microbial sulfate reduction in temperate intertidal surface sediments: controls by temperature and organic matter

The role of microbial sulfate reduction on organic matter oxidation was studied quantitatively in temperate intertidal surface sediments of the German Wadden Sea (southern North Sea) on a seasonal base in the years 1998–2007. The sampling sites represent the range of sediments found in the back-barrier tidal area of Spiekeroog Island: sands, mixed and muddy flats. The correspondingly different contents in organic matter, metals, and porosities lead to significant differences in the activity of sulfate-reducing bacteria with volumetric sulfate reduction rates (SRR) in the top 15 cm of up to 1.4 μmol cm^?3 day^?1. Depth-integrated areal SRR ranged between 0.9 and 106 mmol m^?2 day^?1, with the highest values found in the mudflat sediments and lower rates measured in sands at the same time, demonstrating the impact of both temperature and organic matter load. According to a modeling approach for a 154-km² large tidal area, about 39, 122, and 285 tons of sulfate are reduced per day, during winter, spring/autumn, and summer, respectively. Hence, the importance of areal benthic organic matter mineralization by microbial sulfate reduction increases during spring/autumn and summer by factors of about 2 and 7, respectively, when compared to winter time. The combined results correspond to an estimated benthic organic carbon mineralization rate via sulfate reduction of 78 g C m^?2 year^?1.     

Geochemistry of organic carbon and nitrogen in surface sediments of coastal Bohai Bay inferred from their ratios and stable isotopic signatures

Total organic carbon (TOC), total nitrogen (TN) and their δ(13)C and δ(15)N values were determined for 42 surface sediments from coastal Bohai Bay in order to determine the concentration and identify the source of organic matter. The sampling sites covered both the marine region of coastal Bohai Bay and the major rivers it connects with. More abundant TOC and TN in sediments from rivers than from the marine region reflect the situation that most of the terrestrial organic matter is deposited before it meets the sea. The spatial variation in δ(13)C and δ(15)N signatures implies that the input of organic matter from anthropogenic activities has a more significant influence on its distribution than that from natural processes. Taking the area as a whole, surface sediments in the marine region of coastal Bohai Bay are dominated by marine derived organic carbon, which on average accounts for 62±11% of TOC.     

Fine scale distributions of porosity and particulate excessPb, organic carbon and CaCO3 in surface sediments of the deep equatorial Pacific

Sediment samples were recovered from the central equatorial Pacific Ocean, sectioned at 1-mm intervals, and analyzed for porosity, organic carbon, excess²¹⁰Pb and CaCO₃. Steep porosity gradients were measured in the upper 1 cm of the sediment column with extremely high values observed near the sediment surface. Similarly, particulate organic carbon contents are highest at the sediment surface, decrease sharply in the upper 1 cm, and are relatively constant between 1 and 5 cm. CaCO₃ values, on the other hand, are lowest at the sediment surface and increase to a constant value below 5–10 mm depth. At the carbonate ooze sites, excess²¹⁰Pb is present throughout the upper 5 cm of the sediments suggesting relatively rapid particle mixing rates. However, extremely high excess²¹⁰Pb activities (> 100 dpm/g) are observed at the sediment surface with sharp gradients present in the upper 1 cm which would suggest slow rates of mixing. This apparent contradiction along with the major features of the CaCO₃ and particulate organic carbon profiles can be explained by a particle-selective feeding mechanism in which organic carbon, excess²¹⁰Pb-enriched particles are preferentially maintained at the sediment surface via ingestion and defecation by benthic organisms.     

Ice thickness,internal layers,and surface and subglacial topography in the vicinity of Chinese Antarctic Taishan station in Princess Elizabeth Land,East Antarctica

We present the results of two ground-based radio-echo-sounding (RES) and GPS surveys performed in the vicinity of new Chinese Taishan station, Princess Elizabeth Land, East Antarctica, obtained in two austral summers during CHINARE 21 (2004/2005) and CHINARE 29 (2012/2013). The radar surveys measured ice thickness and internal layers using 60- and 150-MHz radar systems, and GPS measurements showed smooth surface slopes around the station with altitudes of 2607–2636 m above sea level (a.s.l.). Radar profiles indicate an average ice thickness of 1900 m, with a maximum of 1949 m and a minimum of 1856 m, within a square area measuring approximately 2 km × 2 km in the vicinity of the station. The ice thickness beneath the station site is 1870 m. The subglacial landscape beneath the station is quiet sharp and ranges from 662 to 770 m a.s.l., revealing part of a mountainous topography. The ice volume in the grid is estimated to be 7.6 km³. Along a 60-MHz radar profile with a length of 17.6 km at the region covering the station site, some disturbed internal layers are identified and traced; the geometry of internal layers within the englacial stratigraphy may imply a complex depositional process in the area.     

The extent and historical trend of metal pollution recorded in core sediments from the artificial Lake Shihwa, Korea

The vertical distribution of trace metals in sediment cores was investigated to evaluate the extent and the historical record of metal pollution over 30 years in the artificial Lake Shihwa in Korea. A marked increase of trace metals after 1980 was observed due to the operation of two large industrial complexes and dike construction for a reclamation project. There was a decreasing trend of metal concentrations with the distance from the pollution source. The enrichment factor and pollution load index of the metals indicated that the metal pollution was mainly derived from Cu, Zn and Cd loads due to anthropogenic activities. The concentrations of Cr, Ni, Cu, Zn, As and Pb in the upper part of all core sediments exceeded the ERL criteria of NOAA. Our results indicate that inadequate planning and management of industrialization and a large reclamation project accomplished by dike construction have continued to strongly accelerate metal pollution in Lake Shihwa.     

Source and distribution of lead in the surface sediments from the South China Sea as derived from Pb isotopes

Rapid economic development in East Asian countries has inevitably resulted in environmental degradation in the surrounding seas, and concern for the environment and its protection against pollutants is increasing. Identification of sources of contaminants and evaluation of current environmental status are essential to environmental pollution management, but relatively little has been done in the South China Sea (SCS). In order to investigate the abundance, distribution, and sources of Pb within the SCS, stable Pb isotopes and their ratios were employed to assess the contamination status and to differentiate between natural and anthropogenic origins of Pb in the surface sediments. The total Pb concentrations in sediments varied from 4.18 to 58.7 mg kg⁻¹, with an average concentration of 23.6 ± 8.9 mg kg⁻¹. The observed Pb isotope ratios varied from 18.039 to 19.211 for ²⁰⁶Pb/²⁰⁴Pb, 15.228 to 16.080 for ²⁰⁷Pb/²⁰⁴Pb, 37.786 to 39.951 for ²⁰⁸Pb/²⁰⁴Pb, 1.176 to 1.235 for ²⁰⁶Pb/²⁰⁷Pb, and 2.468 to 2.521 for ²⁰⁸Pb/²⁰⁷Pb. The majority of these ratios are similar to those reported for natural detrital materials. Combined with Pb enrichment factor values, our results show that Pb found within most of the SCS sediments was mainly derived from natural sources, and that there was not significant Pb pollution from anthropogenic sources before 1998. Further studies are needed to reconstruct deposition history and for trend analysis.     

Monitoring of organic contaminants in sediments from the Korean coast: Spatial distribution and temporal trends (2001-2007)

Spatial and temporal trends of organic contaminants in sediments along the Korean coast were estimated through a nationwide environmental monitoring program from 2001 to 2007. The concentrations of organic contaminants in sediments along the Korean coast were relatively low or moderate compared with foreign studies. The mean detection frequencies of organic contaminants during the seven years were highest for PAHs and PCDD/Fs, followed by PCBs, DDTs, TBT and HCHs in decreasing order. Based on published sediment quality guidelines, the ecological risks of persistent organic pollutants in sediments along the Korean coast were low, despite exceedances of the ERL at 2-6 sites for DDTs, and the TEL at 9-18 sites for PCDD/Fs. Nonparametric tests to assess temporal trends revealed significant decreasing trends for PCBs and PCDD/Fs at four and three sites, respectively (p < 0.05). These results reflect the effects of regulations on the use of those contaminants.     

DDTs and other chlorinated organic pesticides and polychlorinated biphenyls pollution in the surface sediments of Keratsini harbour, Saronikos gulf, Greece

Sediment samples were collected from Keratsini harbour, Saronikos gulf, Greece and were analysed for chlorinated organic pesticides (DDTs, HCB, Lindane) and polychlorinated biphenyls (PCBs). High total DDTs values were detected in all the sediments samples ranging from 9.1 to 75.6 mug/g, dry weight. PCBs concentrations range from 47.8 to 351.8 ng/g. The results and especially the high concentrations of DDTs reflect the influence of the industrial and urban wastes in the pollution for the Keratsini harbour environment.