Northern Part Of Mexico Research Articles

Wind and solar powered reverse osmosis desalination units - design, start up, operating experience

To demonstrate the operation of RO units with GKSS plate modules coupled with unconventional energy supply systems, two projects are presently carried out by the GKSS research center applying a photovoltaic solar generator and a wind energy converter for a site in the Northern part of Mexico and a small island at the German coast of the North Sea, respectively. The solar generator with a designed peak power of 2.5 kW is developed by AEG and powers a RO unit for the desalination of brackish well water. The plant has been installed in Concepcion del Oro, Zacatecas, in spring 1980 and has been operated by the Mexican company DIGAASES in cooperation with AEG and GKSS since May 1980. The second project is a 6 kw-wind energy converter supplying 3 RO-modules with a total membrane area of 30 m 2. After comprehensive component tests at the GKSS research center at Geesthacht the plant was installed at the very small island of Sūderoog at the German coast of the North Sea. Test operation was started in December 1980. For both plants a measurement program has been started.

Notes on the Distribution of the Russian Thistle (Salsola kali L. var. tenuifolia) in Mexico

THE Russian thistle (Salsola kali L. var. tenuifolia Tausch) called T in some parts of Mexico saladilla is an important weed in the dry regions of the United States. It was introduced in 1873 or 1874 to South Dakota and from there migrated to the West and Southwest, reaching California between 1892 and 1895 (6), where it constitutes a serious problem. The fast invasion by this plant of the United States semiarid lands would be expected to continue into the Northern States of Mexico in which a semiarid climate is found too. However, it was not reported by Muller, either in Nuevo Leon (4) or in Coahuila (5), as late as 1947; also, it is not reported by Leseur who studied the northern part of Chihuahua (3). It seems that S. Kali did not exist abundantly on the other side of the border because Cory and Parks in 1937 (1) mention it in their Catalogue of the Flora of Texas but Reeves and Bain do not include it in 1947 as a component of the flora of South Central Texas (7). Indeed some individuals were present in Mexico, but probably in a very scanty number; thus Johnston (2) reports that Endlich collected the species between Mapiml and Ojuelos, Durango (Figure 1); however the plant was not found by Johnston, who collected in the States of Chihuahua, Coahuila and Northern Durango and Zacatecas. It is interesting to note that the plant was seen by only one worker rather far south from the border and none was found in the northern parts of Mexico. In recent papers by Rzedowski (8, 9) the plant is not mentioned either; however, in a personal communication it was indicated that this author collected Salsola both in Zacatecas (12 Kms. NE from Concepcion del Oro) and San Luis Potosi (10 Kms. S from El Salado). In 1957, Vald's2 collected in various regions of Northern Mexico and found the plant around Torreon, Coahuila (Figure 1). Again, the species was found far from the border and apparently still scarce. In October 1958, the senior author collected samples of S. kali, West from Monterrey, Nuevo Leon (Km. 333 on the highway to Saltillo) and he was told that the weed was established south of Saltillo in potato fields. In the summer of 1959 collected in the central and northeast part of Me1xico and observed Salsola in the following points (Figure 1):

Tectonics of Mexico

It has been attempted to present in this paper, for the first time, an idea of the tectonics of Mexico as a whole, based on the concepts developed mainly by Alpine geologists for the study of orogenic processes. With this object in view, the paper was divided in two parts; the first, in which was established the meaning of the concepts in order to fix the sense in which they will be used and to point out in a general way the orogenic processes to which the region of Mexico was subjected; the second part in which are described the major structural units, from a tectonic point of view, especially as to the character and orientation of their folds, since the character of the major units is mainly established from the character of the folds. There have been established in the foreland of the Mexican geosyncline, three shelves, a large massif, two small ones, and four basins. There have been postulated for the hinterland a great massif or continent, two large massifs, two medium and four small massifs, and three basins. The foredeep of the geosynclinal fold has been indicated in three regions, as established by the flysch sediments deposited therein. It is considered that the geosyncline of the Mexican Cordillera begins west of Ciudad Juarez extending southward to Torreon, where it turns eastward to Monterrey, and from there, southeastward to the Coatzacoalcos River, thence northeastward to the Chalchijapan River, and upon reaching the narrowest part of the Isthmus of Tehuantepec, it turns east-southeastward into Guatemala. It is established that the principal orogeny which gave rise to this folding started at the end of the Cretaceous in the northern part of Mexico and at the beginning of the Eocene in the rest of the country, and ended at the end of the Eocene excepting in the southeast where it lasted until the beginning of the Oligocene. Furthermore, there were embryonic and posthumous movements, the last of which is very important, in the Isthmus and the Macuspana and Pichucalco basins. End_Page 1319------------------------------ Fig. 1. TECTONIC MAP OF THE REPUBLIC OF MEXICO End_Page 1320------------------------------

The Genus Monarda in Oklahoma

The genus Monarda (Labiatae), is indigenous only in North America where its distribution includes all of the southern Canadian provinces, nearly every state in the United States, and the northern part of Mexico. The nine species found in Oklahoma are abundantly distributed on dry plains, in sandy soil, and in open woods. Collections to date have been made from 49 of the 77 counties. M. pune tata appears to be the most widely distributed, occurring in 24 counties. Others in order of frequency are M. mollis which is found in 20 counties; M. clinopodioides in 16; M. dispersa in 14; M. citriodora in 9; M. Russelliana in 8; M. Brad buriana in 7; M. fistulosa in 5; and M. pectinata in 4. Present records are by no means complete, because many counties have received little attention from collectors.