[Objective] The research aimed to study change law of phosphorus content of soil in karst rocky desertification region(KRD) during eco-restoration process such as Northwest Guangxi Province.[Method] The soil samples w...[Objective] The research aimed to study change law of phosphorus content of soil in karst rocky desertification region(KRD) during eco-restoration process such as Northwest Guangxi Province.[Method] The soil samples were collected from typical KRD in Pingguo County and Yizhou City.The determining quotas of different soil samples such as soil total phosphorus content and available phosphorus content were detected,in addition the soil total phosphorus content,available phosphorus content, urease activity, catalase activity and organic matter content in different soil samples were analyzed comparatively.[Result] Aspect,vegetation type and recovery time generated obviously influences on phosphorus contents in different soil samples.The concrete influence order was listed as follow: phosphorus content in soil of south slope was higher than that in soil of north slope;phosphorus content in soil where Zenia insignis Chun was planted was higher than that in soil of closed forest and that of soil where Dendrocalamus minor Var. amoen was planted,additionally,phosphorus increased with recovery time. Urease activity could be used as a monitoring index of soil fertility because it is related to the change of phosphorus content.[Conclusion] The soil of karst rocky desertification region in Northwest Guangxi Province could be recovered gradually if excessive human disturbance was stopped.If proper natural method of recovery promoted by human was taken,the recovery would reach a better result.展开更多
[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a r...[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a research area through previous investigation, and the polluted river was cleaned and restored by 3 methods, i.e. artificial wetland, floating island type wetland and purification floating island. [Resuit] Floating plants （Hydrocotyle verticillata and Myriophyllum spicatum） showed better restoration effects than emergent aquatic plants （Iris wilsonii, Arundo donax, reed, water-cultured Ilex chinensis and Lythrum salicaria）. The two types of plants showed the removal rates of total nitrogen of 37.9% and 34.1%, respectively, the removal rates of total phosphorous of 80.1% and 73.5%, respectively, the removal rates of COD of 81.1% and 74.8%, respectively, the removal rates of ammonia nitrogen of 80.6% and 85.9%, respectively, and the removal rates of SS of 59.1% and 77.3%, respectively. Among the purification floating island, the artificial wetland and the floating island type wetland, the purification floating land restoration technique exhibited the best removal effect, with the removal rates of 87.6%, 71.3%, 87.6%, 97.5% and 81.8% for total nitrogen, total phosphorous, ammonia nitrogen COD and SS, respectively. The nitrification and denitdfication rates of bottom mud and water samples in the engineering segment were remarkably higher than those in the reference segment, by 15.4% and 21.1%, respectively. The nitrification and denitrification rates of bottom mud in the engineering segment and the non-engineering segment were higher than those of water samples by 26.9% and 31.8%, respectively. Restoration plants showed better removal effects of total phosphorous, total nitrogen, COD and SS under aeration condition than noeration condition. [Conclusion] The purification floating island has a significant restoration effect on urban polluted river.展开更多
Slope eco-restoration has always received extensive attention as a positive way to reverse ecosystem deterioration derived from human interventions.A simplified frameworkis proposed to undertake a quantitative evaluat...Slope eco-restoration has always received extensive attention as a positive way to reverse ecosystem deterioration derived from human interventions.A simplified frameworkis proposed to undertake a quantitative evaluation of the engineering disturbed slope eco-restoration success in the alpine region,southeast Qinghai-Tibet Plateau.The Daguhydropower project that disturbsthe local ecosystem to some certainwas selected as the study area.Since August 2018,six types of slope(soil,rock,soil-rock,spoil,construction site,hardened)were served as the demonstration test for the slope eco-restoration with two years monitoring in the study area.Meanwhile,the topography,erosion,soil quality,and vegetation were selected as assessment indicators of the methodology.Finally,combined with the weighting method and the expert panel,the slope eco-restoration quality index(SERQI)was established and applied in the six slopes.The results suggested that the frost-resistant ecological substrate performed well in alpine region,and the SERQI value is in accordance with the actual monitoring level with spoil slope>soil slope>construction site slope>soil-rock slope>rock slope>hardened slope.The proposed framework could support slope eco-restoration practitioners for making a more objective and quantitative evaluation easily for the post-implementation restoration.展开更多
Changes in river cross-section morphology have decisive influences on the flood discharge and sand transport capacity of rivers;thus,these changes strongly reflect the vitality of a river.In this paper,based on the ri...Changes in river cross-section morphology have decisive influences on the flood discharge and sand transport capacity of rivers;thus,these changes strongly reflect the vitality of a river.In this paper,based on the river cross-section and water and sediment data of two different periods(1974−1987 and 2007−2021),the trend analysis,change-point analysis and sediment rating curve method were used to analyze the change process of river cross-section morphology and its response to streamflow and sediment changes in the main river stream of the Yellow River at the Longmen hydrological station.From 1974 to 1987(except in 1977),the riverbed experi-enced siltation,and the riverbed elevation rose.Conversely,from 2007 to 2021,the riverbed experienced scouring,and the riverbed el-evation gradually decreased.The cross-section shape changed from rectangular to U-shaped(deeper on the right side)at the Longmen cross-section.The changes in streamflow and sediment processes significantly impacted the evolution of river cross-section.Stream-flow(P<0.05),sediment discharge(P<0.01),and the sediment load coefficients(P<0.01)decreased significantly.The relationship between the water depth and sediment load coefficients followed a power function.The decreasing trend in sediment discharge was sig-nificantly stronger than that in streamflow.Suspended sediment particles tended to become finer.The sediment rating curve indicates that the sediment supply from upstream decreased while the erosive power in the river channel increased,leading to a gradual decline in riverbed elevation at the Longmen cross-section from 2007 to 2021.These findings help us better understand the impacts of ecological restoration on changes in river streamflow and sediment during river evolution.展开更多
The Jamaica Bay ecosystem is a dichotomy. It encompasses more than 12,000 acres of coastal estuarine marshes and an ecological diversity rivaling any coastal environment in the world. It is considerably altered, and i...The Jamaica Bay ecosystem is a dichotomy. It encompasses more than 12,000 acres of coastal estuarine marshes and an ecological diversity rivaling any coastal environment in the world. It is considerably altered, and is affected by a variety of ecological insults directly related to the fact that more than 14 million people live in its vicinity. Environmental protection institutions responded to the challenge of protecting the bay, surrounding wetlands and recreational benefits by addressing the increasing load of contaminants into the ecosystem. Billions of dollars have been spent during the past five decades on restoration attempts, including upgrading wastewater treatment plantsand the closure of three major sanitary landfills. Even with the curtailment of untreated wastewater release and ending periodic dredging and filling programs, all activities that are necessary processes in maintaining an urban harbor, the Jamaica Bay ecosystem has reached a point where many believe it to be unrecoverable, requiring massive infusions of restoration dollars. This categorization has been perpetuated based on questionable data （the ＂myths＂） that, when investigated in rigorous scientific detail, prove to be unsubstantiated. In this paper, the origin of these myths and the scientific investigation that dispel them are discussed.展开更多
Numerous hypotheses and conceptional models dealing with the grassland deserti-fication or degradation processes recognize that the invasion of shrubs in grasslands is the most striking feature of the variation of veg...Numerous hypotheses and conceptional models dealing with the grassland deserti-fication or degradation processes recognize that the invasion of shrubs in grasslands is the most striking feature of the variation of vegetation patterns in the grassland degradation or desertifica-tion processes in arid and semiarid regions. This is because the invasion of shrubs in grasslands increases the heterogeneity of the temporal and spatial distribution of primary vegetation and soil resources. As a result, the biological processes of the soil-vegetation system are increasingly concentrated in the “fertile islands” under shrub canopies, and the soil between shrubs gradually turns into bare area or moving sand under the influences of prolonged wind and water erosion. Most of relative researches support this bio-ecological interpretation for the degraded process of grassland. However, as viewed from the other aspect, the shrub vegetation distributed in patches also serves as the “trigger spots” for the grassland restoration or desertification reversion, and this has been demonstrated by the practices of combating desertification in China. Nearly 50 years of succession of artificial sand-binding vegetation in the Shapotou area and the regional restoration of eco-environment are the theoretical verification and successful example for the desertification reversion. The establishment of artificial vegetation in the region began with the installation of sand fences and planting xerophytic shrubs relying on less than 200 mm of annual precipitation under the non-irrigation condition, this made the moving sand, an originally uni-formly distributed soil resource, occur the variation of spatial heterogeneity. Through the redis-tribution of precipitation and dustfall by the canopy of xerophytic shrubs, litter accumulation and cryptogamic crust development, soil-forming processes under shrub canopies were accelerated; in the meantime, it also created a favorable condition for the invasion and colonization of annual and perennial plant species. However, with the depletion of soil moisture in the deep layer in the sand stabilization area the coverage of shrubs in the sand-binding vegetation lowered from the highest value of 33% to 6%, the dominant position and leading effect of shrubs in the communi-ties were weakened, furthermore they were gradually taken out from the vegetation composition. This correspondingly weakened the spatial heterogeneity of soil resource distribution. The propagation of numerous cryptogams on fixed sand surface and the colonization of annual and perennial plant species promoted the succession and restoration of the vegetation towards herb-dominated vegetation, which are similar to the primary vegetation types of the adjacent steppified desert and desert steppe. This paper, taking nearly 50 years of succession of sand-binding vegetation in the Shapotou region as an example and using the geostatistical method, puts forward and explains the conceptional model of vegetation restoration or desertifi-cation reversion of grassland in arid zones.展开更多
A modularized and air adjustable constructed submerged plant bed(CSPB)which can be used to restore the eutrophic water is introduced in this paper.This plant bed helps hydrophyte grow under poor conditions such as fre...A modularized and air adjustable constructed submerged plant bed(CSPB)which can be used to restore the eutrophic water is introduced in this paper.This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth,impaired water transparency,algae bloom and substantial duckweed in summer,which are not naturally suitable for growing hydrophyte.This pilot study in Waihuan River of Tianjin,China,revealed that reduction of Chemical Oxygen Demand(COD),Total Nitrogen(TN)and Total Phosphorus(TP)by the use of CSPB could be reached 30%-35%,35%-40%,30%-40%respectively in the growing season(from March to October)and 5%-10%,5%-15%,7%-20%respectively in the winter(from November to February)when the detention time was 6 d.The relationships between the concentration of COD,TN,TP and the detention time fit the first-order kinetic equation well and the coefficients of determination(R^(2))were all above 0.9.The attenuation coefficients k of the kinetic equation were a function of the water temperature.When the water temperature was quite low or quite high,k was not significantly changed with increasing or decreasing water temperature.While when the temperature was in a moderate range,an increase or decrease of water temperature would lead to a rapid increase or decrease in k.展开更多
文摘[Objective] The research aimed to study change law of phosphorus content of soil in karst rocky desertification region(KRD) during eco-restoration process such as Northwest Guangxi Province.[Method] The soil samples were collected from typical KRD in Pingguo County and Yizhou City.The determining quotas of different soil samples such as soil total phosphorus content and available phosphorus content were detected,in addition the soil total phosphorus content,available phosphorus content, urease activity, catalase activity and organic matter content in different soil samples were analyzed comparatively.[Result] Aspect,vegetation type and recovery time generated obviously influences on phosphorus contents in different soil samples.The concrete influence order was listed as follow: phosphorus content in soil of south slope was higher than that in soil of north slope;phosphorus content in soil where Zenia insignis Chun was planted was higher than that in soil of closed forest and that of soil where Dendrocalamus minor Var. amoen was planted,additionally,phosphorus increased with recovery time. Urease activity could be used as a monitoring index of soil fertility because it is related to the change of phosphorus content.[Conclusion] The soil of karst rocky desertification region in Northwest Guangxi Province could be recovered gradually if excessive human disturbance was stopped.If proper natural method of recovery promoted by human was taken,the recovery would reach a better result.
文摘[Objective] This study was conducted to find a restoration method suitable for urban polluted rivers. [Method] A segment of a representative river in the old part of a certain city in south Jiangsu was selected as a research area through previous investigation, and the polluted river was cleaned and restored by 3 methods, i.e. artificial wetland, floating island type wetland and purification floating island. [Resuit] Floating plants （Hydrocotyle verticillata and Myriophyllum spicatum） showed better restoration effects than emergent aquatic plants （Iris wilsonii, Arundo donax, reed, water-cultured Ilex chinensis and Lythrum salicaria）. The two types of plants showed the removal rates of total nitrogen of 37.9% and 34.1%, respectively, the removal rates of total phosphorous of 80.1% and 73.5%, respectively, the removal rates of COD of 81.1% and 74.8%, respectively, the removal rates of ammonia nitrogen of 80.6% and 85.9%, respectively, and the removal rates of SS of 59.1% and 77.3%, respectively. Among the purification floating island, the artificial wetland and the floating island type wetland, the purification floating land restoration technique exhibited the best removal effect, with the removal rates of 87.6%, 71.3%, 87.6%, 97.5% and 81.8% for total nitrogen, total phosphorous, ammonia nitrogen COD and SS, respectively. The nitrification and denitdfication rates of bottom mud and water samples in the engineering segment were remarkably higher than those in the reference segment, by 15.4% and 21.1%, respectively. The nitrification and denitrification rates of bottom mud in the engineering segment and the non-engineering segment were higher than those of water samples by 26.9% and 31.8%, respectively. Restoration plants showed better removal effects of total phosphorous, total nitrogen, COD and SS under aeration condition than noeration condition. [Conclusion] The purification floating island has a significant restoration effect on urban polluted river.
基金Financially supported by the Key Laboratory of Mountain Hazards and Earth Surface Processes,Chinese Academy of Sciences(Grant No.KLMHESP-20-02)the Key Programs of Science and Technology Research Plan,Hubei Provincial Department of Education(Grant No.D20201205)+1 种基金China Huadian Corporation Research Foundation(Grant No.12IJD201800018)National Key Research and Development Project(2017YFC0504902-02).
文摘Slope eco-restoration has always received extensive attention as a positive way to reverse ecosystem deterioration derived from human interventions.A simplified frameworkis proposed to undertake a quantitative evaluation of the engineering disturbed slope eco-restoration success in the alpine region,southeast Qinghai-Tibet Plateau.The Daguhydropower project that disturbsthe local ecosystem to some certainwas selected as the study area.Since August 2018,six types of slope(soil,rock,soil-rock,spoil,construction site,hardened)were served as the demonstration test for the slope eco-restoration with two years monitoring in the study area.Meanwhile,the topography,erosion,soil quality,and vegetation were selected as assessment indicators of the methodology.Finally,combined with the weighting method and the expert panel,the slope eco-restoration quality index(SERQI)was established and applied in the six slopes.The results suggested that the frost-resistant ecological substrate performed well in alpine region,and the SERQI value is in accordance with the actual monitoring level with spoil slope>soil slope>construction site slope>soil-rock slope>rock slope>hardened slope.The proposed framework could support slope eco-restoration practitioners for making a more objective and quantitative evaluation easily for the post-implementation restoration.
基金Under the auspices of the National Natural Science Foundation of China(No.42277354,U2243211)Fundamental Research Funds for the Hebei University of Water Resources and Electric Engineering(No.SYKY2113)Science Research Project of Hebei Education Department(No.QN2025293)。
文摘Changes in river cross-section morphology have decisive influences on the flood discharge and sand transport capacity of rivers;thus,these changes strongly reflect the vitality of a river.In this paper,based on the river cross-section and water and sediment data of two different periods(1974−1987 and 2007−2021),the trend analysis,change-point analysis and sediment rating curve method were used to analyze the change process of river cross-section morphology and its response to streamflow and sediment changes in the main river stream of the Yellow River at the Longmen hydrological station.From 1974 to 1987(except in 1977),the riverbed experi-enced siltation,and the riverbed elevation rose.Conversely,from 2007 to 2021,the riverbed experienced scouring,and the riverbed el-evation gradually decreased.The cross-section shape changed from rectangular to U-shaped(deeper on the right side)at the Longmen cross-section.The changes in streamflow and sediment processes significantly impacted the evolution of river cross-section.Stream-flow(P<0.05),sediment discharge(P<0.01),and the sediment load coefficients(P<0.01)decreased significantly.The relationship between the water depth and sediment load coefficients followed a power function.The decreasing trend in sediment discharge was sig-nificantly stronger than that in streamflow.Suspended sediment particles tended to become finer.The sediment rating curve indicates that the sediment supply from upstream decreased while the erosive power in the river channel increased,leading to a gradual decline in riverbed elevation at the Longmen cross-section from 2007 to 2021.These findings help us better understand the impacts of ecological restoration on changes in river streamflow and sediment during river evolution.
文摘The Jamaica Bay ecosystem is a dichotomy. It encompasses more than 12,000 acres of coastal estuarine marshes and an ecological diversity rivaling any coastal environment in the world. It is considerably altered, and is affected by a variety of ecological insults directly related to the fact that more than 14 million people live in its vicinity. Environmental protection institutions responded to the challenge of protecting the bay, surrounding wetlands and recreational benefits by addressing the increasing load of contaminants into the ecosystem. Billions of dollars have been spent during the past five decades on restoration attempts, including upgrading wastewater treatment plantsand the closure of three major sanitary landfills. Even with the curtailment of untreated wastewater release and ending periodic dredging and filling programs, all activities that are necessary processes in maintaining an urban harbor, the Jamaica Bay ecosystem has reached a point where many believe it to be unrecoverable, requiring massive infusions of restoration dollars. This categorization has been perpetuated based on questionable data （the ＂myths＂） that, when investigated in rigorous scientific detail, prove to be unsubstantiated. In this paper, the origin of these myths and the scientific investigation that dispel them are discussed.
基金This study was supported by the Innovation Project of the Chinese Academy of Sciences(Grant No.KZCX3-SW-324)the Key Research Plan of the National Natural Science Foundation of China(Grant No.90202015).
文摘Numerous hypotheses and conceptional models dealing with the grassland deserti-fication or degradation processes recognize that the invasion of shrubs in grasslands is the most striking feature of the variation of vegetation patterns in the grassland degradation or desertifica-tion processes in arid and semiarid regions. This is because the invasion of shrubs in grasslands increases the heterogeneity of the temporal and spatial distribution of primary vegetation and soil resources. As a result, the biological processes of the soil-vegetation system are increasingly concentrated in the “fertile islands” under shrub canopies, and the soil between shrubs gradually turns into bare area or moving sand under the influences of prolonged wind and water erosion. Most of relative researches support this bio-ecological interpretation for the degraded process of grassland. However, as viewed from the other aspect, the shrub vegetation distributed in patches also serves as the “trigger spots” for the grassland restoration or desertification reversion, and this has been demonstrated by the practices of combating desertification in China. Nearly 50 years of succession of artificial sand-binding vegetation in the Shapotou area and the regional restoration of eco-environment are the theoretical verification and successful example for the desertification reversion. The establishment of artificial vegetation in the region began with the installation of sand fences and planting xerophytic shrubs relying on less than 200 mm of annual precipitation under the non-irrigation condition, this made the moving sand, an originally uni-formly distributed soil resource, occur the variation of spatial heterogeneity. Through the redis-tribution of precipitation and dustfall by the canopy of xerophytic shrubs, litter accumulation and cryptogamic crust development, soil-forming processes under shrub canopies were accelerated; in the meantime, it also created a favorable condition for the invasion and colonization of annual and perennial plant species. However, with the depletion of soil moisture in the deep layer in the sand stabilization area the coverage of shrubs in the sand-binding vegetation lowered from the highest value of 33% to 6%, the dominant position and leading effect of shrubs in the communi-ties were weakened, furthermore they were gradually taken out from the vegetation composition. This correspondingly weakened the spatial heterogeneity of soil resource distribution. The propagation of numerous cryptogams on fixed sand surface and the colonization of annual and perennial plant species promoted the succession and restoration of the vegetation towards herb-dominated vegetation, which are similar to the primary vegetation types of the adjacent steppified desert and desert steppe. This paper, taking nearly 50 years of succession of sand-binding vegetation in the Shapotou region as an example and using the geostatistical method, puts forward and explains the conceptional model of vegetation restoration or desertifi-cation reversion of grassland in arid zones.
基金This work was supported by NSF of Tianjin(Nos.043115111-3,09ZCGYSF00400,200801100)National Key-Projects of Water Pollution Control and Prevention(Nos.2009ZX07209-001 and 2008ZX07314-005-011)the National Natural Science Foundation of China(Grant No.5107906).
文摘A modularized and air adjustable constructed submerged plant bed(CSPB)which can be used to restore the eutrophic water is introduced in this paper.This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth,impaired water transparency,algae bloom and substantial duckweed in summer,which are not naturally suitable for growing hydrophyte.This pilot study in Waihuan River of Tianjin,China,revealed that reduction of Chemical Oxygen Demand(COD),Total Nitrogen(TN)and Total Phosphorus(TP)by the use of CSPB could be reached 30%-35%,35%-40%,30%-40%respectively in the growing season(from March to October)and 5%-10%,5%-15%,7%-20%respectively in the winter(from November to February)when the detention time was 6 d.The relationships between the concentration of COD,TN,TP and the detention time fit the first-order kinetic equation well and the coefficients of determination(R^(2))were all above 0.9.The attenuation coefficients k of the kinetic equation were a function of the water temperature.When the water temperature was quite low or quite high,k was not significantly changed with increasing or decreasing water temperature.While when the temperature was in a moderate range,an increase or decrease of water temperature would lead to a rapid increase or decrease in k.
