Anthropocene最新文献

This study estimated the mass accumulation rates of sediment (MAR), carbon (CMAR), and phosphorus (PMAR) in small Finnish lakes with agricultural clayey catchments over a 25-year period (1986–2011) and compared these with the conditions before major agricultural land use. Twenty-two lakes were cored for recent and reference (pre-disturbance) sediments. The recent sediment section was selected based on the 1986 ¹³⁷Cs fallout peak (TOP), whereas the pre-disturbance section (REF) was selected immediately below the first signs of human-induced erosion. The 50-cm reference section was dated with ¹⁴C at both ends. The mass accumulation rates were estimated based on dating, weighing, and chemical analysis for both sediment sections. Furthermore, sediment-penetrating echo soundings were used to estimate the amount of sediment in the whole lake basins. These data were used to examine area-specific loading from clay-rich catchments. The average whole-basin pre-disturbance MAR, PMAR, and CMAR were 62 g m⁻² a⁻¹, 0.06 g m⁻² a⁻¹, and 4.7 g m⁻² a⁻¹, respectively. The corresponding recent rates were 11, 13, and 8-fold (693 g m⁻² a⁻¹, 0.79 g m⁻² a⁻¹, and 37 g m⁻² a⁻¹). In the recent conditions, sediments were generally more minerogenic and MAR, PMAR, and CMAR were higher in lakes with more arable fields in their catchments. Average area-specific suspended sediment load from the catchment for the region (∼39% clayey soils) was approximately 69–137 kg ha⁻¹ a⁻¹ in the undisturbed state and 767–1534 kg ha⁻¹ a⁻¹ in recent conditions based on 100–50% retention. The results demonstrate that the increases in sediment, nutrient, and organic matter accumulation due to agriculture can be several fold over undisturbed state.

Prescribed fire (Rx-fire) is a common management tool for many forested ecosystems and promotes tree and forest soil health. Although burned materials from Rx-fire areas can enter adjacent aquatic environments, very few studies have focused on the water quality impacts of increased nutrients on aquatic primary producer communities. Here, we applied paleolimnological techniques on a 170-cm sediment core collected from Ditch Pond, AL, USA, a subtropical lake system located in the Conecuh National Forest where Rx-fire has been the primary management tool for ∼90 years. Macroscopic charcoal, nutrients (C, N, P) and photosynthetic pigments were measured throughout the core which spans from the middle Holocene until modern day. Our research questions were: 1) What were the sedimentary nutrient and stoichiometric changes associated with the Rx-Fire period beginning in 1937 CE? and 2) Did these nutrient changes alter historic algae/cyanobacteria groups? Following the onset of Rx-fire, nutrients (C, N, P) increased in deposition in the lake with P showing the greatest proportional increase at over 300%, suggesting that P inputs from Rx-fire are a primary artifact of burning. Photosynthetic pigments showed that increases in nutrients from Rx-fire caused extensive increases in total primary producer abundance and cyanobacteria dominance, called pyroeutrophication. These data suggest a greater need to understand the implications of fire-associated nutrients on aquatic primary producers wherever fire (but especially Rx-fire) is occurring, as well as an increase in collaboration between forest and aquatic ecosystem managers.

With accelerated warming, mountain glaciers in most parts of the world have been in a state of continuous retreat in recent decades. Assessing glacier change and analyzing its influencing factors are essential for developing climate change mitigation and adaptation measures for a given region. This study provides a spatially explicit assessment and quantification of glacier changes in the early 21st century on the Tibetan Plateau (TP) at individual glacier and basin scales. We established a one-to-one correspondence between the Second Chinese Glacier Inventory (CGI-2, collected from 2004 to 2011) and a dataset of glacier inventory in Western China during 2017–2018 (CGI-2018). The majority of TP’s glaciers decreased in size with a mean area retreat rate during the investigated period of 4.1%/decade. In addition, a mean change of the median elevation of the glaciers of 6.7 m/decade was detected. Approximately 2.5% of the total number of glaciers mapped in CGI-2 disappeared, while 681 of them divided to 1758 glaciers as they retreated. The observed variations follow local trends and have different regional characteristics. Generally, the glaciers with the lowest retreat rates are found in the Karakorum and Kunlun Mountains, while those with high retreat rates are concentrated along the Gangdis and Tangula ranges. The observed changes in glaciers are mainly attributed to a significant increase in temperature. Other factors including glacier size, debris cover, orientation and mean elevation also contribute to the heterogeneity of glacier variability. This study provides for the first time a detailed spatially explicit analysis of the glacial changes on the TP in the early 21st century, substantially improving the understanding of glacier response patterns and supporting more sustainable utilization of regional water resources in the TP in the context of climate warming in the 21st century.

The conceptual framework for nature-based solutions (NbS) is well developed, however realizing the potential of NbS at scale and in widespread professional practice in infrastructure systems depends on overcoming operational challenges rooted in the historical policies and engineering practices of the action agencies capable of implementation. In this article, we explore levee setbacks as a NbS for improving the sustainability of leveed river corridors within the context of the United States (US) and its primary action agency of flood risk management, the Army Corps of Engineers (USACE). By identifying the social and environmental consequences of historical levee management and linking these consequences with historical policies and engineering practices, we highlight knowledge gaps, challenges and opportunities for progress with NbS. We also briefly discuss USACE’s decision-making processes for infrastructure investments and the valuation of ecosystem services as it pertains to operationalizing setbacks in practice. We then develop a case study of a recent setback on the Missouri River to showcase how USACE overcame implementation challenges. Lessons from past levee corridor management in the US, and USACE’s current corrective actions, may help foster understanding of how to overcome operational challenges in the implementation of setbacks in other social and political contexts.

Worldwide, trajectories of deterioration of large rivers’ natural structure and functioning have been described and related to anthropogenic pressures acting at different spatio-temporal scales. However, the variety of methodologies, time-scale resolutions and the lack of standard indicators frequently hinder the comparison of outcomes among rivers in different geographic and climatic regions. Covering between 204 and 36 years, this study applied the same multi-temporal analysis of riverine trajectories (i.e., anthropization, changeless, progression, and regression) in five large river segments within temperate (Rhine River, France and Germany), Mediterranean (Ebro and Tagus Rivers, Spain), and semi-arid climates (Aras and the Zayandeh-rud Rivers, Iran). This transferable GIS-based method includes the assessment of historical balances within natural dynamics (Natural Trajectory Index, NTI), the degree of anthropization (Anthropization Ratio, AR), and the degree of stability (Stability Ratio, SR) in the studied river-floodplain systems.

Results show similarities among the European case studies (i.e., Rhine, Ebro and Tagus rivers) in response to hydromorphological impacts, with percentage increases in human-induced changes (i.e., anthropization), and habitat development (i.e., progression). Apart from the Zayandeh-rud River, that presents a marked tendency toward progression, processes of habitat rejuvenation (i.e., regression) have almost disappeared in all case studies, and riverine forms remain unchanged. The differences found between the European and the Asian case studies are considered related to the aims and methods of engineering choices for historical river management, with a long history of river reprofiling and impounding in European rivers, while Iranian regulation is relatively recent, and involves extensive inter-basin water transfers.

This study investigates the relationship between the spatial distribution patterns of heavy metals (HMs) in atmospheric fine particulate matter (PM_2.5) and their influencing factors in China, in order to address air pollution problems. Using HM data from PM_2.5 collected from 88 Chinese cities between 2012 and 2020, the study employed a combination of enrichment factor (EF) analysis, standard deviation ellipses and hot spot analysis to assess spatial distribution patterns; geographical detectors to identify influencing factors; and hybrid single-particle Lagrangian integrated trajectory models (HYSPLIT) to determine air mass movement. The results reveal that the spatial distribution of PM_2.5-bound HMs in China is characterized by high levels in the north and interior and low levels in the south and along the coast. Anthropogenic activities affect HM levels in China's interior more strongly than on the coast. Moreover, the distribution of PM_2.5-bound HMs in China exhibits a northeast-southwest spatial pattern, with significantly higher levels observed in central and northern regions than in eastern regions, particularly along the coast. Industrial waste emissions and energy consumption are key factors contributing to high PM_2.5-bound HMs. In central China, the summer air mass movement predominantly follows a southeast direction, while in winter, it follows a northwest direction, originating from inland. In contrast, in eastern China, summer air mass movement predominantly follows a southeast direction, while in winter, it follows a northeast direction, originating from the ocean. Overall, our findings suggest that HMs in PM_2.5 display high clustering values in central China, due primarily to industrial waste emissions, energy consumption, and air mass movement.

Vegetation dynamics is crucial for understanding vegetation ecosystem processes in arid and semi-arid regions. The Inner Mongolia Autonomous Region (IMAR) is a typical arid and semi-arid region in China, where vegetation has been significantly altered in response to multiple disturbances over recent decades. However, vegetation dynamics under changing environment and the integrated driving effects on natural and anthropogenic factors are unclear for environmentally sensitive and fragile areas. Therefore, Normalized Difference Vegetation Index (NDVI) as an indicator of vegetation status to systematically analyze the temporal and spatial characteristics of the vegetation dynamics in the IMAR from 2000 to 2020, and we quantify the independent and integrated effects of natural and anthropogenic factors on vegetation changes through Geo-detector. Additionally, we quantitatively separate the driving factors of vegetation from the perspective of dry-wet zones, and explored the different regional vegetation dynamics and its relationship with natural and human activities. The results showed that: (1) Vegetation had generally shown an upward trend with an interannual variability of 0.0186 a⁻¹ from 2000 to 2020. (2) The spatial pattern of vegetation had obvious differences. Most of the improvement was mainly concentrated in the east of IMAR covered 69.14%, and degradation in the western desert region. (3) Natural factors were more influential than anthropogenic factors, precipitation had the greatest explanatory power for the spatial heterogeneity of vegetation with a q value of 80.28%, and the integrated effects on vegetation changes were strongest for precipitation and other drivers. (4) The main drivers affecting NDVI changes are more variable in different wet-dry zones, and precipitation gradients determined explanatory power and the relative importance of natural and anthropogenic factors for vegetation changes. These results contributed more insight into the driving mechanisms underlying vegetation dynamics, while being critical for predicting and evaluating vegetation recovery and vegetation ecosystem stability in the context of global climate change, especially in environmentally sensitive and fragile areas.

Land-use change was the main source of anthropogenic CO₂ emissions until the mid-twentieth century, especially due to deforestation processes. In recent decades, however, CO₂ sequestration is being induced in some countries where forest area is experiencing net increases. Despite the key role of these processes, we hardly dispose of any empirical evidence of historical changes in biomass stocks, especially in the long-term (over 50 years) and in cultivated areas. In this study, we quantify the evolution of the surface area, carbon stocks (C) and C density of living biomass in Spain (50 provinces) between 1860 and 2010. According to our results, the C stock fell from 340.3 Tg C to 254.2 Tg C between 1860 and 1950, to then reach 844.0 Tg C in 2010. Although the stock began to increase much later than in other European countries, annual growth rates were much more significant. A decomposition analysis allowed us to observe that the increase in stock was mainly due to the change in C density (61.2% of the effect), surface area (35.3%) and, to a lesser extent, to the effect of location in more productive areas (5.7%). Woody crops – which were historically managed as agroforestry systems when combined with other crops – stored 15.8% of total stocks during the period studied. They play a particularly important role in areas with a Mediterranean climate because in these provinces, crops such as olive groves, vineyards or oranges have proliferated. The reasons for C stock increases are: the substitution of firewood with fossil fuels; agricultural intensification; and the outsourcing of land use to other countries through agricultural imports.

This paper presents a geomorphological reconstruction of the urban landscape of Erbil (Kurdistan Region of Iraq), aimed at explaining how human groups settled the region since the prehistory and contributed modifying natural surface processes. Our reconstruction on landforms evolution is based on satellite and historical aerial images and field control allowing the reconstruction of changes in land use over time. The city of Erbil was established along a fertile alluvial plain during the Chalcolithic period and grew around the pristine citadel, which was likely built on top of fluvial features. Prior to the mid-20th century, Erbil was centred around the citadel and relied on traditional systems for water management such as artificial basins and qanats. The city underwent intense urban expansion since the 1950 s and changed its shape due to the construction of roads and residential and industrial areas, which led to the obliteration of the pristine fluvial network. The analysis of historical and current satellite images highlights the profound modification of the landscape triggered by human actions and a progressive shift of local land use from agricultural to urban. This, coupled with human agency on the natural hydrography led to the increase susceptibility of the city to geomorphological hazard (especially floods). Our investigation suggests that during the Anthropocene the dynamic of urbanization reach a tipping point, when excessive urban growth suffers the effect of geomorphological hazard. For that reason, urbanization in the Anthropocene must consider the existence of natural geomorphological processes.