Distribution of Heavy Metals in Marine Sediments of Palermo Gulf (Sicily, Italy)

Concentrations of Cr, Cu, Hg, Pb and Zn have been measured, by atomic absorption spectrophotometry, in the fine fraction (<63 μm) of surface sediments collected in 30 sites in the Palermo Gulf (Sicily, Italy) in order to assess the levels and the spatial distribution of these elements. Enrichment factors calculated with respect to clean areas have been considered to discriminate between levels due to background or to pollution contributions. The sampling stations, which form a grid inside these areas, are characterized by geographic proximity and by the presence of pollution sources. Ratio matching technique along with hierarchical clustering, minimum spanning tree and principal component analysis have been used for the statistical analysis of data, allowing to better describe the spatial distribution of metal levels. Our work allowed to assess the anthropogenic contribution to the pollution of the area under investigation through industrial and domestic wastes, presence of an harbour area and river inflow.     

Cyclic influences on the heavy metal chronology in a Central Mediterranean area (Palermo Gulf,Italy)

Purpose  

The evaluation of long-term heavy metal concentrations in the Gulf of Palermo (Italy) has been carried out in order to investigate how changes of pollution levels in the last 50 years can be reflected in marine sediments. Measurements of Cr, Cu, Hg, Pb, and Zn concentrations were performed on dated fractions of a sediment core. Time series analysis has allowed to obtain information on the chronology of the heavy metal pollution of the area and to identify seasonal components and trends.     

Sediment Accumulation of Nutrients (N, P) in the Eastern Gulf of Finland (Baltic Sea)

Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m-2 a-1 of N and 1.7 g m-2 a-1 of P corresponding 22 000 t a-1 of N and 6 100 t a-1 of P for the whole eastern Gulf.     

Historical Variations in Lead Fluxes in the Pyrenees (Northeast Spain) from a Dated Lake Sediment Core

Variations in Pb concentration in lake sediments reflect changes in the fluxes of this element in the past. A sediment core from a lake in the Pyrenees (Lake Redó at 2,240 m a.s.l., NE Spain) was studied, with the aim of reconstructing past environmental and climatic conditions in the lake and its catchment area. The core was dated using both 210Pb and 14C. A surface peak of Pb concentration, which was about 10 times higher than the background level, was found. This peak is attributed to mining activities since the beginning of this century. Although Pb pollution due to the combustion of gasoline is expected to be present, no evidence can be deduced from Pb isotope ratios of sediment due to the masking effect of Pb from mines. A second peak appeared in a deeper layer, with a maximum Pb concentration of about 17 times higher than the background level. The origin of this peak is unclear. All evidence suggests that the ancient peak is due to mining operations in the central Pyrenees area, which were not documented historically.     

Heavy Metal Contents and Distribution in Coastal Sediments of the Gulf of Trieste (Northern Adriatic Sea, Italy)

A set of ten heavy metals (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, V, and Zn) was investigated in surface sediments (0–5 cm) collected in 21 sites of the Gulf of Trieste, Northern Adriatic Sea (Italy). The aim of this work was to obtain a preliminary assessment about the levels and spatial distribution of these selected elements. Ancillary parameters such as grain size, total organic carbon, and total nitrogen were also determined. The enrichment factor was calculated to discriminate if a natural condition or a status of anthropogenic contamination occurs. In addition, a set of sediment quality guidelines, mean effect low range and effect medium range quotients, was also applied in order to predict the probability of adverse biological effects on the benthic community.     

贵州省西南部麦岗水库沉积物的137Cs和210Pb测年与沉积速率研究

对贵州省西南部麦岗水库沉积物柱芯MG4-2,采用210Pb和137Cs法进行了测年与现代沉积速率研究.结果表明,该柱芯中存在这3个明显的137Cs蓄积峰,对应1964,1975,1986年3个计年时标.运用210Pb的恒定补给速率(CRS)模式计算得到的年代,总体上与137Cs法的结果吻合较好,但存在一定的偏差,特别是与1964年的计年时标的偏差较大,这可能是因为沉积物柱芯受到了一些人为扰动所致.两种核素测定的平均沉积速率在数值上有一定的偏差,但都反映了麦岗水库沉积物近几十年以来经历了从慢到快再到慢的沉积过程,初步推测,沉积速率的这种变化与人类活动有一定的关系.两种计年方法结合,相互印证,使计年和沉积速率的研究更为准确.     

Ecological Risk Assessment for the Recent Case of DDT Pollution in Lake Maggiore (Northern Italy)

Contamination by DDT of industrial origin was detected in 1996 in Lake Maggiore (Northern Italy) causing concern for wildlife and human health. Starting from 1998 a monitoring programme involving different research laboratories was undertaken to establish the pollution level of the lake. In assessing the ecological risk to Lake Maggiore wildlife during this period, the present study integrates information provided by the Commission for the Protection of Italian and Swiss Waters with further analysis and ecotoxicological tests carried out on some autochthonous target species for this insecticide. Sediments collected at the end of 1997 in the most contaminated bay (total DDT 860.2 ng g^?1 dry weight) caused a decrease in fertility and growth of benthic oligochaetes and chironomids, while the 48 h IC₅₀ for Daphnia galeata (0.76 μg L^?1, c.i. 0.43–1.34) was much higher than the DDT concentration in the lake water. The risk of acute effects on zooplankton should therefore be excluded, while transfer through the trophic web and bioconcentration in fish and fish-eating birds are the most adverse consequences of DDT contamination in Lake Maggiore.     

Using 137Cs and 210Pbex measurements to explore the effectiveness of soil conservation measures in semi-arid lands: a case study in the Kouhin region of Iran

Journal of Soils and Sediments - One of the most fragile agro-ecosystems in Iran is represented by dry farming lands on steep hillslopes that occupy ca. 54% of the national agricultural lands....     

铜、铅单一及其复合污染对鱼腥草吸收累积铜和铅的影响

采用溶液培养法研究铜、铅在单一及其复合污染条件下对鱼腥草吸收累积铜和铅的影响。试验结果表明,随着溶液中离子浓度的增加,鱼腥草对铜和铅的吸收累积量增加。鱼腥草累积铜的趋势以二次曲线拟合最好,累积铅的趋势以对数曲线拟合最好。在一定浓度范围内地下部对铜的富集系数随溶液中铜离子浓度的增加变小,地上部对铜的富集系数随溶液中铜离子浓度的增加变大;各部位对铅的富集系数则随溶液中铅离子浓度的增加变小。铜、铅复合污染影响鱼腥草对铜和铅的吸收累积,通过多元回归分析结果表明,铜、铅在鱼腥草植株内的累积主要表现为协同作用。     

Factors Affecting the use of Dreissena polymorpha as a Bioindicator: the PCB Pollution in Lake Como (N. Italy)

The aim of this study was to assess the PCB pollutionof the South-Western branch of Lake Como by using thezebra mussel (Dreissena polymorpha) as abioindicator since its recent reintroduction. Someenvironmental and physiological variables influencingaccumulation processes of organochlorine compounds inDreissena were investigated because climaticfactors may affect life cycle, reproductive stage andage. PCB levels were highest in the soft tissues ofDreissena close to the industrialized area ofComo (2298 ng g^-1 of lipids) and slowly decrease goingnorth, reaching approximately half this value at theclosing section of the lake branch. Nonetheless, thePCB concentrations are well below the dangerous levelsfor the aquatic environment.     

Seasonal Variations of Sulphate Reduction Rates, Sulphur Pools and Iron Availability in the Sediment of a Dystrophic Lagoon (Sacca di Goro, Italy)

The aim of this work was to analyse factors which regulate sulphide mobility in the sediments of a dystrophic lagoon (Sacca di Goro, the southern lagoon of the Po river delta, Italy). In 1995-96, sediment oxygen demand and variations in organic matter content, redox potential, iron availability, inorganic sulphur concentrations and sulphate reduction rates were measured in sediment profiles at three stations (G, 4 and 17) representative of the main areas of the lagoon. Stations differed mainly in their salinity range and primary producer communities. High concentrations of reactive iron (110-275 µmol ml-1) and low sulphate reduction rates (0.8-16.1 mmol m-2 d-1) were measured in the sediment. Moreover, high concentrations of reactive ferric iron were detected in winter and spring at the stations closest to the freshwater inputs. Nevertheless, in summer, high concentrations of free sulphides were detected in the porewater, although most of the reactive ferrous iron was not sulphide-bound, indicating that not all of the reactive iron pool was available to buffer against sulphide release and thus measures of reactive iron pools may not be a good measure of the true buffering capacity of the sediment. Furthermore, a considerable production of sulphide may occur in the decaying Ulva biomass in the water column, where its concentration will be independent of the potential buffering capacity of iron in the sediment. Therefore when assessing the vulnerability of coastal lagoons to dystrophic events, both the size and availability of the reactive iron pool as well as the site of sulphide production must be taken into consideration.     

滇池沉积物金属污染及潜在生态风险研究

对滇池126个采样点沉积物0～5 cm、5～10 cm和10-20 cm中Cu、Zn、Pb、Cr、Cd、Hg和As等7种金属的含量进行了分析测定,各金属含量测定结果均高于相应的参比值,表明滇池沉积物受到了不同程度的金属污染.各金属含量的水平分布很不均衡,Zn、Pb、Cd、Hg和As含量随沉积物深度的减小而增大,Cu和Cr含量则随沉积物深度减小而减小,表明滇池沉积物中Cu和Cr污染整体上出现了减缓的趋势,而Zn、Pb、Cd、Hg和As污染在不断加剧.用H(a)k(a)nson潜在生态风险指数对滇池沉积物金属污染的生态风险进行了分析,结果表明:滇池沉积物存在轻微的Cu、Zn、Pb、Cr和As污染生态风险,以及中等的Hg和Cd污染生态风险;全湖沉积物金属污染的平均生态风险指数RI值为205.03,属中等生态风险,但有快速加大的趋势.     

Polycyclic Aromatic Hydrocarbons in Seawater, Sediment, and Rock Oyster Saccostrea cucullata from the Northern Part of the Persian Gulf (Bushehr Province)

The concentration of polycyclic aromatic hydrocarbons (PAHs) was determined in seawater, sediment, and Rock oyster Saccostrea cucullata collected from four sampling sites in the inter-tidal areas of Bushehr province. The total concentrations of 14 PAHs varied from 1.5 to 3.6 ng/L in seawater, 41.7 to 227.5 ng/g dry weight in surface sediment, and 126 to 226.1 ng/g dry weight in oyster tissue. In comparing PAH concentrations among the three matrices in Bushehr province, data showed that the pattern of individual PAHs in seawater, oyster, and sediment were different. The oysters tended to accumulate the lower molecular weight and the more water-soluble PAHs. Sediment samples were distinguished from the sea water and oyster samples by the presence of high molecular weight PAHs, especially six-ring PAHs. Three- and four-ring PAHs were the most abundant compounds among the 14 PAHs investigated in surface seawater, sediment, and oyster samples. As expected, differences in octanol/water partition coefficient among individual PAHs and the greater persistence of the higher molecular weight PAHs contributed to the accumulation patterns in oyster and sediment. The results of the study suggested that the main sources of PAHs in the seawater and sediment in the region were mixed pyrolitic and petrogenic inputs.     

History and Trends of Sediment Contamination by Heavy Metals Within and Close to a Marine Area of National Interest: The Ligurian Sea off Cogoleto-Stoppani (Genoa, Italy)

Due to its remarkable sediment pollution caused by past industrial activities, the Mediterranean coastal area facing the town of Cogoleto (near Genoa) has been declared of “national interest”. Seven sediment cores were analysed to provide information on history and trend of heavy metal inputs, with a particular focus on Cr. Grain-size compositions and ²¹⁰Pb chronologies account for a strong influence of terrigenous inputs near the coast and the mouth of the Lerone Creek (draining the industrial settlement), with sand contents and accumulation rates varying from 40.3% and 0.7 cm year^?1 near shore to 2.5% and 0.1 cm year^?1 offshore. Heavy metal concentrations are high, notably Cr and Ni, and to a lesser extent, Ag, Hg, Pb, Cu and Zn. Cr, that shows past values up to 3,642 µg g^?1, presents only minor recent decreases. In the area, it has both natural and anthropogenic sources and their relative contributions were distinguished on the basis of Cr/Ni ratios. These are 1–1.5 in soils and rocks of the Lerone Creek catchment area but reach very high values (up to 10) in marine sediments due to the anthropogenic contribution. The anthropogenic influence is higher near the creek mouth, gradually decreases offshore and is negligible at the most distal site (ca. 2.9 km from the coast).     

Soil properties and metal accumulation by earthworms in the Siena urban area (Italy)

This paper reports the results of a study focused on the metal (Cd, Co, Cr, Cu, Ni, Pb, Sb, U and Zn) distribution in soils and uptake and accumulation by earthworms Nicodrilus caliginosus (Savigny) from urban, peri-urban, green-urban and non-urban zones of Siena municipality (central Italy). The main goal was to define the influence of soil properties and metal soil contents on the uptake of these contaminants by earthworms. Data indicated that Cd, Cu, Pb, Sb and Zn soil contents increased in the following order: non-urban < green-urban < peri-urban < urban soils, suggesting that vehicular traffic affects the distribution of these metals. Pb and Sb were the main soil contaminants and their highest enrichments were found in urban sites where stop-and-go traffic occurs. Concentrations of these traffic-related metals in earthworms showed a distribution pattern similar to that in soil, suggesting that soil contamination influenced the uptake of Cd, Cu, Pb, Sb and Zn by N. caliginosus. There were significant positive correlations between Cd, Pb and Sb earthworm concentrations and their soil contents. The lack of correlation for Cu and Zn could be due to the physiological regulation of these elements by earthworms. Statistical analysis pointed out that the uptake and accumulation of Cd, Cu, Pb, Sb and Zn by earthworms were affected by some soil physicochemical properties such as the organic carbon and carbonate contents that are able to rule the bioavailability of metals in soils.     

Assessment of tillage erosion by mouldboard plough in Tuscany (Italy)

This study was designed to characterise the soil translocation effect induced by mouldboard ploughing with an implement traditionally used in the Tuscany region (Central Italy). We discuss the results of a set of field experiments performed to measure soil displacement along slopes of varying gradient in different directions and at several depths of tillage. Using the Soil Erosion by Tillage (SETi) model, soil translocation patterns for different tillage scenarios were analysed, with special attention paid to the effects of the direction and depth of tillage on the extent and spatial pattern of soil movement. The lateral slope gradient S_P and tillage depth D were found to be the dominant controlling factors for total soil displacement. The effect of the slope gradient in a direction parallel to tillage S_T was much less pronounced. These findings reveal the importance of the asymmetric nature of the soil movement produced by mouldboard ploughing and the predominant effect of the lateral displacement d_P on the actual trajectory of soil motion. Results demonstrate that spatial patterns of soil redistribution due to mouldboard ploughing are highly variable and depend on the particular characteristics of the implement used. This dependence is so strong that maximum downslope soil translocation can occur during both, contour tillage or up–down tillage. For this particular mouldboard plough, maximum downslope soil transport took place at a tillage direction ca. 70° and not when tillage was conducted along the steepest slope direction (0°). These findings highlight the potential of the combined approach applied. The physically based SETi model can be properly calibrated using a relatively limited dataset from field experiments. Once calibrating, the SETi model can then be used to generate synthetic tillage translocation relationships, which can predict the intensity and spatial pattern of soil translocation over a much wider range of tillage scenarios than the particular experimental conditions, in terms of topography complexity (slope gradients and morphology) and the direction and depth of tillage. These synthetic relationships are useful tools for evaluating strategies designed to reduce tillage erosion.     

Metal Pollution by Old Lead-Zinc Mines in Urumea River Valley (Basque Country,Spain). Soil,Biota and Sediment

Soil, aquatic biota (moss: Brachythecium rivulare; aquatic macrophytes: Juncus effusus, Potamogeton crispus; fish: Salmo trutta fario, Anguilla anguilla, Phoxinus phoxinus, Chelon labrosus) and sediment samples from the Urumea river valley were analysed for metals by acid digestion and atomic absorption spectroscopy. The sediments show the presence of metal pollution (Cd: 2.5–24 mg kg^-1; Pb: 125–1,150 mg kg^-1; Zn: 125–2,500 mg kg^-1) because mining and industrial wastes. A selective retention of dense minerals in dam sediments contributes to the load of metal, but interstitial water analysis (Cd: <0.02–0.1 mg L^-1; Pb: 0.3–1.0 mg L^-1; Zn: <0.05–0.6 mg L^-1) shows that precipitation equilibrium controls their mobilisation. Biota samples show evidence of metal accumulation, moss reaching 1,100 mg kg^-1 in lead and 6,800 mg kg^-1 in zinc. Soil from the valley is polluted by both, river carried material and industrial sources (Cd: 1.0–4.0 mg kg^-1; Pb: 26–1,120 mg kg^-1; Zn: 105–1,390 mg kg^-1/math>), but they are used, indistinctly, for farming and pasture.     

Trophic Modifications in Lake Como (N. Italy) caused by the Zebra Mussel (Dreissena Polymorpha)

A large scale study on the western basin of Lake Como (N. Italy) was started in 1995 to examine the effects of the zebra mussel colonization which began in early '90. Our results have been related to '91–92 data (pre-Dreissena period), before the maximum colonization of zebra mussel. In spring and summer of the post-Dreissena period total phosphorus, P-PO₄, nitrate and chlorophyll values decreased, while ammonium and tranparency increased at every sampling station. Zebra mussel does not modify the trophic state of this sub-basin but it plays an important role in nutrient cycling. The entire population can filter epilimnetic craters 2.1 times per year and can produce 2.9 × 10⁴ t y of pseudofaeces which are transferred to sediments.     

historical deposition rates of Cd,Cu, Pb,and Zn in Norway and Sweden estimated by 210Pb dating and measurement of trace elements in cores of peat bogs

From six ombrotrophic mires located far from distinct local sources in Sweden and Norway, a core was sampled in bog hummocks in 1988 and dated by 210_Pb. Ten slices from each core were analyzed for Cd, Cu, Pb, and Zn. Based on the datings, the accumulation rates of Cd, Cu, Pb, and Zn have been estimated for the last 150 years. A reasonable agreement exists in the comparison between the recent deposition in the peat bog and nearby bulk deposition measurements. Highest deposition has been measured in southern Norway and the western part of Sweden. Generally, deposition has increased during the last 150 years, except at a station on the east coast of Sweden. In a study in Sweden where heavy metals have been measured in mosses every five years time since 1970, significant decreases in the concentrations of heavy metals have been found. Similar decreases have not been measured in the present study, although both methods are expected to reflect atmospheric deposition. Several studies have indicated that peat bogs are not suitable for measuring the historical evolution of trace metals. However, despite the disagreement, the recent literature suggests that it can be done with reasonable accuracy when performed with samples from hummocks in the peat bog.