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Liu S, Wang R, Yang Y, Shi W, Jiang K, Jia L, Zhang F, Liu X, Ma L, Li C, Yu P. Changes in soil aggregate stability and aggregate-associated carbon under different slope positions in a karst region of Southwest China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 928:172534. [PMID: 38636852 DOI: 10.1016/j.scitotenv.2024.172534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 03/29/2024] [Accepted: 04/15/2024] [Indexed: 04/20/2024]
Abstract
Soil aggregates are crucial for reducing soil erosion and enhancing soil organic carbon sequestration. However, knowledge regarding influences of different slope positions on compositions and carbon content for different soil aggregates is limited. Soil samples were collected from various slope positions including dip slope, anti-dip slope and valley depression in the Longtan karst valley of Southwest China. Contents of macroaggregate (> 0.25 mm), microaggregate (0.053-0.25 mm) and silt and clay fraction (< 0.053 mm), and aggregate-associated carbon contents under the three slope positions were measured. Compared to the anti-dip slope, the mean weight diameter under the dip slope and valley depression decreased by 28.48 % and 58.79 %, respectively, while the geometric mean diameter decreased by 39.01 % and 62.57 %, respectively. The mean carbon content in silt and clay fraction was 27.59 % and 21.00 % lower than the macroaggregate- and microaggregate-associated carbon content, respectively. Under the valley depression and dip slope, soil organic carbon contents in bulk soil (37.67 % and 10.36 %, respectively), microaggregate (37.56 % and 4.95 %), and silt and clay fraction (39.99 % and 12.84 %, respectively) were significantly lower than those under the anti-dip slope. However, the difference in macroaggregate-associated carbon content among the three slope positions was not significant. The silt and clay fraction was the major contributor to soil carbon pool in bulk soil in the study area because of its high content. Compared to the anti-dip slope, contribution of macroaggregates to soil carbon pool under the dip slope and valley depression decreased by 25.53 % and 47.95 %, respectively, whereas the contribution of silt and clay fraction increased by 22.68 % and 42.66 %, respectively. These results suggested that the anti-dip slope surpassed both the dip slope and valley depression in carbon sequestration and soil and water conservation in karst regions.
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Affiliation(s)
- Shiwei Liu
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Rutong Wang
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Yan Yang
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Weiyu Shi
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Ke Jiang
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Luyao Jia
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Feng Zhang
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Xian Liu
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China
| | - Lei Ma
- Observation and Research Station of Ecological Restoration for Chongqing Typical Mining Areas, Ministry of Natural Resources, Chongqing Institute of Geology and Mineral Resources, Chongqing 401120, China
| | - Cheng Li
- Observation and Research Station of Ecological Restoration for Chongqing Typical Mining Areas, Ministry of Natural Resources, Chongqing Institute of Geology and Mineral Resources, Chongqing 401120, China
| | - Pujia Yu
- Chongqing Jinfo Mountain Karst Ecosystem National Observation and Research Station, School of Geographical Sciences, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing 400715, China.
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Becerra-Lira E, Rodriguez-Achata L, Muñoz Ushñahua A, Corvera Gomringer R, Thomas E, Garate-Quispe J, Hilares Vargas L, Nascimento Herbay PR, Gamarra Miranda LA, Umpiérrez E, Guerrero Barrantes JA, Pillaca M, Cusi Auca E, Peña Valdeiglesias J, Russo R, Del Castillo Torres D, Velasquez Ramírez MG. Spatio-temporal trends of mercury levels in alluvial gold mining spoils areas monitored between rainy and dry seasons in the Peruvian Amazon. ENVIRONMENTAL RESEARCH 2024; 245:118073. [PMID: 38159662 DOI: 10.1016/j.envres.2023.118073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 12/23/2023] [Accepted: 12/27/2023] [Indexed: 01/03/2024]
Abstract
Artisanal and small-scale gold mining (ASGM) in the Amazon has degraded tropical forests and escalated mercury (Hg) pollution, affecting biodiversity, ecological processes and rural livelihoods. In the Peruvian Amazon, ASGM annually releases some 181 tons of Hg into the environment. Despite some recent advances in understanding the spatial distribution of Hg within gold mine spoils and the surrounding landscape, temporal dynamics in Hg movement are not well understood. We aimed to reveal spatio-temporal trends of soil Hg in areas degraded by ASGM.,. We analyzed soil and sediment samples during the dry and rainy seasons across 14 ha of potentially contaminated sites and natural forests, in the vicinities of the Native community of San Jacinto in Madre de Dios, Peru. Soil Hg levels of areas impacted by ASGM (0.02 ± 0.02 mg kg-1) were generally below soil environmental quality standards (6.60 mg kg-1). However, they showed high variability, mainly explained by the type of natural cover vegetation, soil organic matter (SOM), clay and sand particles. Temporal trends in Hg levels in soils between seasons differed between landscape units distinguished in the mine spoils. During the rainy season, Hg levels decreased up to 45.5% in uncovered soils, while in artificial pond sediments Hg increased by up to 961%. During the dry season, uncovered degraded soils were more prone to lose Hg than sites covered by vegetation, mainly due to higher soil temperatures and concomitantly increasing volatilization. Soils from natural forests and degraded soil covered by regenerating vegetation showed a high capacity to retain Hg mainly due to the higher plant biomass, higher SOM, and increasing concentrations of clay particles. Disturbingly, our findings suggest high Hg mobility from gold mine spoil to close by sedimentary materials, mainly in artificial ponds through alluvial deposition and pluvial lixiviation. Thus, further research is needed on monitoring, and remediation of sediments in artificial to design sustainable land use strategies.
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Affiliation(s)
- Edwin Becerra-Lira
- Desarrollo de Tecnologías para el Fortalecimiento de Sistemas Productivos en Base a la Castaña y Shiringa, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Jr. Ica N◦1162, Puerto Maldonado, Apartado Postal, 17001, Peru.
| | - Liset Rodriguez-Achata
- Departamento Académico de Ciencias Básicas, Universidad Nacional Amazónica de Madre de Dios, Av. Jorge Chávez 1160, Puerto Maldonado, Peru.
| | - Adenka Muñoz Ushñahua
- Proyecto Recuperación de áreas Degradadas, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Puerto Maldonado, Peru.
| | - Ronald Corvera Gomringer
- Dirección Regional IIAP Madre de Dios y Selva Sur, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Jr. Ica N◦1162, Puerto Maldonado, Apartado Postal, 17001, Peru.
| | - Evert Thomas
- Bioversity International, Av. La Molina, 1895, Lima, Apartado Postal Lima12, Peru.
| | - Jorge Garate-Quispe
- Departamento Académico de Ingeniería Forestal y Medio Ambiente, Facultad de Ingeniería, Universidad Nacional Amazónica de Madre de Dios, Puerto Maldonado, 17001, Peru.
| | - Litcely Hilares Vargas
- Proyecto Recuperación de áreas Degradadas, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Puerto Maldonado, Peru.
| | - Pedro Romel Nascimento Herbay
- Proyecto Recuperación de áreas Degradadas, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Puerto Maldonado, Peru.
| | | | - Eleuterio Umpiérrez
- Coordinador Empresarial del IPTP, Instituto Polo Tecnológico de Pando Facultad de Química - UDELAR Montevideo-Uruguay, Uruguay.
| | - Juan Antonio Guerrero Barrantes
- Departamento de Suelos, Universidad Nacional Agraria, La Molina (UNALM), Av. La Molina s/n, Lima, Perú, Apartado Postal Lima12, Peru.
| | - Martin Pillaca
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, 17000, Madre de Dios, Peru.
| | - Edgar Cusi Auca
- Desarrollo de Tecnologías para el Fortalecimiento de Sistemas Productivos en Base a la Castaña y Shiringa, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Jr. Ica N◦1162, Puerto Maldonado, Apartado Postal, 17001, Peru.
| | - Joel Peña Valdeiglesias
- Departamento Académico de Ingeniería Forestal y Medio Ambiente, Facultad de Ingeniería, Universidad Nacional Amazónica de Madre de Dios, Puerto Maldonado, 17001, Peru.
| | | | - Dennis Del Castillo Torres
- Programa BOSQUES, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Iquitos, Apartado Postal, 16000, Peru.
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