河口潮间带沉积物重金属累积及生态风险评价

于2015年7月份在闽江口鳝鱼滩湿地布设两条样带(T1和T2),并分别选取5个采样点采集沉积物样品。因重金属Co和V对动物和人类会造成一定危害,且闽江河口潮间带Co和V的研究较少,则对其理化性质、Co和V的空间分布特征以及污染程度等进行了研究,旨在为Co和V的污染研究提供参考。结果显示,该沉积物中Co和V的平均浓度分别为15.19 mg/kg、102.94 mg/kg,均高于福建省背景浓度,与其他河口对比,Co和V浓度处于中等水平。Co和V的含量由陆向海方向略有下降。地累积指数法分析得出沉积物中Co含量呈现轻度污染状态,V呈现无污染状态。此外,Co和V的潜在生态危害系数E_r~i分别为7.24—14.85和1.47—4.17,表明潜在生态危害轻微,闽江河口潮间带沉积物中Co和V属于轻度污染。     

上川岛潮间带不同生境底栖软体动物物种多样性初步研究

目的:研究上川岛潮间带不同生境底栖软体动物物种多样性。方法:对上川岛潮间带(沙滩、泥沙滩、红树林泥滩、岩石滩) 4种不同生境的7个样方的底栖软体动物进行了生物多样性的初步调查。结果:共鉴定底栖软体动物14科30种,上川岛潮间带底栖软体动物物种丰富度指数为岩石滩(平均为1.784 ) >泥沙滩(平均为1.5 2 1) >红树林泥滩(平均为1.2 35 ) >沙滩(平均为0 .6 92 ) ;多样性指数岩石滩(平均为1.5 5 1) >红树林泥滩(平均为1.30 4 ) >泥沙滩(平均为1.16 2 ) >沙滩(平均为0 .4 0 3)。结论:底栖软体动物的种类及数量分布受底质、浪击等因素的影响。     

Factors affecting metal concentrations in reed plants (Phragmites australis) of intertidal marshes in the Scheldt estuary

We aimed to identify the environmental factors which significantly affect metal uptake by reed plants in the intertidal marshes along the river Scheldt. Transfer coefficients, defined as the ratio of metal concentrations in reed stems to the metal contents in specific sediment fractions (i.e. the exchangeable Cd and Zn fraction and total Cr, Cu, Ni and Pb content), were calculated for each sampling site. They were inversely related to the sediment clay and/or organic matter content. Metal mobility and thus plant availability is higher in sediments with a lower clay or organic matter content. Moreover, the plants might actively accumulate in particular essential elements when concentrations in the sediments are rather low, which is the case in sediments low in clay and organic matter contents. Finally, more sandy sediments are expected to be susceptible to occasional oxidation of sulphides, which leads to an increased metal availability. A higher salinity promoted the uptake of Cu, Cr and Zn.     

Diversity and Transport of Microorganisms in Intertidal Sands of the California Coast

Forced by tides and waves, large volumes of seawater are flushed through the beach daily. Organic material and nutrients in seawater are remineralized and cycled as they pass through the beach. Microorganisms are responsible for most of the biogeochemical cycling in the beach; however, few studies have characterized their diversity in intertidal sands, and little work has characterized the extent to which microbes are transported between different compartments of the beach. The present study uses next-generation massively parallel sequencing to characterize the microbial community present at 49 beaches along the coast of California. In addition, we characterize the transport of microorganisms within intertidal sands using laboratory column experiments. We identified extensive diversity in the beach sands. Nearly 1,000 unique taxa were identified in sands from 10 or more unique beaches, suggesting the existence of a group of “cosmopolitan” sand microorganisms. A biogeographical analysis identified a taxon-distance relationship among the beaches. In addition, sands with similar grain size, organic carbon content, exposed to a similar wave climate, and having the same degree of anthropogenic influence tended to have similar microbial communities. Column experiments identified microbes readily mobilized by seawater infiltrating through unsaturated intertidal sands. The ease with which microbes were mobilized suggests that intertidal sands may represent a reservoir of bacteria that seed the beach aquifer where they may partake in biogeochemical cycling.     

Low tide distribution of wintering waders and shelduck on the Severn Estuary in relation to the proposed tidal barrage

Waders and shelduck were counted at low tide on 162 sectors comprising 85% of the intertidal area (21 467 ha) of the Severn Estuary on 12 occasions during winter 1987/88. On average, 50% of birds present at low tide utilized just 13 sectors (12% of the area); 90% of birds occurred on only 56 sectors, leaving large expanses of intertidal sand virtually devoid of birdlife. Dunlin, the numerically dominant species, occurred widely on the middle and outer estuary, whereas shelduck predominantly occurred on the outer estuary and redshank around many tributary river mouths. Curlew, the most ubiquitous species, was the only one concentrated on the inner estuary. Severe gales in both late December and mid-January concentrated all main species within fewer sectors, probably by the short-term removal of surface sediment from substantial areas. It is estimated that the proposed tidal barrage would eliminate intertidal areas accounting for between c. 40% (for shelduck and curlew) and 80% (for redshank) of current total low tide usage by the internationally important populations present.     

Some physical,chemical, and microbiological characteristics of two beaches of anglesey

Observations during 1971 and 1972 of some of the physical, chemical, and microbiological characteristics of contrasting Anglesey beaches, Newborough and Llanddona, are reported. The fine sandy beach at Newborough was observed to be very unstable and topographical changes were recorded. In particular, the movement of a sand wave across the intertidal zone from low water to extinction at the foot of the dune system was observed. The more extensive fine sandy beach at Llanddona had greater stability.Chemically, each beach was variable both spatially and temporally, with ill-defined patterns of concentration changes. Sand from Newborough beach was low in organic carbon (0.07–0.40 mg C/g dry sand) and well aerated, and the soluble inorganic nitrogen in the ground water (up to 30 μg-at. N/l) was dominated by nitrate form (up to 22 μg NO₃-N/l). By contrast, Llanddona sand had a more variable organic carbon content (0.22–2.25 mg C/g dry sand), was wetter, and poorly aerated with consequent sulphide lenses; its dissolved inorganic nitrogen (over 70 μg-at. N/l) was completely dominated by the ammonium form.Microbiologically, the beaches possessed dissimilar bacterial floras, and sediment from Llanddona gave higher bacterial counts than that from Newborough. For both beaches it is shown that estimated bacterial numbers decreased with depth as well as down the intertidal zone.     

Estuaries as Filters: The Role of Tidal Marshes in Trace Metal Removal

Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary.     

Heavy-metal uptake by crops from polluted river sediments covered by non-polluted topsoil

Crop uptake of heavy metals from polluted river clay soils is shown to be reduced by covering the polluted soil with a layer of unpolluted clay soil. Plant experiments have been performed to determine the thickness of such a layer required either to comply with permissible levels for metal concentrations in foods and feeds, or to exclude any effect on plant metal levels. The experiments included cover layers up to 0.7 m and 1.6 m, respectively. Crops grown included cereals, potatoes, sugar beet, maize and various vegetables. Protection of all food crops tested against exceeding permissible levels for cadmium requires a clean topsoil of over 1.6 m; for individual crops ranging from zero (no cover layer required) for red cabbage, leek, onion, potato) to 1.2 m–1.6 m for celery tuber and leaf. Results for feed crops were variable: required topsoil depths for maize range from 0.25–1.2 m, and for wheat straw from 0.55 to 1.6 m. No-effect depths calculated for Cd, Cu and Zn demonstrate that inmany experiments the effect of the polluted soil may be observed at all topsoil depths tested. Heavy-metal concentrations in the soil profile, measured after completion of the experiments, showed no significant migration of metals from the polluted soil into the cover soil.     

Local distribution and thermal ecology of two intertidal fishes

Geographic variability in the physiological attributes of widely distributed species can be a result of phenotypic plasticity or can reflect evolutionary responses to a particular habitat. In the field, we assessed thermal variability in low and high intertidal pools and the distribution of resident fish species Scartichthys viridis and transitory Girella laevifrons along this vertical intertidal gradient at three localities along the Chilean coast: Antofagasta (the northernmost and warmest habitat), Carrizal Bajo (central coast) and Las Cruces (the southernmost and coldest habitat). In the laboratory, we evaluated the thermal sensitivity of fish captured from each locality. The response to temperature was estimated as the frequency of opercular movements and as thermal selectivity in a gradient; the former being a indirect indicator of energy costs in a particular environment and the latter revealing differential occupation of habitat. Seawater temperature in intertidal pools was greatest at Antofagasta, and within each site was greatest in high intertidal pools. The two intertidal fish species showed opposite patterns of local distribution, with S. viridis primarily inhabiting the lower sectors of the intertidal zone, and G. laevifrons occupying the higher sectors of the intertidal zone. This pattern was consistent for all three localities. Locality was found to be a very important factor determining the frequency of opercular movement and thermal selectivity of both S. viridis and G. laevifrons. Our results suggest that S. viridis and G. laevifrons respond according to: (1) the thermal history of the habitat from which they came, and (2) the immediate physical conditions of their habitat. These results suggest local adaptation rather than plasticity in thermoregulatory and energetic mechanisms.     

The magnetic properties of loess and paleosol samples from the Chinese Loess Plateau spanning the last 22 million years

Magnetic measurements (susceptibility, isothermal and anhysteretic remanence, and quotients derived from these) are presented for a suite of loess and paleosol samples from sites on the Chinese Loess Plateau. The three sites, Xifeng, Dongwan and Qinan (QA-I), together span most of the last 22 million years. The results provide the first multi-parameter magnetic measurements from pre-Pleistocene loess/paleosol sequences that began accumulation in the early Miocene. Mass specific measurements have been corrected for carbonate concentrations which peak in the loess layers and range up to 57%. All the magnetic properties recorded indicate variability on both orbital and supra-orbital timescales. The changing magnetic properties allow the record to be divided into a sequence of eight sample groups that broadly parallel the main supra-orbital changes in magnetic susceptibility. The pre-Pleistocene parts of the record include intervals (mainly late Miocene and Pliocene) during which loess as well as paleosol layers are characterized by high values for properties such as frequency dependent susceptibility (χ_fd), usually associated with strong weathering. Most of the Miocene record prior to 8.5 Ma, with the exception of a brief interval from ca. 14.4 to 15.9 Ma, shows reduced values for indicators of pedogenic ferrimagnetic concentrations in both the loess and paleosol layers, as well as a low amplitude of variability between loess and paleosol values. The palaeoenvironmental implications of this part of the sequence are unclear since they hinge on the type of model of pedogenic magnetic mineral formation adopted. High-field remanence measurements indicate that the coercivity of the antiferromagnetic minerals represented declined progressively throughout the whole period in both the loess and the paleosol samples, though there is no unambiguous evidence for long-term diagenetic alteration of the magnetic properties on timescales beyond the orbital ones that drive the loess/paleosol alternations. The present results suggest caution in applying existing climofunctions based on magnetic susceptibility to deposits spanning the whole of the last 22 Ma.     

Relationship between Enterococcal Levels and Sediment Biofilms at Recreational Beaches in South Florida

Enterococci, recommended at the U.S. federal level for monitoring water quality at marine recreational beaches, have been found to reside and grow within beach sands. However, the environmental and ecological factors affecting enterococcal persistence remain poorly understood, making it difficult to determine levels of fecal pollution and assess human health risks. Here we document the presence of enterococci associated with beach sediment biofilms at eight south Florida recreational beaches. Enterococcal levels were highest in supratidal sands, where they displayed a nonlinear, unimodal relationship with extracellular polymeric secretions (EPS), the primary component of biofilms. Enterococcal levels peaked at intermediate levels of EPS, suggesting that biofilms may promote the survival of enterococci but also inhibit enterococci as the biofilm develops within beach sands. Analysis of bacterial community profiles determined by terminal restriction fragment length polymorphisms showed the bacterial communities of supratidal sediments to be significantly different from intertidal and subtidal communities; however, no differences were observed in bacterial community compositions associated with different EPS concentrations. Our results suggest that supratidal sands are a microbiologically unique environment favorable for the incorporation and persistence of enterococci within beach sediment biofilms.     

Spatial Distribution and Uncertainty Assessment of Potential Ecological Risks of Heavy Metals in Soil Using Sequential Gaussian Simulation

The objective of this study is to assess the spatial distribution and uncertainty of the potential ecological risks of heavy metals in soil using sequential Gaussian simulation (SGS) and the Hakanson potential ecological risk index (PERI). We collected 130 soil samples in an area of 150 km² in the High-Tech Park of Wuhan, China, and measured the concentrations of five heavy metals in soil (i.e., Cd, Cr, Cu, Pb, and Zn). We then simulated the spatial distribution of each heavy metal using SGS, and calculated Hakanson PERIs for individual metals and multiple metals based on the simulated realizations. The spatial uncertainty of the Cd PERI and its occurrence probabilities in different risk grades were further assessed. Results show that the potential ecological risks of Cr, Cu, Pb, and Zn are relatively low in the study area, but Cd indeed reaches a serious level that deserves much attention and essential treatment. The total PERI of multiple heavy metals indicates a moderate grade in most of the study area. In general, combining SGS and the Hakanson PERI appears to be an effective method for evaluating the potential ecological risks of heavy metals in soil and the priority areas for remediation.     

High water roost selection by waders: maximizing feeding opportunities or avoiding predation?

During the highest spring tides the intertidal sediment flats of estuaries are fully inundated at high water, and waders have no choice but to move to supratidal roosts, e.g. on open farmland, saltpans or beaches. However, in many estuaries during the lowest neap or intermediate tides there are sectors of upper intertidal sediment flats that remain exposed even at the peak of high water, and so waders have the choice of roosting either there or in supratidal sites. In the Tagus Estuary, Portugal, as elsewhere, waders use both types of roosts during high water. Our main objective was to understand what makes waders opt for one of these two types of available roosts. We monitored wader use of saltpans and intertidal roosts from spring to neap tides, and measured foraging and alarm behaviour, prey availability and disturbance by predators. Most of the wader species studied chose intertidal (mudflat) roosts whenever these were available, and only roosted in saltpans during the peak of spring tides. We hypothesized that this preference was explained either by an attempt (i) to continue feeding into the high water period, or (ii) to minimize predation risk. Extending feeding time into the high water period did not seem to be very relevant for roost choice because both prey availability and foraging activity were low in both types of roosts. However, predator disturbance was several times higher in the saltpans than in the intertidal roosts, suggesting that this factor may be the determinant in the choice of roost type.     

Birds at a Southern California beach: seasonality, habitat use and disturbance by human activity

Use of a Santa Barbara beach by people and birds varied in both time and space. There were 100 birds, 18 people and 2 dogs per kilometer. Bird density varied primarily with the season and tide while human activity varied most between weekend and weekday. Bird distributions along the beach were determined mainly by habitat type (particularly a lagoon and exposed rocky intertidal areas) For crows and western gulls, there was some evidence that access to urban refuse increased abundance. Interactions between birds and people often caused birds to move or fly away, particularly when people were within 20 m. During a short observation period, 10% of humans and 39% of dogs disturbed birds. More than 70% of birds flew when disturbed. Bird species varied in the frequency that they were disturbed, partially because a few bird species foraged on the upper beach where contact with people was less frequent. Most disturbances occurred low on the beach. Although disturbances caused birds to move away from humans, most displacement was short enough that variation in human activity did not alter large-scale patterns of beach use by the birds. Birds were less reactive to humans (but not dogs) when beach activity was low.     

The soil environment of the intertidal area in the Westerschelde

Hydrodynamic forces and sediment discharges determine the sedimentary environment and surface morphology of the intertidal area in the Westerschelde estuary in the S.W. Netherlands. Sandflats (clay content <8%) are found in the central part, mudflats (>8% clay) and especially salt marshes (>15% clay) occur in sheltered places.The semi-terrestrial soil of the intertidal area is a complex environment where hydrosphere, biosphere, lithosphere, and atmosphere interact. Surface morphology and the semi-diurnal tide may significantly modify this interaction pattern. Organic matter and constituents of the clay-size fraction are the most reactive compounds in the soil.The pathway and rate of organic matter decomposition determines the nature of many biogeochemical processes. Sulfur transformations are dominant processes in the sulfidic grey-black coloured horizons underneath the generally thin yellow-brown surface layer. The sulfur geochemistry also affects the sorption-behaviour of metals. Oxygen intrusion by diffusion, burrowing fauna and plant roots cause a local and sometimes temporary oxidation of reduced inorganic compounds. Thus, in the surface layers, and in and around tubes and roots at greater depth in the soil, a dynamic cycling occurs of redox active compounds, which affects the sorption mechanism ofe.g. metals-ions.     

Non-Linear Interactions Determine the Impact of Sea-Level Rise on Estuarine Benthic Biodiversity and Ecosystem Processes

Sea-level rise induced by climate change may have significant impacts on the ecosystem functions and ecosystem services provided by intertidal sediment ecosystems. Accelerated sea-level rise is expected to lead to steeper beach slopes, coarser particle sizes and increased wave exposure, with consequent impacts on intertidal ecosystems. We examined the relationships between abundance, biomass, and community metabolism of benthic fauna with beach slope, particle size and exposure, using samples across a range of conditions from three different locations in the UK, to determine the significance of sediment particle size beach slope and wave exposure in affecting benthic fauna and ecosystem function in different ecological contexts. Our results show that abundance, biomass and oxygen consumption of intertidal macrofauna and meiofauna are affected significantly by interactions among sediment particle size, beach slope and wave exposure. For macrofauna on less sloping beaches, the effect of these physical constraints is mediated by the local context, although for meiofauna and for macrofauna on intermediate and steeper beaches, the effects of physical constraints dominate. Steeper beach slopes, coarser particle sizes and increased wave exposure generally result in decreases in abundance, biomass and oxygen consumption, but these relationships are complex and non-linear. Sea-level rise is likely to lead to changes in ecosystem structure with generally negative impacts on ecosystem functions and ecosystem services. However, the impacts of sea-level rise will also be affected by local ecological context, especially for less sloping beaches.     

15N-1H Residual dipolar coupling analysis of native and alkaline-K79A Saccharomyces cerevisiae cytochrome c

Residual dipolar couplings (RDCs) and pseudocontact shifts are experimentally accessible properties in nuclear magnetic resonance that are related to structural parameters and to the magnetic susceptibility anisotropy. We have determined RDCs due to field-induced orientation of oxidized-K79A and reduced cytochrome c at pH 7.0 and oxidized-K79A cytochrome c at pH 11.1 through measurements of amide (15)N-(1)H (1)J couplings at 800 and 500 MHz. The pH 7.0 RDCs for Fe(III)- and Fe(II)-cytochrome c together with available nuclear Overhauser effects were used to recalculate solution structures that were consistent with both sets of constraints. Molecular magnetic susceptibility anisotropy values were calculated for both redox states of the protein. By subtracting the residual dipolar couplings (RDCs) of the reduced form from those of the oxidized form measured at the same magnetic field (800 MHz), we found the RDC contribution of the paramagnetic metal ion in the oxidized protein. The magnetic susceptibility anisotropy, which was calculated from the structure, was found to be the same as that of the paramagnetic metal ion obtained independently from pseudocontact shifts, thereby indicating that the elements of secondary structure either are rigid or display the same mobility in both oxidation states. The residual dipolar coupling values of the alkaline-K79A form are small with respect to those of oxidized native cytochrome, whereas the pseudocontact shifts are essentially of the same magnitude, indicating local mobility. Importantly, this is the first time that mobility has been found through comparison of RDCs with pseudocontact shifts.     

Geochemical Evidence of Anthropogenic Impacts in Sediment Cores from Mudflats of a Tropical Estuary,Central West Coast of India

The concentration of trace metals (Co, Cr, Zn, Cu, and Pb), major elements (Al, Mn, Fe, Ca, Mg, and K), along with the percentage of sediment components (sand, silt, clay, and organic carbon), was determined in three sediment cores, collected from intertidal regions of the Zuari estuary (ZA and ZR) and Cumbharjua canal (CB). The Cores CB and ZR, collected from the upper middle estuarine environment, showed higher values of finer fractions and total organic carbon as well as metals (except of Ca) than Core ZA, which was sampled from the lower estuarine environment. The concentration of trace metals including Mn and Fe was found to be largely dependent on the proximity to mining areas, with Core ZR and Core CB representing the highest metal concentrations (Mn, Fe, Cr, and Zn). Absence of a significant early diagenetic remobilization might have preserved the metal loadings due to mining and industrial activities in Cores ZR and CB. In Core ZA, all the elements except Cu showed significant enrichment in the upper portion. Enrichment factor computed in all the cores was found to be above 2 for all the studied metals except Zn, which suggests a high degree of metal contamination. All these observations indicate that the present study area is under the strong influence of anthropogenic activities, especially in recent years.     

Humans alter habitat selection of birds on ocean‐exposed sandy beaches

Aim Resource‐selection functions (RSFs) can quantify and predict the density of animal populations across heterogeneous landscapes and are important conservation tools in areas subject to human disturbance. Sandy beach ecosystems have comparatively low habitat heterogeneity and structural relief in the intertidal zone, but intense human use. We aimed to develop predictive RSFs for birds on ocean‐exposed sandy beaches at two spatial scales, 25 ha (local scale) and 250 ha (landscape scale), and to test whether habitat selection of birds that commonly use the surf–beach–dune interface is influenced by the rates of human activities. Location Moreton and North Stradbroke Island, eastern Australia. Methods Avifauna and human activities were mapped on three sandy beaches covering 79 km of coastline for 15 months. Habitat characteristics of the surf–beach–dune interface were derived from remote sensing and ground surveys. RSFs were developed for 12 species of birds at two spatial scales: 25 ha (local scale) and 250 ha (landscape scale). Results  At local (25 ha) and landscape scales (250 ha), dune dimensions and the extent and type of vegetation structure were important predictors of bird density. Adding the frequency of human activities improved the predictive power of RSFs, suggesting that habitat selection of birds on beaches is modified by human use of these environments. Human activities occurred mostly in the mid‐ to lower intertidal zone of the beach, overlapping closely with the preferred habitats of Silver Gulls (Larus novaehollandiae), Pied Oystercatchers (Haematopus longirostris), Red‐capped Plovers (Charadrius ruficapillus) and endangered Little Terns (Sternula albifrons). Main conclusions In addition to demonstrating the appropriateness of RSFs to the surf–beach–dune interface, our results stress the need for systematic conservation planning for these ecosystems, where ecological values have traditionally been subsidiary to the maintenance of sand budgets and erosion control.