This study was conducted to investigate the effects of long-term located fertilization on soil phosphorus,the changes of soil available phosphorus（ OlsenP）,the evolution of soil total phosphorus（ TP） and the ratio...This study was conducted to investigate the effects of long-term located fertilization on soil phosphorus,the changes of soil available phosphorus（ OlsenP）,the evolution of soil total phosphorus（ TP） and the ratio change of Olsen-P to TP（ PAC） by 33-year fertilization experiments in winter wheat-summer maize rotation system in Shandong fluvo-aquic soil. Eight treatments were designed as no fertilization（ CK）,nitrogen fertilizer（ N）,nitrogen and phosphate fertilizer（ NP）,nitrogen and potassium fertilizer（ NK）,phosphate and potassium fertilizer（ PK）,nitrogen-phosphate-potassium fertilizer（ NPK）,reduced NPK fertilizer（ N（15） PK）,and increased NPK fertilizer（ N（25） PK）. Meanwhile,eight organic fertilizer-added treatments were designed based on the application of inorganic fertilizer the same as the above ones. The results showed that TP,Olsen-P and PAC of treatments added with organic fertilizer were higher than those without organic fertilizer,and those of the treatments applied with phosphate fertilizer were higher than those of no phosphate fertilizer. With the increase of years,soil P pool decreased due to crop absorption,nutrient loss and morphological transformation and other causes under the treatments of without and only phosphate fertilizer,while remained stable under the treatments added with organic fertilizer. The PAC values were generally lower in fluvo-aquic soil,and it could be improved by the application of organic fertilizer. On the whole,the application of chemical phosphate fertilizer combined with organic fertilizer could improve the phosphorus content in soil and ensure the supply of phosphorus nutrition. This study would provide scientific basis for fertilization management and soil fertility in fluvo-aquic soil.展开更多
Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of d...Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.展开更多
The accurate assessment of the spatiotemporal changes in soil nutrients influenced by agricultural production provides the basis for development of management strategies to maintain soil fertility and balance soil nut...The accurate assessment of the spatiotemporal changes in soil nutrients influenced by agricultural production provides the basis for development of management strategies to maintain soil fertility and balance soil nutrients. In this paper, we combined spatial measurements from 2 157 soil samples and geostatistical analysis to assess the spatiotemporal changes in soil organic carbon （SOC）, total nitrogen （TN）, available phosphorus （AP） and available potassium content （AK） from the first soil survey （in the 1980s） to the second soil survey （in the 2000s） in the Taihu region of Jiangsu Province in China. The results showed that average soil nutrients in three soil types all exhibited the increased levels in the 2000s （except for AK in the yellow brown soil）. The standard deviation of soil nutrient contents increased （except for TN in the paddy soil）. Agricultural production in the 20 years led to increases in SOC, TN, AP and AK by 74, 82, 89 and 65%, respectively, of the Taihu areas analyzed. From the 1980s to 2000s all the nugget/sill ratios of soil nutrients indices were between 25 and 75% （except for AK in the yellow brown soil in the 2000s）, indicating moderate spatial dependence. The ratio of AP in the yellow brown soil in the 2000s was 88.74%, showing weak spatial dependence. The spatial correlation range values for SOC, TN, AP and AK in the 2000s all decreased. The main areas showing declines in SOC, TN and AP were in the northwest. For AK, the main region with declining levels was in the east and middle of western areas. Apparently, the increase in soil nutrients in the Taihu region can be mainly attributed to the large increase in fertilizer inputs, change in crop systems and enhanced residues management since the 1980s. Future emphasis should be placed on avoiding excess fertilizer inputs and balancing the effects of the fertilizers in soils.展开更多
Phosphatase plays an important role in the microbial liberation of phosphorus in soil systems. In this study, alkaline phosphatase activity （APA） was investigated from tundra ornithogenic soil profiles in Antarctica...Phosphatase plays an important role in the microbial liberation of phosphorus in soil systems. In this study, alkaline phosphatase activity （APA） was investigated from tundra ornithogenic soil profiles in Antarctica and Arctic. The organic carbon （TOC）, total nitrogen （TN）, and phosphorus fractions and pH were also analyzed in these soils. The correlation between APA and soil chemical properties is discussed. In almost all the soil profiles, APA showed the same variation patterns. The maximum APA appeared in the surface layers, and decreased with soil depth. The APA ranged from 1.00 ppm to 1 403.5 ppm with an average of approximately 408.3 ppm. The APA showed a significant positive correlation with TOC （r =0.70, p 〈0.001）, TN （r =0.43, p =0.002）, total phosphorus （r =0.39, p 〈0.05）and inorganic phosphorus （r =0.40, p =0.037）, indicating that they were predominant factors affecting APA in the polar tundra soils. In addition, APA showed a significant negative correlation with Cu and Zn concentrations in the soils, indicating that Cu and Zn may inhibit APA. Our results showed that APA could be used as an important indicator for soil fertility in polar tundra ecosystems.展开更多
The concentration of total nitrogen (TN), total phosphorus (TP) and organic material (OM) at sixty grid division in Lake Chaohu basin around the lake was studied, in order to investigate their spatial distribution cha...The concentration of total nitrogen (TN), total phosphorus (TP) and organic material (OM) at sixty grid division in Lake Chaohu basin around the lake was studied, in order to investigate their spatial distribution characteristics. The results showed that the average concentrations of TN, TP and OM were 1027 mg/kg, 483 mg/kg, 1.95%, and their concentrations ranged from 253 mg/kg to 2273 mg/kg, 223 mg/kg to 1173 mg/kg and 0.291% to 5.48%, respectively. The high concentration areas were located at the basins of Tuogao river and Zhao river while the low concentration areas were located at basins of Pai river, Nanfei river and Dianpu river. The concentrations of TN and OM were higher in East part than in West part. The spatial distribution of TN, TP and OM concentrations of the surface soil showed inconsistent with those of the water quality of the inflow rivers and the lake and the TN and TP of lake sediment studied.展开更多
Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory e...Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory environment as the reported levels may not correlate well with environmental risk. In order to accurately assess potential P runoff and leaching, as well as plant uptake, we must be able to measure organic P mineralized by the biotic community in the soil. Soils with varying rates of biosolid application were evaluated for mineralized organic P during a 112-day incubation using the difference between P measured using a rapid-flow analyzer (RFA) and an axial flow Varian ICP-OES. An increase in the P mineralized from the treated soils was observed from analysis with the Varian ICP-OES, but not with the RFA. These results confirm that even though organic P concentrations have increased due to increasing biosolid application, traditional soil testing using an RFA for detection, would not accurately portray P concentration and potential P loading from treated soils.展开更多
Soil nutrient availability and their spatial distributions are strongly related to land use and landscape morphology.This study aims to address the knowledge gap regarding the interaction between these factors and the...Soil nutrient availability and their spatial distributions are strongly related to land use and landscape morphology.This study aims to address the knowledge gap regarding the interaction between these factors and the underlying mechanisms.We selected five land uses(grassland with Artemisia gmelinii,woodland with Robinia pseudoacacia,shrubland with Caragana korshinskii and Hippophae rhamnoides,and apple orchard with Malus pumila)and nine slope positions across hillslopes in the Loess Plateau,China,to investigate their combined effects on the contents and stocks of soil organic carbon(SOC),total nitrogen(TN)and total phosphorus(TP).Parametric and non-parametric statistical tests were conducted to determine the significant differences in the means or the medians of the soil nutrient variables.Results showed that the SOC and TN contents of shrubland with Caragana korshinskii were statistically significantly greater than those of the grassland(p<0.05).SOC and TN contents generally decreased from the upper slope to the middle slope,and to the foot slope for the grassland,woodland and shrublands,and on the contrary,an increasing trend from the upper slope,to the middle slope,and to the foot slope was identified for the apple orchard.This study highlights that land use,slope position and their interaction have significant effects on the spatial distributions of soil nutrients.It provides essential empirical evidence for the identification of the optimal vegetation type and slope positions in land management and vegetation restoration activities.展开更多
In this paper, the bottom of the Dianshan Lake was selected as a test sample. The dynamic release of contaminated sediments into the overlying water column was experimentally investigated in an open water channel unde...In this paper, the bottom of the Dianshan Lake was selected as a test sample. The dynamic release of contaminated sediments into the overlying water column was experimentally investigated in an open water channel under different hydrodynamic conditions. The experimental results indicate that the Total Phosphorus （TP） release process can be divided into three stages： rapid release, slow release and equilibration release. In the initial release stage the measured TP concentration changes along the depth. The TP concentration near the sediment-water interface is higher than that near the water surface, but the TP concentration becomes uniform along the depth after 3 h. The dynamic release of re-suspension sediment pollutants is about 6 times higher than the static release of sediment-water interface. There are three main types of release mechanism： diffusion release, re-suspended pore water mixing release and re-suspended particles desorbing release.展开更多
Abstract： The water quality of Dianshan Lake in Shanghai Municipality, China, is impacted by nutrient losses from agricultural lands around the lake. In this study, nine types of agricultural land use were monitored ...Abstract： The water quality of Dianshan Lake in Shanghai Municipality, China, is impacted by nutrient losses from agricultural lands around the lake. In this study, nine types of agricultural land use were monitored in 2010 and 2011, and a correlation analysis between nutrient losses from agricultural non-point sources （NPS） and nutrient stocks in the lake was conducted over monthly and seasonal time periods. The results indicate that the monthly average concentration of total nitrogen （TN） ranged from 1.41 to 7.34 mg/L in 2010 and from 1.52 to 5.90 mg/L in 2011, while the monthly average concentration of total phosphorous （TP） ranged from 0.11 to 0.26 mg/L in 2010 and from 0.13 to 0.30 mg/L in 2011. The annual loss of TN from agricultural NPS was 195.55 tons in 2010 and 208.40 tons in 2011. The cultivation of water oat made the largest contribution to the loss of TN. The annual loss of TP was 44.58 tons in 2010 and 48.12 tons in 2011, and multi-vegetable cultivation made the largest contribution to the loss of TP. The results of correlation analysis show that the monthly stocks of TN and TP in the lake have a positive correlation with the monthly losses of TN and TP from agricultural NPS. According to the seasonal data, the stocks of TN and TP in the lake both have a much stronger correlation with the losses of TN and TP from agricultural NPS in summer than in other seasons. Agricultural NPS pollution control should be the main focus for the water resource conservation in this area.展开更多
Water pollution has become a serious worldwide problem, especially for lakes with a large stagnant water body. Is it possible to develop high quality water from a heavily polluted river system quickly? This paper intr...Water pollution has become a serious worldwide problem, especially for lakes with a large stagnant water body. Is it possible to develop high quality water from a heavily polluted river system quickly? This paper introduces an innovative technology termed SPP (separation, prevention and protection) for this purpose. Its feasibility is preliminarily examined using Dianshan Lake in Shang- hai as an example. Due to its very high population density and intensive industrial activities, almost all waterways in Shanghai are heavily polluted, including the lake. However, the data analysis shows that clean water always appears after heavy rains, especially in its suburban areas. Once the 1<sup>st</sup> flush water is discharged to downstream, high-quality water can be developed from its Dianshan Lake by using the SPP strategy. The Vollenweider model is used to analyze SPP’s feasibility. The results show that the water quality of the Dianshan Lake can be remediated as a drinking water source within 120 days if the SPP strategy is applied. It is suggested that Jinze reservoir’s water should come from the Dianshan lake, not Taipu River to improve the quality of water supply. It is highly recommended for other cities in the world to consider the SPP technology if needed.展开更多
Background The rock cut slope(RCS)could cause damage to regional ecological functions and landscapes and requires recovery.Biological soil crusts(BSCs)are pioneer and dominant colonizers during the initial recovery st...Background The rock cut slope(RCS)could cause damage to regional ecological functions and landscapes and requires recovery.Biological soil crusts(BSCs)are pioneer and dominant colonizers during the initial recovery stage.To accelerate the natural recovery of RCS,the development process and influencing agents of BSC should be revealed.Thus,the area index of crevices(IR),BSC coverage(COV)and biomass(BM),soil weight(SW),and major soil nutrients[organic carbon(OC),total nitrogen(TN)and total phosphorus(TP)]content,collected from 164 quadrats on 13 RCSs in the mountainous area of west Sichuan Province,China,were measured,to explore the effect of crevice of RCS on BSC development.Results Soil OC,TN and TP on RCSs ranged from 18.61 to 123.03 g kg^(-1),0.96 to 6.02 g kg^(-1)and 0.52 to 2.46 g kg^(-1),respectively,and were approximately to or higher than those on natural slopes.The OC,TN and TP contents in soils elevated unsystematically with recovery time of RCSs.BSCs on RCS distributed along crevices generally and firstly.During the first 13 years of natural recovery,COV,BM and SW ranged from 6.5 to 28.2%,14.43 to 67.25 g m^(-2),and 127.69 to 1277.74 g m^(-2),respectively.COV,BM and SW increased linearly with IR on RCSs.The positive correlation between COV and BM and IR was insignificantly impacted by bedrock,slope aspect and altitude within the recovery time less than 13 years.COV and BM on RCSs increased significantly when the recovery time is more than 27 years.Conclusions Crevice on RCSs could be a major environmental factor which is conducive to BSC development and soil accumulation through creating a space for water and soil particle.Furthermore,with the increase of recovery time of RCSs,BSCs may grow and reach a stable state with the promotion of soil nutrients,plant growth and microbial activity.These results provide a development process of BSC that from inside to outside the crevices on RCSs.In the areas with stable rock strata and a low risk of geological disasters,purposeful improvement in crevice density on RCS may effectively accelerate BSC development.展开更多
Nutrient loadings from upstream watersheds can have significant impacts on the water quality of receiving water bodies.Usually,a major river is selected as the target for water quality studies,and the impact of minor ...Nutrient loadings from upstream watersheds can have significant impacts on the water quality of receiving water bodies.Usually,a major river is selected as the target for water quality studies,and the impact of minor rivers tends to be ignored.It is very important to evaluate whether the impact of small rivers on the downstream water quality is negligible.River water sampling and discharge modeling using SWAT were used to analyze the contribution of small rivers to water quality in a receiving lake.From this analysis,it was determined that the inflowing total nitrogen(TN)and total phosphorus(TP)concentrations from all target rivers exceeded the lake water environmental standards set by the Ministry of the Environment.The contribution of suspended sediment(SS)and TN loads from small rivers did not vary markedly compared with their relative discharge contributions to the lake,at approximately 20%.However,the impact on TP loads to the lake from small rivers was 9.1%higher than their relative flow contributions,accounting for 28.2% of the TP loading.Thus,there is a potential to underestimate the impact of ungauged small rivers if only the major river is selected to evaluate the downstream lake water quality.展开更多
基金Supported by Sub-project of National Key Research and Development Program of China in the 13thFive-Year Plan of China(2016YFD0300804-5)Special Fund for Agro-scientific Research in the Public Interest(201503106)Special Construction Project of"Overseas Taishan Scholar"
文摘This study was conducted to investigate the effects of long-term located fertilization on soil phosphorus,the changes of soil available phosphorus（ OlsenP）,the evolution of soil total phosphorus（ TP） and the ratio change of Olsen-P to TP（ PAC） by 33-year fertilization experiments in winter wheat-summer maize rotation system in Shandong fluvo-aquic soil. Eight treatments were designed as no fertilization（ CK）,nitrogen fertilizer（ N）,nitrogen and phosphate fertilizer（ NP）,nitrogen and potassium fertilizer（ NK）,phosphate and potassium fertilizer（ PK）,nitrogen-phosphate-potassium fertilizer（ NPK）,reduced NPK fertilizer（ N（15） PK）,and increased NPK fertilizer（ N（25） PK）. Meanwhile,eight organic fertilizer-added treatments were designed based on the application of inorganic fertilizer the same as the above ones. The results showed that TP,Olsen-P and PAC of treatments added with organic fertilizer were higher than those without organic fertilizer,and those of the treatments applied with phosphate fertilizer were higher than those of no phosphate fertilizer. With the increase of years,soil P pool decreased due to crop absorption,nutrient loss and morphological transformation and other causes under the treatments of without and only phosphate fertilizer,while remained stable under the treatments added with organic fertilizer. The PAC values were generally lower in fluvo-aquic soil,and it could be improved by the application of organic fertilizer. On the whole,the application of chemical phosphate fertilizer combined with organic fertilizer could improve the phosphorus content in soil and ensure the supply of phosphorus nutrition. This study would provide scientific basis for fertilization management and soil fertility in fluvo-aquic soil.
基金supported by the National Natural Science Foundation of China (31570634)the Project of Xinjiang Agricultural Vocational College (XJNZYKJ201712)
文摘Forest recovery may be influenced by several factors, of which fire is the most critical.However, moderate-and long-term effects of fire on forest recovery are less researched in Northwest China.Thus, the effects of different forest recovery time after fire(1917(served as the control), 1974, 1983 and 1995) and fire severities(low, moderate and high) on larch(Larix sibirica Ledeb.) forest were investigated in the Kanas National Nature Reserve(KNNR), Northwest China in 2017.This paper analyzed post-fire changes in stand density, total basal area(TBA), litter mass, soil organic carbon(SOC) and soil nutrients(total nitrogen, total phosphorus and total potassium) with one-way analyses of variance.Results indicate that litter mass, TBA, SOC and soil nutrients increased with increasing recovery time after fire and decreasing fire severity, while the stand density showed an opposite response.The effects of fire disturbance on SOC and soil nutrients decreased with increasing soil depth.Moreover, we found that the time of more than 43 a is needed to recover the litter mass, TBA, SOC and soil nutrients to the pre-fire level.In conclusion, high-severity fire caused the greatest variations in stand structure and soil of larch forest, and low-severity fire was more advantageous for post-fire forest stand structure and soil recovery in the KNNR.Therefore, low-severity fire can be an efficient management mean through reducing the accumulation of forest floor fuel of post-fire forests in the KNNR, Northwest China.
基金the funding support from the New Century Exceptional Talent Program of China(NCET-08-0797)the National High-Tech Research and Development Program of China(2013AA100404)+2 种基金the National Basic Research Program of China(2009CB118608)the CSIRO-Chinese Ministry of Education(MOE)PhD Research Fellowship Programthe Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘The accurate assessment of the spatiotemporal changes in soil nutrients influenced by agricultural production provides the basis for development of management strategies to maintain soil fertility and balance soil nutrients. In this paper, we combined spatial measurements from 2 157 soil samples and geostatistical analysis to assess the spatiotemporal changes in soil organic carbon （SOC）, total nitrogen （TN）, available phosphorus （AP） and available potassium content （AK） from the first soil survey （in the 1980s） to the second soil survey （in the 2000s） in the Taihu region of Jiangsu Province in China. The results showed that average soil nutrients in three soil types all exhibited the increased levels in the 2000s （except for AK in the yellow brown soil）. The standard deviation of soil nutrient contents increased （except for TN in the paddy soil）. Agricultural production in the 20 years led to increases in SOC, TN, AP and AK by 74, 82, 89 and 65%, respectively, of the Taihu areas analyzed. From the 1980s to 2000s all the nugget/sill ratios of soil nutrients indices were between 25 and 75% （except for AK in the yellow brown soil in the 2000s）, indicating moderate spatial dependence. The ratio of AP in the yellow brown soil in the 2000s was 88.74%, showing weak spatial dependence. The spatial correlation range values for SOC, TN, AP and AK in the 2000s all decreased. The main areas showing declines in SOC, TN and AP were in the northwest. For AK, the main region with declining levels was in the east and middle of western areas. Apparently, the increase in soil nutrients in the Taihu region can be mainly attributed to the large increase in fertilizer inputs, change in crop systems and enhanced residues management since the 1980s. Future emphasis should be placed on avoiding excess fertilizer inputs and balancing the effects of the fertilizers in soils.
基金supported by the National Natural Science Foundation of China (Grant no.41076124)the KnowledgeInnovation Project of Chinese Academy of Sciences (Grant no.KZCX2-YW-QN510)+1 种基金the Fundamental Research Funds for the Central Universities(Grant no. WK2060190007)the Open Research Foundation of SOA Key Laboratory for Polar Sciences (Grant no.KP2008004)
文摘Phosphatase plays an important role in the microbial liberation of phosphorus in soil systems. In this study, alkaline phosphatase activity （APA） was investigated from tundra ornithogenic soil profiles in Antarctica and Arctic. The organic carbon （TOC）, total nitrogen （TN）, and phosphorus fractions and pH were also analyzed in these soils. The correlation between APA and soil chemical properties is discussed. In almost all the soil profiles, APA showed the same variation patterns. The maximum APA appeared in the surface layers, and decreased with soil depth. The APA ranged from 1.00 ppm to 1 403.5 ppm with an average of approximately 408.3 ppm. The APA showed a significant positive correlation with TOC （r =0.70, p 〈0.001）, TN （r =0.43, p =0.002）, total phosphorus （r =0.39, p 〈0.05）and inorganic phosphorus （r =0.40, p =0.037）, indicating that they were predominant factors affecting APA in the polar tundra soils. In addition, APA showed a significant negative correlation with Cu and Zn concentrations in the soils, indicating that Cu and Zn may inhibit APA. Our results showed that APA could be used as an important indicator for soil fertility in polar tundra ecosystems.
文摘The concentration of total nitrogen (TN), total phosphorus (TP) and organic material (OM) at sixty grid division in Lake Chaohu basin around the lake was studied, in order to investigate their spatial distribution characteristics. The results showed that the average concentrations of TN, TP and OM were 1027 mg/kg, 483 mg/kg, 1.95%, and their concentrations ranged from 253 mg/kg to 2273 mg/kg, 223 mg/kg to 1173 mg/kg and 0.291% to 5.48%, respectively. The high concentration areas were located at the basins of Tuogao river and Zhao river while the low concentration areas were located at basins of Pai river, Nanfei river and Dianpu river. The concentrations of TN and OM were higher in East part than in West part. The spatial distribution of TN, TP and OM concentrations of the surface soil showed inconsistent with those of the water quality of the inflow rivers and the lake and the TN and TP of lake sediment studied.
文摘Phosphorus loading and measurement is of concern on lands where biosolids have been applied. Traditional soil testing for plant-available P may be inadequate for the accurate assessment of P loadings in a regulatory environment as the reported levels may not correlate well with environmental risk. In order to accurately assess potential P runoff and leaching, as well as plant uptake, we must be able to measure organic P mineralized by the biotic community in the soil. Soils with varying rates of biosolid application were evaluated for mineralized organic P during a 112-day incubation using the difference between P measured using a rapid-flow analyzer (RFA) and an axial flow Varian ICP-OES. An increase in the P mineralized from the treated soils was observed from analysis with the Varian ICP-OES, but not with the RFA. These results confirm that even though organic P concentrations have increased due to increasing biosolid application, traditional soil testing using an RFA for detection, would not accurately portray P concentration and potential P loading from treated soils.
基金The authors wish to thank all the technicians involved in field and laboratory work.This work was supported by the National Natural Science Foundation of China Project(grants 41991235,42007052)the Fundamental Research Funds for the Central Universities.
文摘Soil nutrient availability and their spatial distributions are strongly related to land use and landscape morphology.This study aims to address the knowledge gap regarding the interaction between these factors and the underlying mechanisms.We selected five land uses(grassland with Artemisia gmelinii,woodland with Robinia pseudoacacia,shrubland with Caragana korshinskii and Hippophae rhamnoides,and apple orchard with Malus pumila)and nine slope positions across hillslopes in the Loess Plateau,China,to investigate their combined effects on the contents and stocks of soil organic carbon(SOC),total nitrogen(TN)and total phosphorus(TP).Parametric and non-parametric statistical tests were conducted to determine the significant differences in the means or the medians of the soil nutrient variables.Results showed that the SOC and TN contents of shrubland with Caragana korshinskii were statistically significantly greater than those of the grassland(p<0.05).SOC and TN contents generally decreased from the upper slope to the middle slope,and to the foot slope for the grassland,woodland and shrublands,and on the contrary,an increasing trend from the upper slope,to the middle slope,and to the foot slope was identified for the apple orchard.This study highlights that land use,slope position and their interaction have significant effects on the spatial distributions of soil nutrients.It provides essential empirical evidence for the identification of the optimal vegetation type and slope positions in land management and vegetation restoration activities.
基金the National Natural Science Foundation of China (Grant Nos. 10972134, 11032007)the Shanghai Program for Innovative Research Team in Universities
文摘In this paper, the bottom of the Dianshan Lake was selected as a test sample. The dynamic release of contaminated sediments into the overlying water column was experimentally investigated in an open water channel under different hydrodynamic conditions. The experimental results indicate that the Total Phosphorus （TP） release process can be divided into three stages： rapid release, slow release and equilibration release. In the initial release stage the measured TP concentration changes along the depth. The TP concentration near the sediment-water interface is higher than that near the water surface, but the TP concentration becomes uniform along the depth after 3 h. The dynamic release of re-suspension sediment pollutants is about 6 times higher than the static release of sediment-water interface. There are three main types of release mechanism： diffusion release, re-suspended pore water mixing release and re-suspended particles desorbing release.
基金supported by the Project of the Shanghai Science and Technology Committee(Grants No.08DZ1203200 and 08DZ1203205)
文摘Abstract： The water quality of Dianshan Lake in Shanghai Municipality, China, is impacted by nutrient losses from agricultural lands around the lake. In this study, nine types of agricultural land use were monitored in 2010 and 2011, and a correlation analysis between nutrient losses from agricultural non-point sources （NPS） and nutrient stocks in the lake was conducted over monthly and seasonal time periods. The results indicate that the monthly average concentration of total nitrogen （TN） ranged from 1.41 to 7.34 mg/L in 2010 and from 1.52 to 5.90 mg/L in 2011, while the monthly average concentration of total phosphorous （TP） ranged from 0.11 to 0.26 mg/L in 2010 and from 0.13 to 0.30 mg/L in 2011. The annual loss of TN from agricultural NPS was 195.55 tons in 2010 and 208.40 tons in 2011. The cultivation of water oat made the largest contribution to the loss of TN. The annual loss of TP was 44.58 tons in 2010 and 48.12 tons in 2011, and multi-vegetable cultivation made the largest contribution to the loss of TP. The results of correlation analysis show that the monthly stocks of TN and TP in the lake have a positive correlation with the monthly losses of TN and TP from agricultural NPS. According to the seasonal data, the stocks of TN and TP in the lake both have a much stronger correlation with the losses of TN and TP from agricultural NPS in summer than in other seasons. Agricultural NPS pollution control should be the main focus for the water resource conservation in this area.
文摘Water pollution has become a serious worldwide problem, especially for lakes with a large stagnant water body. Is it possible to develop high quality water from a heavily polluted river system quickly? This paper introduces an innovative technology termed SPP (separation, prevention and protection) for this purpose. Its feasibility is preliminarily examined using Dianshan Lake in Shang- hai as an example. Due to its very high population density and intensive industrial activities, almost all waterways in Shanghai are heavily polluted, including the lake. However, the data analysis shows that clean water always appears after heavy rains, especially in its suburban areas. Once the 1<sup>st</sup> flush water is discharged to downstream, high-quality water can be developed from its Dianshan Lake by using the SPP strategy. The Vollenweider model is used to analyze SPP’s feasibility. The results show that the water quality of the Dianshan Lake can be remediated as a drinking water source within 120 days if the SPP strategy is applied. It is suggested that Jinze reservoir’s water should come from the Dianshan lake, not Taipu River to improve the quality of water supply. It is highly recommended for other cities in the world to consider the SPP technology if needed.
基金supported by the National Key Research and Development Programme of China(Grant No.2017YFC0504902)the Project of Assessment on Post-quake Ecosystem and Environment Recovery in Jiuzhaigou(Grant No.5132202020000046).
文摘Background The rock cut slope(RCS)could cause damage to regional ecological functions and landscapes and requires recovery.Biological soil crusts(BSCs)are pioneer and dominant colonizers during the initial recovery stage.To accelerate the natural recovery of RCS,the development process and influencing agents of BSC should be revealed.Thus,the area index of crevices(IR),BSC coverage(COV)and biomass(BM),soil weight(SW),and major soil nutrients[organic carbon(OC),total nitrogen(TN)and total phosphorus(TP)]content,collected from 164 quadrats on 13 RCSs in the mountainous area of west Sichuan Province,China,were measured,to explore the effect of crevice of RCS on BSC development.Results Soil OC,TN and TP on RCSs ranged from 18.61 to 123.03 g kg^(-1),0.96 to 6.02 g kg^(-1)and 0.52 to 2.46 g kg^(-1),respectively,and were approximately to or higher than those on natural slopes.The OC,TN and TP contents in soils elevated unsystematically with recovery time of RCSs.BSCs on RCS distributed along crevices generally and firstly.During the first 13 years of natural recovery,COV,BM and SW ranged from 6.5 to 28.2%,14.43 to 67.25 g m^(-2),and 127.69 to 1277.74 g m^(-2),respectively.COV,BM and SW increased linearly with IR on RCSs.The positive correlation between COV and BM and IR was insignificantly impacted by bedrock,slope aspect and altitude within the recovery time less than 13 years.COV and BM on RCSs increased significantly when the recovery time is more than 27 years.Conclusions Crevice on RCSs could be a major environmental factor which is conducive to BSC development and soil accumulation through creating a space for water and soil particle.Furthermore,with the increase of recovery time of RCSs,BSCs may grow and reach a stable state with the promotion of soil nutrients,plant growth and microbial activity.These results provide a development process of BSC that from inside to outside the crevices on RCSs.In the areas with stable rock strata and a low risk of geological disasters,purposeful improvement in crevice density on RCS may effectively accelerate BSC development.
基金This study was partially supported by two grants-in-aid for scientific research:KAKENHI:24780234 and 25281054.
文摘Nutrient loadings from upstream watersheds can have significant impacts on the water quality of receiving water bodies.Usually,a major river is selected as the target for water quality studies,and the impact of minor rivers tends to be ignored.It is very important to evaluate whether the impact of small rivers on the downstream water quality is negligible.River water sampling and discharge modeling using SWAT were used to analyze the contribution of small rivers to water quality in a receiving lake.From this analysis,it was determined that the inflowing total nitrogen(TN)and total phosphorus(TP)concentrations from all target rivers exceeded the lake water environmental standards set by the Ministry of the Environment.The contribution of suspended sediment(SS)and TN loads from small rivers did not vary markedly compared with their relative discharge contributions to the lake,at approximately 20%.However,the impact on TP loads to the lake from small rivers was 9.1%higher than their relative flow contributions,accounting for 28.2% of the TP loading.Thus,there is a potential to underestimate the impact of ungauged small rivers if only the major river is selected to evaluate the downstream lake water quality.
