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Volume 1: \"The Earth's oceans are currently undergoing unprecedented changes: rivers have suffered a severe reduction in their sediment transport, and as a result, sediment input to the oceans has dropped lower than ever before. These inputs have varied over millennia as a result of both natural occurrences and human actions, such as the building of dams and the extraction of materials from riverbeds. Sedimentary Crisis at the Global Scale 1 examines how river basins have been affected by the sedimentary crises of various historical epochs. By studying global balances, it provides insights into the profound disruption of the solid transport of fluvial bodies. The book also explores studies of various rivers, from the Amazon, which remains relatively unaffected, to dying rivers such as the Colorado and the Nile.\" -- Back cover.

An ecosystem in freefall, a shrinking water supply for cities and agriculture, an antiquated network of failure-prone levees—this is the Sacramento-San Joaquin Delta, the major hub of California's water system. Written by a team of independent water experts, this analysis of the latest data evaluates proposed solutions to the Delta's myriad problems. Through in-depth economic and ecological analysis, the authors find that the current policy of channeling water exports through the Delta is not sustainable for any interest. Employing a peripheral canal-conveying water around the Delta instead of through it—as part of a larger habitat and water management plan appears to be the best strategy to maintain both a high-quality water supply and at the same time improve conditions for native fish and wildlife. This important assessment includes integrated analysis of long term ecosystem and water management options and demonstrates how issues such as climate change and sustainability will shape the future. Published in cooperation with the Public Policy Institute of California

Winner of the 2012 George Perkins Marsh Prize for Best Book in Environmental History In the twentieth century, the Mekong Delta has emerged as one of Vietnam s most important economic regions. Its swamps, marshes, creeks, and canals have played a major role in Vietnam s turbulent past, from the struggles of colonialism to the Cold War and the present day. Quagmire considers these struggles, their antecedents, and their legacies through the lens of environmental history. Beginning with the French conquest in the 1860s, colonial reclamation schemes and pacification efforts centered on the development of a dense network of new canals to open land for agriculture. These projects helped precipitate economic and environmental crises in the 1930s, and subsequent struggles after 1945 led to the balkanization of the delta into a patchwork of regions controlled by the Viet Minh, paramilitary religious sects, and the struggling Franco-Vietnamese government. After 1954, new settlements were built with American funds and equipment in a crash program intended to solve continuing economic and environmental problems. Finally, the American military collapse in Vietnam is revealed as not simply a failure of policy makers but also a failure to understand the historical, political, and environmental complexity of the spaces American troops attempted to occupy and control. By exploring the delta as a quagmire in both natural and political terms, Biggs shows how engineered transformations of the Mekong Delta landscape - channelized rivers, a complex canal system, hydropower development, deforestation - have interacted with equally complex transformations in the geopolitics of the region. Quagmire delves beyond common stereotypes to present an intricate, rich history that shows how closely political and ecological issues are intertwined in the human interactions with the water environment in the Mekong Delta. Watch the book trailer: https://www.youtube.com/watch?v=gp1-UItZqsk Winner of the 2012 George Perkins Marsh Prize for Best Book in Environmental History In the twentieth century, the Mekong Delta has emerged as one of Vietnam s most important economic regions. Its swamps, marshes, creeks, and canals have played a major role in Vietnam s turbulent past, from the struggles of colonialism to the Cold War and the present day. Quagmire considers these struggles, their antecedents, and their legacies through the lens of environmental history. Beginning with the French conquest in the 1860s, colonial reclamation schemes and pacification efforts centered on the development of a dense network of new canals to open land for agriculture. These projects helped precipitate economic and environmental crises in the 1930s, and subsequent struggles after 1945 led to the balkanization of the delta into a patchwork of regions controlled by the Viet Minh, paramilitary religious sects, and the struggling Franco-Vietnamese government. After 1954, new settlements were built with American funds and equipment in a crash program intended to solve continuing economic and environmental problems. Finally, the American military collapse in Vietnam is revealed as not simply a failure of policy makers but also a failure to understand the historical, political, and environmental complexity of the spaces American troops attempted to occupy and control. By exploring the delta as a quagmire in both natural and political terms, Biggs shows how engineered transformations of the Mekong Delta landscape - channelized rivers, a complex canal system, hydropower development, deforestation - have interacted with equally complex transformations in the geopolitics of the region. Quagmire delves beyond common stereotypes to present an intricate, rich history that shows how closely political and ecological issues are intertwined in the human interactions with the water environment in the Mekong Delta. Watch the book trailer: http://www.youtube.com/user/UWashingtonPress#p/u/2/gp1-UItZqsk

This Delta, This Land is a comprehensive environmental history of the Yazoo-Mississippi Delta--the first one to place the Delta's economic and cultural history in an environmental context. The Delta, the floodplain between two great rivers in the northwestern corner of Mississippi, has changed enormously since the Civil War. Agriculture, lumbering, and flood-management schemes have transformed it beyond recognition--and beyond any prospects for a full recovery. However, says Mikko Saikku, the 150 years following the Civil War brought greater environmental change than we generally realize. Indeed, the long-term environmental history of the Delta is much more complex than our current view of it, which privileges recent periods rather than presenting the entire continuum. Looking across thousands of years, Saikku examines successive human societies in the Delta, drawing connections between environmental and social problems and noting differences between Native Americans and Euro-Americans in their economies, modes of production, and land-use patterns. Saikku's range of sources is astonishing: travel literature, naturalists' writings, government records, company archives, archaeological data, private correspondence, and more. As he documents how such factors as climate and water levels shaped the Delta, he also reveals the human aspects of the region's natural history, including land reclamation, slave and sharecropper economies, ethnic and racial perceptions of land ownership and stewardship, and even blues music.

The world’s river deltas are increasingly vulnerable due to pressures from human activities and environmental change. In deltaic regions, the distribution of salinity controls the resourcing of fresh water for agriculture, aquaculture and human consumption; it also regulates the functioning of critical natural habitats. Despite numerous insightful studies, there are still significant uncertainties on the spatio-temporal patterns of salinity across deltaic systems. In particular, there is a need for a better understanding of the salinity distribution across deltas’ channels and for simple predictive relationships linking salinity to deltas’ characteristics and environmental conditions. We address this gap through idealized three-dimensional modelling of a typical river-dominated delta configuration and by investigating the relationship between salinity, river discharge and channels’ bifurcation order. Model results are then compared with real data from the Mississippi River Delta. Results demonstrate the existence of simple one-dimensional and analytical relationships describing the salinity field in a delta. Salinity and river discharge are exponentially and negatively correlated. The Strahler-Horton method for stream labelling of the delta channels was implemented. It was discovered that salinity increases with decreasing stream order. These useful relationships between salinity and deltas’ bulk features and geometry might be applied to real case scenarios to support the investigation of deltas vulnerability to environmental change and the management of deltaic ecosystems.

Regional air pollution is significantly associated with dominant weather systems. In this study, the relationship between the particle pollution over the Yangtze River Delta (YRD) region and weather patterns is investigated. First, the pollution characteristics of particles in the YRD are studied using in situ monitoring data (PM2.5 and PM10) in 16 cities and Terra/MODIS AOD (aerosol optical depth) products collected from December 2013 to November 2014. The results show that the regional mean value of AOD is high in the YRD, with an annual mean value of 0.71±0.57. The annual mean particle concentrations in the cities of Jiangsu Province all exceed the national air quality standard. The pollution level is higher in inland areas, and the highest concentrations of PM2.5 and PM10 are 79 and 130 µg m−3, respectively, in Nanjing. The PM2.5  :  PM10 ratios are typically high, thus indicating that PM2.5 is the overwhelmingly dominant particle pollutant in the YRD. The wintertime peak of particle concentrations is tightly linked to the increased emissions during the heating season as well as adverse meteorological conditions. Second, based on NCEP (National Center for Environmental Prediction) reanalysis data, synoptic weather classification is conducted and five typical synoptic patterns are objectively identified. Finally, the synthetic analysis of meteorological fields and backward trajectories are applied to further clarify how these patterns impact particle concentrations. It is demonstrated that air pollution is more or less influenced by high-pressure systems. The relative position of the YRD to the anti-cyclonic circulation exerts significant effects on the air quality of the YRD. The YRD is largely influenced by polluted air masses from the northern and the southern inland areas when it is located at the rear of the East Asian major trough. The significant downward motion of air masses results in stable weather conditions, thereby hindering the diffusion of air pollutants. Thus, this pattern is quite favorable for the accumulation of pollutants in the YRD, resulting in higher regional mean PM10 (116.5 ± 66.9 µg m−3), PM2.5 (75.9 ± 49.9 µg m−3), and AOD (0.74) values. Moreover, this pattern is also responsible for the occurrence of most large-scale regional PM2.5 (70.4 %) and PM10 (78.3 %) pollution episodes. High wind speed and clean marine air masses may also play important roles in the mitigation of pollution in the YRD. Especially when the clean marine air masses account for a large proportion of all trajectories (i.e., when the YRD is affected by the cyclonic system or oceanic circulation), the air in the YRD has a lesser chance of being polluted. The observed correlation between weather patterns and particle pollution can provide valuable insight into making decisions about pollution control and mitigation strategies.

Abstract Rapid warming in Arctic tundra may lead to drier soils in summer and greater lightning ignition rates, likely culminating in enhanced wildfire risk. Increased wildfire frequency and intensity leads to greater conversion of permafrost carbon to greenhouse gas emissions. Here, we quantify the effect of recent tundra fires on the creation of methane (CH 4 ) emission hotspots, a fingerprint of the permafrost carbon feedback. We utilized high-resolution (∼25 m 2 pixels) and broad coverage (1780 km 2 ) airborne imaging spectroscopy and maps of historical wildfire-burned areas to determine whether CH 4 hotspots were more likely in areas burned within the last 50 years in the Yukon–Kuskokwim Delta, Alaska, USA. Our observations provide a unique observational constraint on CH 4 dynamics, allowing us to map CH 4 hotspots in relation to individual burn events, burn scar perimeters, and proximity to water. We find that CH 4 hotspots are roughly 29% more likely on average in tundra that burned within the last 50 years compared to unburned areas and that this effect is nearly tripled along burn scar perimeters that are delineated by surface water features. Our results indicate that the changes following tundra fire favor the complex environmental conditions needed to generate CH 4 emission hotspots. We conclude that enhanced CH 4 emissions following tundra fire represent a positive feedback that will accelerate climate warming, tundra fire occurrence, and future permafrost carbon loss to the atmosphere.

A regional fully coupled meteorology–chemistry model, Weather Research and Forecasting model with Chemistry (WRF-Chem), was employed to study the seasonality of ozone (O3) pollution and its sources in both China and India. Observations and model results suggest that O3 in the North China Plain (NCP), Yangtze River Delta (YRD), Pearl River Delta (PRD), and India exhibit distinctive seasonal features, which are linked to the influence of summer monsoons. Through a factor separation approach, we examined the sensitivity of O3 to individual anthropogenic, biogenic, and biomass burning emissions. We found that summer O3 formation in China is more sensitive to industrial and biogenic sources than to other source sectors, while the transportation and biogenic sources are more important in all seasons for India. Tagged simulations suggest that local sources play an important role in the formation of the summer O3 peak in the NCP, but sources from Northwest China should not be neglected to control summer O3 in the NCP. For the YRD region, prevailing winds and cleaner air from the ocean in summer lead to reduced transport from polluted regions, and the major source region in addition to local sources is Southeast China. For the PRD region, the upwind region is replaced by contributions from polluted PRD as autumn approaches, leading to an autumn peak. The major upwind regions in autumn for the PRD are YRD (11 %) and Southeast China (10 %). For India, sources in North India are more important than sources in the south. These analyses emphasize the relative importance of source sectors and regions as they change with seasons, providing important implications for O3 control strategies.

Background: The occurrence of halogenated analogs of the xenoestrogen bisphenol A (BPA) has been recently demonstrated both in environmental and human samples. These analogs include brominated [e.g., tetrabromobisphenol A (TBBPA)] and chlorinated [e.g., tetrachlorobisphenol A (TCBPA) bisphenols, which are both flame retardants. Because of their structural homology with BPA, such chemicals are candidate endocrine disruptors. However, their possible target(s) within the nuclear hormone receptor superfamily has remained unknown. Objectives: We investigated whether BPA and its halogenated analogs could be ligands of estrogen receptors (ERs) and peroxisome proliferator-activated receptors (PPARs) and act as endocrine-disrupting chemicals. Methods: We studied the activity of compounds using reporter cell lines expressing ERs and PPARs. We measured the binding affinities to PPARγ by competitive binding assays with [³H]-rosiglitazone and investigated the impact of TBBPA and TCBPA on adipocyte differentiation using NIH3T3-L1 cells. Finally, we determined the binding mode of halogenated BPAs to PPARγ by X-ray crystallography. Results: We observed that TBBPA and TCBPA are human, zebrafish, and Xenopus PPARγ ligands and determined the mechanism by which these chemicals bind to and activate PPARγ. We also found evidence that activation of ERα, ERß, and PPARγ depends on the degree of halogenation in BPA analogs. We observed that the bulkier brominated BPA analogs, the greater their capability to activate PPARγ and the weaker their estrogenic potential. Conclusions: Our results strongly suggest that polyhalogenated bisphenols could function as obesogens by acting as agonists to disrupt physiological functions regulated by human or animal PPARγ.

The WRF-Chem model coupled with a single-layer urban canopy model (UCM) is integrated for 5 years at convection-permitting scale to investigate the individual and combined impacts of urbanization-induced changes in land cover and pollutant emissions on regional climate in the Yangtze River Delta (YRD) region in eastern China. Simulations with the urbanization effects reasonably reproduced the observed features of temperature and precipitation in the YRD region. Urbanization over the YRD induces an urban heat island (UHI) effect, which increases the surface temperature by 0.53 °C in summer and increases the annual heat wave days at a rate of 3.7 d yr−1 in the major megacities in the YRD, accompanied by intensified heat stress. In winter, the near-surface air temperature increases by approximately 0.7 °C over commercial areas in the cities but decreases in the surrounding areas. Radiative effects of aerosols tend to cool the surface air by reducing net shortwave radiation at the surface. Compared to the more localized UHI effect, aerosol effects on solar radiation and temperature influence a much larger area, especially downwind of the city cluster in the YRD. Results also show that the UHI increases the frequency of extreme summer precipitation by strengthening the convergence and updrafts over urbanized areas in the afternoon, which favor the development of deep convection. In contrast, the radiative forcing of aerosols results in a surface cooling and upper-atmospheric heating, which enhances atmospheric stability and suppresses convection. The combined effects of the UHI and aerosols on precipitation depend on synoptic conditions. Two rainfall events under two typical but different synoptic weather patterns are further analyzed. It is shown that the impact of urban land cover and aerosols on precipitation is not only determined by their influence on local convergence but also modulated by large-scale weather systems. For the case with a strong synoptic forcing associated with stronger winds and larger spatial convergence, the UHI and aerosol effects are relatively weak. When the synoptic forcing is weak, however, the UHI and aerosol effects on local convergence dominate. This suggests that synoptic forcing plays a significant role in modulating the urbanization-induced land-cover and aerosol effects on individual rainfall event. Hence precipitation changes due to urbanization effects may offset each other under different synoptic conditions, resulting in little changes in mean precipitation at longer timescales.