Environmental magnetic and geochemical characteristics of Chennai coastal sediments,Bay of Bengal,India

In this study, environmental magnetic, heavy metal and statistical analyses were conducted on 21 surface sediments collected from Chennai coast, India, to examine the feasibility of heavy metal pollution using magnetic susceptibility. The Chennai coastal sediment samples are dominated by ferrimagnetic minerals corresponding to magnetite-like minerals. The percentage of frequency dependent magnetic susceptibility reflects the presence of super-paramagnetic/single domain magnetic minerals in Chennai harbour, Cooum and Adayar rivers sediments. High pollution load index in sample E1, E2, CH7, C11, C12 and A16 is mainly due to anthropogenic activities such as, harbour activities, Cooum and Adayar rivers input and industrial effluent. Factor analysis shows that the magnetic concentration dependent parameters (χ, χ _ARM and SIRM) covary with the heavy metal concentrations, suggesting that the input of magnetic minerals and heavy metals in Chennai coastal sediments are derived from the same anthropogenic sources. Strong correlation obtained between pollution load index (PLI) and concentration dependent parameters (χ, χ _ARM and SIRM) for the polluted samples with magnetic susceptibility excess of 50×10^− 8 m³kg^− 1. Significant correlations between heavy metals and magnetic susceptibility point out the potential of magnetic screening/monitoring for simple and rapid proxy indicator of heavy metal pollution in marine sediments.     

Magnetic enhancement of urban roadside soils as a proxy of degree of pollution by traffic-related activities

Detailed magnetic and geochemical measurements were performed on urban roadside soils collected from Lishui city, China, to establish a possible link between the enhanced concentration of traffic-related magnetic particles and heavy metals. Relatively higher magnetic susceptibility (mean: 124.1 × 10⁻⁸ m³ kg⁻¹) and concentrations of metals (Cd, Cu, Pb and Zn) were observed for roadside soils. Concentration-dependent magnetic parameters (χ and SIRM) are highly significantly positively correlated to the concentration of metals (Ca, Cr, Ni, Cu, Zn, Cd, Pb, Fe, and V), but not significantly correlated with As, Mn, Co, Mg, and K. The principal component analysis showed that χ and SIRM significantly correspond to elements Ca, Cd, Cu, Pb, and Zn. The χ and SIRM also have significant linear correlation with integrated pollution index, indicating that χ and SIRM can be used as effective proxy indicators for the pollution of heavy metals. Magnetite in the pseudo-single-domain/multidomain (PSD/MD) grain size was identified as the dominant magnetic carrier by temperature-dependent measurements of saturation magnetization (Ms–T curve), XRD and hysteresis loops. Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS) analysis of the magnetic particles revealed the presence of large traffic-related angular-subangular, blocky, and spherical iron oxide particles. These iron oxide particles are typical for particles produced by traffic-related anthropogenic activities. It is concluded that vehicle emissions may be the major source of elevated heavy metals and magnetic particles in roadside soils. The results proved the applicability of magnetic method in detecting roadside pollution derived from vehicle emissions.     

Magnetic signature of heavy metals pollution of sediments: case study from the East Lake in Wuhan,China

Detailed magnetic measurements and geochemical analyses were performed on 114 sediment samples collected from the East Lake, Wuhan city, China, to establish a possible link between the enhanced concentration of anthropogenic magnetic particles and heavy metals with known sources. Relatively higher magnetic susceptibility values (mass-specific, χ, >150 × 10⁻⁸ m³ kg⁻¹) were observed for samples near the pollution sources: e.g. the Wuhan Iron and Steel Company (WISC), the Qingshan Thermal Power Plant (QTPP), the banks (driveways) of the lake and near the sightseeing route of yachts on the lake. Moreover, χ is positively correlated to the concentration of Pb (correlation coefficient r = 0.682), but negatively or weakly correlated with both Zn and Cu. In contrast, anhysteretic remanent magnetization (ARM) is significantly correlated with these major heavy metals (r = 0.645 for Zn–ARM, 0.699 for Pb–ARM and 0.841 for Cu–ARM, respectively), which indicate that ARM serves a better indicator for the pollution of heavy metals in this lake. Thermomagnetic analysis combined with magnetic hysteresis measurements revealed that magnetites in the pseudo-single-domain/multidomain grain-size regions are dominant. Scanning electron microscopy and energy dispersive X-ray examinations of the magnetic extracts showed that these Fe-rich particles have different morphologies: orange-peel structure, hollow structure with adhered smaller particles, Zr-rich melted-like irregular particles, pear-shaped spherules and spherules with slick surfaces. These features are typical for particles produced by anthropogenic activities. Because of the genetic relationship between the environmental setting of the East Lake and the nearby pollution sources, this study suggests that in situ magnetic surveys are sensitive to evaluate the environmental pollution on the lake bottom.     

Comparison of magnetic parameters with vehicular Br levels in urban roadside soils

Chemical methods are generally chosen to monitor soil pollution but magnetic measurements proved to yield additional information at low cost and less time consumption. In this investigation, the novel use of rapid and non-destructive magnetic measurements to characterize Br levels in Xuzhou (China) urban roadside soils was reported. X-ray fluorescence spectrometry (XRF) was used to quantify Br in the soil samples. Data from 21 roadside soil samples confirm Br contamination, with a mean level of 4.36 mg kg⁻¹ and a range of 2.4–8.7 mg kg⁻¹. These values are higher than that of unpolluted soils in Xuzhou that averages 1.1 mg kg⁻¹. Hierarchical clustering analysis shows Br in Xuzhou roadside soils is mainly from road traffic. Clear correlations between Br levels and simple magnetic parameters [mass specific susceptibility (χ _LF), susceptibility of anhysteretic remanent magnetization (χ _ARM), saturation isothermal remanence (SIRM)] are observed. The present study shows that these three magnetic parameters can be used as a proxy for Br levels in Xuzhou urban roadside soils.     

Carbon and oxygen isotope records and paleoclimate reconstruction (140–250 ka B.P.) from a stalagmite of Shuinan Cave, Guilin, China

The time sequence of paleoclimatic changes from 245.2 to 147.9 ka B.P. has been established by high precision U-series dating by Thermal Ionization Mass Spectrometry and the analysis of the oxygen isotopes from a stalagmite of Shuinan Cave in Guilin. The oxygen isotope pattern is divided into three main intervals. The top part of the stalagmite (interval C) displays mainly relatively heavy oxygen isotopes, mostly −7 to −5‰_VPDB, but at a depth of 86.5 cm below the top, there is a sharp change to values lighter than −8 ‰. This boundary, dated at 192.6 ±3.9 ka B.P. is correlated with the boundary between marine oxygen isotope stages 6 and 7. The underlying interval B has δ¹⁸O values consistently between −7.5 and −8.5‰ until 271 cm depth when there is a sharp rise in δ¹⁸O values towards values as heavy as −5‰. The upper position of this change is dated at 242.5±6.4 ka B.P. and is correlated with the boundary between marine isotope stages 7 and 8. Carbon isotope values lie between −8.5 and −11‰ and are not uniquely high or low in the three intervals, but also show rapid changes at the boundaries between intervals in the same sense as the shifts in δ¹⁸O. The pronounced shifts in δ¹⁸O are attributed to changes in the paleo-monsoon intensity which reflect major reorganizations of the climate system, but some regional characteristics are also present. The results are also consistent with previous studies of climate proxies from loess-palaesol sequences in northern China. These characteristics show that paleo-climate evolution since the late stage of the middle Pleistocene Epoch in the Guilin area not only follows the global characteristics, but also has the strong district or regional patterns.     

Magnetic properties and heavy metal content of sanitary leachate sludge in two landfill sites near Bandung,Indonesia

Magnetic properties and heavy metal content of landfill leachate sludge samples from two municipal solid waste disposal sites near Bandung, West Java, Indonesia, and their correlation with heavy metals are studied in the present work. Leachate was found to be sufficiently magnetic with mass-specific magnetic susceptibility that varies from 64.8 to 349.0 × 10⁻⁸ m³ kg⁻¹. It is, however, less magnetic than the soils around the landfill sites. The magnetic minerals are predominantly pseudo-single domain and multidomain magnetite. Leachate samples from the older but inactive disposal site, Jelekong, are found to be more magnetic than that from Sarimukti, the younger and active site. The enhancement of leachate due to the soil-derived ferrimagnetic particles is possibly the same for both Sarimukti and Jelekong. The fact that strong correlation between magnetic parameters and heavy metals is observed in Jelekong but is absent in Sarimukti suggests that the use of magnetic measurement as a proxy measurement for heavy metal content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Moreover, the accumulation of magnetic minerals and heavy metals in leachate might depend on the activity and the age of landfill site.     

Relationship between magnetic properties and heavy metals of urban soils with different soil types and environmental settings: implications for magnetic mapping

Two types of soil (fluvisols and anthrosols) were collected from different environmental settings (suburb and industrial area) in Wuhan, central China, aiming to examine the applicability of magnetic mapping for heavy metal pollution of urban soil in a large region. Magnetic measurements and chemical analysis indicated elevated magnetization and heavy metal concentrations of topsoils in the industrial area. Magnetic susceptibility (χ), anhysteretic remanent magnetization (ARM) and saturation isothermal remanent magnetization (SIRM) of fluvisols are much higher than those of anthrosols, but contrary for frequency-dependent susceptibility, indicating that soil magnetism strongly depends on the soil type/condition. Predominant magnetic carrier in topsoils in industrial area is pseudo-single-domain/multi-domain magnetite. Environmental scanning electron microscope/energy dispersive X-ray examination of the magnetic extracts from these topsoils revealed abundant spherical particles with diameters of 10–50 μm that are rich in iron-oxides, and could be attributed to the nearby industrial activities (e.g., steel work and power generation). Significant correlations were observed between magnetic concentration-related parameters (e.g., χ, ARM and SIRM) and concentrations of Cu, Pb, Zn, Hg and Tomlinson pollution load index. These results proposed that magnetic proxy mapping of soil pollution is an effective, fast and inexpensive tool for delineation of heavy metal pollution. However, interpretation of magnetic properties for such a purpose must be done on a site-specific basis, taking into account the possibilities of pedogenic enhancement/depletion under the specific soil conditions.     

Vertical patterns of stable carbon isotope in soils and particle-size fractions of karst areas, Southwest China

Taking limestone soil and yellow soil, the two major soil types in karst areas as examples, analyzing stable carbon isotope composition (δ¹³C value) of soil organic matter (SOM) in bulk soils and particle-size fractions of four soil profiles under three vegetable forms, the following results are reached: in the limestone soil profile, soil organic carbon contents are all above 1.0%, the highest value is 7.1% in the surface soil; however, they are between 0.3% and 4.6% in the three yellow soil profiles. From the surface to the bottom of the soil profiles, the variation of δ¹³C value of soil organic carbon for limestone soil profile is only between −24.1‰ and −23.0‰, however, it’s between −24.8‰ and −21.1‰ for yellow soil profiles. The variation range of δ¹³C value of soil organic carbon associated with particle-size separates is slight for limestone soil but is considerable for yellow soil. The contrast research indicates that the changes between the contents and the δ¹³C value of soil organic carbon with depth are complex. The vertical patterns of stable carbon isotope in soil organic matter have a distinct regional characteristic in karst areas.     

Use of multivariate statistical analysis to determine the relationship between the magnetic properties of urban topsoil and its metal, S, and Br content

Multivariate statistical analysis has been used for detailed examination of the relationship between the magnetic properties of Xuzhou urban topsoil, for example concentration-dependent properties (mass magnetic susceptibility (χ), susceptibility of anhysteretic remanent magnetization (χ _ARM), saturation isothermal remanent magnetization (SIRM), soft remanent magnetization (SOFT), and frequency-dependent magnetic susceptibility (χ _FD)) and feature-dependent properties (S _{−100 mT} ratio, SIRM/χ ratio and F _{300 mT} ratio), and the concentrations of metals (Ti, Fe, Cr, Al, Ga, Pb, Sc, Ba, Li, Cd, Be, Co, Cu, Mn, Ni, V, Zn, Mo, Pt, Pd, Au, As, Sb, Se, Hg, Bi, Ag, and Sn), S, and Br in the soil. The results show that SIRM/χ ratios correlate best with the heavy metals (Hg, Cr, Sb, As, and Bi) which are mainly derived from coal-combustion emissions whereas χ _FD correlates best with the metals (Al, Ti, V, Be, Co, Ga, Mn, and Li) which principally originate from soil parents. Concentration-dependent magnetic properties (χ _ARM, χ, SIRM, and SOFT) correlate well with elements (Se, Pb, Cu, Zn, Fe, Ag, Sc, Ba, Mo, Br, S, Cd, Ni, etc.) which are mainly derived from road-traffic emissions. For the same chemical element, χ _ARM, SIRM, and SOFT values are frequently better correlated than χ values, and χ _ARM values are the best indicators of the concentrations of these elements associated with traffic emissions in this study area. In addition, S _{−100 mT} ratios significantly correlate positively with Se, Sc, Pb, Cu, Zn, Mo, and S whereas F _{300 mT} ratios only correlate positively with Pt and negatively with Fe. These results confirm the suitability of different magnetic properties for characterizing the concentrations of heavy metals, S, and Br in Xuzhou urban topsoil.     

Relationship between chemical composition and magnetic susceptibility in sediment cores from Central Indian Ocean Basin

Three sediment cores in a north-south transect (3°N to 13°S) from different sediment types of the Central Indian Ocean Basin (CIOB) are studied to understand the possible relationship between magnetic susceptibility (χ) and Al, Fe, Ti and Mn concentrations. The calcareous ooze core exhibit lowest χ (12.32 × 10⁻⁷ m³ kg⁻¹), Al (2.84%), Fe (1.63%) and Ti (0.14%), terrigenous clay core with moderate χ (29.93 × 10⁻⁷ m³ kg⁻¹) but highest Al (6.84%), Fe (5.20%) and Ti (0.44%), and siliceous ooze core with highest χ (38.06 × 10⁻⁷ m³ kg⁻¹) but moderate Al (4.49%), Fe (2.80%) and Ti (0.19%) contents. The distribution of χ and detrital proxy elements (Al, Fe, and Ti) are identical in both calcareous and siliceous ooze. Interestingly, in terrigenous core, the behaviour of χ is identical to only Ti content but not with Al and Fe suggesting possibility of Al and Fe having a non-detrital source. The occurrence of phillipsite in terrigenous clay is evident by the Al-K scatter plot where trend line intersects K axis at more than 50% of total K suggesting excess K in the form of phillipsite. Therefore, the presence of phillipsite might be responsible for negative correlation between χ and Al (r = −0.52). In siliceous ooze the strong positive correlations among χ, Al_exc and Fe_exc suggest the presence of authigenic Fe-rich smectite. High Mn content (0.5%) probably in the form of manganese micronodules is also contributing to χ in both calcareous and siliceous ooze but not in the terrigenous core where mean Mn content (0.1%) is similar to crustal abundance. Thus, χ systematically records the terrigenous variation in both the biogenic sediments but in terrigenous clay it indirectly suggests the presence of authigenic minerals.     

Root biomass distribution in alpine ecosystems of the northern Tibetan Plateau

The root biomass distribution in alpine ecosystems (alpine meadow, alpine steppe, desert grassland and alpine desert) was investigated along a transect on the northern Tibetan Plateau in 2009. The results showed that roots were mainly concentrated in the 0–20 cm layer, and root biomass decreased exponentially with increasing soil depth. Root biomass was estimated to be 1,381.41 ± 245.29 g m⁻² in the top 20 cm soil, accounting for 85% of the total root biomass. The distribution pattern of the root biomass proportion along the soil profile was similar in different alpine ecosystems. The root biomass density varied with different alpine ecosystems and the total average root biomass was 1,626.08 ± 301.76 g m⁻². Root biomass was significantly correlated with average relative humidity, annual precipitation and soil organic matter. This indicates that precipitation and soil organic matter might be crucial for plant growth in the study area, while temperature is not an important factor controlling root growth.     

Soil organic carbon storage changes in Yangtze Delta region,China

Soil carbon sequestration plays an essential role in mitigating CO₂ increases and the global greenhouse effect. This paper calculates soil organic carbon (SOC) storage changes during the course of industrialization and urbanization in Yangtze Delta region, China, based on the data of the second national soil survey (1982–1985) and the regional geochemical survey (2002–2005), with the help of remote sensing images acquired in periods of 1980, 2000, 2005. The results show that soils in the top 0–20 and 0–100 cm depth in this region demonstrate the carbon sink effect from the early 1980s to the early 2000s. The SOC storage in 0–20 cm depth has resulted in increase from 213.70 to 238.65 Tg, which corresponds to the SOC density increase from 2.94 ± 1.08 to 3.28 ± 0.92 kg m⁻², and mean carbon sequestration storage and rate are 1.25 Tg a⁻¹, 17.14 g m⁻² a⁻¹, respectively. The SOC storage in 0–100 cm depth has resulted in increase from 690.26 to 792.65 Tg, which corresponds to the SOC density increase from 9.48 ± 4.22 to 10.89 ± 3.42 kg m⁻², and mean carbon sequestration storage and rate are 5.12 Tg a⁻¹, 70.32 g m⁻² a⁻¹, respectively. Urban area in Yangtze Delta region, China, increased more than 3,000 km² and the urban growth patterns circled the central city region in the past 20 years. The SOC densities in 0–20 cm depth decrease gradually along urban–suburban–countryside and the urban topsoil is slightly enriched with SOC. Compared to the data of the second national soil survey in the early 1980s, the mean SOC density in urban area increased by 0.76 kg m², or up 25.85% in the past 20 years. With the characteristics of SOC storage changes offered, land-use changes, farming system transition and ecological city construction are mainly attributed to SOC storage increases. Because of lower SOC content in this region, it is assumed that the carbon sink effect will go on in the future through improved soil management.     

Simulation modelling of pollutant transport from leachate in Shiraz landfill

A one-dimensional mathematical model based on convection–dispersion equation in unsaturated porous media is presented to compute inorganic total solid concentration in the soil column under the Shiraz landfill. In addition, a dynamic mathematical model is formulated to simulate concentrations of ions such as Ca²⁺ , Mg²⁺, Fe²⁺, K⁺, Na⁺, Cl⁻, SO₄ ²⁻ and HCO₃ ⁻ as well as PH and EC in soil profile under the Shiraz landfill. Leachw model was applied to simulate water flow, water content and hydraulic conductivity in soil depth. The model was calibrated and verified by using different sets of data collected from several segments of soil depth in the study area. The numerical solution obtained using finite element method. The simulated values for the parameters were compared with measured values as well as analytical solution. The simulated results are in good agreement with measured values. This model could be applied to field scale problems for the landfill management.     

Comparison of soil organic carbon content,hydraulic conductivity,and particle size fractions between a grassland and a nearby black pine plantation of 40 years in two surface depths

In highlands of semiarid Turkey, ecosystems have been significantly transformed through human actions, and today changes are taking place very rapidly, causing harmful consequences such as soil degradation. This paper examines two neighboring land use types in Indagi Mountain Pass, Cankiri, Turkey, to determine effects of the conversion of Blackpine (Pinus nigra Arn. subsp. pallasiana) plantation from grassland 40 years ago on soil organic carbon (SOC) and soil erodibility (USLE-K). For this purpose, a total of 302 disturbed and undisturbed soil samples were taken at irregular intervals from two sites and from two soil depths of 0–10 cm (D₁) and 10–20 cm (D₂). In terms of SOC, conversion did not make any statistical difference between grassland and plantation; however, there were statistically significant differences with soil depth within each land use, and SOC contents significantly decreased with the soil depth (P < 0.05) and mostly accumulated in D₁. SOC values were 2.4 and 1.8% for grassland and 2.8 and 1.6% for plantation, respectively, at D₁ and D₂. USLE-K values also statistically differed significantly with the land use, and in contrast to the statistics of SOC, there was no change in USLE-K with the soil depth. Since USLE-K was estimated using SOC, hydraulic conductivity (HC) and soil textural composition––sand (S), silt (Si), and clay (C) contents of soils––as well as SOC did not change with the land use, we ascribed the changes of USLE-K with the land uses to the differences in the HC as strongly affected by the interactions between SOC and contents of S, Si, and C. On an average, the soil of the grassland (USLE-K = 0.161 t ha h ha⁻¹ MJ⁻¹ mm⁻¹) was more erodible than those of the plantation (USLE-K = 0.126 t ha h ha⁻¹ MJ⁻¹ mm⁻¹). Additionally, topographic factors, such as aspect and slope, were statistically effective on spatial distribution of the USLE-K and SOC.     

Transport and fate of nitrate within soil units of glacial origin

Questions concerning the influence of soil type and crop cover on the fate and transport of nitrate (NO₃⁻) were examined. During a growing season, soils derived from glacial material underlying either corn or soybeans were sampled for levels of NO₃⁻ within the pore water. Measured levels of NO₃⁻ ranged from below detection limit to 14.9 g NO₃⁻ per kilogram of soil (g/kg). In fields with the same crop cover, the silty-clayey soil exhibited a greater decrease in NO₃⁻ levels with depth than the sandier soil. Crop uptake of NO₃⁻ occurs within the root zone; however, the type of crop cover did not have a direct impact on the fate or transport during the growing season. The soils underlying soybeans had an increase in NO₃⁻ levels following harvest, suggesting that the decomposition of the soybean roots contributed to the net gain of NO₃⁻ in the shallow soil. For all of the soil types, conditions below 100 cm are conducive for microbial denitrification, with both a high water saturation level (>60%) and moderate organic carbon content (1–2%). At depths below 100 cm, temporal differences in NO₃⁻ levels of over a magnitude, up to a 95% reduction, were recorded in the soil units as the growing season progressed. Physical properties that control the transport of NO₃⁻ or denitrification have a larger influence on NO₃⁻ levels than crop type.

Heavy metals pollution in the soil of an irregular urban settlement built on a former dumpsite in the city of Tijuana, Mexico

The aim of this study was to evaluate soil pollution by heavy metals in an irregular settlement built on a dumpsite. The soil samples were analyzed for Cd, Cr, Cu, Pb and Ni. None of the concentrations found for the heavy metals analyzed were higher than the established Mexican official standards for contaminated soils. The mean concentrations found for the analyzed metals were as follows: 1.4 mg kg⁻¹ for Cd, 4.7 in mg kg⁻¹ for Cr, 304 mg kg⁻¹ for Cu, 74 mg kg⁻¹ for Pb and 6 mg kg⁻¹ for Ni. The results of the geoacummulation index values show that the site was very polluted with Cu and Pb (class 7), polluted to strongly polluted with Ni (class 4); moderately polluted to polluted with Cd (class 3), and moderately polluted with Cr (class 1). The correlation analysis shows a high correlation between Pb and Cu (r ² = 0.98), which would be explained if the main source of the polluting heavy metals was the result of electrical wire burning to recover Copper. Principal component analysis shows three principal components. The first main component (PC1) encompasses Cr, Cd, Pb and Cu. These heavy metals most likely have their origins from the open burning of municipal solid waste, tires and wire. The other two components are encompassed by Cr (PC2) and Ni (PC3). The sources of these pollutants are more likely related to the corrosion of junk metal objects and automobile use.     

Hydraulic properties of the crystalline basement

Hydraulic tests in boreholes, up to 4.5 km deep, drilled into continental crystalline basement revealed hydraulic conductivity (K) values that range over nine log-units from 10⁻¹³−10⁻⁴ m s⁻¹. However, K values for fractured basement to about 1 km depth are typically restricted to the range from 10⁻⁸ to 10⁻⁶ m s⁻¹. New data from an extended injection test at the KTB research site (part of the Continental Deep Drilling Program in Germany) at 4 km depth provide K=5 10⁻⁸ m s⁻¹. The summarized K-data show a very strong dependence on lithology and on the local deformation history of a particular area. In highly fractured regions, granite tends to be more pervious than gneiss. The fracture porosity is generally saturated with Na–Cl or Ca–Na–Cl type waters with salinities ranging from <1 to >100 g L⁻¹. The basement permeability is well within the conditions for advective fluid and heat transport. Consequently, fluid pressure is hydrostatic and a Darcy flow mechanism is possible to a great depth. Topography-related hydraulic gradients in moderately conductive basement may result in characteristic advective flow rates of up to 100 L a⁻¹ m⁻² and lead to significant advective heat and solute transfer in the upper brittle crust. An erratum to this article can be found at     

Groundwater flow and velocity in a 500 ka pre-Illinoian till, eastern Iowa

Few hydrology studies have investigated glacial till older than Illinoian time (> 300,000 BP) despite these older tills overlying a large portion of North America. An 8- and 6-well monitoring well nest installed into a 31 m thick pre-Illinoian till sequence near Cedar Rapids, Iowa was characterized using traditional hydrologic methods and chemical tracers. The aquitard system consists of about 9 m of fine-grained oxidized pre-Illinoian till overlying 22 m of unoxidized till and Devonian dolomite bedrock. Hydraulic conductivity ranged from 10⁻⁷ m/s in oxidized till and 10⁻¹⁰ m/s in unoxidized till. Hydraulic head relations indicated downward groundwater flow through the till profile with hydraulic gradients steepest near the unoxidized till/bedrock interface. Tritium and nitrate concentrations indicated recent (< 50 years old) recharge to a depth of 9–12 m below land surface. ¹⁸O and ²H results ranged between −6.2 to −7.9% and −38.0 to −50.9%, respectively, and plotted near the local Meteoric Water Line. A 1 per mil shift toward less negative ¹⁸O values with depth may suggest a climate change signal contained in the till water but more data are needed to verify this trend. Vertical groundwater velocity through the unoxidized till was estimated to range from 0.4 to 5.7 cm/year. The thickness of unoxidized pre-Illinoian till in Linn County was estimated from available records and contoured against vertical travel times to evaluate the effectiveness of pre-Illinoian till in preventing nitrate migration to underlying bedrock aquifers.     

Environment impact of heavy metals on urban soil in the vicinity of industrial area of Baoji city,P.R. China

Heavy metals in soils are of great environmental concern, in order to evaluate heavy metal contents and their relationships in the surface soil of industrial area of Baoji city, and also to investigate their influence on the soils. Soil samples were collected from 50 sites, and the concentration of Pb, Zn, Cu, Cr, Ni heavy metals and the contents of characteristics in soil from industrial area of Baoji city were determined with X-ray fluorescence method. The concentrations of Pb, Zn, Cu, Cr and Ni in the investigated soils reached the amount of 2,682.00–76,979.42, 169.30–8,288.58, 62.24–242.36, 91.96–110.54 and 36.14–179.28 mg kg⁻¹, respectively. The major element Pb contents of the topsoils were determined. to highlight the influence of ‘anthropic’ features on the heavy metal concentrations and their distributions. To compare, all values of elements were much higher than those of unpolluted soils in the middle of Shaanxi province that average 16.0–26.5, 67.1–120.0, 17.8–57.0, 46.9–65.6 and 24.7–34.6 mg kg⁻¹ for Pb, Zn, Cu, Cr and Ni, respectively. An ensemble of basic and relativity analysis was performed to reduce the precipitate of Pb in soil was extremely high and greatly relativity with other elements. Meanwhile, Pb, Zn, Cu, Cr, Ni heavy metals were typical elements of anthropic activities sources, so it was easy to infer to the tracers of anthropic pollutions from the factorial analysis, which was coming from the storage battery manufactory pollutions. The pollutant distributions were constructed for the urban area which identified storage battery manufactory soot precipitate as the main source of diffuse pollution and also showed the contribution of the topsoils of industrial area of Baoji city as the source point of pollution. Consequently, the impact of heavy metals on soil was proposed and discussed. These results highlight the need for instituting a systematic and continuous monitoring of heavy metals and other forms of pollutants in Baoji city to ensure that pollution does not become a serious problem in the future.     

Study of litter influence on magnetic susceptibility measurements of urban forest topsoils using the MS2D sensor

Field magnetometry is fast and convenient method used to detect areas contaminated by technogenic magnetic particles and potentially polluted with heavy metals. Frequently, measurements of soil magnetic susceptibility (κ) are carried out with MS2D Bartington sensor, which penetration range equals 10 cm, although 90% of the total signal is detected from a depth of up to 6 cm. Thick uppermost organic soil layers may significantly influence on the measured κ because the penetration range may be not large enough to cover the layers where the most of anthropogenic contaminants are cumulated. The aim of the study was to investigate on how the removal of the litter improves the MS2D measurements of soil pollution. Accordingly, the correlations between κ values measured on the successively removed overlying soil sub-horizons were investigated. Measurements were performed at 15 sites located in different forest in the Upper Silesian Industrial Area, Poland. The results showed that the litter removal enabled the MS2D to measure the κ more related to the anthropogenic pollution, and did not affect the measuring variance.