Metal ratio mixing models clarify metal contamination sources to lake sediments in Yunnan, China.

Contaminated legacy sediments contribute to modern pollution loadings, particularly trace metals. These contributions are challenging to quantify as metal histories reconstructed from sediment records cannot be easily divided into legacy and concurrent contamination. In particular, the contribution from re-mobilization and delivery of legacy metals stored in catchment soil, colluvial, and fluvial environments are rarely considered or quantified when interpreting sediment records.

Severe Little Ice Age drought in the midcontinental United States during the Mississippian abandonment of Cahokia.

Drought has long been suspected as playing an important role in the abandonment of pre-Columbian Native American settlements across the midcontinental United States between 1350 and 1450 CE. However, high-resolution paleoclimatic reconstructions reflecting local effective moisture (the ratio of precipitation to evaporation) that are located in proximity to Mississippi period (1050-1450 CE) population centers are lacking. Here, we present a 1600-year-long decadally resolved oxygen isotope (δO) record from Horseshoe Lake (Collinsville, IL), an evaporatively influenced oxbow lake that is centrally located within the largest and mostly densely populated series of Mississippian settlements known as Greater Cahokia.

Contrasting ecosystem responses to climatic events and human activity revealed by a sedimentary record from Lake Yilong, southwestern China.

Global climate change and human activities have significantly impacted lake ecosystems at an accelerating rate in recent decades, but the differences between the responses of lake ecosystems to these two stressors remain unclear. Thus an improved understanding of the long-term influences of climatic and anthropogenic disturbances is necessary for the management of lake ecosystems. In order to address these issues, a sedimentary record was obtained from Lake Yilong in Yunnan Province in southwestern China, where the climate and natural environment are dominated by the Indian Summer Monsoon and there is a long history of human occupation and intensive human activity.

Reconstructing Early Industrial Contributions to Legacy Trace Metal Contamination in Southwestern Pennsylvania.

Early industrial trace metal loadings are poorly characterized but potentially substantial sources of trace metals to the landscape. The magnitude of legacy contamination in southwestern Pennsylvania, the cradle of North American fossil fuel industrialization, is reconstructed from trace metal concentrations in a sediment core with proxies including major and trace metal chemistry, bulk density, and magnetic susceptibility. Trace metal chemistry in this sediment record reflects 19th and 20th century land use and industry.

Environmental legacy of copper metallurgy and Mongol silver smelting recorded in Yunnan Lake sediments.

Geochemical measurements on well-dated sediment cores from Lake Er (Erhai) are used to determine the timing of changes in metal concentrations over 4500 years in Yunnan, a borderland region in southwestern China noted for rich mineral deposits but with inadequately documented metallurgical history. Our findings add new insight into the impacts and environmental legacy of human exploitation of metal resources in Yunnan history. We observe an increase in copper at 1500 BC resulting from atmospheric emissions associated with metallurgy.