Pb pollution from leaded gasoline in South America in the context of a 2000-year metallurgical history

Exploitation of the extensive polymetallic deposits of the Andean Altiplano in South America since precolonial times has caused substantial emissions of neurotoxic lead (Pb) into the atmosphere; however, its historical significance compared to recent Pb pollution from leaded gasoline is not yet resolved. We present a comprehensive Pb emission history for the last two millennia for South America, based on a continuous, high-resolution, ice core record from Illimani glacier. Illimani is the highest mountain of the eastern Bolivian Andes and is located at the northeastern margin of the Andean Altiplano. The ice core Pb deposition history revealed enhanced Pb enrichment factors (EFs) due to metallurgical processing for silver production during periods of the Tiwanaku/Wari culture (AD 450–950), the Inca empires (AD 1450–1532), colonial times (AD 1532–1900), and tin production at the beginning of the 20th century. After the 1960s, Pb EFs increased by a factor of 3 compared to the emission level from metal production, which we attribute to gasoline-related Pb emissions. Our results show that anthropogenic Pb pollution levels from road traffic in South America exceed those of any historical metallurgy in the last two millennia, even in regions with exceptional high local metallurgical activity.

Biodiversity and Fishery Sustainability in the Lake Victoria Basin: An Unexpected Marriage?

Lake Victoria is Africa’s single most important source of inland fishery production. After it was initially fished down in the first half of the 20th century, Lake Victoria became home to a series of introduced food fishes, culminating in the eventual demographic dominance of the Nile perch, Lates niloticus. Simultaneously with the changes in fish stocks, Lake Victoria experienced dramatic changes in its ecology. The lake fishery during most of the 20th century was a multispecies fishery resting on a diverse lake ecosystem, in which native food fishes were targeted. The lake ended the century with a much more productive fishery, but one in which three species — two of them introduced — made up the majority of the catch. Although many fish stocks in Lake Victoria had declined before the expansion of the Nile perch population, a dramatic increase in the population size of Nile perch in the 1980s roughly coincided with the drastic decline or disappearance of many indigenous species. Now, two decades after the rise of Nile perch in Lake Victoria, this species has shown signs of being overfished, and some of the native species that were in retreat — or even thought extinct — are now reemerging. Data on the resurgence of the indigenous species suggest that heavy fishing of Nile perch may enhance biodiversity; this has spawned renewed interest in management options that promote both fishery sustainability and biodiversity conservation.

A History of Organized Medicine in Harris County, Texas

The item was written by the Historical Committee of the Harris County Medical Society and signed on October 28, 1948. A brief history of medicine in Texas is given before the focus shifts to the Harris County and Houston area. Information on the early years is taken from various sources such as Pat Ireland Nixon’s The Medical Story of Early Texas and the writings of George Plunkett (Mrs. S. C.) Red. Significant information comes from the Minutes of the Harris County Medical Society.

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Early Conceptual Sketch of Site Plan], untitled. Blue ink sketch on tracing paper, initialed, 12 x 28 1/2 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Early Conceptual Sketch of Site Plan], untitled. Green ink sketch on tracing paper, 12x23 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Conceptual Sketch], untitled. Blue ink sketch on tracing paper, 12 x 18 1/2 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Conceptual Sketch], untitled. Blue ink sketch on tracing paper, 12x13 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Conceptual Sketch], untitled. Blue and green ink sketch with yellow and green marker coloring on tracing paper, 18 x 20 1/4 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Conceptual Sketch of Structure], untitled. Blue ink sketch on tracing paper with notations, initialed, 12x16 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Conceptual Sketches], untitled. Ink sketches on graph paper, 8 1/2 x 11 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Conceptual Sketches], untitled. Ink sketches on graph paper, 8 1/2 x 11 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Facade Study], untitled. Blue ink sketch on tracing paper, 12 x 21 1/2 inches [from photographic copy by Lance Burgharrdt]

Minnesota History Center Competition, St. Paul, Minnesota, 1984-1986 (unbuilt project)

[Facade Study], untitled. Pencil and purple pencil drawing on vellum, 13 3/4 x 24 inches [from photographic copy by Lance Burgharrdt]