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Elucidating details of biology’s selective uptake and trafficking of rare earth elements, particularly the lanthanides, has the potential to inspire sustainable biomolecular separations of these essential metals for myriad modern technologies. Here, we biochemically and structurally characterizeMethylobacterium(Methylorubrum)extorquensLanD, a periplasmic protein from a bacterial gene cluster for lanthanide uptake. This protein provides only four ligands at its surface-exposed lanthanide-binding site, allowing for metal-centered protein dimerization that favors the largest lanthanide, La^III. However, the monomer prefers Nd^IIIand Sm^III, which are disfavored lanthanides for cellular utilization. Structure-guided mutagenesis of a metal-ligand and an outer-sphere residue weakens metal binding to the LanD monomer and enhances dimerization for Pr^IIIand Nd^IIIby 100-fold. Selective dimerization enriches high-value Pr^IIIand Nd^IIIrelative to low-value La^IIIand Ce^IIIin an all-aqueous process, achieving higher separation factors than lanmodulins and comparable or better separation factors than common industrial extractants. Finally, we show that LanD interacts with lanmodulin (LanM), a previously characterized periplasmic protein that shares LanD’s preference for Nd^IIIand Sm^III. Our results suggest that LanD’s unusual metal-binding site transfers less-desirable lanthanides to LanM to siphon them away from the pathway for cytosolic import. The properties of LanD show how relatively weak chelators can achieve high selectivity, and they form the basis for the design of protein dimers for separation of adjacent lanthanide pairs and other metal ions. 

The Great Atlantic Sargassum Belt (GASB) first appeared in 2011 and quickly became the largest interconnected floating biome globally. Sargassum spp. requires both phosphorus (P) and nitrogen (N) for growth, yet the sources fueling the GASB are unclear. Here, we use coral–bound nitrogen isotopes from six coral cores to reconstruct N2 fixation, the primary source of bioavailable N to the surface ocean across the wider Caribbean over the past 120 years. Our data indicate that changes in N2 fixation were controlled by multidecadal and interannual changes in the supply of excess P from equatorial upwelling in the Atlantic. We show that the supply of P from equatorial upwelling and N from the N2 fixation response can explain the extent of the GASB since 2011. # Equatorial upwelling of phosphorus drives Atlantic N~2~ fixation and *Sargassum* blooms This Excel file contains time series data combining coral geochemical records (δ¹⁵N and δ¹⁸O), climate indices, Sargassum biomass, and major riverine outflows. The dataset integrates multiple spatially distributed records to examine long-term variability in nutrient dynamics, climate forcing, and ecological responses in the Caribbean and tropical Atlantic. Values that were not available or are missing are indicated as N/A. ## Column Reference Table File: Caribbean_data_for_DRYAD.xlsx | Column Name | Description | | :----------------------------------- | :------------------------------------------------------------------------------------------------- | | **Year\_CR\_Turneffe** | Calendar year of sampling for coral records from Turneffe Atoll (Belize) and Cahuita (Costa Rica). | | **Cahuita Costa Rica\_d18O\_ts** | Coral δ¹⁸O time series from Cahuita, Costa Rica (proxy for SST and freshwater input). | | **d15N\_CR** | Coral-bound δ¹⁵N from Cahuita, Costa Rica (proxy for nitrogen source/processing). | | **Turneffe Atoll\_d18O\_ts** | Coral δ¹⁸O time series from Turneffe Atoll, Belize. | | **d15N\_Turneffe** | Coral-bound δ¹⁵N from Turneffe Atoll. | | **Date\_MQ** | Sampling date for Martinique (MQ) site. | | **d18O\_MQ** | Coral δ¹⁸O from Martinique. | | **d15N\_MQ** | Coral δ¹⁵N from Martinique. | | **Year Bermuda** | Calendar year for Bermuda coral samples. | | **d15N Bermuda** | Coral δ¹⁵N from Bermuda. | | **Year\_CUBA** | Calendar year for Cuban coral records. | | **d15N\_CUBA** | Coral δ¹⁵N from Cuba. | | **d15N\_Mexico** | Coral δ¹⁵N from Mexico. | | **Year\_Tobago** | Calendar year for Tobago coral samples. | | **d15N\_Tobago** | Coral δ¹⁵N from Tobago. | | **Year AMM** | Year corresponding to Atlantic Meridional Mode (AMM) values. | | **AMM\_SST** | Sea Surface Temperature anomalies associated with the AMM. | | **AMM\_Wind** | Wind anomalies associated with the AMM. | | **AMO** | Atlantic Multidecadal Oscillation index value. | | **average\_year** | Averaged year across all coral records included. | | **AVERAGE\_rescaled** | Composite δ¹⁵N record rescaled across sites. | | **error\_propagated** | Propagated error estimate for the rescaled average. | | **AVERAGE\_rescaled\_noCR\_BM\_TB** | Rescaled δ¹⁵N average excluding Costa Rica, Bermuda, and Tobago. | | **error\_propagated2** | Propagated error for the reduced-site average. | | **Months Sargassum** | Month of Sargassum observation. | | **Monthly Sargassum biomass (tons)** | Monthly biomass estimates of pelagic Sargassum (tons). | | **Year\_SST\_SSS** | Year corresponding to SST/SSS data. | | **SST\_10-20N\_20-60W** | Sea Surface Temperature average over 10–20°N, 20–60°W. | | **SSS\_10-20N\_20-60W** | Sea Surface Salinity average over the same region. | | **U\_windstress\_10\_20N\_58\_62W** | Zonal wind stress (10–20°N, 58–62°W). | | **windspeed\_0\_20N\_20\_50W** | Mean wind speed (0–20°N, 20–50°W). | | **Geo\_u\_12\_18N\_60\_80W (CC)** | Geostrophic zonal velocity (12–18°N, 60–80°W), Caribbean Current proxy. | | **DU\_scav\_areaweight** | Dust deposition (scavenging flux, area-weighted). | | **DU\_ddep\_areaweight** | Dust dry deposition (area-weighted). | | **BC\_scav\_areaweight** | Black carbon scavenging flux (area-weighted). | | **Bc\_ddep\_areaweight** | Black carbon dry deposition (area-weighted). | | **BC\_total\_areaweight** | Total black carbon deposition (area-weighted). | | **DU\_total\_areaweight** | Total dust deposition (area-weighted). | | **Obidos\_Amazon\_m3\_s** | Amazon River discharge at Óbidos station (m³/s). | | **Ciudad Bolivar\_Orinoco\_m3\_s** | Orinoco River discharge at Ciudad Bolívar (m³/s). | | **Year Pstar** | Year corresponding to P\* (phosphorus excess) record. | | **Pstar** | Phosphorus excess (indicator of nutrient balance, micro Molar). | | **Amazon\_outflow\_date** | Date of Amazon outflow measurement. | | **Amazon\_outflow\_km3** | Amazon River outflow volume (km³). | | **Orinoco\_outflow\_date** | Date of Orinoco outflow measurement. | | **Orinoco\_outflow\_km3** | Orinoco River outflow volume (km³). | Links to other publicly accessible locations of the data: * [https://climexp.knmi.nl](http://...) Data was derived from the following sources: * Climate Explorer was used for gridded satellite-derived products (SST, SSS, windspeed, windstress) by using the geographical extent as indicated in the manuscript ## Code/Software No software was used for data analysis, and the codes used for figures and data analyses are available on GitHub ([https://github.com/marinejon/](https://github.com/marinejon/)) 

Abstract Technologically critical rare-earth elements are notoriously difficult to separate, owing to their subtle differences in ionic radius and coordination number^1–3. The natural lanthanide-binding protein lanmodulin (LanM)^4,5is a sustainable alternative to conventional solvent-extraction-based separation⁶. Here we characterize a new LanM, fromHansschlegelia quercus(Hans-LanM), with an oligomeric state sensitive to rare-earth ionic radius, the lanthanum(III)-induced dimer being >100-fold tighter than the dysprosium(III)-induced dimer. X-ray crystal structures illustrate how picometre-scale differences in radius between lanthanum(III) and dysprosium(III) are propagated toHans-LanM’s quaternary structure through a carboxylate shift that rearranges a second-sphere hydrogen-bonding network. Comparison to the prototypal LanM fromMethylorubrum extorquensreveals distinct metal coordination strategies, rationalizingHans-LanM’s greater selectivity within the rare-earth elements. Finally, structure-guided mutagenesis of a key residue at theHans-LanM dimer interface modulates dimerization in solution and enables single-stage, column-based separation of a neodymium(III)/dysprosium(III) mixture to >98% individual element purities. This work showcases the natural diversity of selective lanthanide recognition motifs, and it reveals rare-earth-sensitive dimerization as a biological principle by which to tune the performance of biomolecule-based separation processes. 

The proposed Anthropocene Global Boundary Stratotype Section and Point (GSSP) candidate site of West Flower Garden Bank (27.8762°N, 93.8147°W) is an open ocean location in the Gulf of Mexico with a submerged coral reef and few direct human impacts. Corals contain highly accurate and precise (<±1 year) internal chronologies, similar to tree rings, and their exoskeletons are formed of aragonite and can be preserved in the rock record. Here we present results from a large Siderastrea siderea coral (core 05WFGB3; 1755–2005 CE) sampled with annual and monthly resolutions that show clear markers of global and regional human impacts. Atmospheric nuclear bomb testing by-products (¹⁴C,^239+240Pu) have clear increases in this coral starting in 1957 for¹⁴C and the first increase in 1956 for^239+240Pu (potential bases for the Anthropocene GSSP). Coral δ¹³C declined especially after 1956 consistent with the Suess Effect resulting from the burning of fossil fuels. Coral skeletal δ¹⁵N starts to increase in 1963 corresponding with the increase in agricultural fertilizers. Coral Hg concentrations (1933–1980) loosely track fluctuations in industrial pollution and coral Ba/Ca increases from 1965–1983 when offshore oil operations expand after 1947. Coral temperature proxies contain the 20th-century global warming trend whereas coral growth declines during this interval.