EPHor, IRSTV, AGROCAMPUS OUEST, 49045 Angers, France; Université de Lorraine, Inra, Laboratoire Sols et Environnement, F-54000 Nancy, France; Agence de l'Environnement et de la Maîtrise de l'Energie (ADEME), 75015 Paris, France.
United States Department of Agriculture, Natural Resources Conservation Service, Somerset, NJ 08873, USA.
Sci Total Environ. 2018 Dec 10;644:452-464. doi: 10.1016/j.scitotenv.2018.06.322. Epub 2018 Jul 11.
In cities, the strong heterogeneity of soils, added to the lack of standardized assessment methods, serves as a barrier to the estimation of their soil organic carbon content (SOC), soil organic carbon stocks (SOCS; kgC m) and soil organic carbon citywide totals (SOCCT; kgC). Are urban soils, even the subsoils and sealed soils, contributing to the global stock of C? To address this question, the SOCS and SOCCT of two cities, New York City (NYC) and Paris, were compared. In NYC, soil samples were collected with a pedological standardized method to 1 m depth. The bulk density (D) was measured; SOC and SOCS were calculated for 0-30 cm and 30-100 cm depths in open (unsealed) soils and sealed soils. In Paris, the samples were collected for 0-30 cm depth in open soils and sealed soils by different sampling methods. If SOC was measured, D had to be estimated using pedotransfer functions (PTFs) refitted from the literature on NYC data; hence, SOCS was estimated. Globally, SOCS for open soils were not significantly different between both cities (11.3 ± 11.5 kgC m in NYC; 9.9 ± 3.9 kgC m in Paris). Nevertheless, SOCS was lower in sealed soils (2.9 ± 2.6 kgC m in NYC and 3.4 ± 1.2 kgC m in Paris). The SOCCT was similar between both cities for 0-30 cm (3.8 TgC in NYC and 3.5 TgC in Paris) and was also significant for the 30-100 cm layer in NYC (5.8 TgC). A comparison with estimated SOCCT in agricultural and forest soils demonstrated that the city's open soils represent important pools of organic carbon (respectively 110.4% and 44.5% more C in NYC and Paris than in agricultural soils, for 0-30 cm depth). That was mainly observable for the 1 m depth (146.6% more C in NYC than in agricultural soils). The methodology to assess urban SOCS was also discussed.
在城市中，土壤的强烈异质性，加上缺乏标准化的评估方法，成为估算土壤有机碳含量（SOC）、土壤有机碳储量（SOCS；kgC m）和城市范围内土壤有机碳总量（SOCCT；kgC）的障碍。城市土壤，甚至是底土和封套土壤，是否有助于全球碳储量的增加？为了解决这个问题，比较了两个城市，纽约市（NYC）和巴黎的 SOCS 和 SOCCT。在纽约市，使用标准化的土壤学方法采集土壤样本，深度达 1 米。测量了土壤容重（D）；计算了开放（未封套）土壤和封套土壤 0-30 cm 和 30-100 cm 深度的 SOC 和 SOCS。在巴黎，使用不同的采样方法在开放土壤和封套土壤中采集 0-30 cm 深度的样本。如果测量了 SOC，则必须使用根据纽约市数据的文献重新拟合的土壤转移函数（PTFs）来估计 D；因此，估算了 SOCS。总体而言，两个城市的开放土壤的 SOCS 没有显著差异（纽约市为 11.3±11.5 kgC m；巴黎为 9.9±3.9 kgC m）。然而，封套土壤的 SOCS 较低（纽约市为 2.9±2.6 kgC m；巴黎为 3.4±1.2 kgC m）。对于 0-30 cm，两个城市的 SOCCT 相似（纽约市为 3.8 TgC，巴黎为 3.5 TgC），在纽约市的 30-100 cm 层也具有重要意义（5.8 TgC）。与农业和森林土壤中估计的 SOCCT 进行比较表明，城市开放土壤代表了重要的有机碳库（对于 0-30 cm 深度，纽约市和巴黎的开放土壤分别比农业土壤多 110.4%和 44.5%的 C）。这在 1 m 深度上更为明显（纽约市比农业土壤多 146.6%的 C）。还讨论了评估城市 SOCS 的方法。
