14. September 2022 | Magazine:

Tracking down traces in the mega-city Joint study trip of environmental scientists and physicists to Mexico City

Geoelectrics, seismics, georadar within sight of volcanoes, water and sediment investigations in the nature reserves of the megacity: Students from Technische Universität Braunschweig recently spent ten days researching in Mexico City and getting to know the country’s culture. On their study trip – organised by Dr Liseth Pérez from the Institute of Geosystems and Bioindication and Professor Matthias Bücker from the Institute of Geophysics and Extraterrestrial Physics – the prospective environmental scientists and physicists investigated urban ecosystems in one of the largest cities in the world. Students Nora Kraatz and Natalie Müller report on their excursion:

“We – five environmental science students and five physics students – went on a study trip to Mexico City for ten days in August 2022. The environmental scientists collected lots of water and sediment samples on lakes, canals and ponds in nature reserves and parks in and around Mexico City in order to then analyse them for water chemistry, chlorophyll content and biodiversity. In cooperation with the Universidad Nacional Autónoma de México (UNAM), the Instituto Politécnico Nacional (IPN) and the company Geotem Ingeniería, the physicists investigated the subsoil in the south of the city using various geophysical methods. They worked together with students from UNAM and IPN.

In addition to the field measurements and sampling, a varied cultural programme was also on the agenda. Whether delicious Mexican cuisine or trips to the indigenous peoples of Mexico, there was something for everyone. But just take a look for yourself at what we experienced on our trip!”

Arrival in Mexico: Our journey begins early in the morning in Berlin, where our group meets at the BER check-in. After everyone has passed through the security check more or less quickly, the plane can take off in the direction of Newark (USA). Around 9 hours later, the first stage is completed and we are allowed to fight our way through American immigration and customs. After a short stopover, we continue to our final destination, Mexico City. Five hours later we have finally made it: We are in Mexico! Here you can see us after our about 21-hour long journey at the airport in Mexico City at 10 p.m. local time. Photo credit: Matthias Bücker/TU Braunschweig

Campus of the Universidad Nacional Autónoma de México (UNAM): After a much too short night, we set off from the hotel at 8.30 a.m. The first item on our agenda is a visit to the UNAM campus in the south of the city. There we can get an idea of the huge dimensions of this university (UNAM has over 300,000 members). Photo credit: Nora Kraatz/TU Braunschweig

A lecture programme offers us insights into the many study opportunities in the geosciences and an overview of the geological development of the Mexico City valley. Of particular interest is the omnipresent influence of the volcanoes surrounding the city on its development, as well as the possibility of reconstructing climate changes through the laborious analysis of sediment deposits at the bottom of the lakes that once covered the entire floor of Mexico City's high valley. Photo credit: Liseth Pérez/TU Braunschweig

Museo Nacional de Culturas Populares: After lunch on campus, where we get to taste Mexican cuisine for the first time, we head to a popular nightlife district of the city: Coyoacán. There we first visit the Museo Nacional de Culturas Populares, which offers us an insight into Mexican folk dances. Here we look at colourful headdresses and masks that are traditionally worn during the dances. Photo credit: Liseth Pérez/TU Braunschweig

A small highlight of the museum is a craft room. There we build dolls with individual masks. We all take on this little challenge and create our own personal dolls. You can see the creative results in this photo. Photo credit: Nora Kraatz/TU Braunschweig

Fried grasshoppers and guacamole: Afterwards, we stroll through a market hall and end the evening in one of Coyoacán's many restaurants. In addition to our first tequila, we also have a culinary delicacy there: Fried grasshoppers (chapulines) with guacamole and nachos! Photo credit: Natalie Müller/TU Braunschweig

Museo Nacional de Antropología: Our second day is all about Mexico's history. Our first stop is the Museo Nacional de Antropologiá, which invites us on a journey through time to the many ancient peoples of Mexico. Photo credit: Liseth Pérez/TU Braunschweig

... The morning planned for this is just enough to visit the exhibitions on the Mayas, the culture of Teotihuacán and the Aztecs. Photo credit: Liseth Pérez/TU Braunschweig

Mexican caviar: To round things off, we get to taste something really exquisite in the museum's restaurant: "escamoles", deliciously spiced ant larvae and pupae. Photo credit: Liseth Pérez/TU Braunschweig

Ángel de la Independencia: After the museum visit, we take a short walk through the city to the Ángel de la Independencia, in front of which we are posing here. Photo credit: Liseth Pérez/TU Braunschweig

Templo Mayor: To continue our journey through the city's history, we then drive to the historic centre of the city, where the remains of the pre-Hispanic indigenous Mexica culture (seen in the picture in the form of the pyramid ruins of the Templo Mayor) meet the culture of the Spanish conquerors. Photo credit: Matthias Bücker/TU Braunschweig

After a long day full of history, we head to Plaza Garibaldi. There we listen to the sounds of countless mariachi bands and visit the Tequila Museum. Photo credit: Liseth Pérez/TU Braunschweig

On the third day we have an early start to the pyramids of Teotihuacán. First we have a delicious breakfast buffet near the pyramids and then we head off strengthened to the impressive ruins, with a small stopover at a local agave mining area, where we learn something about the use of the agave plant and get to feel like "real" Mexicans. Photo credit: Nora Kraatz/TU Braunschweig

Here we are seen strolling along the Calzada de los Muertos, the huge boulevard that cuts through the once 20 square kilometre city from north to south. The Pyramid of the Moon can be seen in the background. Photo credit: Matthias Bücker/TU Braunschweig

The impressive Pyramid of the Sun at Teotihuacán is the third largest pyramid in the world. Photo credit: Nora Kraatz/TU Braunschweig

On the way back to Mexico City, we make a spiritual stop at a shaman's house. The shaman makes contact with the old gods of the Aztecs and frees us from evil spirits and misfortune in a traditional "limpia". Photo credit: Francisco Mendez

The Basílica de Santa María de Guadalupe is the last stop on this eventful day. It can accommodate 10,000 believers, making it one of the largest churches in Latin America. The visit to the Basílica marks the end of the intensive cultural programme. The next day, the work begins, as from now on, the field work, sampling and microscopy are on the programme. Photo credit: Nora Kraatz/TU Braunschweig

Morning atmosphere with volcanoes: The geophysicists already set off at 7.30 a.m. for the test site in Xochimilco in the south of the city, from where, with luck, you can also see Popocatepetl (on the horizon at the back right) in the morning. Geoelectrics, seismics, georadar, transient electromagnetics and magnetics are on the agenda for the next four days. Photo credit: Dennis Kreith/TU Braunschweig

Geophysics team: Together with ten Mexican students from UNAM (Universidad Nacional Autónoma de México) and IPN (Instituto Politécnico Nacional), the otherwise quite strenuous field work is instantly much easier. Photo credit: Matthias Bücker/TU Braunschweig

Hammer impact seismics: Seismic waves are generated by powerful blows with a sledgehammer, which propagate in the subsurface, are reflected at layer boundaries and refract. The vibrations are recorded at the surface. From the measured data, the geophysicists can reconstruct the layered structure of the subsurface. Photo credit: Matthias Bücker/TU Braunschweig

Cables, cables and cables again: In the morning, we often first have to get the cables in order for the day. Here we are preparing particularly long cables (600 m in total) for transient electromagnetic measurements, which will help us to "see" down to a depth of several hundred metres. Photo credit: Matthias Bücker/TU Braunschweig

Full commitment: The environmental scientists also set off not quite so early in the morning. On the first day, for example, to the UNAM Botanical Garden. Here, samples are to be taken for later analysis of water chemistry, sediments and biodiversity (plankton, benthos). We use various nets and vials for this. Sometimes we have to use our whole bodies and get into the water. In the course of the afternoon we finish the work so that we can end the evening with delicious Mexican food and cervezas (beer). Photo credit: Nora Kraatz/TU Braunschweig

Ballet Folklórico: Wednesday evening offers a cultural highlight in the middle of the internship week. After a joint dinner, we go to the Mexican ballet, which is not comparable to the usual ballet... Photo credit: Nora Kraatz/TU Braunschweig

... Traditional Mexican dances are performed in extravagant dresses to the music of mariachi groups. Photo credit: Nora Kraatz/TU Braunschweig

Mexico's first national park: The environmental scientists visit Mexico's oldest national park, the Desierto de los Leones, which was established in 1917 high in the mountains above the city. Photo credit: Liseth Pérez/TU Braunschweig

... Compared to the heavily polluted urban waters, the water quality here is much better. On the way back, the bus driver spontaneously turns his vehicle into a party bus and drives us back to the city as a closed party with 80s music cranked up to full blast! Photo credit: Liseth Pérez/TU Braunschweig

Wrap-up on the canals of Xochimilco: On the last day, after a first rough evaluation of their collected data, the geophysicists meet the environmental scientists for a last sampling on the canals of the nature reserve of Xochimilco. After the samples have been collected, the end of a successful internship week can be celebrated here again to mariachi music and with lots of delicious food and drinks! Photo credit: Nora Kraatz/TU Braunschweig

Farewell to Mexico and to the group: On our last day, we visit the beautiful historic district of San Ángel to stroll through the Mexican street markets together one last time and buy some nice souvenirs. Here you can see our joint souvenir of this eventful excursion. Photo credit: Dennis Kreith/TU Braunschweig

Expression of gratitude by the students
This excursion was supported by government funding for educational quality of the Faculty of Architecture, Civil Engineering and Environmental Sciences and the Faculty of Electrical Engineering, Information Technology, Physics. It was organised by Liseth Pérez (Institute of Geosystems and Bioindication) and Matthias Bücker (Institute of Geophysics and Extraterrestrial Physics). We would also like to thank Itzel Sigala, Sergio Rodríguez, María del Pilar Ortega, María Martínez, Margarita Caballero, Marie Guilbaud, Socorro Lozano, Susana Sosa, Christina Siebe, and Ricardo Barragán (UNAM) as well as Gerson Ríos and Carlos Pita (Geotem Ingeniería) for their great support on site.