The United States Department of the Interior (DOI) is one of the executive departments of the U.S. federal government headquartered at the Main Interior Building, located at 1849 C Street NW in Washington, D.C.. It is responsible for the management and conservation of most federal lands and natural resources, and the administration of programs relating to Native Americans, Alaska Natives, Native Hawaiians, territorial affairs, and insular areas of the United States, as well as programs related to historic preservation. About 75% of federal public land is managed by the department, with most of the remainder managed by the Department of Agriculture's Forest Service. The department was created on March 3, 1849.The department is headed by the Secretary of the Interior, who reports directly to the President of the United States and is a member of the president's Cabinet. The current secretary is Deb Haaland. Despite its name, the Department of the Interior has a different role from that of the interior ministries of other nations, which are usually responsible for police matters and internal security. In the United States, national security and immigration functions are performed by the Department of Homeland Security primarily and the Department of Justice secondarily. The Department of the Interior has often been humorously called "the Department of Everything Else" because of its broad range of responsibilities.
The Neuwied Basin within the East Eifel Volcanic Field (EEVF) is characterized by increased microseismicity, long hypothesized to be linked to the subsurface Ochtendung Fault Zone (OFZ). However, the source of this unrest remained elusive due to limited hypocentre resolution. Here, we present an extended local earthquake catalogue, compiled from a year-long Large-N deployment and a machine learning-based detection and location approach, including over 1000 microearthquakes recorded between September 2022 and August 2023. This high-resolution data set reveals new seismicity clusters, repeated waveforms and distinct temporal bursts of activity, suggesting fluid-induced earthquake triggering. Probabilistic moment tensor inversion for 192 high-quality events (Mw 0.6-2.7) resolves predominantly strike-slip faulting along the OFZ, with localized clusters of normal faulting nearby, potentially associated with a previously unknown border fault of the NWB. Notably, we observe systematic rotations in P-axis orientations along the OFZ, which we interpret as localized stress perturbations induced by an overpressured reservoir beneath the Laacher See volcano-the youngest explosive eruption centre in the EEVF. These patterns, coupled with elevated magmatic $\rm {CO}_2$ emissions in the region and high waveform similarity, suggest that active magmatic and transcrustal fluid processes are influencing the stress regimes and driving the seismicity in the NWB. Our high-resolution seismicity and moment tensor catalogue offers new insights into the interplay between tectonics and fluid-driven processes beneath the youngest volcanoes in the EEVF.
Many eutrophication studies focus on the external supply of critical nutrients like nitrogen and phosphorus, but hydrology and geomorphology can enhance or dampen the effects of excessive nutrient supply. We studied six backwater lakes in the Upper Mississippi River that varied in water residence time and water depth. Eutrophication in these systems is responsible for negative impacts such as cyanobacterial blooms and toxicity, and floating plant and algal mats that disrupt recreational water uses. Increasing backwater residence time was associated with more nitrate removal and a greater likelihood of nitrogen limitation, as well as greater accumulations of duckweed. Backwaters with greater depth and lower nitrogen concentration had less likelihood of filamentous algal accumulations. The median water residence time of backwaters with low duckweed (11.7 days) and no filamentous algae (16.9 days) approached the 12-day target to maintain overwintering conditions in backwaters for fisheries survival, supporting that water residence times in this range would likely improve both winter and summer water quality. Mean depth in backwaters with low duckweed and no filamentous algae was similar to 1.3 m, while shallower backwaters were more likely to produce duckweed and filamentous algae mats. This indicates that deeper backwaters might reduce the likelihood of eutrophication impacts. Natural resource management at the local level may not always be able to answer global and regional threats, but habitat restoration of hydrology and geomorphology can possibly alleviate or reduce large-scale threats at the local level.
Economic concentrations of rare earth element (REE) minerals are uncommon in the Earth's crust, with most occurring in carbonatites. Unlike most igneous rocks composed of silicate minerals, carbonatites are dominated by carbonate minerals, some of which can incorporate substantial light REEs (LREEs; La, Ce, Pr, Nd). Technological applications of REEs are numerous, and they have been identified as some of the most critical mineral commodities to the global economy. The Mountain Pass carbonatite stock in the Mojave Desert of California is the most economically significant REE deposit in the U.S.A. It contains a few to tens of percent (by volume) of the carbonate REE ore mineral bastn & auml;site. Despite the economic significance of the Mountain Pass deposit, studies of its ore mineralogy are limited. Here, we present new carbonate ore mineralogy data for a compositionally diverse suite of carbonatitic rocks from the Mountain Pass stock and related dikes. Whole-rock geochemical data are integrated with mineral-scale textural and chemical data obtained by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and microRaman spectroscopy. Our results document a complex spectrum of REE-bearing carbonate minerals and intermediate mixed-layer structures. Mineral species include bastn & auml;site [REE(CO3)F], hydroxylbastn & auml;site [REE(CO3)OH], parisite [Ca(REE)2(CO3)3F2], synchysite [Ca(REE)(CO3)2F], r & ouml;ntgenite [Ca2(Ce,La)3(CO3)5F3], and sahamalite [(Mg,Fe)(REE)2(CO3)4]. Carbonate ore mineralogy is heterogeneous within and between samples, including at the intracrystal scale. Complexly zoned crystals exhibit as many as five to six different compositional domains and syntaxial intergrowths, commonly with the more Ca-rich varieties (parisite, synchysite) forming crystal rims that surround relict bastn & auml;site cores. We attribute the phenocryst variability to changes in the chemistry and temperature of primary carbonatite magmas and evolved/exsolved fluids. Cross-cutting vein textures of calcite, celestine and various REE carbonate minerals, breccia blocks lined by fine-grained bastn & auml;site, and the presence of hydroxylbastn & auml;site and partially hydroxylated bastn & auml;site point to the role of secondary hydrothermal processes in REE mineralization. Fluorcarbonate mineral compositions demonstrate that La and Ce are more structurally abundant in bastn & auml;site, whereas parisite and synchysite contain a greater proportion of REE heavier than Pr (Nd, Sm, Eu, Gd) and Y. Atomic ratios of Pr/(Nd+Pr) are likewise variable, with the highest average value for bastn & auml;site (0.25) compared to parisite (0.22) and synchysite (0.21). This finding has geometallurgical implications, given that current mining operations are focused on recovering Nd and Pr for high field strength permanent magnets, and the Nd/Pr ratios are a critical factor in ore processing and magnet manufacture.
