A metropolitan city such as Los Angeles (LA) is an ideal study site with a very high population density, and it houses at least 3 treatment plants where sewage is treated preliminarily and then progressing to tertiary...A metropolitan city such as Los Angeles (LA) is an ideal study site with a very high population density, and it houses at least 3 treatment plants where sewage is treated preliminarily and then progressing to tertiary treatment before discharging into the LA River. We will gain a better understanding of the water quality in the LA River and the nitrate load in the watershed system by examining the influence of waste water treatment plants (WWTPs). The goal of this study is to pinpoint the exact source of nitrate in the LA River using the isotope signatures. We have selected sampling locations both upstream and downstream of the WWTP. This serves to monitor nitrate levels, aiding in the assessment of treatment plant effectiveness, pinpointing nitrate pollution sources, and ensuring compliance with environmental regulations. The research explores the isotopic composition of NO3 in relation to atmospheric nitrogen and Vienna Standard Mean Ocean Water, shedding light on the contributions from various sources such as manure, sewage, soil organic nitrogen, and nitrogen fertilizers. Specifically, there is a change in the δ15NAir value between the dry and wet seasons. The isotope values in the Tillman WWTP sample changed between dry and wet seasons. Notably, the presence of nitrate originating from manure and sewage is consistent across seasons, emphasizing the significant impact of anthropogenic and agricultural activities on water quality. This investigation contributes to the broader understanding of nitrogen cycling in urban water bodies, particularly in the context of wastewater effluent discharge. The findings hold implications for water quality management and highlight the need for targeted interventions to mitigate the impact of nitrogen-containing compounds on aquatic ecosystems. Overall, the study provides a valuable framework for future research and environmental stewardship efforts aimed at preserving the health and sustainability of urban water resources. This data informs decisions regarding additional treatment or mitigation actions to safeguard downstream water quality and ecosystem health.展开更多
As a typical car-dependent city,Los Angeles(LA) is extensively used as an example in research to illustrate car influences on city form. Focusing on the features of LA's geologic conditions and civil circumstances...As a typical car-dependent city,Los Angeles(LA) is extensively used as an example in research to illustrate car influences on city form. Focusing on the features of LA's geologic conditions and civil circumstances,we argued that the relationship between LA's low-density pattern and car dependence is more involved than previously deemed simple causality. The low density should be primarily credited to the spacious requirement of the mining industry,frequent earthquakes and multiethnic population of the city. Oil reserves in LA fueled its economic boom and fast urbanization that coincided with the start of mass production of cheap cars,and cars became medium-priced consumables for average families. Politicians preference for short construction-period projects enabled fast establishment of LA's highway infrastructure. The popularity of car use in return faciliatated further development of the low-density pattern of the city. The low-density urban form and car dependence created environmental and social problems for LA. Looking at P. R. China's motorization and urban development,we found that the trajectory of Beijing's motorization between 1978 and 2003 coincides with that of the U.S. in the 1910s and 1920s. Lessons from LA's urban and transportation development should be suggestive to China's urban and transportation planning.展开更多
There thought to be a great weakness in the construction of Angel in Tess for Angel's illogically changeable character.The author holds,however,that Angel's character is reasonable as he is a man in the Victor...There thought to be a great weakness in the construction of Angel in Tess for Angel's illogically changeable character.The author holds,however,that Angel's character is reasonable as he is a man in the Victorian Age.This article tries to interpret the male subject deconstruction with post-modern theory to demonstrate the concern to the female in Hardy's work.展开更多
文摘A metropolitan city such as Los Angeles (LA) is an ideal study site with a very high population density, and it houses at least 3 treatment plants where sewage is treated preliminarily and then progressing to tertiary treatment before discharging into the LA River. We will gain a better understanding of the water quality in the LA River and the nitrate load in the watershed system by examining the influence of waste water treatment plants (WWTPs). The goal of this study is to pinpoint the exact source of nitrate in the LA River using the isotope signatures. We have selected sampling locations both upstream and downstream of the WWTP. This serves to monitor nitrate levels, aiding in the assessment of treatment plant effectiveness, pinpointing nitrate pollution sources, and ensuring compliance with environmental regulations. The research explores the isotopic composition of NO3 in relation to atmospheric nitrogen and Vienna Standard Mean Ocean Water, shedding light on the contributions from various sources such as manure, sewage, soil organic nitrogen, and nitrogen fertilizers. Specifically, there is a change in the δ15NAir value between the dry and wet seasons. The isotope values in the Tillman WWTP sample changed between dry and wet seasons. Notably, the presence of nitrate originating from manure and sewage is consistent across seasons, emphasizing the significant impact of anthropogenic and agricultural activities on water quality. This investigation contributes to the broader understanding of nitrogen cycling in urban water bodies, particularly in the context of wastewater effluent discharge. The findings hold implications for water quality management and highlight the need for targeted interventions to mitigate the impact of nitrogen-containing compounds on aquatic ecosystems. Overall, the study provides a valuable framework for future research and environmental stewardship efforts aimed at preserving the health and sustainability of urban water resources. This data informs decisions regarding additional treatment or mitigation actions to safeguard downstream water quality and ecosystem health.
基金Funded by Key Project of the Natural Science Foundation of China under the grant No. 40635026.
文摘As a typical car-dependent city,Los Angeles(LA) is extensively used as an example in research to illustrate car influences on city form. Focusing on the features of LA's geologic conditions and civil circumstances,we argued that the relationship between LA's low-density pattern and car dependence is more involved than previously deemed simple causality. The low density should be primarily credited to the spacious requirement of the mining industry,frequent earthquakes and multiethnic population of the city. Oil reserves in LA fueled its economic boom and fast urbanization that coincided with the start of mass production of cheap cars,and cars became medium-priced consumables for average families. Politicians preference for short construction-period projects enabled fast establishment of LA's highway infrastructure. The popularity of car use in return faciliatated further development of the low-density pattern of the city. The low-density urban form and car dependence created environmental and social problems for LA. Looking at P. R. China's motorization and urban development,we found that the trajectory of Beijing's motorization between 1978 and 2003 coincides with that of the U.S. in the 1910s and 1920s. Lessons from LA's urban and transportation development should be suggestive to China's urban and transportation planning.
文摘There thought to be a great weakness in the construction of Angel in Tess for Angel's illogically changeable character.The author holds,however,that Angel's character is reasonable as he is a man in the Victorian Age.This article tries to interpret the male subject deconstruction with post-modern theory to demonstrate the concern to the female in Hardy's work.
