Estimating background and threshold nitrate concentrations using probability graphs

Because of the ubiquitous nature of anthropogenic nitrate (NO3(-)) in many parts of the world, determining background concentrations of NO3(-) in shallow ground water from natural sources is probably impossible in most environments. Present-day background must now include diffuse sources of NO3(-) such as disruption of soils and oxidation of organic matter, and atmospheric inputs from products of combustion and evaporation of ammonia from fertilizer and livestock waste. Anomalies can be defined as NO3(-) derived from nitrogen (N) inputs to the environment from anthropogenic activities, including synthetic fertilizers, livestock waste, and septic effluent. Cumulative probability graphs were used to identify threshold concentrations separating background and anomalous NO(3)-N concentrations and to assist in the determination of sources of N contamination for 232 spring water samples and 200 well water samples from karst aquifers. Thresholds were 0.4, 2.5, and 6.7 mg/L for spring water samples, and 0.1, 2.1, and 17 mg/L for well water samples. The 0.4 and 0.1 mg/L values are assumed to represent thresholds for present-day precipitation. Thresholds at 2.5 and 2.1 mg/L are interpreted to represent present-day background concentrations of NO(3)-N. The population of spring water samples with concentrations between 2.5 and 6.7 mg/L represents an amalgam of all sources of NO3(-) in the ground water basins that feed each spring; concentrations > 6.7 mg/L were typically samples collected soon after springtime application of synthetic fertilizer. The 17 mg/L threshold (adjusted to 15 mg/L) for well water samples is interpreted as the level above which livestock wastes dominate the N sources.

Characterization and identification of na-cl sources in ground water

Elevated concentrations of sodium (Na+) and chloride (Cl-) in surface and ground water are common in the United States and other countries, and can serve as indicators of, or may constitute, a water quality problem. We have characterized the most prevalent natural and anthropogenic sources of Na+ and Cl- in ground water, primarily in Illinois, and explored techniques that could be used to identify their source. We considered seven potential sources that included agricultural chemicals, septic effluent, animal waste, municipal landfill leachate, sea water, basin brines, and road deicers. The halides Cl-, bromide (Br), and iodide (I) were useful indicators of the sources of Na+-Cl- contamination. Iodide enrichment (relative to Cl-) was greatest in precipitation, followed by uncontaminated soil water and ground water, and landfill leachate. The mass ratios of the halides among themselves, with total nitrogen (N), and with Na+ provided diagnostic methods for graphically distinguishing among sources of Na+ and Cl- in contaminated water. Cl/Br ratios relative to Cl- revealed a clear, although overlapping, separation of sample groups. Samples of landfill leachate and ground water known to be contaminated by leachate were enriched in I and Br; this provided an excellent fingerprint for identifying leachate contamination. In addition, total N, when plotted against Cl/Br ratios, successfully separated water contaminated by road salt from water contaminated by other sources.

Adolescent motherhood. Comparison of outcome with older mothers

The purpose of this study was to determine whether there were differences in maternal role attainment behaviors for three age groups (15-19, 20-29, 30-42 years) of 294 first-time mothers over a 1-year period. Interviews and questionnaires were completed at early postpartum, 1, 4, 8, and 12 months. Findings are in agreement with more recent research that the health status of adolescent mothers and their infants does not differ greatly from that of older mothers during the first year of motherhood. The adolescent's infant's growth and development were not handicapped. There were no group differences in feelings of love for the infant. The adolescent mother consistently scored lower than older mothers on observed and self-rated maternal competency behaviors. The adolescent mother derived greater gratification in the mothering role than older mothers through 8 months; at 12 months, the 20-29-year-old mother scored higher in gratification. The help received from the adolescent's mother declined at 8 and 12 months suggesting an increased need for social support from other sources at this time.

Relationship of psychosocial and perinatal variables to perception of childbirth

This study reported on a sample of 294 first-time mothers. Fifty-six women who delivered by cesarean birth perceived their childbirth experience more negatively than those who delivered vaginally. However, the type of delivery accounted for only 1% of the variance when entered with 24 other psychosocial and obstetrical variables for stepwise multiple regression analysis. Mate emotional support contributed 20% and early maternal-infant interaction contributed 9.8% of the variance, with total positive self-concept, fewer medical complications, informative support, instrumental support, and type of delivery accounting for the remainder of the total 39%.