UAV-borne LiDAR revolutionizing groundwater level mapping.

In hydrogeological research, the systematic and periodic measurement of the piezometric level is fundamental to assess aquifer storage, identify recharge and discharge areas, define flow directions and to infer the balance between inputs and withdrawals. Furthermore, knowledge of this variable and its fluctuations is essential for the efficient management and protection of groundwater resources. In this work, a novel methodology is proposed for the remote acquisition of piezometric information from traditional large-diameter wells, using drone-borne LiDAR observations. The workflow developed consists of different stages, from flight planning and parameter setting, to point cloud generation, data processing and validation and its statistical treatment to extract piezometric information. This methodology has been applied in a small coastal aquifer with numerous wells that have served as monitoring points. The UAV-LiDAR has enabled the straightforward obtention of measurements of the piezometric level with very high vertical accuracies (RMSE of 5 cm) with minimum and maximum residuals of -8.7 and 7.9 cm respectively. Likewise, the method has shown vertical accuracies 3 times better than those inferred from the official DTM of best resolution available in Spain, which is usually used in hydrogeological works. Since the technique provides absolute values of the piezometric level, it eliminates the need for laborious levelling work prior to hydrogeological campaigns. This method has proved to be an effective alternative/complementary technique to traditional measurements of the piezometric level, allowing to monitor extensive or inaccessible areas over short periods of time and to potentially reduce gaps in hydrogeological databases.

Fractionation of U and heavy metals into the colloidal fraction in acid mine drainage conditions in the Río Tinto area (SW Spain).

The Río Tinto mining area provides ideal conditions for studying the role of colloidal particles in concentrating. All the elements are present in higher concentrations respect to their content in common natural waters. 234U/238U activity ratio ranges between 2.286 ±â€¯0.149 and 2.531 ±â€¯0.151. Concentration of Fe and Al are in the order of 104-103 mg/L; Co, Zn and Cu values are three times lower than Fe and Al, but still much greater than in natural waters; U reaches values up to 40.73 µg/L. To evaluate the partitioning of these elements into the colloidal fraction, ultrafiltration (UF) experiments were made. A permeation model describing the relationship between concentration of the elements or isotopes in the permeate solution and the concentration factor (CF) was calculated. Experiments were carried out using CF from 1.5 to 25.0. The behaviour of investigated heavy metals and U can be predicted by a permeation model that provides similar permeation coefficient (Pc) for all of them (Pc = 0.95-0.97 for 50 kDa, Pc = 0.86-0.88 for 10 kDa, and Pc = 0.80-0.86 for 3 kDa). Retention for all the investigated elements occurs, resulting in up to 23% of the element associated to the 3 kDa colloidal fraction. The increase in U and heavy metals concentrations in the retentate fraction with the increasing CF is due to the retention of the colloidal fraction. The colloidal abundance of related metals increased with decreasing membrane MWCO even though the difference is small between 3 and 10 kDa fraction for some metals Characterization of colloidal material is needed to better understand the state of play in this context.

[The heterotopic heart transplantation: first clinical experiences (author's transl)]. / Il trapianto cardiaco eterotopico. Esperienza clinica iniziale.

Ten patients, all men, have been operated of heterotopic heart transplantation since the end of 1974. Ages ranged from 59 to 24 years with an average of 38 years. Six of them suffered from ischaemic heart disease, two from cardiomiopathy and two from rheumatic heart disease. All of them presented end stage cardiac disease. The first two patients underwent to left ventricular bypass only, in the remaining eight a right and left bypass was performed. At the present time, June 1977, 6 of the original 10 patients are alive all of them in functional class I. Five of them have resumed a full time job, the sixth will be soon able to do so. Four patients died. There were no deaths from acute rejection, but three died from infection, and the fourth one from a pulmonary embolus, 4 months after transplantation. There has been only one episode of acute rejection which has responded well to the treatment. The advantages of the heterotopic versus the orthotopic cardiac transplantation are discussed.