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1.
Evaluation of EDI derived from the exponential evapotranspiration model for monitoring China’s surface drought 总被引:5,自引:4,他引:1
Yunjun Yao Qiming Qin Ayad M. Fadhil Yufu Li Shaohua Zhao Shaomin Liu Xinxin Sui Heng Dong 《Environmental Earth Sciences》2011,63(2):425-436
Drought has become the most severe natural disaster in many provinces of China. In this paper, evaporative drought index (EDI)
has been used to monitor China’s surface dryness conditions based on the exponential evapotranspiration (ET) model and Hargreaves
equation from JAXA-MODIS Insolation products, GEWEX, NCEP-2 and MODIS NDVI data. The exponential ET model based on the surface
net radiation, vegetation index, mean air temperature and diurnal air temperature range (DTaR) has been developed to estimate
surface ET of China and has been independently validated using ground-measured data collected from two sites (Arou and Miyun)
in China, indicating that the bias varies from −5.96 to 5.02 W/m2. The good agreement between daily estimated and ground-measured ET using ground observation data collected from all 22 sites
further supports the validity of the exponential ET model for regional ET estimation. Moreover, EDI is closely correlated
to the average soil moisture at 0–10 cm soil depth of the Yongning site with coefficient of determination of R
2 = 0.52. The spatio-temporal patterns of monthly ET and EDI from April to September of 2004 over China are explored and the
result indicates EDI is accordant with the precipitation by comparing the 15-day smoothed EDI with precipitation over six
representative sites. The EDI based on the exponential ET model by integrating energy fluxes in response to soil moisture
stress has demonstrated its validity for monitoring China’s surface drought events. 相似文献
2.
J. Jiménez-Martínez K. Tamoh L. Candela F. J. Elorza D. Hunkeler 《Mathematical Geosciences》2012,44(2):187-208
Tritium is a short-lived radioactive isotope (T
1/2=12.33 yr) produced naturally in the atmosphere by cosmic radiation but also released into the atmosphere and hydrosphere
by nuclear activities (nuclear power stations, radioactive waste disposal). Tritium of natural or anthropogenic origin may
end up in soils through tritiated rain, and may eventually appear in groundwater. Tritium in groundwater can be re-emitted
to the atmosphere through the vadose zone. The tritium concentration in soil varies sharply close to the ground surface and
is very sensitive to many interrelated factors like rainfall amount, evapotranspiration rate, rooting depth and water table
position, rendering the modeling a rather complex task. Among many existing codes, SOLVEG is a one-dimensional numerical model
to simulate multiphase transport through the unsaturated zone. Processes include tritium diffusion in both, gas and liquid
phase, advection and dispersion for tritium in liquid phase, radioactive decay and equilibrium partitioning between liquid
and gas phase. For its application with bare or vegetated (perennial vegetation or crops) soil surfaces and shallow or deep
groundwater levels (contaminated or non-contaminated aquifer) the model has been adapted in order to include ground cover,
root growth and root water uptake. The current work describes the approach and results of the modeling of a tracer test with
tritiated water (7.3×108 Bq m−3) in a cultivated soil with an underlying 14 m deep unsaturated zone (non-contaminated). According to the simulation results,
the soil’s natural attenuation process is governed by evapotranspiration and tritium re-emission. The latter process is due
to a tritium concentration gradient between soil air and an atmospheric boundary layer at the soil surface. Re-emission generally
occurs during night time, since at day time it is coupled with the evaporation process. Evapotranspiration and re-emission
removed considerable quantities of tritium and limited penetration of surface-applied tritiated water in the vadose zone to
no more than ∼1–2 m. After a period of 15 months tritium background concentration in soil was attained. 相似文献
3.
Xiaojia Li Xianzhou Zhang Jianshuang Wu Zhenxi Shen Yangjian Zhang Xingliang Xu Yuzhi Fan Yuping Zhao Wei Yan 《Environmental Earth Sciences》2011,64(7):1911-1919
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. 相似文献
4.
Characteristics of winter mass balance of Glacier No.1 at the headwaters of the Urumqi River,Tianshan Mountains 总被引:1,自引:1,他引:0
This study analyzes the response of glacier to climate change during the past 49 years in Urumqi River source region, the
Tianshan Mountains of China. The temporal and spatial variations of winter mass balance (bn-w) at different time scales were
analyzed to identify their response to climate change during 1988–2006 (The observation of winter mass balance observation
began in 1988) on the Glacier No.1 at the headwaters of the Urumqi River, Tianshan Mountains, China. The winter accumulation
shows a significantly decreasing trend. The results show that the cumulative values on Glacier No.1 is 2,202 mm water equivalent
during 1988–2006 and the mean values is 116 mm a−1. Furthermore, the trend analysis of the winter mass balance indicates a rapid decrease since 1990, and the mean mass balance
is only 79 mm a−1 during 1997–2006. Winter mass balance correlates well negatively with the total evaporation from September to April (r = −0.68, α = 0.01), and positively with the total precipitation from September to April (r = 0.74, α = 0.01). However, winter mass balance shows a weak correlation with mean minimum air temperature during September
to April (r = −0.35), and runoff on September (r = −0.13). 相似文献
5.
Ivan Barnet 《Environmental Earth Sciences》2012,66(4):1149-1153
The construction of the European Geogenic Radon Map in a proposed grid system 10 × 10 km requires the data test to derive the probability of exceeding the indoor action level 200 Bq m−3 from the geologically based data. The Czech Republic disposes both indoor and soil gas data sets to test the real probability to exceed 200 Bq m−3 from indoor radon measurements and to compare it with the probability calculated from soil gas radon concentrations. Comparison of real and calculated probability enables to delineate the areas, where under- or overestimation can be expected. The results of data processing show minor differences between processing the raw data in generalised polygons of geological units and in a grid net, when using the generalised geological characteristics of grid cells. 相似文献
6.
K Charan Kumar T Rajendra Prasad M Venkat Ratnam Kamsali Nagaraja 《Journal of Earth System Science》2016,125(7):1391-1397
Analysis of one year measurements of in situ radon (222Rn) and its progenies along with surface air temperature, relative humidity and pressure near to the Earth’s surface has been carried out for the first time at the National Atmospheric Research Laboratory (NARL, 13.5°N and 79.2°E) located in a rural site in Gadanki, south India. The dataset was analysed to understand the behaviour of radon in relation to the surface air temperature and relative humidity at a rural site. It was observed that over a period of the 24 hours in a day, the activity of radon and its progenies reaches a peak in the morning hours followed by a remarkable decrease in the afternoon hours. Relatively, a higher concentration of radon was observed at NARL during fair weather days, and this can be attributed to the presence of rocky hills and dense vegetation surrounding the site. The high negative correlation between surface air temperature and activity of radon (R = – 0.70, on an annual scale) suggests that dynamical removal of radon due to increased vertical mixing is one of the most important controlling processes of the radon accumulation in the atmospheric surface layer. The annual averaged activity of radon was found to be 12.01±0.66 Bq m?3 and 4.25±0.18 Bq m?3 for its progenies, in the study period. 相似文献
7.
Effects of nitrogen fertilization on soil respiration in temperate grassland in Inner Mongolia,China 总被引:5,自引:0,他引:5
Qin Peng Yunshe Dong Yuchun Qi Shengsheng Xiao Yating He Tao Ma 《Environmental Earth Sciences》2011,62(6):1163-1171
Nitrogen addition to soil can play a vital role in influencing the losses of soil carbon by respiration in N-deficient terrestrial
ecosystems. The aim of this study was to clarify the effects of different levels of nitrogen fertilization (HN, 200 kg N ha−1 year−1; MN, 100 kg N ha−1 year−1; LN, 50 kg N ha−1 year−1) on soil respiration compared with non-fertilization (CK, 0 kg N ha−1 year−1), from July 2007 to September 2008, in temperate grassland in Inner Mongolia, China. Results showed that N fertilization
did not change the seasonal patterns of soil respiration, which were mainly controlled by soil heat-water conditions. However,
N fertilization could change the relationships between soil respiration and soil temperature, and water regimes. Soil respiration
dependence on soil moisture was increased by N fertilization, and the soil temperature sensitivity was similar in the treatments
of HN, LN, and CK treatments (Q
10 varied within 1.70–1.74) but was slightly reduced in MN treatment (Q
10 = 1.63). N fertilization increased soil CO2 emission in the order MN > HN > LN compared with the CK treatment. The positive effects reached a significant level for HN
and MN (P < 0.05) and reached a marginally significant level for LN (P = 0.059 < 0.1) based on the cumulative soil respiration during the 2007 growing season after fertilization (July–September
2007). Furthermore, the differences between the three fertilization treatments and CK reached the very significant level of
0.01 on the basis of the data during the first entire year after fertilization (July 2007–June 2008). The annual total soil
respiration was 53, 57, and 24% higher than in the CK plots (465 g m−2 year−1). However, the positive effects did not reach the significant level for any treatment in the 2008 growing season after the
second year fertilization (July–September 2008, P > 0.05). The pairwise differences between the three N-level treatments were not significant in either year (P > 0.05). 相似文献
8.
Ahmed Melegy Igor Slaninka Tomas Pa?es Stanislav Rapant 《Environmental Earth Sciences》2011,64(2):549-555
Inputs of As to a small catchment due to chemical weathering of bedrock, mechanical weathering of bedrock, and atmospheric
precipitation were 71.53, 23.98 and 0.02 g ha−1 year−1, respectively. The output fluxes of As due to mechanical erosion of soil, biological uptake, stream discharge, and groundwater
flow were 6.32, 4.77, 0.37 and 0.02 g ha−1 year−1, respectively. The results indicate that arsenic accumulates in soil and regolith with a very high rate. This is attributed
to the selective weathering and erosion with respect to arsenic and fixation of arsenic in the secondary solids produced by
weathering. The output fluxes of As in stream and groundwater in Vydrica catchment in Slovak Republic (0.39 g ha−1 year−1) based on muscovite–biotite granites and granodiorites were much lower compared to catchments in a gold district in the Czech
Republic. These results may be ascribed to the low levels of arsenic pollution measured in Vydrica catchment. The arsenic
fluxes were estimated by calculation of mechanical and chemical weathering rates of the bedrocks in Vydrica catchment from
mass balance data on sodium and silica. The justification of the steady state of Na and Si is that neither of the elements
is appreciably accumulated in plants and in exchangeable pool of ions in soil. 相似文献
9.
M. G. García K. L. Lecomte Y. Stupar S. M. Formica M. Barrionuevo M. Vesco R. Gallará R. Ponce 《Environmental Earth Sciences》2012,65(2):535-545
Symptoms of dental fluorosis have been observed in rural communities located in the Sierras Pampeanas de Córdoba, a mountainous
area in Central Argentina. The clinical assessment was performed in the Charbonier Department, where the fluoride (F−) intake was determined to be 3.90 ± 0.20 mg day−1 (n = 16). In this community, mild and severe fluorosis reach an incidence of 86.7% (total teeth surface = 636 teeth) among the
children population. To determine the origin and distribution of fluorine in natural waters from the Charbonier Department
and nearby regions, sampling was performed in the area covering the San Marcos River basin. The obtained results show that
F− concentrations vary between ~1 to ~2.5 mg l−1, with an outlier value of 8 mg l−1. The spatial distribution of F− shows that the lowest concentrations are found at the basin’s catchments. Maximum values are located in two sectors of the
basin: the Charbonier depression in the eastern part and at the San Marcos village, downstream the main collector, in the
western part of the basin. In these two regions, the F− contents in ground- and surface waters are >2.0 mg l−1 and nearly constant. Dissolved F− in natural waters from the study area has its origin in the weathering of F-bearing minerals present in the region’s dominant
lithology. The extent of mineral weathering is mostly determined by the residence time of water within the aquatic reservoir.
Longer residence times and a major solid–water interaction lead to enhanced release of F−. This explains the higher F− concentrations found in basin areas with lower run off. The removal of F− from water appears to occur by neither fluorite precipitation, nor by adsorption. Hence, variations in F− concentrations seem to be more related to regional hydrological conditions. 相似文献
10.
Calibrating a rainfall erosivity assessment model at regional scale in Mediterranean area 总被引:3,自引:1,他引:2
Sergio Grauso Nazzareno Diodato Vladimiro Verrubbi 《Environmental Earth Sciences》2010,60(8):1597-1606
A simplified regression model is here calibrated on the basis of rainfall data records of Sicily (southern Italy), in order
to show the model reliability in assessing the R-factor of the Universal Soil Loss Equation and its revised version (RUSLE) and to provide an estimate of long-term rainfall
erosivity at medium-regional scale. The proposed model is a rearrangement of a former simplified model, formulated for the
Italian environment, grouping three easily available rainfall variables on various time scales, which has been shown to be
more successful than others in reproducing the rainfall erosive power over different locations of Italy. A geostatistical
interpolation procedure is then applied for generating the regional long-term erosivity map with associated standard error.
Areas with severe erosive rainfalls (from 2,000 up to more than 6,000 MJ mm ha−1 h−1) are pointed out which will correspond to areas suffering from severe soil erosion. Solving the problem of calculating the
R-factor value in the RUSLE equation by means of such a simplified model here formulated will allow to predict the related
soil loss. Moreover, given the availability of long time-series of concerned rainfall data, it will be possible to analyse
the variability of rainfall erosivity within the last 50 years, and to investigate the application of RUSLE or similar soil
erosion models with forecasting purposes of soil erosion risk. 相似文献
11.
Núria Marbà Carlos M. Duarte Jorge Terrados Zayda Halun Esperança Gacia Miguel D. Fortes 《Estuaries and Coasts》2010,33(1):107-117
We examined the rhizosphere structure of 14 seagrass meadows (seven mixed, three Enhalus acoroides, two Zostera japonica, one Thalassia hemprichii, and one Halophila ovalis) in the Philippines and Vietnam and tested their effect on sediment redox potential by comparing the redox potential in vegetated
vs unvegetated sediments. The effect of seagrass photosynthesis on sediment redox potential was tested in an E. acoroides meadow during a short-term (2-day) clipping experiment. In all the meadows, the centroidal depth (i.e., depth comprising
50%) of seagrass belowground biomass was within the top 15 cm sediment layer. Redox potentials in vegetated sediments tended
to be higher than those in adjacent unvegetated ones; sediment redox potential anomaly ranged from −61 to 133 mV across the
meadows. The centroidal depths of positive redox potential anomaly and seagrass root biomass were significantly correlated
across the meadows investigated (type II regression analysis, slope = 0.90, lower confidence limit [CL] = 0.42 upper CL = 1.82,
R
2 = 0.59, p < 0.01). Experimental removal of E. acoroides leaves resulted in a decrease in rhizosphere redox potential by 20 mV, further confirming the positive effect of seagrass
roots and rhizomes on sediment redox potential and, thus, the general conditions for microbial processes in the coastal zone. 相似文献
12.
Geochemical mixing models were used to decipher the dominant source of freshwater (rainfall, canal discharge, or groundwater
discharge) to Biscayne Bay, an estuary in south Florida. Discrete samples of precipitation, canal water, groundwater, and
bay surface water were collected monthly for 2 years and analyzed for salinity, stable isotopes of oxygen and hydrogen, and
Sr2+/Ca2+ concentrations. These geochemical tracers were used in three separate mixing models and then combined to trace the magnitude
and timing of the freshwater inputs to the estuary. Fresh groundwater had an isotopic signature (δ
18O = −2.66‰, δD −7.60‰) similar to rainfall (δ
18O = −2.86‰, δD = −4.78‰). Canal water had a heavy isotopic signature (δ
18O = −0.46‰, δD = −2.48‰) due to evaporation. This made it possible to use stable isotopes of oxygen and hydrogen to separate canal water
from precipitation and groundwater as a source of freshwater into the bay. A second model using Sr2+/Ca2+ ratios was developed to discern fresh groundwater inputs from precipitation inputs. Groundwater had a Sr2+/Ca2+ ratio of 0.07, while precipitation had a dissimilar ratio of 0.89. When combined, these models showed a freshwater input
ratio of canal/precipitation/groundwater of 37%:53%:10% in the wet season and 40%:55%:5% in the dry season with an error of
±25%. For a bay-wide water budget that includes saltwater and freshwater mixing, fresh groundwater accounts for 1–2% of the
total fresh and saline water input. 相似文献
13.
A comparative study on isotopic composition of precipitation in wet tropic and semi-arid stations across southern India 总被引:2,自引:0,他引:2
Isotopic composition of monthly composite precipitation samples from Kozhikode (n = 31), a wet tropic station and Hyderabad (n = 25), a semi-arid station across southern India were studied for a period of four years from 2005 to 2008. During the study
period, the Kozhikode station recorded an average rainfall of 3500 mm while the Hyderabad station showed an average rainfall
of 790 mm. The average stable isotope values in precipitation at the Kozhikode station were δ
18O = −3.52‰, d-excess = 13.72‰; δ
18O = −2.94‰, d-excess = 10.57‰; and δ
18O = −7.53‰, d-excess = 13.79‰, respectively during the pre-monsoon (March–May), monsoon (June–September) and post-monsoon
(October–February) seasons. For the Hyderabad station, the average stable isotope values were δ
18O = −5.88‰, d-excess = 2.34‰; δ
18O = −4.39‰, d-excess = 9.21‰; and δ
18O = −8.69‰, d-excess = 14.29‰, respectively for the three seasons. The precipitation at the two stations showed distinctive
isotopic signatures. The stable isotopic composition of precipitation at the Hyderabad station showed significant variations
from the global trend while the Kozhikode station almost followed the global value. These differences are mainly attributed
to the latitudinal differences of the two stations coupled with the differences in climatic conditions. 相似文献
14.
Hyperaccumulation of lead,zinc, and cadmium in plants growing on a lead/zinc outcrop in Yunnan Province,China 总被引:3,自引:0,他引:3
A field survey was conducted to identify potential hyperaccumulators of Pb, Zn or Cd in the Beichang Pb/Zn mine outcrop in
Yunnan Province, China. The average total concentrations of Pb, Zn, and Cd in the soils were up to 28,438, 5,109, and 52 mg kg−1, respectively. A total of 68 plant species belonging to 60 genera of 37 families naturally colonizing the outcrop were recorded.
According to metal accumulation in the plants and translocation factor (TF), Silene viscidula was identified as potential hyperaccumulator of Pb, Zn, and Cd with mean shoot concentrations of 3,938 mg kg−1 of Pb (TF = 1.2), 11,155 mg kg−1 of Zn (TF = 1.8) and 236 mg kg−1 of Cd (TF = 1.1), respectively; S. gracilicanlis (Pb 3,617 mg kg−1, TF = 1.2) and Onosma paniculatum (Pb 1,837 mg kg−1, TF = 1.9) were potential Pb hyperaccumulators. Potentilla griffithii (Zn 8,748 mg kg−1, TF = 1.5) and Gentiana sp. (Zn 19,710 mg kg−1, TF = 2.7) were potential Zn hyperaccumulators. Lysimachia deltoides (Cd 212 mg kg−1, TF = 3.2) was a potential Cd hyperaccumulator. These new plant resources could be used to explore the mechanisms of Pb,
Zn and/or Cd hyperaccumulation, and the findings could be applied for the phytoremediation of Pb, Zn and/or Cd-contaminated
soils. 相似文献
15.
The 18O and 2H (HDO) compositions are summarized for sampled springs (n = 81) within the Elwha watershed (≈692 km2) on the northern Olympic Peninsula. Samples, collected during 2001–2009, of springs (n = 158), precipitation (n = 520), streams (n = 176), and firn (n = 3) assisted the determinations for meteoric composition of recharge waters. The local mean water line (LMWL) is defined
as δ2H = 8.2δ18O − 9.3 for the watershed. Recharge history is surmised from groundwater ages ranging from 5 ± 3 years (apparent 85Kr) to 9,490 ± 420 14C cal years BP. About 56% of the springs were recharged over the last 1,000 years while 13% of springs were recharged over
5,000 years ago. Spring HDO values fluctuate between −11.8 to −15.6‰ δ18O and −90.9 to −119.4‰ δ2H. Deuterium excess values predominate around 4–6‰. The HDO proxy records from springs suggest a pronounced paleoclimate shift
in air masses near 5,000 year BP on the Peninsula. 相似文献
16.
N. M. Ershaidat N. S. Abu-Jaber B. A. Al-Bataina J. M. Shobaki A. S. Jaradat 《Environmental Earth Sciences》2009,59(2):261-268
Herein, the relationship between soil radon behavior and groundwater recharge in the town of Hosha, a semi-arid area of Jordan
is explored. The annual rainfall average in this area is between 60–100 mm year−1. Soil radon concentration levels, using CR-39 detectors, have been measured at several depths. Nine sampling sites on a hill
slope, in the summer and winter 2006 were chosen. Other soil parameters such as moisture, soil type and porosity were also
measured. Correlation between the latter and the calculated effective diffusion coefficients, based on a linear approximation,
was done in order to explore water movement. A weak correlation between the soil radon concentration and water recharge in
this particular semi-arid area is observed. The results show that water recharge takes place vertically, i.e., water moves
downward and in one of the nine sampling sites this movement seems to be more rapid compared to the other sites. 相似文献
17.
Siruvani watershed with a surface area of 205.54 km2 (20,554 hectare), forming a part of the Western Ghats in Attapady valley, Kerala, was chosen for testing RUSLE methodology
in conjunction with remote sensing and GIS for soil loss prediction and identifying areas with high erosion potential. The
RUSLE factors (R, K, LS, C and P) were computed from local rainfall, topographic, soil classification and remote sensing data. This study proved that the
integration of soil erosion models with GIS and remote sensing is a simple and effective tool for mapping and quantifying
areas and rates of soil erosion for the development of better soil conservation plans. The resultant map of annual soil erosion
shows a maximum soil loss of 14.917 t h−1 year−1 and the computations suggest that about only 5.76% (1,184 hectares) of the area comes under the severe soil erosion zone
followed by the high-erosion zone (11.50% of the total area). The dominant high soil erosion areas are located in the central
and southern portion of the watershed and it is attributed to the shifting cultivation, and forest degradation along with
the combined effect of K, LS and C factor. The RUSLE model in combination with GIS and remote sensing techniques also enables the assessment of pixel based
soil erosion rate. 相似文献
18.
Observations and box model analysis of radon-222 in the atmospheric surface layer at L’Aquila,Italy: March 2009 case study 总被引:1,自引:1,他引:0
Giovanni Pitari Eleonora Coppari Natalia De Luca Piero Di Carlo 《Environmental Earth Sciences》2014,71(5):2353-2359
Two years of radon-222 observations collected at L’Aquila (Italy) in the atmospheric surface layer during 2004–2006 were analyzed in correlation with meteorological data and other atmospheric tracers. A box model was developed to better understand the mechanisms of diurnal and seasonal variability of the tracer and to indirectly assess the magnitude of the monthly averaged radon soil flux in the L’Aquila measurement site. The model was successfully validated with measurements, with a 0.8 average correlation coefficient between hourly values for the whole period of radon observations. Measurements taken during March 2009 were analyzed to find possible signs of perturbation due to the ongoing seismic activity that would have reached its peak on the 6 April 2009 destructive earthquake. Contrary to the professed (and unpublished) dramatic increases of radon activity unofficially announced to the inhabitants at that time, the study presented here shows that no radon activity increase took place in L’Aquila with respect to a previous ‘seismically unperturbed’ year (same month with similar meteorological conditions), but that an average 30 % decrease was experienced. This conclusion is reached from a direct comparison of observed data and also as a result of the previously validated radon box model constrained by actual meteorological data, from which an indirect estimate of a 17 % reduction of the radon soil flux is obtained. 相似文献
19.
The impact of acid rain on phosphorus leaching from a sandy loam calcareous soil of western Iran 总被引:1,自引:0,他引:1
Simulated acidic precipitation (1:1 equivalent basis H2SO4:HNO3) at pH values of 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 and 7.0 were conducted using column leaching to determine impacts of simulated
acid rain on phosphorus (P) leaching from a calcareous sandy loam soil over a 40-day period. Soil columns were irrigated every
day to make a total of 1,061 mm, equivalent to 3.5 years of rainfall (based on average annual rainfall). Leachates were collected
and analyzed for anions and cations. There was significant nonlinear correlation between the amount of P leached and the simulated
acid rain (R
2 = 0.61). Losses of P from the pH 2.5 and 7.0 treatments were 1.23, and 1.32 mg kg−1, respectively. The results showed that the amount of P leached from pH 4 (1.46 mg kg−1) and 5 treatments (1.52 mg−1 kg−1) were significantly larger than other treatments. Linear equation adequately described leaching of P in different treatments.
The slope (mg kg−1 day−1) in the linear equation was defined as the leaching rate and for the pH 2.5 was 0.0354, and 0.0382 and 0.0406 for pH 4.5
and 7.0, respectively. The geochemical code Visual MINTEQ was used to calculate saturation indices. Leaching of P in different
treatments was controlled by rate-limited dissolution of hydroxyapatite, β-tricalcium phosphate and to some extent octacalcium
phosphate. The results indicate that acid rain in calcareous sandy loam soils may pose a risk in terms of groundwater contamination
with P. 相似文献
20.
Ilhami Bayramin Mustafa Basaran Gunay Erpul Melda Dolarslan Mustafa R. Canga 《Environmental Geology》2009,56(8):1563-1575
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. 相似文献