Loss of organic carbon in suburban soil upon urbanization of Chengdu megacity, China

Luo, Youlin; Shen, Jie; Chen, Aifang; Qi, Tao; Li, Qiquan; White, Philip J.; Li, Tingqiang; Li, Bing; Chen, Lin; Li, Huanxiu; Gao, Xuesong; Xu, Qiang; Wang, Changquan

doi:10.1016/j.scitotenv.2021.147209

Cited by 27 publications

(15 citation statements)

References 83 publications

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“…According to ( Figure 9 ), the stability of SOC density in suburban areas is poor and the risk of loss is high. This finding is generally consistent with comparable case studies [ 53 , 54 ] indicating that urbanization has a variable impact on SOC stock, with rapid urbanization leading to significant losses of SOC in suburban areas. Urbanization has led to the spreading of built-up areas and transport facilities to suburban areas and the conversion of a large amount of cultivated land to urban use, resulting in soil compaction and sealing as well as increased organic carbon loss [ 11 ].…”

Section: Discussion and Impactsupporting

confidence: 91%

Spatio-Temporal Variation and Its Driving Forces of Soil Organic Carbon along an Urban–Rural Gradient: A Case Study of Beijing

Liu

Qian

Zhao

et al. 2022

IJERPH

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Rapid urbanization has reshaped land cover and the ecological environment, potentially improving or deteriorating soil organic carbon (SOC). However, the response of SOC to urbanization has not yet been fully exploited. Herein, by using the land-use transfer matrix, the Sen & Mann–Kendall tests, the Hurst index, and a geographical and temporal weighted regression (GTWR) model, as well as an urban–rural gradient perspective, we assessed the dynamic response of SOC to Beijing’s urbanization from 2001 to2015 and identified the main drivers. The results found that SOC stock decreased by 7651.50 t C during the study period. SOC density varied significantly along an urban–rural gradient, with high value areas mainly being located in remote mountainous rural areas and low value areas mainly being located in urban areas on the plains. There was an uneven variation in SOC density across the urban–rural gradient, with suburban areas (25–40 km away from urban cores) losing the most SOC density while urban areas and rural areas remained relatively unchanged. GTWR model revealed the spatio-temporal non-flat stability of various driving forces. Precipitation, the proportion of forest, the proportion of grassland, the population, distance to the urban center, the slope, and the silt content are the main factors related to SOC stock change. As a result, we suggest policy makers reconceptualize the uneven variation in the SOC between urban and rural areas, emphasize suburban areas as a target for controlling SOC loss, and take into consideration the spatial and temporal heterogeneity of the factors influencing SOC stock when evaluating policies.

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Section: Discussion and Impactsupporting

confidence: 91%

Spatio-Temporal Variation and Its Driving Forces of Soil Organic Carbon along an Urban–Rural Gradient: A Case Study of Beijing

Liu

Qian

Zhao

et al. 2022

IJERPH

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“…According to our previous researches, the impact of agricultural land use on soil C and nitrogen reached down to 100 cm depths (Luo et al, 2019, 2021; Shen et al, 2021). In the sampling phase, we used a square pit of 1 × 1 m, three undisturbed soil samples (three sides of the pit), and mixed them to form a composite sample of each soil layer.…”

Section: Methodsmentioning

confidence: 87%

Impact of suburban cropland intensification and afforestation on microbial biodiversity and C sequestration in paddy soils

Luo,

Shen,

Dou

et al. 2023

Land Degrad Dev

Self Cite

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Rapid urbanization drives changes in suburban cropland and afforestation, but the impact on soil microbes and carbon (C) dynamics remains unclear. Using genetic sequencing (16S rRNA sequence and functional prediction), we assessed the effects of cropland intensification and afforestation on the soil microbial communities and C sequestration potential in a suburban agricultural area. Traditional rotation (rice–wheat) homogenized microbial diversity along soil depth (0–100 cm). Cropland intensification (rice–wheat to rice–vegetables) and afforestation (rice–wheat to forest) decreased fungal diversity below 20 cm, while bacterial diversity and dominant taxa were less affected, due to the advantages of bacterial diversity and dominant taxa distribution. Cropland intensification increased profile C accumulation, mainly due to excessive fertilization (obviously decreased aerobic_chemoheterotrophy below 20 cm in bacterial function), but not C stability (significantly increased permanganate oxidizable C (POXC), and microbial‐dependent C sources tend to from crop litter to soil sources). Afforestation offset C accumulation through no fertilization and inundation, but increased saprophytic function for C sequestration. In addition, pH and C had opposing effects on dominant microbial taxa, mitigating extreme differentiation. Subsoil was more sensitive to changes than topsoil. Altogether, soil C stability decoupled from C accumulation in the suburban agricultural area. Cropland intensification increased C accumulation yet decreased bacterial C sequestration potential and C stability; cropland afforestation facilitated fungi‐derived C accumulation and its C sequestration. Deep soil C sequestration was more vulnerable to suburban agriculture practices, emphasizing the need to consider subsoil C‐cycling in agricultural practices amid urbanization.

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“…1b; Dai et al, 2021). Luo et al (2021) reported that Chengdu's urban area has increased 4-fold from 1996 to 2016. Because of the substantial anthropogenic emissions from human activities and the poor atmospheric diffusion ca- pacity associated with terrain, Chengdu is one of the most polluted cities in China and has suffered from severe PM 2.5 and O 3 pollution in recent years (Shu et al, 2021;Yang et al, 2020;Zhan et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Impacts of urbanization on air quality and the related health risks in a city with complex terrain

Zhan

Lu²,

Liu³

et al. 2023

Atmos. Chem. Phys.

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Abstract. Urbanization affects air pollutants via urban expansion and emission growth, thereby inevitably changing the health risks involved with air pollutants. However, the health risks related to urbanization are rarely estimated, especially for cities with complex terrain. In this study, a highly urbanized city with severe air pollution and complex terrain (Chengdu) is selected to explore this issue. The effects of urban expansion are further compared with emission growth because air quality management is usually achieved by regulating anthropogenic emissions. Air pollution in Chengdu was mainly caused by PM2.5 and O3 from 2015 to 2021. PM2.5 pollution tended to appear in cold months (November to February) owing to the blocking of air and the stable atmospheric layer, whereas O3 pollution was likely to occur in warm months (April to August) that experience high-temperature and strong-sunlight conditions and are dominated by high-pressure systems. From 2015 to 2021, the 7-year annual average of premature mortality from all non-accidental causes (ANACs) due to PM2.5 and O3 was 9386 (95 % confidence interval (CI) of 6542–11 726) and 8506 (95 % CI of 4817–11 882), respectively. Based on the characteristics of PM2.5 and O3, six numerical experiments were conducted to investigate the impacts of urban expansion and emission growth on the health risks related to air pollutants. The results show that urban land use led to an increase in the air temperature and boundary layer height compared with cropland, which was conducive to the diffusion of PM2.5. Thus, the monthly average surface PM2.5 concentrations decreased by 10.8 µg m−3 (7.6 %) in January. However, the monthly average daily maximum 8 h average (MDA8) O3 concentrations increased by 10.6 µg m−3 (6.0 %) in July owing to the stronger photochemical production and better vertical mixing during daytime. In this case, premature mortality from ANACs due to PM2.5 decreased by 171 (95 % CI of 129–200, or about 6.9 %) in January, and that due to O3 increased by 203 (95 % CI of 122–268, or about 9.5 %) in July. As for the effects of emission growth, the monthly average PM2.5 and MDA8 O3 concentrations increased by 23.9 (16.8 %) and 4.8 µg m−3 (2.7 %), respectively, when anthropogenic emissions were taken into account. Premature mortality from ANACs due to PM2.5 and O3 then increased by 388 (95 % CI of 291–456, or about 15.7 %) and 87 (95 % CI of 54–112, or about 4.1 %), respectively. From a health risk perspective, the effects of urban land use on the health risks related to PM2.5 are about half that of anthropogenic emissions, whereas the effects of urban land use on the health risks related to O3 can be 2 times that of anthropogenic emissions. This emphasizes that, in addition to regulating anthropogenic emissions, urban planning is also important for urban air quality, especially for secondary pollutants like O3.

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Loss of organic carbon in suburban soil upon urbanization of Chengdu megacity, China

Cited by 27 publications

References 83 publications

Spatio-Temporal Variation and Its Driving Forces of Soil Organic Carbon along an Urban–Rural Gradient: A Case Study of Beijing

Spatio-Temporal Variation and Its Driving Forces of Soil Organic Carbon along an Urban–Rural Gradient: A Case Study of Beijing

Impact of suburban cropland intensification and afforestation on microbial biodiversity and C sequestration in paddy soils

Impacts of urbanization on air quality and the related health risks in a city with complex terrain

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