Contamination of green bay water with lead and cadmium by a 37-m long, 2-m draft research vessel

During late April 1989, Green Bay, Lake Michigan water was sampled for dissolved concentrations of lead and cadmium. Samples used to document horizontal contamination of the water by a research vessel were collected using a rubber boat rowed 2, 50, 100, and 200 m upwind of the anchored mother ship. Samples used to document vertical contamination of the water column by the research vessel were collected from the vessel at water depths of 0.2, 2, 5, 10, and 20 m. Both lead and cadmium blanks were < 0.5 ng/l and below their limits of detection at the 95% level of confidence of 3.5 and 0.98 ng/l, respectively. Concentrations of lead in the horizontal direction varied between 3.5 ng/l at 200 m from the ship and 7.7 ng/l at 2 m from the ship. Cadmium concentrations varied from 2.8 ng/l at 2 m from the ship to 1.5 ng/l at 200 m from the ship. Lead concentrations in the vertical direction varied between 8.4 ng/k at a depth of 0.2 m and 3.3 ng/l at 5 m. Cadmium concentrations ranged between 4.5 ng/l at 2 m and 2.2 ng/l at 20 m. The vertical studies were inconclusive and appeared to be influenced by resuspension of bottom sediments. Uncontaminated samples can be collected as close as 100 m to the research vessel.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29851/1/0000198.pd

A numerical simulation of trichromatic equations in chlorophyll estimation using the spectrophotometric technique

A numerical simulation of trichromatic pigment equations is made with the aid of a computer utility program. Significant quantitative differences in the estimates of pigment concentration result from using different sets of trichromatic equations. Estimates of chlorophylls a, b , and c were found highly correlated with the application of the equations, even though the absorbance values used as input for the stimulation are not correlated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42911/1/10750_2004_Article_BF00006323.pd

Changes in the abundance of blue-green algae related to nutrient loadings in the nearshore of Lake Michigan

Nutrient loadings to the nearshore of southeastern Lake Michigan have undergone a remarkable reduction. This reduction can affect the nutrient supply and result in biological changes. Changes in phytoplankton community, particularly the blue-green algae, can be related to nutrient changes. After thermal stratification, sudden increases in the blue-green algae population were significantly correlated to soluble reactive phosphorus concentrations. Phosphorus-stimulated low dissolved silica and phosphorus limitations after stratification appear to be primary factors contributing to the success of these algae.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42875/1/10750_2004_Article_BF00004203.pd

¿Es posible la felicidad en estudiantes universitarios?: un estudio no paramétrico

The question, Is happiness possible in university students? guides the present quantitative research aimed at 237 students (men and women) of the University of the Autonomous Regions of the Nicaraguan Caribbean Coast. This Research is based on a descriptive design, applying the Alarcon’s scale of happiness (2006) taking into account the variables of gender, age, ethnicity and years of study. For this, different types of analysis were performed, among them: internal consistency of the questionnaire, the analysis of main components, and a study of correlations between the categories applying the Kolmogorov normality tests, the Mann-Whitney U test, test from Wilcoxon, Kruskal Wallis, and the Friedman test, using the SPSS statistical package. The results show that happiness in university students is possible taking into account that it is merely subjective in people and, around it, different elements are included that make it possible. In this sense, it is concluded that the variables ethnicity, age, gender and years of study do not have a direct relationship with the state of happiness of the students, since they are not determinants to define this state in the human being.La pregunta ¿es posible la felicidad en estudiantes universitarios? guía la presente investigación cuantitativa dirigida a 237 estudiantes (hombres y mujeres) de la Universidad de las Regiones Autónomas de la Costa Caribe Nicaragüense. Investigación que está sustentada en un diseño descriptivo, aplicando la escala de felicidad de Alarcón (2006) tomando en consideración las variables de género, edad, etnia y años de estudio. Para ello, se realizó diferentes tipos de análisis, entre estos: de consistencia interna del cuestionario, el análisis de componentes principales, y un estudio de correlaciones entre las categorías aplicando las pruebas de normalidad de Kolmogorov, la prueba U de Mann-Whitney, prueba de Wilcoxon, Kruskal Wallis, y la prueba de Friedman, utilizando el paquete estadístico de SPSS. Los resultados demuestran que la felicidad en estudiantes universitarios sí es posible tomando en cuenta que la misma es meramente subjetiva en las personas y, a su alrededor se engloban diferentes elementos que la hacen posible. En este sentido, se concluye que las variables etnia, edad, género y años de estudio no tienen una relación directa con el estado de felicidad de los estudiantes, pues no son determinantes para definir este estado en el ser humano

Lake Michigan Ferromanganese Nodules.

PhDFreshwater ecologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/189730/2/7324669.pd

Geochemistry of Lake Michigan manganese nodules

Manganese nodules, similar in composition to other freshwater and shallow marine nodules, occur on the sediment surface of green bay and northern lake Michigan. Samples have been analyzed for their iron, manganese, calcium, magnesium, sodium, potassium, inorganic carbon, organic carbon, and total nitrogen content. The nodules average 20% iron and 6% manganese. the trace metal content (copper, zinc, cobalt, and nickel) of the samples is considerably lower than that of marine material. Interstitial water is one of the major contributors of manganese and iron for the growth of nodules in lake Michigan. Cores of green bay sediment show an inverse relationship between sedimentary and interstitial manganese with the sedimentary manganese increasing to a maximum at or near the sediment-water interface. Sedimentary iron remains fairly constant throughout the length of these cores while interstitial iron decreases slightly toward the sediment-water interface. in addition, lake water may be more than a passive contributor of iron and manganese. There are indications that as much as one-half of the manganese found in lake water is particulate. The source of this material is believed to be the iron deposits of the Canadian shield that have been subsequently leached of manganese and iron

(Table 1, page 1124), Chemical composition of Lake Michigan manganese nodules

Manganese nodules containing up to 22 percent manganese oxide were found in Green Bay and the western and northern parts of Lake Michigan. The chemical composition of these nodules resembles that of shallow-water lacustrine and marine nodules. The manganese content of interstitial water is in some places enriched as much as 4000 times over that of lake water