During spring runoff events, herbicides in the Platte River are transported through an alluvial aquifer into collector wells located on an island in the river in 6 to 7 d. During two spring runoff events in 1995 and 1996, atrazine [2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine] concentrations in water from these wells reached approximately 7 µg/L, 70 times more than the background concentration in ground water. Concentrations of herbicides and metabolites in the collector wells generally were one‐half to one‐fifth the concentrations of herbicides in the river for atrazine, alachlor [2‐chloro‐2′‐6′‐diethyl‐N‐(methoxymethyl)‐acetanilide], alachlor ethane‐sulfonic acid (ESA) [2‐((2,6‐diethylphenyl) (methoxymethyl)amino)‐2‐oxoethane‐sulfonic acid], metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide], cyanazine [2‐((4‐chloro‐6‐(ethylamino)‐1,3,5 triazin‐2‐yl)‐amino)‐2‐methylpropionitrile], and acetochlor [2‐chloro‐N‐(ethoxymethyl)‐N‐(2‐ethyl‐6methyl‐phenyl) acetamide], suggesting that 20 to 50% river water could be present in the water from the collector wells, assuming no degradation. The effect of the river on the quality of water from the collector wells can be reduced through selective management of horizontal laterals of the collector wells. The quality of the water from the collector wells is dependent on the (i) selection of the collector well used, (ii) number and selection of laterals used, (iii) chemical characteristics of the contaminant, and (iv) relative mixing of the Platte River and a major upstream tributary.
The nature, occurrence and analysis of water pollutants is interesting chemically and relates well to the interdisciplinary nature of the modern chemistry curriculum. The issue is of worldwide significance and affects both wealthy and poor nations. In the first part of this paper we present an overview of water pollution in the United States and Mexico, including sources, federal regulations and standards, and standard methods for the assessment of overall water quality. The second part of the paper focuses on three water pollutants, lead, atrazine, and nitrate. We chose these as important representative examples of heavy metals, organic herbicides and inorganic pollutants. In addition to a background discussion of each substance and analysis methods for it, we describe laboratory activities that are suitable for the high school audience.
Current research on USS Arizona is focused on a minimum-impact technique for calculating corrosion rate of the battleship's steel hull by analysing physical and chemical properties of marine encrustation covering the exposed hull. An equation is derived that allows concretion thickness, density, and total iron content to be used to calculate corrosion rate of steel hull plate. © 2006 The AuthorsKey words: USS Arizona , steel corrosion, battleship, concretion, marine encrustation. The National Park Service's (NPS) Submerged Resources Center (SRC) and USS Arizona Memorial (USAR) are collaborating with the University of NebraskaLincoln (UNL) on research directed at understanding the nature and rate of natural processes affecting the deterioration of USS Arizona in Pearl Harbour, Hawaii (Fig. 1). The Pennsylvaniaclass battleship USS Arizona , completed in 1916, was sunk in Pearl Harbour on 7 December 1941 during the Japanese attack on the US Navy's Pacific Fleet. In the first 15 minutes of the attack, Arizona endured hits from several bombs, was strafed, and then at about 08.10 the battleship suffered a mortal blow. A Japanese Nakajima B5N2 'Kate' horizontal bomber dropped a single 1760-pound projectile that struck near Turret No. 2, penetrating deep into the battleship's interior before exploding and sympathetically detonating the forward magazine. When the forward magazine exploded most of the battleship's forward half was destroyed below the upper deck, including the forward oil bunkers. The ship sank in minutes, but the explosion ignited fires that raged for 2 1 / 2 days. A total of 1177 sailors and marines aboard Arizona were killed, and nearly 1000 men are still entombed within the ship. USS Arizona 's loss remains the largest single-ship loss of life in US naval history. The USS Arizona Preservation Project is multiyear, interdisciplinary and cumulative, with each element contributing to provide the basic research required to make informed management decisions for the battleship's long-term preservation. This project builds upon prior documentation and research conducted by SRC during the 1980s (Lenihan, 1989) and follows the minimumimpact approach advocated by the NPS (Murphy and Russell, 1997). The primary project focus is acquiring requisite data to understand the complex corrosion and deterioration processes affecting Arizona 's hull, both internally and externally, and modelling and predicting the nature and rate of structural changes ).An important aspect of this project is accurately to determine remaining hull thickness for inclusion in a Finite Element Analysis (FEA) being conducted by the National Institute of Standards and Technology (NIST) in Gaithersburg, MD. The FEA is designed to model Arizona 's structural deterioration and eventual collapseinformation critical for developing a sound, scientifically-based management plan and for determining when, or if, intervening in the vessel's natural deterioration should be considered. A key first-step in this process is determining the remaining thicknes...
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