Effect of application of phosphate and organic manure-based fertilizers on arsenic transformation in soil columns

The mobility of arsenic in Cambisol under the influence of added barnyard manure and application of a phosphate solution to the soil was described on the basis of column experiments. A soil sample containing 126 mg/kg total As and 3.72 mg/kg specifically-sorbed As was extracted using demineralized water (DIW) or a 28 μmol/l phosphate solution in a column containing untreated soil and in a column with added barnyard fertilizer. The pH, Eh, alkalinity, main components, including DOC, and selected trace elements (Al, Mn, Pb, Cu, Zn, Cd, Cr, Co, Ni, Ba and As) were determined in the extracts. Hydrodynamic tests of the flow and transport of the substances in the columns were carried out. The addition of barnyard manure was manifested in elevated concentrations of the main inorganic components, DOC and Al and a decrease in the Eh value and Mn concentration. Application of a phosphate solution was manifested in a decrease in the NO₃ and SO₄ concentrations, probably as a result of the effect of increased biological fixation. The As concentration in extracts varied from 8.8 to 15.5 μg/l and was not dependent on the composition of the extracting solution or the addition of barnyard fertilizer.     

Field scale variability of cadmium and zinc in soil and barley

CaCl₂-extractable soil Cd and Zn contents have been suggested as a measure of bioavailability. To investigate the ability of this measure to reflect spatial patterns of Cd and Zn concentrations in barley (Hordeum vulgare L.) in an arable field, plant and soil samples were taken from a 0.5 ha area sandy soil contaminated with Cd and Zn. Cd and Zn contents in barley and yield were spatially variable. Yield was low, which may have been caused by Zn toxicity or atrazine turnover. For Cd, CaCl₂-extractable soil contents explained only 17% of the variation in Cd contents in grain, and for Zn no significant correlation was observed. Nevertheless, surface plots of CaCl₂-extractable soil contents and contents of barley grain illustrated their corresponding spatial patterns. Despite the poor linear correlation between CaCl₂-extractable soil-Cd and grain-Cd, a stochastic model for long term behaviour of Cd in field soils predicted observed variability in Cd contents of barley grain well from spatial variability of soil pH and organic matter content. The probabilistic model predicted behaviour of Cd in terms of probability, and was more appropriate than the deterministic approach.     

Toxic effect caused on microflora of soil by pesticide picloram application

The toxic effect of the herbicide picloram on the microbial population of a typical Brazilian red Latosol soil was studied in a series of microcalorimetric experiments. The activity of the soil was stimulated by the addition of 6.0 mg of glucose and 6.0 mg of ammonium sulfate, under 34.8% controlled moisture, to a 1.50 mg soil sample, at 298.15 +/- 0.02 K. The net thermal effect due to the addition of the picloram to the soil was determined by interpreting the power-time curves, which were recorded on the microcalorimeter. The total thermal effect evolved by the microorganisms was affected by the increasing doses of herbicide, and varied from 0 to 10.00 micrograms g-1. An increase in picloram exposure caused a decrease of the original thermal effect, reaching a null value above 20.89 micrograms of herbicide per gram of soil. The decreases of the thermal effect evolved by microorganisms and the increase of the lag phase period are associated with the death of the microbial population. The effects caused by picloram application in this typical Brazilian soil resulted in a strong effect on the soil microbial communities.     

Spatial variability of soil salinity in coastal saline soil at different scales in the Yellow River Delta,China

The objectives of this study were to explore the spatial variability of soil salinity in coastal saline soil at macro, meso and micro scales in the Yellow River delta, China. Soil electrical conductivities (ECs) were measured at 0–15, 15–30, 30–45 and 45–60 cm soil depths at 49 sampling sites during November 9 to 11, 2013. Soil salinity was converted from soil ECs based on laboratory analyses. Our results indicated that at the macro scale, soil salinity was high with strong variability in each soil layer, and the content increased and the variability weakened with increasing soil depth. From east to west in the region, the farther away from the sea, the lower the soil salinity was. The degrees of soil salinization in three deeper soil layers are 1.14, 1.24 and 1.40 times higher than that in the surface soil. At the meso scale, the sequence of soil salinity in different topographies, soil texture and vegetation decreased, respectively, as follows: depression >flatland >hillock >batture; sandy loam >light loam >medium loam >heavy loam >clay; bare land >suaeda salsa >reed >cogongrass >cotton >paddy >winter wheat. At the micro scale, soil salinity changed with elevation in natural micro-topography and with anthropogenic activities in cultivated land. As the study area narrowed down to different scales, the spatial variability of soil salinity weakened gradually in cultivated land and salt wasteland except the bare land.     

Redistribution of zinc, cadmium, and lead among soil fractions in a sandy calcareous soil due to application of poultry litter

This study was conducted to evaluate, using soil columns, the mobilization and redistribution of heavy metals (Zn, Cd, and Pb) among different soil fractions by soluble organic ligands within poultry litter. Uncontaminated soil was amended with Zn, Cd, and Pb to achieve concentration levels of 400, 8, and 200 mg kg⁻¹ soil, respectively. Columns repacked with this amended soil were leached with distilled water, 0.01 M EDTA, 0.01 M CaCl₂, or poultry litter extract (PLE) solutions. After leaching, the soil samples in the columns were sequentially extracted for exchangeable (EXC), carbonate (CARB) organic matter (OM), Mn oxide (MNO), Fe oxide (FEO), and residual (RES) fractions. Considerable mobilization of Zn, Cd, and Pb occurred in soil during EDTA leaching. Leaching with PLE and CaCl₂ solutions significantly decreased Zn and Cd concentrations in the EXC, CARB, and OM fractions. These solutions significantly decreased Pb concentration in the EXC fraction, while PLE solubilized more Pb from EXC fraction than CaCl₂. Thus, the applied poultry litter may change Zn, Cd, and Pb fractions in metal-amended soil and possibly enhance metal mobility.     

Temporal-spatial variability and fractal characteristics of soil nitrogen and phosphorus in Xinji District, Hebei Province, China

Traditional statistics, geostatistics, fractal dimensions, and geographic information systems (GIS) were employed to study the temporal?Cspatial variability of soil total nitrogen (TN) and total phosphorus (TP) levels in Xinji District, Hebei Province area of the North China Plain from 1980 to 2007. The results indicate that nutrient levels follow normal or lognormal distributions. The TN content was 0.59 ±0.155 g kg^???1 in 2007, an increase of 0.44 g kg^???1 compared with that of 1980. In 2007, the TP content was 1.21 ±0.227 g kg^???1, an increase of 0.01 g kg^???1 from 1980. The geostatistical analysis showed that the distribution of these soil nutrients in the study area exhibits a trend and anisotropy. The range and [C ₀/(C ₀?+?C)] of TN and TP in 1980 were all less than in 2007. The ordinary kriging interpolation method was used to analyze the nutrient contents differences between 1980 and 2007. The results indicate that soil TN levels have increased over the 27-year period, and the area where the TN level had increased by at least 0.4 g kg^???1 was about 61.7% of the district. The area where the TP content increased covered about 58.4% of the district. The variance analysis indicated that land-use type had a clear influence on the distribution and change in TN and TP content. Using the 3-D box-counting dimension method combined with GIS, the fractal dimension of soil nutrient spatial distribution over the two periods showed that in 27 years, the fractal dimension of TN increased from 1.95 to 2.02, and the fractal dimension of TP increased from 1.89 to 2.01, indicating that the complexity of the spatial distribution of all nutrient contents had increased. This study can provide a basis for accurate fertilizing and to enhance the conversion of soil characteristics under different spatial scales.     

Spatial distribution characteristics of soil organic carbon in subtropical forests of mountain Lushan,China

The study on the spatial distribution of forest soil organic carbon (SOC) is of great significance for accurate assessment of carbon storage in forest ecosystems. In the present study, by taking eight kinds of forest soils of Mountain Lushan in the subtropical area as the research object, we studied the spatial distribution characteristics of SOC in this mountainous area. The results showed that the SOC content and SOC density (SOCD) of main forest types in the Mountain Lushan were lower than the national and the world average. The soil layer of Lushan forest was thinner, and the SOC and active SOC (ASOC) contents of different forest types and SOCDs are the highest in the surface soil. SOCD of the topsoil accounts for 32.64–54.03% of the total SOCD in the whole soil profile. Surface litter is an important source of SOC, and the different vegetation types are the important reason for the different spatial distribution of SOC in this area. Soil SOC contents in the high-altitude forest (bamboo forest, deciduous broadleaf forest, Pinus taiwanensis forest, evergreen-deciduous forest, and coniferous-broadleaved mixed forest) were higher than those in the low-altitude forest (evergreen broadleaf forest, shrub, and Pinus massoniana forest). However, the difference in SOC content exhibited at the altitude gradient is significantly lower than that in SOC in the soil profile. This indicates that both soil depth and elevation are the important factors that affected SOC distribution. However, the influence of soil depth on spatial distribution of SOC may be more complex than that of altitude. Vegetation types and soil properties are the main reasons for the large differences of reduction rate in the contents of SOC and ASOC.     

Spatial variability of soil heavy metals in the three gorges area: multivariate and geostatistical analyses

There is a growing concern about environmental contamination in the three gorges area. The objectives of this study were to investigate the spatial variability and the possible influence factors of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the center of this area based on multivariate and geostatistical approaches. All analyzed heavy metals were below their background levels, except Cd. The average concentrations of the analyzed elements in topsoil (0-20 cm) were 5.83 mg As kg(-1), 0.21 mg Cd kg(-1), 78.79 mg Cr kg(-1), 21.53 mg Cu kg (-1), 0.049 mg Hg kg(-1), 24.12 mg Pb kg(-1), and 68.5 mg Zn kg(-1). The concentration of As was mostly due to parent materials, whereas the source of Pb was mainly due to vehicle exhaust. The high concentration of Cd was resulted from agricultural practices and parent materials. The concentrations of Cr, Cu, Hg, and Zn were associated with parent materials and human activities.     

Correlation between soil characteristics and lead and cadmium content in the aboveground biomass of Virginia tobacco

The study was conducted on alluvial-meadow, maroon-forest soils and vertisols with Virginia tobacco. The total content of lead and cadmium is measured through decomposition by HF, HClO₄, and HNO₃ acids. A solution of 0.005 M diethylentriaminepentaacetic acid + 0.1 M triethanolamine, pH 7.3 was used for extraction of the elements’ mobile forms from soils. The preparation of plant samples was made by means of dry ashing and dissolution in 3 M HCl. An atomic absorption spectrometer “Spektra AA 220” of the Australian company Varian was used for determination of Pb and Cd content in the soil and plant samples. Certified reference materials (three soils and tobacco leaves) were also analyzed for the verification of the accuracy of Pb and Cd determination. A correlation/regression analysis was conducted between pH, humus content, total and mobile forms of lead and cadmium in the soil, and the concentration of these elements in the aboveground biomass of Virginia tobacco. It was established that there are no statistically significant dependencies determined between soil pH and lead concentration in the plant organs of Virginia tobacco. Regressional dependencies of great significance were determined between the humus content, total and mobile lead and cadmium in the soil, and the element concentration in the leaves of the three harvesting zones.     

Spatial variability of the shallow groundwater level and its chemistry characteristics in the low plain around the Bohai Sea,North China

To characterize the spatial distribution of groundwater level (GWL) and its chemistry characteristics in the low plain around the Bohai Sea, shallow groundwater depth of 130 wells were determined. Water soluble ions composition, total dissolved solid (TDS), electric conductivity (EC), total hardness (TH), total alkalinity (TA), and total salt content (TS) of 128 representative groundwater samples were also measured. Classical statistics, geostatistical method combined with GIS technique were then used to analyze the spatial variability and distribution of GWL and groundwater chemical properties. Results show that GWL, TDS, EC, TH, TA, and TS all presented a lognormal distribution and could be fitted by different semivariogram models (spherical, exponential, and Gaussian). Spatial structure of GWL, TDS, EC, TH, TA, and TS changed obviously. GWL decreased from west inland plain to the east coastal plain, however, TDS, EC, and TS increased from west to east, TH and TA were higher in the middle and coastal plain area. Groundwater chemical type in the coastal plain was SO₄²⁻·Cl⁻—Na⁺ while chemical types in the inland plain were SO₄²⁻·Cl⁻—Ca²⁺·Mg²⁺ and HCO₃⁻—Ca²⁺·Mg²⁺.     

Determination of lead, cadmium and copper in roadside soil and plants in Elazig, Turkey

The concentrations of lead, cadmium and copper in roadside soil and plants in Elazig, Turkey were investigated. Soil samples were collected at distances of 0, 25 and 50 m from the roadside. The concentrations of lead, cadmium and copper were measured by Flame Atomic Absorption Spectrophotometry (FAAS). A slotted tube atom trap (STAT) was used to increase the sensitivity of lead and cadmium in FAAS. Lead concentrations in soil samples varied from 1.3 to 45 mg kg⁻¹ while mean lead levels in plants ranged from120 ng g⁻¹ for grape in point-4 to 866 ng g⁻¹ for apple leaves in point-2. Lead analyses showed that there was a considerable contamination in both soil and plants affected from traffic intensity. Overall level of Cd in soil samples lies between 78 and 527 ng/g while cadmium concentration in different vegetations varied in the range of 0.8–98.0 ng g⁻¹. Concentrations of copper in soil and plant samples were found in the range of 11.1–27.9 mg kg⁻¹ for soil and 0.8–5.6 mg kg⁻¹ for plants. Standard reference material (SRM) was used to find the accuracy of the results of soil analyses.     

Spatial and temporal variability of metals in inter-tidal beach sediment of Mumbai, India

Nine metals were monitored in the beach sediment in Mumbai from May 2011 to March 2012 to evaluate the spatial and temporal distributions. The average heavy metal concentrations exhibited the following order: Fe > Mn > Cr > Co > Ni > Pb > Zn > Cu > Cd for the four sampling sites. The mean concentrations (± SD) of Fe, Mn, Cr, Co, Ni, Pb, Zn, Cu and Cd were estimated to be 31.15?±?10.02 g kg^?1, 535.04?±?76.42, 151.98?±?97.90, 92.76?±?14.18, 67.52?±?11.32, 59.57?±?15.19, 54.65?±?15.01, 32.24?±?8.07 and 18.75?±?1.76 mg kg^?1, respectively. The results indicated that the sediments were polluted with Cd, Cr, Co and Pb due to high anthropogenic influences. Spatial variation of metals revealed that most of the metals were high in Dadar beach and low in Aksa beach. Cd was the highest contaminant metal studied with a mean contamination factor of 93.75. The pollution load indices of the studied beaches ranged from 1.63 (Aksa) to 1.91 (Dadar) and indicated that the beach sediments were polluted with heavy metals. The heavy metal contents increased in relation to monsoon, and most of the heavy metals showed significantly high concentrations in November during the post-monsoon. The statistical analysis revealed significant effect of study site on all the metals studied. Further, there was a significant difference on metal accumulation on bimonthly basis in relation to weather pattern in Mumbai beaches.     

Metal immobilization and phosphorus leaching after stabilization of pyrite ash contaminated soil by phosphate amendments

In this study we would like to show the importance of a holistic approach to evaluation of chemical stabilization using phosphate amendments. An extensive evaluation of metal stabilization in contaminated soil and an evaluation of the leaching of phosphorus induced after treatment were performed. The soil was highly contaminated with Cu (2894 mg kg(-1)), Zn (3884 mg kg(-1)), As (247 mg kg(-1)), Cd (12.6 mg kg(-1)) and Pb (3154 mg kg(-1)). To immobilize the metals, mixtures of soil with phosphate (from H(3)PO(4) and hydroxyapatite (HA) with varying ratios) were prepared with a constant Pb : P molar ratio of 1: 10. The acetic acid extractable concentration of Pb in the mixture with the highest amount of added phosphoric acid (n(H(3)PO(4)) : n(HA) = 3 : 1) was reduced to 1.9% (0.62 mg L(-1)) of the extractable Pb concentration in the untreated soil, but the content of water extractable phosphorus in the samples increased from 0.04 mg L(-1) in the untreated soil sample up to 14.3 mg L(-1) in the same n(H(3)PO(4)) : n(HA) = 3 : 1 mixture. The high increase in arsenic mobility was also observed after phosphate addition. The PBET test showed phosphate induced reduction in Pb bioavailability. In attempting to stabilize Pb in the soil with the minimum treatment-induced leaching of phosphorus, it was found that a mixture of soil with phosphate addition in the molar ratio of H(3)PO(4) : HA of 0.75 : 1 showed the most promising results, with an acetic acid extractable Pb concentration of 1.35 mg L(-1) and a water extractable phosphorus concentration of 1.76 mg L(-1). The time-dependent leaching characteristics of metals and phosphorus for this mixture were evaluated by a column experiment, where irrigation of the soil mixture with the average annual amount of precipitation in Slovenia (1000 mm) was simulated. The phosphorus concentration in the leachates decreased from 2.60 mg L(-1) at the beginning of irrigation to 1.00 mg L(-1) at the end.     

A low-tech, low-cost passive sampler for the long-term monitoring of phosphate loads in rivers and streams

The concentration of dissolved reactive phosphorus (DRP) in rivers can change intermittently within minutes depending on the weather and water discharge (Q), or activities in the watershed. Accordingly, accurate estimation of the annual DRP load requires frequent sampling or even continuous monitoring, which is laborious and cost-intensive. We present the design and laboratory evaluation of a new, robust, low-cost, low-tech device based on passive samplers (P-traps). The traps use Fe-(oxy)hydroxide coated quartz sand as an adsorbent enclosed in a vertical grid of individual cells separated from the river water by filter membranes. They are inexpensive, easy to handle, resistant to repeated desiccation and immersion and exposable for several months. They permit estimation of discharge dependent time weighted average DRP concentrations (C-Q relationships) and annual P loads of rivers characterized by highly variable DRP concentrations with a relative accuracy of +/- 3%.     

Distribution and fractionation of cadmium, copper, lead, nickel, and zinc in a calcareous sandy soil receiving municipal solid waste

This study was conducted to evaluate the degree of mobility and fractionation of cadmium (Cd), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn) after the addition of municipal solid sewage sludge (MSS) in a sandy calcareous soil. Treatments were (1) soil application of MSS, (2) soil application of enriched municipal solid waste compost (EMSS), and (3) control soil. The MSS application represented a dose of 200 Mg dry weight per hectare. Soil columns were incubated at room temperature for 15 days and irrigated daily with deionized water to make a total of 505 mm. At the end of leaching experiments, soil samples from each column were divided into 14 layers, each being 1 cm down to 10 and 2.5 cm below that and analyzed for diethylenetriaminepentaacetic acid (DTPA)-extractable Cd, Cu, Pb, Ni, and Zn. The fractionation of the heavy metals in the top five layers of the surface soil samples was investigated by the sequential extraction method. All soil layers of the columns receiving MSS and EMSS had significantly higher concentrations of DTPA-extractable heavy metals than control soil. The maximum concentration of heavy metals in treated soil was in the surface layer and declined significantly with depth. Sequential extraction results showed that in the treated soil, a major proportion of Cd, Pb, and Ni was associated with organic matter (OM) and exchangeable (EXCH) fractions, and a major proportion of Cu and Zn was associated with residual (RES) and OM fractions. Based on relative percent, Pb, Cd, and Ni in the EXCH fraction was higher than Cu and Zn in soil leached with MSS and EMSS, suggesting that application of this MSS to a sandy calcareous soil, at the loading rate used here, may pose a risk in terms of groundwater contamination with Pb, Cd, and Ni.     

Spatial and temporal variability of water quality in the coral reefs of Tayrona National Natural Park,Colombian Caribbean

Tayrona National Natural Park (TNNP) is a hotspot of coral reef biodiversity in the Colombian Caribbean, located between the city of Santa Marta (>455,000 inhabitants) and several smaller river mouths (Rio Piedras, Mendihuaca, Guachaca). The region also experiences a strong seasonal variation in physical parameters (temperature, salinity, wind, and water currents) due to alternating dry seasons with coastal upwelling and rainy seasons. However, the spatial and temporal effects on water quality parameters relevant for coral reef functioning have not been investigated. Therefore, inorganic nutrient, chlorophyll a, and particulate organic carbon (POC) concentrations along with biological O₂ demand (BOD), pH, and water clarity directly above local coral reefs (~10 m water depth) were monitored for 25 months in four bays along a distance gradient (12–20 km) to Santa Marta in the southwest and to the first river mouth (17–27 km) in the east. This is by far the most comprehensive coral reefs water quality dataset for the region. Findings revealed that particularly during non-upwelling, chlorophyll a and POC concentrations along with BOD significantly increased with decreasing distance to the rivers in the east, suggesting that the observed spatial water quality decline was triggered by riverine runoff and not by the countercurrent-located Santa Marta. Nitrate, nitrite, and chlorophyll a concentrations significantly increased during upwelling, while pH and water clarity decreased. Generally, water quality in TNNP was close to oligotrophic conditions adequate for coral reef growth during non-upwelling, but exceeded critical threshold values during upwelling and in relation to riverine discharge.     

Spatial variability of air pollutants in the city of Taranto, Italy and its potential impact on exposure assessment

Epidemiological studies typically use monitored air pollution data from a single station or as averaged data from several stations to estimate population exposure. In industrialized urban areas, this approach may present critical issues due to the spatial complexities of air pollutants which are emitted by different sources. This study focused on the city of Taranto, which is one of the most highly industrialized cities in southern Italy. Epidemiological studies have revealed several critical situations in this area, in terms of mortality excess and short-term health effects of air pollution. The aims of this paper are to study the variability of air pollutants in the city of Taranto and to interpret the results in relation to the applicability of the data in assessing population exposure. Meteorological and pollution data (SO2, NO2, PM10), measured simultaneously and continuously during the period 2006–2010 in five air quality stations, were analyzed. Relative and absolute spatial concentration variations were investigated by means of statistical indexes. Results show significant differences among stations. The highest correlation between stations was observed for PM10 concentrations, while critical values were found for NO2. The worst values were observed for the SO2 series. The high values of 90th percentile of differences between pairs of monitoring sites for the three pollutants index suggest that mean concentrations differ by large amounts from site to site. The overall analysis supports the hypothesis that various parts of the city are differently affected by the different emission sources, depending on meteorological conditions. In particular, analysis revealed that the influence of the industrial site may be primarily identified with the series of SO2 data which exhibit higher mean concentration values and positive correlations with wind intensity when the monitoring station is downwind from the industrial site. Results suggest evaluating the population exposure to air pollutants in industrialized cities by taking into account the possible zones of influence of different emission sources. More research is needed to identify an indicator, which ought to be a synthesis of several pollutants, and take into account the meteorological variables.     

Dissipation of cypermethrin,chlorpyriphos, and profenofos in tomato fruits and soil following application of pre-mix formulations

In this study, changes in heavy metal accumulation in U. rigida J. Agardh taxon and seawater have been investigated with respect to different stations and seasons. For this purpose, the severity of heavy metal pollution in the Dardanelles has been presented through the determination of Cu, Pb, Zn, and Cd concentrations in U. rigida macroalgae and seawater taken seasonally from the stations located on six different regions on the strait. While the metal concentrations in alga specimens were found to be high in spring and winter in all stations; the metal concentrations in the seawater, particularly the Pb concentration, were found to be high in all seasons.