Soil organic carbon and nitrogen accumulation on coal mine spoils reclaimed with maritime pine (Pinus pinaster Aiton) in Agacli–Istanbul

Mining operations on open coal mines in Agacli-Istanbul have resulted in the destruction of vast amounts of land. To rehabilitate these degraded lands, plantations on this area began in 1988. Twelve tree species were planted, however, the most planted tree species was maritime pine (Pinus pinaster Aiton). This study performed on 14 sample plots randomly selected in maritime pine plantations on coal mine soil/spoils in 2005. Soil samples were taken from eight different soil layers (0-1, 1-3, 3-5, 5-10, 10-20, 20-30, 30-40 and 40-50 cm) into the soil profile. On soil samples; fine soil fraction (<2 mm), soil acidity (pH), organic carbon (C(org)) and total nitrogen (N(t)) contents were investigated, and results were compared statistically among soil layers. As a result, 17 years after plantations, total forest floor accumulation determined as 17,973.20 kg ha(-1). Total nitrogen and organic matter amounts of forest floor were 113.90 and 14,640.92 kg ha(-1) respectively. Among soil layers, the highest levels of organic carbon (1.77%) and total nitrogen (0.096%) and the lowest pH value (pH 5.38) were found in 0-1 cm soil layer, and the variation differs significantly among soil layers. Both organic carbon and total nitrogen content decreased, pH values increased from 0-1 to 5-10 cm layer. In conclusion, according to results obtained maritime pine plantations on coal mine spoils; slow accumulation and decomposition of forest floor undergo simultaneously. Depending on these changes organic carbon and total nitrogen contents increased in upper layer of soil/spoil.     

Pollution of intensively managed greenhouse soils by nutrients and heavy metals in the Yellow River Irrigation Region,Northwest China

The present study aimed to assess the potential ecological risk of heavy metals and nutrient accumulation in polytunnel greenhouse soils in the Yellow River irrigation region (YRIR), Northwest China, and to identify the potential sources of these heavy metals using principal component analysis. Contents of available nitrogen (AN), phosphorus (AP), and potassium (AK) in the surface polytunnel greenhouse soils (0–20 cm) varied from 13.42 to 486.78, from 39.10 to 566.97, and from 21.64 to 1,156.40 mg kg^?1, respectively, as well as AP, soil organic matter (SOM) and AK contents tended to increase significantly at the 0–20- and 20–40-cm soil layers. Heavy metal accumulations occurred in the polytunnel greenhouse soils as compared to arable soils, especially at a depth of 20 cm where Cd, Zn and Cu contents were significantly higher than arable soil. Cd and As were found to be the two main polluting elements in the greenhouse soils because their contents exceeded the thresholds established for greenhouse vegetable production HJ333-2006 in China and the background of Gansu province. It has been shown that Cd, Cu, Pb and Zn at the 0–20-cm soil layer were derived mainly from agricultural production activities, whereas contents of Cr and Ni at the same soil layer were determined by ‘natural’ factors and As originated from natural sources, deposition and irrigation water.     

Atmospheric NO2 and NH3 deposition into a typical agro-ecosystem in Southeast China

The dry deposition of atmospheric nitrogen (including NO(2) and NH(3)) into a typical agro-ecosystem in Southeast China during 2006-2007 was estimated. Results indicated that the dry deposition velocities of NO(2) and NH(3) ranged from 0.04-0.24 cm s(-1) and 0.09-0.47 cm s(-1), respectively. The higher values appeared in the non-crop growing period. Concentrations of atmospheric NO(2) and NH(3) ranged from 24.64-104.10 μgN m(-3) and 14.40-389.6 μgN m(-3), respectively. Variation of the NH(3) mixing ratio showed a clear double-peak. NO(2) and NH(3) deposition fluxes were 74.68-80.75 kgN ha(-1), which was equivalent to 162.4 and 175.5 kg ha(-1) of urea applied in 2006-2007. The N deposition fluxes were 13.91-40.38 and 5.33-22.73 kgN ha(-1) in peanut and rice growing periods, accounting for 8.18%-40.38% and 2.13%-23.06% of N fertilizer usages, respectively. NO(2) and NH(3) deposition were significant for the red soil farmland.     

Spatial variability of salinity and alkalinity of a field having salination risk in semi-arid climate in northern Turkey

Spatial variability of salinity and alkalinity is important for site-specific management since they are the most important factors influencing soil quality and agricultural production. The objectives of this study were to analyze spatial variability in salinity and alkalinity and some soil properties affecting salinity and alkalinity, using classical statistics and geostatistical methods, in an irrigated field with low-quality irrigation water diverted from drainage canals. A field of 5 da was divided into 10 m x 10 m grids (5 lines in the east-west direction and 10 lines in the north-south direction). The soil samples were collected from three depths (0-30, 30-60 and 60-90 cm) at each grid corner. The variation coefficients of OM and sand contents were higher than other soil properties. OM had the maximum variability, with a mean of 1.63% at 0-30 cm depth and 0.71% at 30-60 cm depth. Significant correlations occurred between ESP, EC and each of Ca, Mg, K and CaCO(3) contents of the soils (p<0.01). Experimental semivariograms were fitted to spherical and gaussian models. All geostatistical range values were greater than 36 m. The soil properties had spatial variability at small distances at 60-90 cm depth. EC was variable within short distances at 30-60 cm depth. The nugget effect of ESP increased with soil depth. Kriged contour maps revealed that soils had a salinisation and alkalisation tendency at 60-90 cm depth based on spatial variance structure of the EC and ESP values. Spatial variability in EC and ESP can depend on ground water level, quality of irrigation water, and textural differences.     

Agro-potentiality of distillery effluent on soil and agronomical characteristics of Abelmoschus esculentus L. (okra)

The present study showed that irrigation of soil with different effluent concentrations (10, 25, 50, 75, and 100 %) of distillery effluent (DE) for 60 days resulted in significant (P?<?0.001) changes in moisture content; electrical conductivity (EC), pH, chlorides (Cl^?), total organic carbon (TOC), exchangeable sodium (Na⁺), available potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), iron (Fe²⁺), total Kjeldahl nitrogen (TKN), available phosphorus (P), and sulfate (SO₄ ^2?) of soil. The non-significant (P?>?0.05) changes were observed for water-holding capacity and bulk density of the soil. Among various concentrations of DE irrigation, irrigation with 100 % effluent concentration increased moisture content, (24.85 %), EC (77.88 %), Cl^? (285.95 %), TOC (3,171.42 %), exchangeable Na⁺ (241.04 %), available K⁺ (52.49 %), Ca²⁺ (990.37 %), Mg²⁺ (1,751.72 %), TKN (1,417.00 %), available P (305.00 %), and SO₄ ^2? (75.32 %) in the soil and decreased pH (?20.22 %). The more stimulation in agronomical parameters such as shoot length, root length, number of leaves, flowers, pods, dry weight, fresh weight, chlorophyll content, leaf area index, and crop yield of A. esculentus were observed to be inversely proportional to the concentration of effluent water, with the best results being obtained at a dilution of 25 % of DE concentration.     

Assessment of spatial variability in some soil properties as related to soil salinity and alkalinity in Bafra plain in northern Turkey

The objectives of this study were to assess the variability in soil properties affecting salinity and alkalinity, and to analyze spatial distribution patterns of salinity (EC) and alkalinity (ESP) in the plain, which was used irrigation agriculture with low quality waters. Soil samples were collected from 0–30cm, 30–60cm, 60–90cm and 90–120cm soil depths at 60 sampling sites. Soil pH had the minimum variability, and hydraulic conductivity (Ks) had the maximum variability at all depths. The mean values of pH, EC, ESP and Ks increased while the mean values of CEC decreased with soil depth. Values pH, EC and ESP were generally high in the east and northeastern sides. Soil properties indicated moderate to strong spatial dependence. ESP and pH were moderately spatially dependent for three of the four depths, EC exhibited moderate spatial dependence for one of the four depths, CEC had a moderate spatial dependence at all depths, and Ks exhibited a strong spatial dependence. EC, CEC, and ESP were considerably variable in small distances. The spatial variability in small distances of EC, CEC, pH and ESP generally increased with depth. All geostatistical range values were greater than 1230m. It was inferred that the strong spatial dependency of soil properties would be resulted in extrinsic factors such as ground water level, drainage, irrigation systems and microtopography.     

Chemical, biochemical, and biological impact of untreated domestic sewage water use on Vertisol and its consequences on wheat (Triticum aestivum) productivity

In the peri-urban areas of central India, sewage water is a valuable resource for agricultural production. In this study, impact of domestic sewage water irrigation for 5 years on Vertisol with no previous history of sewage irrigation was investigated in an ongoing field experiment at Bhopal (India) under subtropical monsoon type climate. The wheat (Triticum aestivum) crop was grown during post-rainy winter season with 30 cm of irrigation (groundwater or sewage water) and four nutrient treatments (T₁, 0; T₂, 100%; T₃, 50%; and T₄, 50% of general recommended doses of NPK + FYM at 10 Mg/ha). Results showed that sewage irrigation of about 150 cm over a period of 5 years resulted significant increases in salinity as well as available fractions of N, P, K, and micronutrients, viz., Zn, Fe, and Mn in soils. Carbon and phosphorus applied through sewage water were accumulated more in subsoil layer compared to topmost plough layer. Soil microbiological activity, as indicated by soil respiration, microbial biomass C, as well as dehydrogenase enzyme activity was higher in sewage water-irrigated soils. There was also significant increase in fungal and actinomycetes as well as total coliform population in such soils. Nutrients supplied through sewage water were not able to raise the productivity of wheat to the level that obtained through fertilizers at the recommended level which indicated that additional nutrients through fertilizers are required to obtain higher productivity of wheat under sewage farming. Protein and Zn content in wheat grains were more when the crop was grown with sewage irrigation. Overall results show that except for increase in coliform population, short duration (5 years) of municipal sewage water irrigation did not have any appreciable harmful effect on soil quality as well as crop productivity; rather, it proved beneficial in improving soil fertility, wheat productivity, and produce quality.     

Persistence of metsulfuron-methyl in wheat crop and soil

Possible bioaccumulation of pesticides in crop produce may cause ailing effect on animal and human. Thus there is a need to evaluate these chemicals in the soil and crop produce at harvest. Metsulfuron-methyl is a post-emergence herbicide. It is highly active to control broad-leaf weeds in cererals, pasture and plantation crops. Metsulfuron-methyl was applied at 3, 4, 5, and 8 g a.i. ha(-1) rates, after 30 days of sowing in wheat as post-emergence herbicide. Soil samples treated with metsulfuron-methyl were collected after 30 and 60 days along with control and at harvest after herbicide application and analyzed for residues by High Performance Liquid Chromatography (HPLC) using photo diode array detector at 220 nm. Wheat grains and straw samples were sampled at harvest. At harvest the residue level of metsulfuron-methyl in soil was found below the detection limit at 3-5 g a.i. ha(-1) application rates and 0.002 microg g(-1) at 8 g a.i. ha(-1), respectively. No residues of metsulfuron-methyl were detected in wheat grains at 3-4 g a.i. ha(-1) rates. However 0.002 microg g(-1) residues were detected in wheat straw at 5 and 8 g a.i. ha(-1) application rates. It can be concluded that metsulfuron-methyl application at 3-4 g a.i. ha(-1) can be safely applied to the wheat crop as post-emergence herbicide.     

Field-scale monitoring of the long-term impact and sustainability of drainage water reuse on the west side of California's San Joaquin Valley

Diminishing freshwater resources have brought attention to the reuse of degraded water as a water resource rather than a disposal problem. Drainage water from tile-drained, irrigated agricultural land is degraded water that is often in large supply, but the long-term impact and sustainability of its reuse on soil is unknown. Similarly, nothing is known of the ramifications of terminating drainage water reuse. The objective of this study is (i) to monitor the long-term impact on soil chemical properties and thereby the sustainability of drainage water reuse on a marginally productive, saline-sodic, 32.4 ha field located on the west side of California's productive San Joaquin Valley and (ii) to assess spatially what happens to soil when drainage water reuse is terminated. The monitoring and assessment were based on spatial chemical data for soil collected during 10 years of irrigation with drainage water followed by 2 years of no applied irrigation water (only rainfall). Geo-referenced measurements of apparent soil electrical conductivity (EC(a)) were used to direct the soil sampling design to characterize spatial variability of impacted soil properties. Chemical analyses of soil samples were used (i) to characterize the spatial variability of salinity, Na, B, and Mo, which were previously identified as critical to the yield and quality of Bermuda grass (Cynodon dactylon (l.) Pers.) grown for livestock consumption and (ii) to monitor their change during the 12 year study. Soil samples were taken at 0.3 m increments to a depth of 1.2 m at each of 40 sample sites on five occasions: August 1999, April 2002, November 2004, August 2009, and May 2011. Drainage water varying in salinity (1.8-16.3 dS m(-1)), SAR (5.2-52.4), Mo (80-400 μg L(-1)), and B (0.4-15.1 mg L(-1)) was applied from July 2000 to June 2009. Results indicate that salts, Na, Mo, and B were leached from the root zone causing a significant improvement in soil quality from 1999 to 2009. Salinity and SAR returned to original levels or higher in less than two years after termination of irrigation. Boron and Mo showed significant increases. Long-term sustainability of drainage water reuse was supported by the results, but once application of irrigation water was terminated, the field quickly returned to its original saline-sodic condition.     

Ecological restoration of mined-out areas of dry tropical environment, India

The objective of the present study was to evince the long-term changes after natural revegetation and experimental revegetation of the coal mine spoils with respect to total plant biomass, available plant nutrients, nitrogen transformation and microbial biomass N (MBN) in dry tropical environment of India. Total plant biomass (above- and below-ground), plant available nitrogen, soil nitrogen mineralization and microbial biomass N (MBN) were studied for 2 years in 5 and 10 years old naturally vegetated and revegetated coal mine spoils, and dry tropical forest ecosystem of India. In forest ecosystem, the above ground biomass values ranged from 3,520 to 3,630 kg ha(-1) and belowground from 6,280 to 6,560 kg ha(-1). Plant available nitrogen ranged from 16.76 to 23.21 microg g(-1), net N-mineralization from 9.8 to 48.53 microg g(-1) month(-1) and MBN from 26.4 to 80.02 microg g(-1). In naturally revegetated mine spoil, the above ground biomass values ranged from 1,036 to 1,380 kg ha(-1) and belowground from 2,538 to 3,380 kg ha(-1). Plant available nitrogen ranged from 7.33-17.14 microg g(-1), net N-mineralization from 3.1 to 12.46 microg g(-1) month(-1) and MBN from 14.2 to 35.44 microg g(-1). In revegetated mine spoil, the above ground biomass values ranged from 1,224 to 1,678 kg ha(-1) and belowground from 2,870 to 4,130 kg ha(-1). Plant available nitrogen ranged from 9.4 to 18.83 microg g(-1), net N-mineralization from 4.2 to 16.2 microg g(-1) month(-1) and MBN from 21.6 to 42.6 microg g(-1). The mean plant biomass values in 5 and 10 years mine spoils was lower compared to forest ecosystem by 2.5 and 2 times, respectively. N-mineralization value in 5 year mine spoil was 3.5 times lower and in 10 years mine spoil 2 times lower compared to forest ecosystem. The MBN value was about 2 times lower in both 5 and 10 year mine spoils compared to native forest. MBN was positively related to the re-vegetation age of the mine spoil.     

Persistence of dicofol residues in cotton lint seed, and soil

A supervised field trial was conducted at the CCS Haryana Agricultural University, Hisar to assess the residues of dicofol on cotton, during Kharif season, 2008. Dicofol (Kelthane 18.5EC) was applied at 500 g a.i./ha (T(1)) and 1,000 g a.i./ha T(2)) after 105 days of sowing of cotton crop (Varity Cotton/H-1226). Soil samples were collected on 0 (1 h after treatment), 3, 7, 10, 15, 30, and 60 days after spray and cotton samples were collected at harvest. Samples were processed and residues were quantified by GC-ECD system equipped with capillary column. Limit of detection and limit of quantification (LOQ) were 0.001 and 0.010 mg kg(?-1), respectively, for soil and LOQ for cotton lint and seed was 0.020 mg kg(?-1). Initial residues of 0.588 and 1.182 mg kg(?-1) in soil reached below detectable level (BDL) of 0.010 mg kg(?-1) in T(1) and to the level of BDL (0.010 mg kg(?-1)) in T(2) at harvest (60 days after treatment). In 60 days, residues dissipated almost completely (100 and >99%) in both the treatments. Half-life period was calculated as 8.57 days at single dose and 8.69 days at double dose in soil. Residues of dicofol were detected in cotton lint to the levels of 0.292 and 0.653 mg kg(?-1) and in seed 0.051 and 0.090 mg kg(?-1) in T(1) and T(2) doses, respectively at harvest. Residues in cotton seed were below MRL value of 0.01 mg kg(?-1) in both the doses.     

Depth profiling of Pu, 241Am and 137Cs in soils from southern Belarus measured by ICP-MS and alpha and gamma spectrometry

The depth distribution of plutonium, americium, and 137Cs originating from the 1986 accident at the Chernobyl Nuclear Power Plant (NPP) was investigated in several soil profiles in the vicinity from Belarus. The vertical migration of transuranic elements in soils typical of the 30 km relocation area around Chernobyl NPP was studied using inductively coupled plasma mass spectrometry (ICP-MS), alpha spectrometry, and gamma spectrometry. Transuranic concentrations in upper soil layers ranged from 6 x 10(-12) g g(-1) to 6 x 10(-10) g g(-1) for plutonium and from 1.8 x 10(-13) g g(-1) to 1.6 x 10(-11) g g(-1) for americium. These concentrations correspond to specific activities of (239+240)Pu of 24-2400 Bq kg(-1) and specific activity of 241Am of 23-2000 Bq kg(-1), respectively. Transuranics in turf-podzol soil migrate slowly to the deeper soil layers, thus, 80-95%, of radionuclide inventories were present in the 0-3 cm intervals of turf-podzol soils collected in 1994. In peat-marsh soil migration processes occur more rapidly than in turf-podzol and the maximum concentrations are found beneath the soil surface (down to 3-6 cm). The depth distributions of Pu and Am are essentially identical for a given soil profile. (239+240)Pu/137Cs and 241Am/137Cs activity ratios vary by up to a factor of 5 at some sites while smaller variations in these ratios were observed at a site close to Chernobyl, suggesting that 137Cs is dominantly particle associated close to Chernobyl but volatile species of 137Cs are of relatively greater importance at the distant sites.     

Persistence and vertical distribution of termiticide fipronil in modified ground board test

Fipronil termiticide belongs to phenyl-pyrazole class of chemical compounds. It has broad-spectrum activity particularly against house hold pests such as cockroaches, mosquitoes, locusts, ticks, and fleas at both larval and adult stages. At high dosage it can be used to control subterranean termites in building foundations. To evaluate long term efficacy against termites the persistence and vertical distribution of fipronil was studied under natural weather conditions of Dehradun, India. Fipronil was applied at four concentrations i.e. 0.05, 0.1, 0.25 and 0.5% a.i ha⁻¹ by drenching 17 × 17 in.² plot prepared as per modified ground board test. Soil samples were collected after 22, 38 and 56 months of treatment up to the depth of 75 cm. The soil core was cut into five distinct sections i.e. 0–15, 15–30, 30–45, 45–60 and 60–75 cm depth. The residues were extracted by shaking 20 g soil sample with acetone. The acetone extract was concentrated and cleaned-up over florisil column. Fipronil residues were estimated on GLC at 220, 260, and 300°C oven, injector and detector temperature respectively. Fipronil was found to persist beyond 56 months after application. Two metabolites viz. desulfinyl and sulfide-fipronil were detected in sampling after 22 months of application that also dissipated with time. Fipronil residues were found up to 60 cm depth. The residues in deeper layers dissipate slowly with time and after 56 months of treatment residues were detected only up to 30 cm depth.     

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.     

Phosphorus run-off assessment in a watershed

The Watershed Assessment Model was used to simulate the runoff volume, peak flows, and non-point source phosphorus loadings from the 5870 km(2) Lake Okeechobee watershed as a case study. The results were compared to on-site monitoring to verify the accuracy of the method and to estimate the observed/simulated error. In 2008, the total simulated phosphorus contribution was 9634, 6524 and 3908 kg (P) y(-1) from sod farms, citrus farms and row crop farmlands, respectively. Although the dairies represent less than 1% of the total area of Kissimmee basin, the simulated P load from the dairies (9283 kg (P) y(-1) in 2008) made up 5.4% of the total P load during 2008. On average, the modeled P yield rates from dairies, sod farms and row crop farmlands are 3.85, 2.01 and 0.86 kg (P) ha(-1) y(-1), respectively. The maximum sediment simulated phosphorus yield rate is about 2 kg (P) ha(-1) and the particulate simulated phosphorus contribution from urban, improved pastures and dairies to the total phosphorus load was estimated at 9%, 3.5%, and 1%, respectively. Land parcels with P oversaturated soil as well as the land parcels with high phosphorus assimilation and high total phosphorus contribution were located. The most critical sub-basin was identified for eventual targeting by enforced agricultural best management practices. Phosphorus load, including stream assimilation, incoming to Lake Okeechobee from two selected dairies was also determined.     

Soil carbon storage as influenced by tree cover in the Dehesa cork oak silvopasture of central-western Spain

The extent of carbon (C) stored in soils depends on a number of factors including soil characteristics, climatic and other environmental conditions, and management practices. Such information, however, is lacking for silvopastoral systems in Spain. This study quantified the amounts of soil C stored at various depths (0-25, 25-50, 50-75, and 75-100 cm) under a Dehesa cork oak (Quercus suber L.) silvopasture at varying distances (2, 5, and 15 m) to trees. Soil C in the whole soil and three soil fractions (<53, 53-250, and 250-2000 μm) was determined. Results showed soil depth to be a significant factor in soil C stocks in all soil particle sizes. Distance to tree was a significant factor determining soil C stocks in the whole soil and the 250-2000 μm soil fraction. To 1 m depth, mean total C storage at 2, 5, and 15 m from cork oak was 50.2, 37, and 26.5 Mg ha(-1), respectively. Taking into account proportions of land surface area containing these C stocks at varying distances to trees to 1 m depth, with a tree density of 35 stems ha(-1), estimated landscape soil C is 29.9 Mg ha(-1). Greater soil C stocks directly underneath the tree canopy suggest that maintaining or increasing tree cover, where lost from disease or management, may increase long term storage of soil C in Mediterranean silvopastoral systems. The results also demonstrate the use of soil aggregate characteristics as better indicators of soil C sequestration potential and thus a tool for environmental monitoring.     

Atmospheric inorganic nitrogen deposition to a typical red soil forestland in southeastern China

A 2-year monitoring study was conducted to estimate nitrogen deposition to a typical red soil forestland in southeastern China. The dry deposition velocities (V(d)) were estimated using big leaf resistance analogy model. Atmospheric nitrogen dry deposition was estimated by combing V(d) and nitrogen compounds concentrations, and the wet deposition was calculated via rainfall and nitrogen concentrations in rainwater. The total inorganic nitrogen deposition was 83.7 kg ha(-1) a(-1) in 2004 and 81.3 kg ha(-1) a(-1) in 2005, respectively. The dry deposition contributed 78.6% to total nitrogen deposition, in which ammonia was the predominant contributor that accounted for 86.1%. Reduced nitrogen compounds were the predominant contributors, accounting for 78.3% of total nitrogen deposition. The results suggested that atmospheric inorganic nitrogen could be attributed to intensive agricultural practices such as excessive nitrogen fertilization and livestock production. Therefore, impacts of atmospheric nitrogen originated from agriculture practices on nearby forest ecosystems should be evaluated.     

Impact of elevated O3 on visible foliar symptom, growth and biomass of Cinnamomum camphora seedlings under different nitrogen loads

The effects of elevated ozone (O(3)) and enhanced nitrogen (N) on the growth and biomass of Cinnamomum camphora, a subtropical evergreen broad-leaved tree species, were investigated. The seedlings, supplied with N (NH(4)NO(3) solution) at 0, 30 and 60 kg ha(-1) year(-1) (simplified as N0, N30, N60, respectively), were exposed to ambient (AA) or elevated O(3) (AA + 60 nmol mol(-1) and AA + 120 nmol mol(-1), designated as AA + 60 and AA + 120, respectively) for the 2009 and 2010 growing seasons. Symptomatic leaf percentages were significantly increased with O(3) concentration. AA + 120 significantly decreased the mean leaf size and chlorophyll content of both 2009- and 2010-emerged leaves, inhibited the growth of stem height and basal diameter, and reduced biomass accumulation of all plant parts except for leaves. By comparison, only the chlorophyll content of 2009-emerged leaves and root dry weight were significantly reduced under AA + 60. Specific leaf area, total leaf area and foliar biomass were not affected even at a higher O(3) level. On the other hand, N loads, especially N60, exerted significantly positive effects on all variables except mean leaf size and shoot/root ratio. No significant interactions between O(3) and N were detected, suggesting that the N supply at ≤60 kg ha(-1) year(-1) did not significantly modify the response of C. camphora to O(3) in terms of seedling growth and biomass accumulation.     

Some soil properties on coal mine spoils reclaimed with black locust (Robinia pceudoacacia L.) and umbrella pine (Pinus pinea L.) in Agacli-Istanbul

This study performed on randomly selected seven sample plots in leguminous black locust (Robinia pceudoacacia L.) plantations and five sample plots in umbrella pine (Pinus pinea L.) plantations on coal mine soil/spoils. Soil samples were taken from eight different soil depths (0–1, 1–3, 3–5, 5–10, 10–20, 20–30, 30–40, and 40–50 cm) into the soil profile. On soil samples, bulk density, fine soil fraction (Ø < 2 mm), sand, silt and clay rates, soil acidity (pH), organic carbon (C_org), and total nitrogen (N_t) contents were investigated. Also, some forest floor properties (unit mass, organic matter, and total nitrogen) were determined, and results were compared statistically between umbrella pine and black locust. As a result, 17 years after plantations, total forest floor accumulation determined as 6,107 kg ha^???1 under black locust compared to 13,700 kg ha^???1 under umbrella pine. The more rapid transformation of leguminous black locust forest floor creates organic carbon that migrates further into the mineral profile, and rapid accumulation of C and N in the soil profile was registered. Slower transformation processes of forest floor under umbrella pine result in lower soil N ratio and greater quantity of forest floor. Higher soil pH under leguminous black locust was determined significantly than umbrella pine. In conclusion, the composition of symbiotic nitrogen fixation of black locust appears to be a possible factor favoring carbon and nitrogen accumulation and, consequently, soil development. Clearly, both tree species have favorable impacts on initial soil formation. The umbrella pine generates the more forest floor layer; in contrast, black locust forest floor incorporates into the soil more rapidly and significantly increases soil nitrogen in upper soil layers.     

Determination of irradiated reactor uranium in soil samples in Belarus using 236U as irradiated uranium tracer

This work presents experimental results on the distribution of irradiated reactor uranium from fallout after the accident at Chernobyl Nuclear Power Plant (NPP) in comparison to natural uranium distribution in different soil types. Oxidation processes and vertical migration of irradiated uranium in soils typical of the 30 km relocation area around Chernobyl NPP were studied using 236U as the tracer for irradiated reactor uranium and inductively coupled plasma mass spectrometry as the analytical method for uranium isotope ratio measurements. Measurements of natural uranium yielded significant variations of its concentration in upper soil layers from 2 x 10(-7) g g(-1) to 3.4 x 10(-6) g g(-1). Concentrations of irradiated uranium in the upper 0-10 cm soil layers at the investigated sampling sites varied from 5 x 10(-12) g g(-1) to 2 x 10(-6) g g(-1) depending on the distance from Chernobyl NPP. In the majority of investigated soil profiles 78% to 97% of irradiated "Chernobyl" uranium is still contained in the upper 0-10 cm soil layers. The physical and chemical characteristics of the soil do not have any significant influence on processes of fuel particle destruction. Results obtained using carbonate leaching of 236U confirmed that more than 60% of irradiated "Chernobyl" uranium is still in a tetravalent form, ie. it is included in the fuel matrix (non-oxidized fuel UO2). The average value of the destruction rate of fuel particles determined for the Western radioactive trace (k = 0.030 +/- 0.005 yr(-1)) and for the Northern radioactive trace (k = 0.035 + 0.009 yr(-1)) coincide within experimental errors. Use of leaching of fission products in comparison to leaching of uranium for study of the destruction rate of fuel particles yielded poor coincidence due to the fact that use of fission products does not take into account differences in the chemical properties of fission products and fuel matrix (uranium).