Phosphorus (P) is an essential nutrient element that is critical for plant growth and ecosystem functionality.The soil P cycle plays multiple roles,such as sustaining plant growth and productivity,regulating nutrient ...Phosphorus (P) is an essential nutrient element that is critical for plant growth and ecosystem functionality.The soil P cycle plays multiple roles,such as sustaining plant growth and productivity,regulating nutrient balance within ecosystems,and enhancing ecosystem adaptability and resilience.This cycle is influenced by factors such as the restoration approach and microbial community dynamics.However,the extent to which the restoration approach alters the P cycle in karst ecosystems and the underlying microbial mechanisms remain poorly understood.The P-cycle multifunctionality index (P-cycle MFI) serves as a comprehensive indicator for evaluating soil P cycle function,and it provides insights into changes in the P cycle between different restoration approaches.To investigate the shifts in soil P-cycle MFI and microbial mechanisms between different restoration approaches,we analyzed soil available P (AP),total P (TP),microbial biomass P (MBP),and the activities of acid phosphatase (ACP) and alkaline phosphatase (ALP).These data were used to calculate the P-cycle MFI by averaging the Z-scores between two restoration approaches(artificial restoration of forest (AF) and natural restoration of forest (NF)) and a control (cropland,CP) at six subtropical karst ecosystem sites in China.We also determined the soil organic carbon (SOC),exchangeable calcium (Ca) and magnesium (Mg),pH,bulk density (BD),microbial biomass C (MBC),and microbial biomass nitrogen (MBN),as well as the community structure,relative abundance,diversity indices,and co-occurrence networks of phoD-harboring bacteria.The results showed that the community structure of phoD-harboring bacteria varied significantly among AF,NF,and CP and across different temperature gradients.These bacteria exhibited increasing complexity and tightness in co-occurrence networks from CP to AF and then to NF,along with the ACP and ALP activities,but not the TP and AP contents.The P-cycle MFI values were significantly higher in NF compared to AF and CP,and the variation was significantly explained by restoration approach,temperature,MBC,MBN,SOC,exchangeable Ca,BD,community structure of phoD-harboring bacteria,and exchangeable Mg.Furthermore,natural restoration had a more substantial impact on the P-cycle MFI than temperature by enhancing SOC,microbial biomass,the complexity and co-occurrence network tightness of the phoD-harboring bacterial community structure,and ACP and ALP activities,but it reduced soil BD.The rare genera of phoD-harboring bacteria significantly influenced the variation of soil P-cycle MFI compared to the dominant genera.This study highlights the importance of rare genera of phoD-harboring bacteria in driving soil P-cycle multifunctionality in karst ecosystems,with natural restoration being more effective than artificial methods for enhancing soil organic matter and microbial community complexity.展开更多
Autogenic, or direct aquifer recharge can best be measured as the remainder of a water balance utilizing precise measurement of precipitation, evapotranspiration (ET) and runoff. ET is the largest component of a preci...Autogenic, or direct aquifer recharge can best be measured as the remainder of a water balance utilizing precise measurement of precipitation, evapotranspiration (ET) and runoff. ET is the largest component of a precipitation water balance and can be measured within 5% using an eddy covariance system with Bowen-ratio energy balance corrections. Water balance components of precipitation, evapotranspiration, internal runoff, soil moisture were measured using a eddy covariance system, tipping bucket and visual rain gauges, flumes, and soil-moisture sensors. The research site was located within a 0.19-km2 (46-acre) internal drainage sinkhole basin where runoff never flows beyond the basin, but potentially reaches a cave serving as a drain to the sinkhole. Other than the cave drain, the basin slopes are indistinguishable from other slopes across the Barton Springs Segment of the Edwards Aquifer. Over a 505-day water balance interval where change in soil moisture was negligible and precipitation was 42% above average, ET was 68% of precipitation, discrete internal runoff was 6%, and remaining component of diffuse autogenic recharge was measured as the residual of total rainfall as 26% of rainfall. Over a longer period of average rainfall, internal runoff diminished to 3%, but was as high as 42% of precipitation during single storms when the soils were near saturation. These results closely match results from a five-year water balance over the Trinity Aquifer of Central Texas where ET was measured to be 65% of precipitation using a Bowen-ratio climate tower, runoff was measured to be 5% of precipitation, and recharge was calculated as the residual at 30% of rainfall. ET flux tower data from other sites across Central Texas indicate that under average precipitation conditions, autogenic recharge is about 28% and intervening recharge area runoff is about 3% of precipitation. During years of higher than average precipitation, authogenic recharge and intervening recharge area runoff combined increase within the range of 30% to 45% of precipitation.展开更多
Maintaining beneficial, native plant structure and diversity while reducing invasive, nuisance species dominance is an important management domain for natural resource managers. One such vegetation component in North ...Maintaining beneficial, native plant structure and diversity while reducing invasive, nuisance species dominance is an important management domain for natural resource managers. One such vegetation component in North American lakes and reservoirs is submerged aquatic vegetation—a valuable aquatic resource which serves as productive habitat for fish, aquatic macroinvertebrates, and other wildlife. Reservoirs in the southern parts of the United States have experienced varying aquatic plant dominance dynamics due to historical water resource management actions, including drawdowns and introduction of herbivorous fish for the purpose of controlling invasive aquatic vegetation. Some of these management options have also been detrimental to native submerged aquatic vegetation. This paper explores an adaptive management research effort by installing herbivore-protected, fenced-pen submerged aquatic vegetation sites in a high-herbivore reservoir to determine effectiveness of protecting habitat and serving as founder colony sources for propagule spread. Four experimental sites with three management treatments each were planted with American eelgrass. Each site utilized one un-fenced treatment and two treatments with varying mesh sizes for protective fencing-pens. Site integrity, species survival and spread, and grazing were documented. One additional site was installed and planted with other native submerged aquatic vegetation species for nominal species performance descriptions. No plants survived unprotected in the high-herbivore system and plants, in general, performed consistently better within the smaller mesh size. These test planting results were ultimately used to inform adaptive management decision making for plant installation and expansion designs for managing reservoirs invested with Hydrilla, considered one of the most serious invasive aquatic plants in the United States.展开更多
Groundwater is a vital drinking water source for populations in remote karst regions. However, the highly developed karst tube systems facilitate the infiltration of surface wastewater containing N-nitrosamines, raisi...Groundwater is a vital drinking water source for populations in remote karst regions. However, the highly developed karst tube systems facilitate the infiltration of surface wastewater containing N-nitrosamines, raising concerns about groundwater safety. To assess the safety of groundwater and identify which types are safer for consumption, this study investigated N-nitrosamines in various groundwater types, including ground river, karst cavern, well, and mountain spring waters, in Guangxi, a typical karst region in southwestern China. The total concentrations of eight N-nitrosamines in groundwater ranged from 5.1 to 70.3 ng/L, with N-nitrosodiethylamine (NDEA), N-nitrosodimethylamine (NDMA), and N-nitrosopyrrolidine (NPYR) being the dominant species. Ground river water exhibited significantly higher N-nitrosamine concentrations than karst cavern, well, and mountain spring waters. Significant correlations between N-nitrosamines and dissolved inorganic nitrogen suggested their co-emissions from domestic wastewater and the secondary formation potential of N-nitrosamines in groundwater. Redundancy analysis further identified domestic and swine wastewater as the primary sources. Ground river and mountain spring waters posed the highest risks among the four groundwater types, with 30 % and 20 % of sites, respectively, exceeding acceptable cancer risk thresholds. These findings underscore the importance of thorough water treatment before groundwater is used for drinking. Strict livestock farming and domestic wastewater discharge regulations are essential to mitigate contamination risks, particularly in karst areas.展开更多
基金supported by the National Key Research and Development Program of China (2022YFF1300705)the Key Research and Development Project of Guangxi,China (Guike AB24010051)+1 种基金the National Natural Science Foundation of China (42261011,32271730 and U20A2011)the Central Public Welfare Research Institutes,Chinese Academy of Geological Sciences (2023020)。
文摘Phosphorus (P) is an essential nutrient element that is critical for plant growth and ecosystem functionality.The soil P cycle plays multiple roles,such as sustaining plant growth and productivity,regulating nutrient balance within ecosystems,and enhancing ecosystem adaptability and resilience.This cycle is influenced by factors such as the restoration approach and microbial community dynamics.However,the extent to which the restoration approach alters the P cycle in karst ecosystems and the underlying microbial mechanisms remain poorly understood.The P-cycle multifunctionality index (P-cycle MFI) serves as a comprehensive indicator for evaluating soil P cycle function,and it provides insights into changes in the P cycle between different restoration approaches.To investigate the shifts in soil P-cycle MFI and microbial mechanisms between different restoration approaches,we analyzed soil available P (AP),total P (TP),microbial biomass P (MBP),and the activities of acid phosphatase (ACP) and alkaline phosphatase (ALP).These data were used to calculate the P-cycle MFI by averaging the Z-scores between two restoration approaches(artificial restoration of forest (AF) and natural restoration of forest (NF)) and a control (cropland,CP) at six subtropical karst ecosystem sites in China.We also determined the soil organic carbon (SOC),exchangeable calcium (Ca) and magnesium (Mg),pH,bulk density (BD),microbial biomass C (MBC),and microbial biomass nitrogen (MBN),as well as the community structure,relative abundance,diversity indices,and co-occurrence networks of phoD-harboring bacteria.The results showed that the community structure of phoD-harboring bacteria varied significantly among AF,NF,and CP and across different temperature gradients.These bacteria exhibited increasing complexity and tightness in co-occurrence networks from CP to AF and then to NF,along with the ACP and ALP activities,but not the TP and AP contents.The P-cycle MFI values were significantly higher in NF compared to AF and CP,and the variation was significantly explained by restoration approach,temperature,MBC,MBN,SOC,exchangeable Ca,BD,community structure of phoD-harboring bacteria,and exchangeable Mg.Furthermore,natural restoration had a more substantial impact on the P-cycle MFI than temperature by enhancing SOC,microbial biomass,the complexity and co-occurrence network tightness of the phoD-harboring bacterial community structure,and ACP and ALP activities,but it reduced soil BD.The rare genera of phoD-harboring bacteria significantly influenced the variation of soil P-cycle MFI compared to the dominant genera.This study highlights the importance of rare genera of phoD-harboring bacteria in driving soil P-cycle multifunctionality in karst ecosystems,with natural restoration being more effective than artificial methods for enhancing soil organic matter and microbial community complexity.
文摘Autogenic, or direct aquifer recharge can best be measured as the remainder of a water balance utilizing precise measurement of precipitation, evapotranspiration (ET) and runoff. ET is the largest component of a precipitation water balance and can be measured within 5% using an eddy covariance system with Bowen-ratio energy balance corrections. Water balance components of precipitation, evapotranspiration, internal runoff, soil moisture were measured using a eddy covariance system, tipping bucket and visual rain gauges, flumes, and soil-moisture sensors. The research site was located within a 0.19-km2 (46-acre) internal drainage sinkhole basin where runoff never flows beyond the basin, but potentially reaches a cave serving as a drain to the sinkhole. Other than the cave drain, the basin slopes are indistinguishable from other slopes across the Barton Springs Segment of the Edwards Aquifer. Over a 505-day water balance interval where change in soil moisture was negligible and precipitation was 42% above average, ET was 68% of precipitation, discrete internal runoff was 6%, and remaining component of diffuse autogenic recharge was measured as the residual of total rainfall as 26% of rainfall. Over a longer period of average rainfall, internal runoff diminished to 3%, but was as high as 42% of precipitation during single storms when the soils were near saturation. These results closely match results from a five-year water balance over the Trinity Aquifer of Central Texas where ET was measured to be 65% of precipitation using a Bowen-ratio climate tower, runoff was measured to be 5% of precipitation, and recharge was calculated as the residual at 30% of rainfall. ET flux tower data from other sites across Central Texas indicate that under average precipitation conditions, autogenic recharge is about 28% and intervening recharge area runoff is about 3% of precipitation. During years of higher than average precipitation, authogenic recharge and intervening recharge area runoff combined increase within the range of 30% to 45% of precipitation.
文摘Maintaining beneficial, native plant structure and diversity while reducing invasive, nuisance species dominance is an important management domain for natural resource managers. One such vegetation component in North American lakes and reservoirs is submerged aquatic vegetation—a valuable aquatic resource which serves as productive habitat for fish, aquatic macroinvertebrates, and other wildlife. Reservoirs in the southern parts of the United States have experienced varying aquatic plant dominance dynamics due to historical water resource management actions, including drawdowns and introduction of herbivorous fish for the purpose of controlling invasive aquatic vegetation. Some of these management options have also been detrimental to native submerged aquatic vegetation. This paper explores an adaptive management research effort by installing herbivore-protected, fenced-pen submerged aquatic vegetation sites in a high-herbivore reservoir to determine effectiveness of protecting habitat and serving as founder colony sources for propagule spread. Four experimental sites with three management treatments each were planted with American eelgrass. Each site utilized one un-fenced treatment and two treatments with varying mesh sizes for protective fencing-pens. Site integrity, species survival and spread, and grazing were documented. One additional site was installed and planted with other native submerged aquatic vegetation species for nominal species performance descriptions. No plants survived unprotected in the high-herbivore system and plants, in general, performed consistently better within the smaller mesh size. These test planting results were ultimately used to inform adaptive management decision making for plant installation and expansion designs for managing reservoirs invested with Hydrilla, considered one of the most serious invasive aquatic plants in the United States.
基金supported by the National Natural Science Foundation of China(No.42203002)Guangxi Science and Technology Program(Guike AD25069074)+1 种基金Guangzhou Municipal Science and Technology Bureau(No.2023A04J0948)Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology(No.PM-zx960-202305-154).
文摘Groundwater is a vital drinking water source for populations in remote karst regions. However, the highly developed karst tube systems facilitate the infiltration of surface wastewater containing N-nitrosamines, raising concerns about groundwater safety. To assess the safety of groundwater and identify which types are safer for consumption, this study investigated N-nitrosamines in various groundwater types, including ground river, karst cavern, well, and mountain spring waters, in Guangxi, a typical karst region in southwestern China. The total concentrations of eight N-nitrosamines in groundwater ranged from 5.1 to 70.3 ng/L, with N-nitrosodiethylamine (NDEA), N-nitrosodimethylamine (NDMA), and N-nitrosopyrrolidine (NPYR) being the dominant species. Ground river water exhibited significantly higher N-nitrosamine concentrations than karst cavern, well, and mountain spring waters. Significant correlations between N-nitrosamines and dissolved inorganic nitrogen suggested their co-emissions from domestic wastewater and the secondary formation potential of N-nitrosamines in groundwater. Redundancy analysis further identified domestic and swine wastewater as the primary sources. Ground river and mountain spring waters posed the highest risks among the four groundwater types, with 30 % and 20 % of sites, respectively, exceeding acceptable cancer risk thresholds. These findings underscore the importance of thorough water treatment before groundwater is used for drinking. Strict livestock farming and domestic wastewater discharge regulations are essential to mitigate contamination risks, particularly in karst areas.
