快速评估近岸海洋水体与沉积物中E.coli与S.aureus抗生素抗性水平的新方法

随着抗生素抗性污染日益严重,快速评估环境中典型病原菌与条件性致病菌的抗生素抗性水平,对掌握区域环境抗生素抗性污染状况、揭示抗性污染传播规律至关重要。通过以最低抑菌浓度浸入抗生素改进MI、VJ培养基,并结合滤膜法,建立了针对近岸海洋环境中指示性病原微生物大肠杆菌(Escherichia coli,E.coli)与金黄色葡萄球菌(Staphylococcus aureus,S.aureus)的抗生素抗性监测方法。水体和沉积物样品抗生素抗性水平评估实验结果显示,该方法具有较好重现性(水体和沉积物中E.coli和S.aureus抗生素抗性水平的相对标准偏差分别为11%、8%)与准确度(水体和沉积物中E.coli和S.aureus的平均回收率分别为83.5%、68.4%;相对于CLSI药敏试验的偏离度为±0.1)。且与CLSI药敏实验相比,该方法过程简便、耗时短(36 h/84 h),能最大限度节约经济和人员成本提高抗性评价效率。应用该方法评估辽河口与莱州湾环境中2种病原微生物磺胺类抗生素抗性水平,结果显示辽河口水体中E.coli和S.aureus磺胺二甲嘧啶的平均抗性率分别为27.0%、28.4%,沉积物中分别为35.5%、34.6%;莱州湾水体中E.coli和S.aureus磺胺二甲嘧啶的平均抗性率分别为26.0%、14.5%,沉积物中分别为12.0%、32.9%。该方法适用于河口、近岸海洋及入海排污口水体与沉积物样品中E.coli与S.aureus的快速分析及抗生素抗性水平评估。     

Sedimentary records of anthropogenic contribution to heavy metal content in Oum Er Bia estuary (Morocco)

Levels of heavy metals (Cd, Hg, Cr, Cu, Fe, Mn, Ni, Pb and Zn), organic carbon content and textural characteristics in the superficial and cored sediments of Oum Er Bia estuary have been studied. The anthropogenic fluxes of heavy metals were determined in two sediment cores collected in the estuary, facing urban sewages. A dated estuarine core from the inter-tidal area was assessed using ²¹⁰Pb and ¹³⁷Cs data. These data indicate that the mean sedimentation rates are 0.38–68 cm year^?1. The analytical results and the radio-dating of sediment cores show extremely high concentrations of Zn, Pb and Cu in the sediments that can be ascribed mostly to the discharge of the liquid effluent from the sewage since the late 1960s, decreasing towards the present day. The pollution intensity of the estuary is determined by the enrichment factors, which show that the Oum Er Bia estuary is moderately polluted to polluted.     

The relative abundance and feeding habits of the grey mullet species occurring in an Estuary in Sierra Leone,West Africa

The occurrence and relative frequency of the 5 grey mullet species found in the Black Johnson Estuary, Sierra Leone, have been observed by sampling throughout the year. Examination of stomach contents and scales has also been made. Salinity within the estuary is maximum during the dry season and minimum at the height of the rains. The organic content of the sediment reaches a peak towards the end of the rains, but is low both at the end of the dry season and during the rains. Mullet tend to be most abundant as the rains are finishing and at the beginning of the dry season when the salinity is rising and the organic matter in the sediment is maximum. The mullet encountered in the estuary were Liza falcipinnis (Cuvier and Valenciennes), L. dumerilii hoefleri (Steindachner), Mugil cephalus ashanteensis Bleeker, M. curema Cuvier and Valenciennes and L. grandisquamis (Cuvier and Valenciennes). L. falcipinnis and L. dumerilii hoefleri penetrated furthest up the estuary and have been caught in freshwater some distance up rivers. All species feed principally on the detritus and algae in the estuarine sediment. There is some seasonal variation in the composition of the diet. Comparative data on the organic content of the estuarine sediment and the sand in the stomach of the mullet are given. A field experiment with L. falcipinnis suggests an assimilation efficiency of 52% for this species. Well-marked rings have been found upon the scales of four species, and their possible significance and use are discussed.     

Allocation of nitrogen and carbon in an estuarine salt marsh in Portugal

Above and below-ground biomass and nitrogen and carbon composition ofSpartina maritima, Halimione portulacoides andArthrocnemum perenne, dominating species in plant communities of the lower, middle and higher salt marsh, respectively, were compared in an estuarine salt marsh in Portugal. Plant and soil nitrogen and carbon pools were estimated. For all three species root biomass was significantly higher (70–92% of total biomass) than above-ground biomass. The percentage of root biomass was related to the location of the plants in the marsh: higher values were found in plants growing in the lower salt marsh where the sediment was more unstable and subject to tidal action, which stresses the role of the roots as an anchor. For all three species nitrogen concentrations were highest in leaves, reflecting the photosynthetic role of the tissue. For carbon higher concentrations were found in the stems, with the exception ofS. maritima. In general, lower nitrogen concentrations were found in summer, which can be explained by dilution processes due to plant growth. For both nitrogen and carbon, higher concentrations were found in the soil surface layers. Higher soil nitrogen and carbon levels were associated with higher organic matter contents. Most of the nitrogen in the salt marsh occurred in the sediments (0–40 cm) and only ca. 5.7–13.3% of the total was found in the plants. The greater portion (76.5%–86%) of carbon was found in the sediment.     

Speciation of heavy metals in sediments from the Scheldt estuary,Belgium

A simple three-step sequential extraction procedure was applied to study the speciation of heavy metals in sediment from Scheldt estuary, and their relationship to sediment grain size and organic matter content. The sedimentary metal content was fractionated into carbonate and exchangeable, metals bound to organic matter and residual fractions. Sedimentary total metal content was also determined using an industrial microwave (ETHOS 900) HF/HNO₃ extraction method. The extracts were analysed for metals using inductively coupled plasma atomic emission spectrometry. The bioavailable fraction (exchangeable and metals bound to organic matter) comprised less than the other forms. Residue metals were the dominant form of metals in almost all studied sites. The average total metal content for the studied sites decreased in the order Fe>Cr>Cu>Co>Zn>Pb>Cd. Based on average values for the studied sites, the highest bioavailable metals in sediments were Cd (38%) from Westkapelle, Zn (17%) from Yerseke, Co (12%) from Domburg, Cr (9%) from Vlissingen, Fe and Pb each (2%) from Yerseke, and Cu (1%) from Domburg. Metal recovery was good, with<10% difference between the total metal recovered through the extractant steps and the total metal determined using HF/HNO₃ extract.     

Mineralization of particulate organic matter derived from coral-reef organisms in reef sediments of the Gulf of Aqaba

In situ and laboratory incubation experiments in a fringing reef in the Gulf of Aqaba were performed to study degradation rates of particulate organic matter in reef sediments. Coral mucus, clam eggs, and zooxanthellae were used as model particulate organic compounds for these experiments. Aerobic and anaerobic mineralization rates were calculated by dissolved inorganic carbon (DIC) and O₂ fluxes from the sediments under different particulate organic matter additions. Fast enhancement (approximately twofold) of O₂ and DIC fluxes were found with the addition of coral mucus and clam eggs compared with control incubations without addition. Most of the degradation is believed to have occurred anaerobically rather than aerobically (DIC:O₂ ratios were 4.3–28.1). Higher degradation rates of coral mucus and clam eggs were estimated in carbonate sediment than in silicate sediment (1.2–1.6-fold), which was attributed to the different physical and chemical properties of both sediments. Our study shows the significance of the reef sediment as a suitable site for microbial degradation of particulate organic material excreted from different reef community organisms. This may increase the regeneration of nutrients in the reef environment necessary to sustain high biological productivity.     

中华圆田螺对沉积物中十溴联苯醚工业品DE-83的生物积累与转化

为研究沉积物中十溴联苯醚(BDE-209)的生物有效性,将淡水生态系统中常见的底栖动物中华圆田螺(Cipangopaludina cahayensis)暴露于商品DE-83(主要包含92%的BDE-209、6%的BDE-206、1.5%的BDE-207和0.5%的BDE-208)染毒的沉积物,进行60 d养殖实验。根据暴露期间中华圆田螺体内PBDEs含量与同系物组成的变化,探讨了田螺对DE-83的富集动力学、积累常数以及可能发生的生物转化。实验结果显示,DE-83主要同系物均能够被中华圆田螺积累,但是生物有效性非常低,BDE-209、BDE-207和BDE-206的吸收速率常数(k_s)为0.029～0.042 d^-1,BDE-207 > BDE-206 > BDE-209。依据动力学参数推算的生物-沉积物积累因子(BSAF)非常低,分别为0.05(BDE-209)和0.02(BDE-206和BDE-207)。暴露20 d后,中华圆田螺体内有低溴代同系物检出,其含量随暴露时间延长而增加,说明BDE-209在中华圆田螺体内发生了生物转化。     

Seasonal variation of heavy metals in sediment of Lake Ulansuhai,China

Sediment samples were collected from 10 sites in Lake Ulansuhai during summer and winter 2009 to reveal seasonal variations in sediment heavy metal levels. The geoaccumulation index (GI) was calculated to assess the severity of metal pollution. The GI values suggest that, in winter, the lake sediments were polluted slightly with Cu (GI=0.66–1.34), Zn (GI=0.59–1.35), Cr (GI=0.49–0.82) and Pb (GI=0.60–0.96), and moderately with Cd (GI=1.03–4.23). The degree of pollution was higher in winter than in summer. By contrast, the degree of pollution was higher in summer than in winter for Hg and As. Correlation analysis can be used to identify factors influencing seasonal variations in heavy metals. The concetrations of Cu, Zn, Pb, Cr and Cd were negatively correlated with water temperature and hydrodynamic conditions, but positively correlated with organic matter concentration in the sediments and with a sediment particle size of<63 μm (p<0.01). Meanwhile, Hg and As concentrations were affected by redox state and salinity. Among the metals tested, Hg and Cd posed a more serious pollution risk.     

Distribution and retention of the copepodEurytemora affinis hirundoides in a turbid estuary

The spatial and temporal distribution of the copepodEurytemora affinis hirundoides (Nordquist, 1888) in the Gironde estuary, southwest France, was investigated in 1976, and between 1981 and 1983. The distribution pattern of the population bore a clear relationship to the patterns of water circulation and transport of particulate matter. Laboratory experiments suggested thatE. affinis hirundoides is incapable of autonomous displacement against the direction of general circulation and behaves as passive particles. A major problem faced by species living in estuaries is that of the maintenance of endemic populations. Some authors have suggested that behavioural responses may play an important role in minimising population losses. Our study indicated that hydrodynamic processes are sufficient to explain the distribution and retention ofE. affinis hirundoides, whose populations are retained in the estuary in the same manner as the suspended sediment. Since the outflow of particulate matter from the Gironde estuary to the sea is very sporadic, we hypothesize that most of the production ofE. affinis hirundoides remains within the estuary, and does not fertilize the continental shelf, at least not in the form of particulate organic matter.     

Microbial reaction rates and bacterial communities in sediment surrounding burrows of two nereidid polychaetes (Nereis diversicolor and N. virens)

The effects of infaunal mode of life on sediment properties, microbial reaction rates, as well as abundance and composition of bacterial communities were studied in sediment surrounding burrows (mucus lining, oxidised wall, ambient anoxic and surface sediment) of two closely related, but behaviourally different, nereidid polychaete worms: the facultative suspension-feeder Nereis (Hediste) diversicolor and the obligate deposit-feeder Nereis (Neanthes) virens. Burrow sediment of the two species was collected from two adjacent (50 m distance) shallow sandy locations (Kertinge Nor, Denmark). The burrow lining and wall of both polychaete species were enriched in organic matter originating from mucous secretions by the inhabitants and phytoplankton trapped through irrigation. This was more evident for N. diversicolor that shows a significantly higher irrigation rate than N. virens. Both the organic matter mineralisation rates (based on anaerobic incubations) and bacterial abundance were higher along the burrow linings and walls. However, accumulation of porewater TCO₂ and dissolved organic carbon in sediments adjacent to burrows increased most rapidly in the presence of N. diversicolor, suggesting higher heterotrophic activity associated with this species. Surprisingly, bacterial abundance was lower around burrows of N. diversicolor than those from N. virens indicating that burrow environments from the first species harbour a more active bacterial community. Molecular fingerprints of the 16S rRNA gene from bacterial communities showed that the composition of the burrow linings and walls resembled the ambient anoxic sediment rather than the oxic sediment surface. On the other hand, the bacterial fingerprints of the sediment surrounding the burrows of the two polychaete species were markedly different suggesting either a site-specific difference in sediment parameters or a significant species-specific impact of the burrow inhabitants.     

Role of grapsid crabs, Parasesarma erythrodactyla, in entry of mangrove leaves into an estuarine food web: a mesocosm study

The influence of the crab Parasesarma erythrodactyla on the entry of the organic matter derived from Avicennia marina mangrove leaves in a sub-tropical mangrove ecosystem of southeast Queensland, Australia, was simulated using tidal mesocosms. Degradation of mangrove leaf organic matter was followed by analysing the fatty acid composition, carbon, and nitrogen isotopic signatures of the surface sediment and suspended particulate organic matter (SPOM) with and without the presence of crabs. Assimilation of mangrove organic matter by P. erythrodactyla was also assessed by stable isotope and fatty acid analyses in tissues and faeces. Results of the chemical tracer analyses question the adaptability of P. erythrodactyla to a diet comprised exclusively of mangrove leaves, and suggest that these organisms were dependent on additional food sources in their natural environment. Crab processing of senescent leaves significantly accelerated the transfer of mangrove organic matter to the surface sediments, as shown by a higher C/N ratio, a higher contribution of long-chain fatty acids and a more depleted C isotopic signature of sediment samples in the mesocosms with crabs compared to those without crabs.     

Selectivity in feeding by the deposit-feeding bivalve Macoma nasuta

Macoma nasuta Conrad is primarily a deposit-feeding bivalve sucking the top millimeter of the sediment surface. Growth experiments show that surface sediment supports growth better than detritus falling from the water column. Gut clearance time is between 1 and 9 h (12°C). Fecal pellets are ejected in a regular rhythm. However, the total amount of feces per unit time shows considerable individual variation. Due to sorting in the mantle cavity, about 97% (dry weight) of the surface material is ejected again as pseudofeces. Selectivity by the bivalve is estimated by comparison of particle size and organic composition of sandy and muddy sediments and compared with feces produced by clams fed these sediments. Fecal pellets are in all cases richer in organic components than the sediment, indicating a high degree of selectivity. Ingestion and digestion of small animals (meiofauna) occur, but many of the ingested specimens survive. It is not possible to estimate the assimilation of organic matter by simple difference between the ingested sediment and the ejected feces. The difficulties in calculating energy budgets which arise from selective feeding and associated bacteria are discussed.     

Fluxes and Transport of Organic Carbon and Trace Metals in the Tropical Tsengwen Estuary,Southwestern Taiwan

Distributions of organic carbon and trace metals were investigated in the tropical Tsengwen river end-member and in the estuary to better understand thoroughly the riverine fluxes and estuarine transports of constituents into the sea. Experimental results indicated that riverine fluxes of organic carbon and trace metals possessed a highly temporal variability, attributed primarily to temporal variation in river water discharge and suspended load. More than 70% of annual fluxes of dissolved constituents and >90% of particulate constituents arose from river floods caused by summer typhoons. the flushing time of fresh water in the estuary varied from a half month in the dry season to a half day in the flood period. Dissolved organic carbon (DOC) and nutrienttype metals (Cd, Cu, Zn) were conservatively transported through the estuary. Dissolved particle-reactive metals (Mn, Pb), however, were apparently transported non-conservatively through the estuary. Particulate organic carbon (POC) and trace metals (PTM) were transported non-conservatively by following the transport mode of total suspended matter (TSM) in the estuary. DOC slightly dominates the transport of organic carbon while particle-reactive PTM predominates the transport of trace metals through the estuary. Total organic carbon (TOC) in estuarine sediment was progressively enriched with ¹³C downstream, as derived by mixing the overlying TSM between terrestrial and marine end-members. Distributions of trace metals in sediment were subsequently controlled by sedimentary TOC and particle size. Based on results presented here, we believe that enrichments of trace metals in the estuary are attributed primarily to the natural processes of transport and sedimentation of fluvial TSM     

Microbial activity and accumulation of organic matter in the burrow of the mud shrimp, <Emphasis Type="Italic">Upogebia major</Emphasis> (Crustacea: Thalassinidea)

Microbial activity and accumulation of organic matter in the burrow of the thalassinidean mud shrimp, Upogebia major, were studied on a tidal flat along the northern coast of Tokyo Bay, Japan. The burrow of U. major is Y-shaped with an upper U-shaped part plus a lower I-shaped part. Its lower part can extend to a depth of 2 m. In the present study, we compare electron transport system activity (ETSA), bacterial abundance and organic matter content [total organic carbon (TOC), total nitrogen (TN) and chlorophyll a (chl. a)] of the burrow wall sediment with the tidal flat surface and non-burrow sediments. We also compared the U- and I-shaped part in terms of these parameters. ETSA in the burrow wall was higher than at the tidal flat surface in the warmer season, and was always higher than at surrounding non-burrow sediments. Bacterial abundance in the burrow wall was higher than at the tidal flat surface and surrounding sediment. TOC and TN contents in the burrow wall were two to three times higher than those at the tidal flat surface and non-burrow sediments, regardless of season. However, there was no significant difference in chl. a content between burrow wall and tidal flat surface. These results suggest that organic enrichment of the burrow wall is a result of organic matter particles such as phytodebris accumulation along the burrow wall. For all parameters of the burrow walls, no statistical differences were found between the two parts. Present results indicate that U. major actively transports the water containing suspended organic particles not only through the U-part but also into the deeper I-part. These indicate that burrow of the mud shrimp provides a dynamic environment for microbial community in tidal flat sediment.     

Sedimentary Pigments and Organic Matter in Relation to Benthic Fauna in the Tan-Shui Estuary,Taiwan

The benthic ecological structure of the Tan-Shui estuary, Taiwan is changed due to long term effects of dumping of urban wastewater and of engineering actions. to monitor these changes, we sampled and analyzed benthos and sediment from 12 stations on the estuary.

The composition of the dominant species of benthos varied seasonally, with molluscan and crustacean species having greater numbers and higher frequencies of occurrence than other species. the dominant taxa during winter were Nassarius sp. and Maldanidae at two stations. Analysis using Simpson's index and Shannon's index showed the benthic community varied more in coastal areas than in offshore areas.

Physicochemical analysis showed that most of the Tan-Shui estuary consisted of sandy sediment. the variations in concentrations of organic carbon and total nitrogen at each station were small. Although the concentrations of chlorophyll-a and carotenoid at all stations were generally low, the two stations had the highest concentrations, and we concluded that the concentration of pigments in these sediments was related to the abundance of benthos. the community structure of the benthos reflected the characteristics of the sediments, and benthic species exhibited selection of and adaptation to specific sedimentary environments.     

Productivity of bacteria and microalgae and the effect of grazing by holothurians in sediments on a coral reef flat

Bacterial productivity in sandy sediments on reef flats at Lizard Island, Great Barrier Reef was determined from the rate of incorporation of tritiated thymidine into DNA. The study was conducted during January 1982 and July 1983. A small diurnal increase occurred in sediments having a dense population of microalgae. Bacterial production was 120 to 370 mg C m^-2 d^-1 in summer on reef flats, which was equivalent to 30–40% of primary production by benthic microalgae. In winter, rates of primary production by benthic microalgae and secondary production by bacteria were about one-half to one-fifth of those in summer. There was much variation in production, due to patchiness in the distribution of benthic microbes, especially microalgae. Doubling times for the bacteria in surface sediment were 1 to 2 d in summer and 4 to 16 d in winter on the reef flats. These high productivity values for bacteria indicated that a net input of organic matter to the sediment was needed to support the growth of bacteria. Sediment bacteria thus have a very important role in transforming organic matter on the reef flats. Grazing by Holothuria atra depressed both primary production and bacterial production. It was estimated that these holothurians ate about 10 to 40% of bacterial carbon produced each day in summer, and thus have an important role in the carbon cycle. Harpacticoid copepods were numerically important components of the benthic meiofaunal community and probably had a significant impact on bacterial density as grazers.     

Loss of organic matter and nutrients from a coastal dune heath in Northwest Denmark caused by fire

The loss of organic matter and nutrients due to a natural fire in a Danish coastal dune heath system (175 ha) was studied for three heath types: dryEmpetrum nigrum heath, moistE. nigrum-Vaccinium uliginosum heath, and wetErica tetralix-Molinia coerulea heath. The highest loss of organic matter, as well as N, P and K, was found in the moist heath (67%, 68%, 20% and 25% respectively). The lowest loss was found in the wet heath (35%, 28%, 14%, and 11% respectively). The loss in the dry heath was intermediate. For the burnt heath in total, loss of organic matter, N, P and K of about 13000, 192, 10 and 6 tons respectively, was estimated. Processes of nutrient loss by fire and regeneration of nutrients are discussed.     

Experimental field study of the effects of crude oil,drill cuttings and natural biodeposits on microphyto- and macrozoobenthic communities in a Mediterranean area

Effects of an experimental pollution by neogenous and fossil organic matter on microphyto- and macrozoobenthic communities were studied in situ over a 1 yr period (July 1989 to May 1990) in a shallow microtidal bay (Gulf of Fos, south coast of France). Three experimental enclosures of 1 m² non-defaunated sediments were covered with 1 cm of polluted defaunated sediments. The sediment in one enclosure contained natural biodeposits with a high organic matter content (BD), that in a second enclosure contained Arabian light crude oil (BAL), and the sediment in the third enclosure contained diesel oil-based cuttings (CUT). Pollution by contaminants did not prevent microphytobenthos from colouizing sediments. Population changes over time were quite similar in all enclosures, except in CUT, where a four times higher chlorophyll a content appeared to be related to a decreased number of grazers and consequently lower grazing rates of animals. Toxicity to the fauna was immediate in the case of BAL and occurred within 3 mo at CUT. Opportunistic species settled in all contaminated sediments; this occurred quite rapidly in BD and BAL which recovered within 3 mo to levels comparable with control sediments. In CUT, natural populations had not recovered after 1 yr, whereas a quasi-monospecific population of Capitella capitata was still present. During the first 3 mo, the oxygen demand of the sediment was higher in oil-contaminated sediments than in controls. On the whole, the changes in fluxes and organism assemblages in our weakly tidal area appear to be consistent with other findings in macrotidal seas.     

Sediment organic matter and meiofauna community response to long-term fish-farm impact in the Ligurian Sea (Western Mediterranean)

Quantitative and qualitative changes in meiofauna community structure were investigated to assess the impact of a fish farm, which was operating continuously for 15 years (La Spezia Gulf, W Mediterranean). Sediment samples were collected in June, July, September, October 2000 and February 2001 for the analysis of phytopigments (chlorophyll-a and phaeopigments), the biochemical composition of organic matter (proteins, carbohydrates and lipids) and related to meiofaunal parameters.

Sediment organic matter reached extremely high concentrations beneath the fish cages when compared to the control. Particularly lipids, carbohydrates and chlorophyll-a were significantly higher in fish-farm sediments. On a long-term basis meiofauna displayed adaptations in sediments beneath the cages resulting in an increase of density. Organic impact on meiofaunal community structure was evident in terms of an increase of the nematodes to copepods (Ne/Co) and nauplius to copepods (Na/Co) ratios in fish farm sediments. Cumaceans and kinorhynchs were encountered in control sediments, but disappeared in fish-farm samples. These data suggest that meiofauna is a sensitive tool for evaluating the effects of organic enrichment in fish farm impacted areas.     

Spatial variation of phosphorus fractionation in the coral reef sediments of Lakshadweep Archipelago,Indian Ocean

Surface sediments were collected from the shore and lagoons of Kavaratti, Kadamat and Agatti islands of Lakshadweep Archipelago during May 2015 and analysed for the spatial distribution of the micronutrient element, phosphorus. Phosphorus was separated by sequential extraction procedure into five fractions – exchangeable (Ex-P), iron bound, (Fe-P), calcium bound (Ca-P), organic and residual fractions (OP) and total phosphorus (TP). The average relative contribution of each P species to TP was: OP?>?Ca –P?>?Ex – P?>?Fe – P. The high concentration of organic and residual phosphorus (87–96%) compared to inorganic phosphorus is particularly evident at stations characterised by higher total phosphorus concentrations. Among the three forms of IP in the sediments, Ca-P was dominant at all stations. The OC/OP ratio ranged from 3 to 163 in the sediments, suggesting that the organic matter in sediments had been subjected to degradation. Hence, the major contribution towards organic and residual phosphorus form is from the residual fraction comprising biologically resistant or non-available phosphorus form composed of refractory materials. The concentration of phosphorus reported in the present study is higher than that of the earlier studies in Lakshadweep, indicating a terrestrial and anthropogenic in?uence on the sediment.