Northern Sites Research Articles

A wide-ranging investigation of the COVID-19 lockdown effects on the atmospheric composition in various Italian urban sites (AER – LOCUS)

A widE-Ranging investigation of the first COVID-19 LOCkdown effects on the atmospheric composition in five Italian Urban Sites (AER–LOCUS) has been carried out and is presented in this study. The analysis uses particle and gas concentrations from surface in situ sampling, column aerosol and gas properties from photometer/spectrometers, and satellite NO2 determinations at five sites distributed over the whole Italian territory: Aosta, Milan, Bologna, Rome, and Taranto. These data are related to meteorological conditions to identify the numerous events of long-range transport and separate local from remote influences. Four different types of long-range transport over Italy are identified during the lockdown period, affecting PM10, PM2.5, and NO2 concentrations, and aerosol optical depths: fires plumes from Eastern Europe and Montenegro, dust from the Caspian area and from the Sahara, and pollution from the Po Valley. Once the long-range transport events are identified and excluded, the variation of gas and particle concentrations occurring during the containment period is calculated with respect to the period 2015–2019. A general decrease of PM10 (ranging from a maximum of −52% in Aosta to a minimum of −4% in Taranto), PM2.5 (from −46% in Aosta and Milan to −0.6% in Bologna), BC (from −77% in Aosta to −25% in Milan), NO2 (from −72% in Rome to −4% in Taranto), and benzene (about −50%) concentration is found. A positive variation of PM2.5 is conversely found during March in the southern sites due to some stagnation events, and a strong increase of benzene (up to +104%) in the industrial area of Taranto. Ozone is found to increase by an average of about 30% in all sites. The removal of the long-range transport contributions affects the variations with respect to the reference period reducing the concentrations by up to 22% for PM10 and 29% for PM2.5 in the northern sites, and 18% for PM10 and 16% for PM2.5 in the southern sites. For NO2 the reduction due to the removal is up to 14% in Milan and 6% in the southern sites, while for the aerosol optical depth it is up to 70% in Aosta and 50% in Rome.

SELECTIVE MEMORY: MONUMENTAL POLITICS OF THE YAXUNÁ E GROUP IN THE FIRST MILLENNIUM B.C.

AbstractIn seeking continuities and disjuncture from the precedents of past authorities, the Mesoamerican emergent ruling class during the Formative period were active agents in directing changes to monumental space, suggesting that memory played a vital role in developing an early shared character of Maya lifeways (1000b.c.toa.d.250). The trend is most visible in the civic ceremonial complexes known as E Groups, which tend to show significant patterns of continuity (remembering) and disjuncture (forgetting). This article uses the northern lowland site of Yaxuná in Yucatan, Mexico, to demonstrate the use of early selective strategies to direct collective memory. While there are E Groups in the northern Maya lowlands, few Formative period examples are known, making Yaxuná a critical case study for comparative assessment with the southern lowlands. One implication of the Yaxuná data is that the broader pattern of Middle Formative E Groups resulted from sustained social, religious, political, and economic interaction between diverse peer groups across eastern Mesoamerica. With the emergence of institutionalized rulership in the Maya lowlands during the Late Formative, local authorities played a significant role in directing transformations of E Groups, selectively influencing their meanings and increasingly independent trajectories through continuity and disjuncture.

Effects of Spatial Boreal Forest Harvesting Practices on Efficiency through a Benchmarking Approach in Eastern Canada

In eastern Canada, harvesting practices and spatial organization of harvested sites are modulated according to ecosystem forest management objectives. We determined how spatial organization affects efficiency by evaluating wood procurement costs. A comparative analysis of efficiency was presented using a non-parametric technique, i.e., data envelopment analysis (DEA), which allows multiple variable analyses of different factors. A database of 50 harvested sites during the period 2015–2018, located along a north-south latitudinal gradient between 46° to 50°, was constructed with variables describing spatial organization (roads and dispersion of patches) and operational aspects (wood procurement costs). The evaluated financial efficiencies show high values greater than 70%. The causes of inefficiency were dispersion of the patches, distance to the mill, and the number of kilometers of built roads. When efficiency values were arranged by latitudinal location, northern sites exhibited a lower value of overall and scale efficiency due to the high values in the wood harvested, and developed road density of the zone.

First Record of the Inquiline Ant Leptothorax kutteri Buschinger, 1965 from Turkey

We report on the occurrence of the ant Leptothorax kutteri Buschinger, 1965 in two sites in Northern and Eastern Turkey. Leptothorax kutteri is a workerless inquiline living in the colonies of L. acervorum (Fabricius, 1793) so far known from various parts of Northern and Central Europe. Our findings greatly increase the range of this small and rare ant.

Growth of Eastern oyster (Crassostrea virginica) using two oyster - bag float configurations

ABSTRACT Two bag float configurations (on-side; on-top) for the culture of four length classes of Eastern oyster (Crassostrea virginica) were tested at two sites in Tracadie Bay, Canada. An interaction between the site and the float configurations was observed at the northern site for the 21–30, 31–45 and 46–65 mm oyster classes for their length, and in the 46–65 mm for width as well. The observed differences give a potential increase of 32.5% in growth on a 4-year cycle when on-top configuration is used. About 12.7% more market size oysters were produced in this configuration representing an increase of $9.24 (CAN) per bag. This study shows the potential benefit of the on-top configuration, but also the interaction between the site and the float configurations. Since the on-top configuration needs more maintenance time, it is suggested that the float configurations be chosen based on biofouling, growth variation, effect on oyster shape, and cost/advantage.

The late Quaternary mountain-front terrace sequences along the Langshan Mountains: Implications for the evolution of the western Hetao Graben

As the extensional boundary between Langshan Mountains and the Hetao Basin, the vertical displacement of the Langshan Piedmont Fault (LPF) forms the typical basin and range landform and controls the uplift of the Langshan Mountains and the deposition of the Hetao Basin. Based on the 10Be concentrations for the quartz gravel samples collected from two different mountain-front terrace sequences, we can calculate that the exposure ages for T3, T2 and T1 terraces on the northern site of the LPF (Site 1) are ~136 ka, ~72 ka and ~29ka, and the exposure ages for T3, T2 and T1 terraces on the southern site of the LPF (Site 2) are ~96 ka, ~65 ka and ~45 ka, respectively. Furthermore, the vertical slip rates are ~0.33 mm/a since about late Pleistocene, ~0.21 mm/a since ~72 ka, ~0.17 mm/a since ~29 ka for the northern part of the LPF, and ~0.61 mm/a since about late Pleistocene, ~0.74 mm/a since ~65 ka, ~0.27 mm/a since ~45 ka for the southern part. The vertical slip for different part and different periods of the LPF shows different rates. In addition, the decrease of the vertical slip rates since late Pleistocene suggest that the activity of the LPF is becoming weak.

Non-growing season plant nutrient uptake controls Arctic tundra vegetation composition under future climate

Plant growth and distribution in high-latitude tundra ecosystems is strongly limited by nutrient availability and is critical for quantifying centennial-scale carbon-climate interactions. However, land model representations of plant–nutrient interactions are uncertain, leading to poor comparisons with high-latitude observations. Although it has been recognized for decades in the observational community that plants continue to acquire nutrients well past when aboveground activity has ceased, most large-scale land models ignore this process. Here we address the role tundra plant nutrient acquisition during the non-growing season (NGS) has on centennial-scale vegetation growth and dynamics, with a focus on shrub expansion. We apply a well-tested mechanistic model of coupled plant, microbial, hydrological, and thermal dynamics that explicitly represents nutrient acquisition based on plant and microbial traits, thereby allowing a prognostic assessment of NGS nutrient uptake. We first show that the model accurately represents observed seasonality of NGS plant nutrient uptake in a northern Alaskan tundra site. Applying the model across the North America tundra indicates that NGS nutrient uptake is consistent with observations and ranges between ∼5% and 50% of annual uptake, with large spatial variability and dependence on plant functional type. We show that NGS plant nutrient acquisition strongly enhances modeled 21st century tundra shrub growth and expansion rates. Our results suggest that without NGS nutrient uptake, total shrub aboveground dominance would be ∼50% lower, limited primarily by their inability to grow tall enough to maximize their inherent capacity for light competition. Evergreen shrubs would be more strongly affected because of their relatively lower capacity for nutrient remobilization and acquisition compared to deciduous shrubs. Our results highlight the importance of NGS plant and soil processes on high-latitude biogeochemistry and vegetation dynamics and motivate new observations and model structures to represent these dynamics.

Carbon Stock Evaluation and Potential Carbon Market Value Determination of Ashaavieen Nature Reserve, Msallata, Libya

This study targets to assign the total carbon stock of Ashaavieen Nature Reserve, Msallata, Libya, as-sisting its potential carbon market value based on different global market sources. Northern and Southern sites were adopted representing the dominant tree species; (Pinus halepensis, Ziziphus lotus, and Ceratonia siliqua). The samples were conducted across the summer and winter of 2020 to get an annual average. These samples were classified into leaves, stems, bark (aboveground), and roots (be-lowground). The soil samples were collected at 0-10 cm, 10-20 cm, and 20-30 cm depth. Organic car-bon content was assessed based on the Loss on Ignition method (LOI). The results have shown that the bark has recorded the highest carbon content rate, followed by the stem, leaf, and root. Also, the carbon in soil samples has a direct relationship with depth in the order of (0-10 cm) > (10-20 cm) > (20-30 cm). Total carbon stock was 870.47 (t/ha/yr) and 1858.21 (t/ha/yr) in Northern and Southern sites. Total tree coverage of the study area was estimated at 91.26 hectares, while the potential carbon market value ranged from 0.72 t0 32.09 million USD.

Circadian and Seasonal Patterns of Body Temperature in Arctic Migratory and Temperate Non-migratory Geese

Arctic migration presents unique challenges to circadian physiology. In addition to the metabolic cost of maintaining a relatively high body temperature (Tb) above ambient temperature, migratory birds are also exposed to rapidly changing light conditions as they transition between light-dark cycles and a 24-hour polar day. A previous study suggested that Arctic-migratory barnacle geese (Branta leucopsis) may utilise adaptive heterothermy (i.e., a controlled decrease in core Tb) during and around the autumn migratory period in order to minimise the metabolic cost of migration, but the impact of seasonally changing daylight conditions on other parameters of the circadian profile of Tb in these geese remained obscure. Here, we provide a detailed comparative analysis on the circadian rhythm of Tb and its seasonal development in free-living barnacle geese from three study populations that differ in their migratory behaviour and in the environments they occupy. We recorded abdominal Tb in non-migratory geese from a temperate breeding colony in Netherlands and in migratory geese from a colony in the Russian low Arctic, and analysed these data together with previously published Tb data on geese from a migratory colony in the high Arctic of Svalbard. We found that the circadian Tb profile in the barnacle goose was well aligned with the daily and seasonally changing daylight conditions. In the migratory populations, a fast re-entrainment of the rhythm and its phase was observed when zeitgeber conditions changed during migratory movements. The circadian rhythmicity of Tb was lost once the geese encountered permanent daylight at their northern staging and breeding sites. Circadian Tb rhythmicity was re-established when the period of permanent daylight ended, at rates corresponding to rates of seasonal changes in daylength in the high and low Arctic. Although our data corroborated findings of a decrease in daily mean Tb before autumn migration in both migratory populations in this study, the pre-migratory decrease in Tb was less drastic than previously reported. Moreover, in contrast to previous study, the decrease in Tb stopped at the onset of migration. Overall, our data reveal no evidence that heterothermy in the barnacle goose is functionally linked to migration.

Chronofunctions for new Mexico, USA soils show relationships among climate, dust input, and soil development

Rates of soil development provide critical information about the types and rates of geomorphic and landscape evolutionary processes. Soil development in arid and semiarid regions of the southwestern United States is predominantly controlled by influx of eolian dust, yet our ability to quantify the rates of morphologic development and of dust and carbonate incorporation is limited by available age control. We describe 10 pedons in the Socorro area of central New Mexico and analyze their silt, clay, and carbonate contents. These soils have well-established direct or indirect age control that we used to estimate average rates of dust and carbonate accumulation over the past ~0.5–800 ka. We also computed the profile development index (PDI) for these soils using 10 common morphologic properties and compare our resulting PDI chronofunction to those from northern and southern New Mexico. We find that the net silt-and-clay content increases in progressively older soils at rates similar to the profile-mass carbonate contents, presumably sourced primarily from eolian dust. Our chronofunction comparison indicates that soil development occurs more rapidly in higher latitude regions of New Mexico than in the drier warmer climates of the Socorro area and southern New Mexico. We interpret the N–S regional trend of soil development considering a regional climate gradient. We conclude that greater mean annual precipitation and cooler mean annual temperatures and/or slower rates of eolian dust accumulation into the soil profile at higher latitude northern sites cause the observed differences in regional soil development. This would promote greater mobility of available silt and clay, and also increase rates of soil formation, as indicated by the presence of argillans in late-Pleistocene soils of northern New Mexico.

New ages of the world's largest-ever marsupial: Diprotodon optatum from Pleistocene Australia

The extinction of large-bodied terrestrial ‘megafauna’ during earlier phases of the Quaternary had a significant impact on the transforming structure of ecosystems. However, the causes of such losses remains difficult to determine in part because of a paucity of reliable geochronological information about the taxa involved. This is especially true for continents such as Australia where the majority of extinct species have never been dated using radiometric and/or luminescence methods. Here we add new understanding about the geochronology of the world's largest-ever marsupial, the giant wombat-like Diprotodon optatum, an iconic member of the large herbivore guild of Pleistocene Australia. We present 28 new direct U-series ages (dentine) and 10 luminescence ages (sediments) for D. optatum fossils from three sites in tropical north and subtropical eastern Australia. The luminescence ages lie close to saturation for the tropical northern site of Floraville and therefore indicate minimum ages, and sediments from Gowrie Creek in the Darling Downs were mixed and can only be stated as a likely age range. Nevertheless the results assist in our broader understanding of the timing of persistence of the species. Our results demonstrate that the species roamed the northern tropics at least until the mid-Pleistocene (ca. 420 ka). They likely remained widespread during Marine Isotope Stage 5 (ca. 110 ka) and were abundant on the Darling Downs of eastern Australia. The youngest of the new ages that we report (ca. 60 ka) are from Neds Gully on the Darling Downs, a catchment previously considered by some to contain among the last survivors of the now-extinct megafauna. The new dated record demonstrates that deposits of varying ages occur within the catchment. Consequently, existing species lists that treat Neds Gully as a single faunal assemblage are likely significantly time-averaged and overinflated in terms of palaeo-diversity.

The Distribution Pattern of Marine Bivalve Death Assemblage From the Western Margin of Bay of Bengal and Its Oceanographic Determinants

The global pattern of shallow marine biodiversity is constructed primarily using the data from extra-tropical sites. A severe knowledge gap in the shallow benthic diversity exists for the tropical Indian Ocean, especially along the coastline of peninsular India. Latitudinal biodiversity gradient (LBG)—a poleward decrease in diversity, even though accepted as a pervasive global pattern, often differs from regional trends. Although several oceanographic variables are known to influence regional patterns, their relative effect in shaping the shallow benthic community in tropical seas remains unclear. The east coast of India bordering the Bay of Bengal (BoB) presents a 2,500 km stretch (8–22°N) of tropical coastline with a spatial variation in oceanographic parameters including freshwater mixing, primary productivity, temperature, and shelf area. Here, we documented the marine bivalve distribution using spatially-temporally averaged beach samples and evaluated their relationship with the oceanographic variables. Our data reveal the existence of a highly diverse fauna, comparable to other tropical shallow marine sites. Overall species composition reflects a typical assemblage of the Indian Ocean, dominated by Veneridae but shows an uncharacteristically low proportion of Tellinidae and Lucinidae. The latitudinal variation in diversity shows a mid-latitude drop at around 14°N—a pattern inconsistent with the prediction of latitudinal biodiversity gradient (LBG). The functional groups are dominated by infauna (65%), unattached groups (69%), and suspension feeders (87%). There is only a slight difference in species composition between southern and the northern sites pointing to a predominantly continuous circulation and considerable mixing within the BoB. Productivity range, shelf area, and salinity emerge as best predictors of the species richness. All environmental variables together explain the species composition across the latitudinal bins satisfactorily. The species composition of the east coast shows no distinct nature in comparison to the Indo-Malayan biodiversity hotspot; the proximity to this hotspot and biological exchange with it may have contributed to the high diversity of the east coast fauna. Our study highlights the complex interplay between multiple oceanographic variables in determining the distribution and diversity of tropical shallow marine benthos at a regional scale generating biodiversity patterns that are at odds with global trends such as LBG.

Morphology, geometric morphometrics, and taxonomy in relict deciduous oaks woods in northern Italy

The Euganean Hills are a well-known refugee site for thermophilous woody flora in northern Italy. Among the species recorded here, there is Quercus dalechampii. The Euganean Hills are the only northern Italy site where the occurrence of this oak species is considered. The aim of this paper was to verify the presence of Q. dalechampii in the study area and to select possible diagnostic morphological traits that are usable to distinguish it from Q. petraea and Q. pubescens. Forest stands dominated by Q. petraea, Q. pubescens, and the presumed Q. dalechampii were sampled using the phytosociological approach to highlight their ecological features. Leaf and fruit material from 104 oak individuals was analysed from a macro-morphological and micro-morphological point of view. Leaf shape was also analysed using the geometric morphometric approach. All multivariate analysis procedures applied on the matrices of leaf and fruit traits highlighted two main clusters of morphological diversity. One was restricted to Q. pubescens individuals, and the other one was a mix of Q. petraea and presumed Q. dalechampii individuals. According to the twig and leaf trichome traits, all presumed Q. dalechampii individuals were classified as belonging to the Q. petraea collective group. Morphological differences between Q. petraea and presumed Q. dalechampii were considered not significant. In conclusion, the occurrence of a third oak species, in addition to Q. petraea and Q. pubescens, was not confirmed for the study area by the results of this paper.Graphic abstract

Catchment Runoff in Industrial Areas Exports Legacy Pollutant Zinc from the Topsoil Rather than Geogenic Zn.

In highly industrialized, densely populated parts of Central Europe, mobilization of legacy Zn pollution from forest ecosystems may negatively affect the quality of water resources. To test this hypothesis, we determined the 66Zn/64Zn isotope ratios of 15 Zn reservoirs and fluxes in an acidified, spruce die-back affected mountain-slope catchment in northern Czech Republic. The δ66Zn values of precipitation, organic horizon, and runoff were statistically indistinguishable. In contrast, δ66Zn values of bedrock orthogneiss and mineral soil were significantly different from δ66Zn values of runoff. The magnitude of within-site Zn isotope fractionations appeared to be relatively small. Despite the large potential source of Zn in bedrock, runoff exported mostly young pollutant Zn that had been temporarily stored in the organic horizon. This conclusion was corroborated by comparing Zn input-output mass balances in the polluted northern catchment and in a relatively unpolluted catchment situated 250 km to the south. Seven-times higher Zn export via runoff at the northern site was controlled by a combination of 10-times higher atmospheric Zn input and five-times higher DOC leaching, compared to the southern site. In industrial areas, atmospherically deposited Zn is leached from headwater catchments in a direct analogy to leaching of highly toxic pollutant Pb.

Acoustic Pressure, Particle Motion, and Induced Ground Motion Signals from a Commercial Seismic Survey Array and Potential Implications for Environmental Monitoring

An experimental marine seismic source survey off the northwest Australian coast operated a 2600 cubic inch (41.6 l) airgun array, every 5.88 s, along six lines at a northern site and eight lines at a southern site. The airgun array was discharged 27,770 times with 128,313 pressure signals, 38,907 three-axis particle motion signals, and 17,832 ground motion signals recorded. Pressure and ground motion were accurately measured at horizontal ranges from 12 m. Particle motion signals saturated out to 1500 m horizontal range (50% of signals saturated at 230 and 590 m at the northern and southern sites, respectively). For unsaturated signals, sound exposure levels (SEL) correlated with measures of sound pressure level and water particle acceleration (r2= 0.88 to 0.95 at northern site and 0.97 at southern) and ground acceleration (r2= 0.60 and 0.87, northern and southern sites, respectively). The effective array source level was modelled at 247 dB re 1µPa m peak-to-peak, 231 dB re 1 µPa2 m mean-square, and 228 dB re 1 µPa2∙m2 s SEL at 15° below the horizontal. Propagation loss ranged from −29 to −30log10 (range) at the northern site and −29 to −38log10(range) at the southern site, for pressure measures. These high propagation losses are due to near-surface limestone in the seabed of the North West Shelf.

Searching for the earliest use of limestone as a flux in Chinese high-fired ceramic glazes—evidence from Sr isotopic analysis of Chinese northern porcelain

Samples of northern porcelain wares dating to between the 6th and 13th centuries from the three most important northern Chinese ceramic kiln sites, Gongyi, Xing and Ding have been studied in this work. The Sr isotope and chemical compositions of the ceramic glazes of these wares have been determined. Based on the scientific results we have been able to suggest the raw materials used to make the glazes. Using Strontium isotopic analysis we have successfully shown that the earliest use of limestone as a glaze flux so far identified is during the period from the Sui to mid-Tang Dynasties (late 6th-early 9th century) to produce white slip glazed ware in the Xing kilns so it may have been ‘invented’ there.

Effect of stocking density on growth and survival of juvenile Manila clams (Ruditapes philippinarum) farmed in suspended lanterns in a North Italian lagoon

To evaluate the effect of stocking density on pre-fattening growth and survival, Manila clam seeds from three different batches (B1, B2, and B3) were farmed in plastic net lanterns at two sites (western and northern) in Sacca degli Scardovari (Italy). Different stocking densities were compared, i.e. EXTRA (50,000 clams m−2), HIGH (30,000), and MEDIUM (20,000) for B1 and B2 clams; HIGH, MEDIUM, and LOW (10,000 clams m−2) for B3 clams. At the end of pre-fattening at the western site, the shell length decreased with increasing stocking density of both B1 (14.2 mm vs. 13.6 mm vs. 12.9 mm at HIGH vs. MEDIUM vs. EXTRA density; P < 0.001) and B2 (14.9 mm vs. 13.6 mm vs. 12.5 mm at MEDIUM vs. HIGH vs. EXTRA density; P < 0.001) clams. At the northern site, the shell length decreased in the following manner: MEDIUM to HIGH to EXTRA density for B1 clams (P < 0.001) and MEDIUM to EXTRA to HIGH density for B2 clams (P < 0.001). The same trend was recorded for B3 clams at both western (16.1 mm vs. 14.3 mm vs. 12.7 mm at LOW vs. MEDIUM vs. HIGH density; P < 0.001) and northern (15.6 mm vs. 13.9 mm vs. 13.2 mm; P < 0.001) sites. The stocking density did not affect the survival rate at the northern site and of the B3 clams, whereas the survival rate significantly decreased from MEDIUM and HIGH to EXTRA density for B1 (84.8 % and 85.4 % vs. 52.8 %; P < 0.05) and B2 (92.5 % and 87.6 % vs. 67.0 %; P < 0.01) clams at the western site where pre-fattening ended one week later than at the northern site. In the present conditions, clams in suspended lanterns reached the minimum sowing size (shell length 11 mm, weight 0.3 g) in 10 weeks. However, an increase in stocking density decreased clam growth and drastically increased mortality when water conditions became less favourable.

New data on the chemical composition of the non-ferrous metal products of the X–XVIII centuries on the territory of Northern and Central Belarus

The article presents the results of analysis of new data on the elemental composition of non-ferrous metal products on the territory of certain archaeological sites in Northern and Central Belarus. The author distinguishes two main stages in the non-ferrous metalworking of the region: the X–XIII centuries and XIV–XVIII centuries. It is noted that the period of the X–XIII centuries is characterized by a significant predominance of copper-zinc alloys with average and high concentrations of zinc in metal. Meanwhile, bronze alloys also play an important role, accounting for 35 % of the total number of the items studied. Samples made of copper-zinc and bronze alloys are also characterized by a significant amount of lead. As a result of the analysis of the data on the elemental composition of non-ferrous metal products of the XIV–XVIII centuries, it is concluded that non-ferrous metalworking of this period is characterized by the continuity of traditions with handicraft production of the previous period, which manifested itself in the widespread use of copper-zinc alloys, as well as of tin-lead and multicomponent bronzes. At the same time, a significant difference is the increase in the proportion of alloys with high concentrations of alloying components.

Latitudinal influence on gametogenesis and host-parasite ecology in a marine bivalve model.

Reproduction and parasites have significant impacts on marine animal populations globally. This study aimed to investigate the associative effects of host reproduction and a host–parasite interplay on a marine bivalve, along a geographic gradient of latitude. Cockles Cerastoderma edule were sampled from five European sites (54°N to 40°N), between April 2018 and October 2019. A histological survey provided data on trematode (metacercaria and sporocyst life stages), prevalence, and cockle stage of gametogenesis to assess the influence of a latitudinal gradient on both interplays. Sex ratios at the northernmost sites were skewed toward females, and spawning size was reduced at the lower latitudes. Trematode infection did not follow a latitudinal gradient. Localized site‐related drivers, namely seawater temperature, varied spatially, having an impact on cockle–trematode interactions. Spawning was related to elevated temperatures at all sites. Prolonged spawning occurred at southern latitudes, where seawater temperatures were warmer. Trematode prevalence and the impact of trematodes on gametogenesis were found to be spatially variable, but not latitudinally. Therefore, it is not possible to determine the likelihood of boom and bust events in cockles, based on the latitudinal location of a population. In terms of sublethal impacts, it appeared that energy was allocated to reproduction rather than somatic growth in southern populations, with less energy allocated to reproduction in the larger, northern cockles. The demonstrated spatial trend of energy allocation indicates the potential of a temporal trend of reduced cockle growth at northern sites, as a result of warming sea temperatures. This awareness of the spatially varying drivers of populations is crucial considering the potential for these drivers/inhibitors to be exacerbated in a changing marine environment.

Speciation of rare earth elements in acid mine drainage precipitates by sequential extraction

Recent efforts have shown that acid mine drainage precipitates (AMDp) may be a promising source of rare earth elements and critical materials (REE/CM). To better understand this resource, several particle characterization studies were conducted on AMDp samples from three AMD treatment sites in Northern and Central Appalachia. This work included the determination of particle size, size distribution, morphology, mineralogy, chemical speciation, and rare earth content. While the particle characteristics and mineralogy varied considerably from site to site, sequential extraction tests showed that the largest portion of REEs (45% to 75%) were found in soluble phases bound to Fe-Mn oxides. Carbonates (5% to 16%) and insoluble residues (4% to 24%) were also found to be significant in some samples, suggesting that different AMD chemistry and AMD treatment approaches can lead to substantial variation in the deportment of REEs to the various chemical phases. Altogether, the results suggest that chemical extraction of REEs from AMDp can be achieved under mild conditions with high recovery values; however, the significant site-by-site variation will necessitate detailed testing of individual samples to determine the overall economic viability.