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At least 379 records · Page 21Linked to original sources

USGS2026

Effects of warming on growth and leaf colonization by litter mat-forming fungi in a wet tropical forest in Puerto Rico

Wet tropical forests are experiencing rising temperatures and increased frequency and intensity of extreme climatic events, such as cyclones, which can increase rates of soil erosion and surface runoff. Fungal litter mats, formed by agaric decomposer fungi, play a crucial role in stabilizing slopes, preventing erosion, and aiding nutrient cycling; however, little is known about how warming affects litter mat growth and function. We investigated two litter mat-forming fungi, Gymnopus johnstonii and Marasmius aff. crinis-equi , in warmed (+4°C above ambient) and control plots in the Luquillo Experimental Forest, Puerto Rico. Growth and time-to-leaf colonization were monitored over 6 weeks in spring (both species) and summer ( G. johnstonii only). We hypothesized that warming would inhibit fungal mat growth and slow leaf colonization, particularly for G. johnstonii since it is drought sensitive. As expected, warming significantly reduced relative growth rates (RGR) in spring, though M. aff. crinis-equi showed slightly higher RGR than G. johnstonii . Leaf colonization was also delayed by 22% in warmed plots, with M. aff. crinis-equi colonizing leaves 4.3 times faster than G. johnstonii . There were significant seasonal differences in response to warming for G. johnstonii , with warming increasing RGR during the consistently wetter summer sampling period. Overall, warming led to significant inhibition of leaf colonization when conditions were dry, whereas there was a trend toward increased colonization in warm and wet conditions. Our findings suggest that warming, combined with drier conditions, is likely to suppress drought-sensitive fungal mat growth, reducing their ability to prevent nutrient and soil loss via erosion.

Luquillo↗

USGS2014

Long-term growth-increment chronologies reveal diverse influences of climate forcing on freshwater and forest biota in the Pacific Northwest

Analyses of how organisms are likely to respond to a changing climate have focused largely on the direct effects of warming temperatures, though changes in other variables may also be important, particularly the amount and timing of precipitation. Here, we develop a network of eight growth-increment width chronologies for freshwater mussel species in the Pacific Northwest, United States and integrate them with tree-ring data to evaluate how terrestrial and aquatic indicators respond to hydroclimatic variability, including river discharge and precipitation. Annual discharge averaged across water years (October 1–September 30) was highly synchronous among river systems and imparted a coherent pattern among mussel chronologies. The leading principal component of the five longest mussel chronologies (1982–2003; PC1 mussel ) accounted for 47% of the dataset variability and negatively correlated with the leading principal component of river discharge (PC1 discharge ; r = −0.88; P < 0.0001). PC1 mussel and PC1 discharge were closely linked to regional wintertime precipitation patterns across the Pacific Northwest, the season in which the vast majority of annual precipitation arrives. Mussel growth was also indirectly related to tree radial growth, though the nature of the relationships varied across the landscape. Negative correlations occurred in forests where tree growth tends to be limited by drought while positive correlations occurred in forests where tree growth tends to be limited by deep or lingering snowpack. Overall, this diverse assemblage of chronologies illustrates the importance of winter precipitation to terrestrial and freshwater ecosystems and suggests that a complexity of climate responses must be considered when estimating the biological impacts of climate variability and change.

Idaho, Oregon, Washington↗

USGS2016

Predicting tree biomass growth in the temperate-boreal ecotone: is tree size, age, competition or climate response most important?

As global temperatures rise, variation in annual climate is also changing, with unknown consequences for forest biomes. Growing forests have the ability to capture atmospheric CO 2 and thereby slow rising CO 2 concentrations. Forests’ ongoing ability to sequester C depends on how tree communities respond to changes in climate variation. Much of what we know about tree and forest response to climate variation comes from tree-ring records. Yet typical tree-ring datasets and models do not capture the diversity of climate responses that exist within and among trees and species. We address this issue using a model that estimates individual tree response to climate variables while accounting for variation in individuals’ size, age, competitive status, and spatially structured latent covariates. Our model allows for inference about variance within and among species. We quantify how variables influence aboveground biomass growth of individual trees from a representative sample of 15 northern or southern tree species growing in a transition zone between boreal and temperate biomes. Individual trees varied in their growth response to fluctuating mean annual temperature and summer moisture stress. The variation among individuals within a species was wider than mean differences among species. The effects of mean temperature and summer moisture stress interacted, such that warm years produced positive responses to summer moisture availability and cool years produced negative responses. As climate models project significant increases in annual temperatures, growth of species like Acer saccharum , Quercus rubra , and Picea glauca will vary more in response to summer moisture stress than in the past. The magnitude of biomass growth variation in response to annual climate was 92–95% smaller than responses to tree size and age. This means that measuring or predicting the physical structure of current and future forests could tell us more about future C dynamics than growth responses related to climate change alone.

Minnesota↗

USGS2006

Relationships among condition indices, feeding and growth of walleye in Lake Erie

Condition indices are often used as surrogates of fish health, growth, and feeding and to compare ecological well-being among fish populations. In an effort to identify easily measured indices, growth and food consumption were compared with gonadal-somatic index, liver-somatic index (LSI), fat-somatic index and relative weight (Wr) for ages 1-3 walleye, Sander vitreus (Mitchill), in Lake Erie from 1986 to 1988. The LSI and Wr were significantly correlated with growth rate or food consumption, but correlations were too small to be considered biologically meaningful. Furthermore, no consistent relationships between condition indices and growth or consumption were found among combinations of fish age and season. None of the indices are considered reliable surrogates for more laborious estimates of growth and food consumption for Lake Erie walleye. Significant relationships between Wr and relative abundance of key prey species warrant further investigation. ?? 2006 Blackwell Publishing Ltd.

Fisheries Management and Ecology↗

USGS2009

Growth, carbon-isotope discrimination, and drought-associated mortality across a Pinus ponderosa elevational transect

Drought- and insect-associated tree mortality at low-elevation ecotones is a widespread phenomenon but the underlying mechanisms are uncertain. Enhanced growth sensitivity to climate is widely observed among trees that die, indicating that a predisposing physiological mechanism(s) underlies tree mortality. We tested three, linked hypotheses regarding mortality using a ponderosa pine ( Pinus ponderosa ) elevation transect that experienced low-elevation mortality following prolonged drought. The hypotheses were: (1) mortality was associated with greater growth sensitivity to climate, (2) mortality was associated with greater sensitivity of gas exchange to climate, and (3) growth and gas exchange were correlated. Support for all three hypotheses would indicate that mortality results at least in part from gas exchange constraints. We assessed growth using basal area increment normalized by tree basal area [basal area increment (BAI)/basal area (BA)] to account for differences in tree size. Whole-crown gas exchange was indexed via estimates of the CO 2 partial pressure difference between leaf and atmosphere ( p a − p c ) derived from tree ring carbon isotope ratios ( δ 13 C), corrected for temporal trends in atmospheric CO 2 and δ 13 C and elevation trends in pressure. Trees that survived the drought exhibited strong correlations among and between BAI, BAI/BA, p a − p c , and climate. In contrast, trees that died exhibited greater growth sensitivity to climate than trees that survived, no sensitivity of p a − p c to climate, and a steep relationship between p a − p c and BAI/BA. The p a − p c results are consistent with predictions from a theoretical hydraulic model, suggesting trees that died had a limited buffer between mean water availability during their lifespan and water availability during drought – i.e., chronic water stress. It appears that chronic water stress predisposed low-elevation trees to mortality during drought via constrained gas exchange. Continued intensification of drought in mid-latitude regions may drive increased mortality and ecotone shifts in temperate forests and woodlands.

Global Change Biology↗

USGS2023

Oligocene–Miocene northward growth of the Tibetan Plateau: Insights from intermontane basins in the West Qinling Belt, NW China

Growth of the Tibetan Plateau, Earth’s broadest and highest elevation collisional system, shapes orographic barriers, reorganizes drainage networks, and influences surface erosion and sediment delivery, whose changes in space and provenance feed back to intracontinental tectonic processes. Studies of interior basins within the northern Tibetan Plateau provide new sediment accumulation, provenance, paleodrainage, and deformation timing data that enable a reconstruction of the far-field tectono-geomorphic evolution of the rising Tibetan Plateau. Along the northern plateau margin, topographic growth in the West Qinling Belt is inferred to have initiated in the Eocene, nearly coeval with the India-Asia collision, as well as in the late Miocene. However, geological knowledge about the intervening period remains at present enigmatic, and the kinematics and dynamics are uncertain. This study presents a multidisciplinary data set from the intermontane Anhua-Huicheng Basin (AHB; Gansu Province, China) to fill this gap. Magnetostratigraphic dating, regional mapping, and sedimentological analysis imply that contractional deformation and thrust-top basin systems formed within the West Qinling Belt in the Oligocene (not later than ca. 24 Ma). A combination of observations including paleocurrent changes, detrital zircon U-Pb age variations, and appearance of growth strata along the Anhua-Huicheng Basin reveal the rapid uplift of the West Qinling Belt at ca. 15 Ma. Sedimentation in the intermontane basins ended after the late Miocene (ca. 8 Ma), when the region experienced intrabasinal deformation, uplift, and erosion with the establishment of an external drainage system. Since the late Miocene, the growth of the West Qinling Belt reached a climax with the lack of substantial contractional deformation in Cenozoic sequences heralding the onset of the modern kinematic regime and attainment of high elevation. Observed transitions in the tectonostratigraphy and paleodrainage define different phases of deformation and plateau-wide shifts in stress reorganization, which led to the northward growth and later lateral expansion of the Tibetan Plateau.

GSA Bulletin↗

USGS2013

Modeling volcano growth on the Island of Hawaii: Deep-water perspectives

Recent ocean-bottom geophysical surveys, dredging, and dives, which complement surface data and scientific drilling at the Island of Hawaii, document that evolutionary stages during volcano growth are more diverse than previously described. Based on combining available composition, isotopic age, and geologically constrained volume data for each of the component volcanoes, this overview provides the first integrated models for overall growth of any Hawaiian island. In contrast to prior morphologic models for volcano evolution (preshield, shield, postshield), growth increasingly can be tracked by age and volume (magma supply), defining waxing alkalic, sustained tholeiitic, and waning alkalic stages. Data and estimates for individual volcanoes are used to model changing magma supply during successive compositional stages, to place limits on volcano life spans, and to interpret composite assembly of the island. Volcano volumes vary by an order of magnitude; peak magma supply also varies sizably among edifices but is challenging to quantify because of uncertainty about volcano life spans. Three alternative models are compared: (1) near-constant volcano propagation, (2) near-equal volcano durations, (3) high peak-tholeiite magma supply. These models define inconsistencies with prior geodynamic models, indicate that composite growth at Hawaii peaked ca. 800–400 ka, and demonstrate a lower current rate. Recent age determinations for Kilauea and Kohala define a volcano propagation rate of 8.6 cm/yr that yields plausible inception ages for other volcanoes of the Kea trend. In contrast, a similar propagation rate for the less-constrained Loa trend would require inception of Loihi Seamount in the future and ages that become implausibly large for the older volcanoes. An alternative rate of 10.6 cm/yr for Loa-trend volcanoes is reasonably consistent with ages and volcano spacing, but younger Loa volcanoes are offset from the Kea trend in age-distance plots. Variable magma flux at the Island of Hawaii, and longer-term growth of the Hawaiian chain as discrete islands rather than a continuous ridge, may record pulsed magma flow in the hotspot/plume source.

Hawai'i↗

USGS2016

Seasonal and spatial patterns of growth of rainbow trout in the Colorado River in Grand Canyon, AZ

Rainbow trout ( Oncorhynchus mykiss ) have been purposely introduced in many regulated rivers, with inadvertent consequences on native fishes. We describe how trout growth rates and condition could be influencing trout population dynamics in a 130 km section of the Colorado River below Glen Canyon Dam based on a large-scale mark–recapture program where &sim;8000 rainbow trout were recaptured over a 3-year period (2012–2014). There were strong temporal and spatial variations in growth in both length and weight as predicted from von Bertalanffy and bioenergetic models, respectively. There was more evidence for seasonal variation in the growth coefficient and annual variation in the asymptotic length. Bioenergetic models showed more variability for growth in weight across seasons and years than across reaches. These patterns were consistent with strong seasonal variation in invertebrate drift and effects of turbidity on foraging efficiency. Highest growth rates and relative condition occurred in downstream reaches with lower trout densities. Results indicate that reduction in rainbow trout abundance in Glen Canyon will likely increase trout size in the tailwater fishery and may reduce downstream dispersal into Grand Canyon.

Arizona↗

USGS2021

A framework for assessing the ability to detect macroscale effects on fish growth

Various abiotic and biotic factors affect fish and their habitats at macroscales. For example, changes in global temperatures will likely alter demographic rates, including growth. However, to date, there is no statistical framework for assessing the ability to detect macroscale effects on fish growth under different sampling scenarios. We provide a generalized framework for calculating the frequentist and Bayesian power of detecting macroscale effects on fish growth. We illustrate this framework for a range of sampling scenarios that varied in the number of fish sampled per lake, the number of lakes sampled, and the magnitude of the temperature effect on growth for two case study species. However, the framework can be adapted to investigate other species, sampling scenarios, and environmental drivers. The ability to detect macroscale effects was more affected by the number of lakes sampled rather than the number of fish sampled from each lake. Confidently detecting macroscale effects likely requires sampling hundreds of lakes. This was true for both case study species, despite different life histories and extents of spatial variability in growth.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2021

Do lake-specific characteristics mediate the temporal relationship between walleye growth and warming water temperatures?

Walleye ( Sander vitreus ) population declines have been linked to climate change, but it is unclear how the growth of this cool-water species may be affected by warming water temperatures. Because warming rates vary among lakes, it is uncertain whether lake characteristics may mediate the temperature effects on walleye growth or may vary as a result of differences in lake habitat or productivity. In this study, we ( i ) quantified walleye annual growth from 1983 to 2015 in 61 lakes in midwestern United States; ( ii ) estimated the relationship between annual early life growth ( ω ; mm·year –1 ) and water growing degree days (GDD); and ( iii ) identified lake characteristics affecting log e ( ω )–GDD relationships. On average, ω estimates significantly increased with increasing GDD; however, this relationship varied in direction and magnitude among lakes. We estimated an 84% posterior probability of a negative effect of water clarity on the log e ( ω )–GDD relationship, suggesting that water clarity may mediate the effect of warming water temperatures by affecting the magnitude and direction of the log e ( ω )–GDD relationship. Our results provide insights into the conservation of cool-water species in a changing environment and identify lakes characteristics in which walleye growth may be more resilient to climate change.

Minnesota, Wisconsin↗

USGS2025

Native Yellowstone cutthroat trout Oncorhynchus virginalis bouvieri growth and survival in a headwater stream primarily driven by warming stream temperatures, with non-native brown trout Salmo trutta posing an additional threat to survival

Warming rivers and interactions with non-native species impact salmonid species globally. Understanding how hydroclimatic conditions synergistically and independently interact with non-native species is critical for effectively managing salmonids into the future. We used a 10-year mark–recapture dataset to assess how native Yellowstone cutthroat trout (YCT) Oncorhynchus virginalis bouvieri and non-native brown trout Salmo trutta growth rates and apparent survival were affected by hydroclimatic conditions and (for YCT) the presence of brown trout in a tributary. Growth (YCT) and survival (both species across size classes) were negatively related to warming stream temperatures. Brown trout growth was positively related to increasing daily streamflow variability (a proxy for streamflow), but this variable was not included in the top YCT growth model. Density-dependent effects appeared to be non-existent (growth) or weakly positive (survival). When sympatric with brown trout, YCT displayed worse survival than allopatric YCT across environmental conditions. Broadly, we found native and non-native trout respond to different hydroclimatic conditions that shift with changing climatic conditions, and brown trout represent an additional threat to YCT survival.

Montana↗

USGS2025

Negative growth in body mass of trout and salmon in a small stream network

In species inhabiting stressful environments, some individuals experience negative growth in body mass during their lives, potentially influencing survival, reproduction, populations, and ecosystems. Using data from a long-term (1997–2015) study of brook trout ( Salvelinus fontinalis ), brown trout ( Salmo trutta ), and juvenile Atlantic salmon ( Salmo salar ) in Massachusetts, USA, we analyzed the frequency, causes, and consequences of seasonal mass loss. Negative growth occurred in 14.8% of observations (3573 instances), with the highest prevalence during summer (June–September). Species differed markedly: 42.5% of juvenile Atlantic salmon, 24.9% of brook trout, but only 7.7% of brown trout exhibited negative growth. The likelihood of mass loss increased with size, age, and low stream flows, particularly in summer. Brook trout in the small or isolated tributaries exhibited less summer mass loss than those in the larger streams. Other factors, including temperature and population density, had minimal or inconsistent effects. Individuals experiencing negative growth, especially brook trout in summer and autumn, were less likely to be re-encountered. As we observed no association of mass loss with movement, this suggests a potential survival cost of negative body mass growth.

Massachusetts↗

USGS2009

Atlantic salmon (Salmo salar) smolt production: the relative importance of survival and body growth

The complex life history of Atlantic salmon (Salmo salar) coupled with interacting abiotic and biotic factors leads to extreme demographic variability across the species' range. Our goal was to evaluate the relative importance of survival and body growth in determining smolt production across space and time. We used passive integrated transponder tags and capture-mark-recapture analyses to estimate survival, emigration, and growth for six cohorts of presmolt Atlantic salmon in two streams (three cohorts per stream) in New England, USA. We observed remarkable among-cohort consistency in mean monthly survival during a 17-month period from age-0+ autumn to age-2+ spring yet high variability in monthly survival over shorter time intervals (seasons). Despite this latter variability, survival did not translate into amongcohort differences in proportions of age-2+ versus age-3+ smolts. Alternatively, the high variability across seasons and cohorts in mean individual growth rate did lead to differences in within-cohort proportions of age-2+ versus age-3+ smolts (regardless of stream). We conclude that in our two small study streams, variability in growth and size impacted smolt age and, ultimately, smolt production. Density-dependent effects on growth at the scale of the entire study site represent a possible mechanism underlying our observations.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2009

Hierarchical Bayesian analysis to incorporate age uncertainty in growth curve analysis and estimates of age from length: Florida manatee (Trichechus manatus) carcasses

Age estimation of individuals is often an integral part of species management research, and a number of ageestimation techniques are commonly employed. Often, the error in these techniques is not quantified or accounted for in other analyses, particularly in growth curve models used to describe physiological responses to environment and human impacts. Also, noninvasive, quick, and inexpensive methods to estimate age are needed. This research aims to provide two Bayesian methods to (i) incorporate age uncertainty into an age-length Schnute growth model and (ii) produce a method from the growth model to estimate age from length. The methods are then employed for Florida manatee (Trichechus manatus) carcasses. After quantifying the uncertainty in the aging technique (counts of ear bone growth layers), we fit age-length data to the Schnute growth model separately by sex and season. Independent prior information about population age structure and the results of the Schnute model are then combined to estimate age from length. Results describing the age-length relationship agree with our understanding of manatee biology. The new methods allow us to estimate age, with quantified uncertainty, for 98% of collected carcasses: 36% from ear bones, 62% from length.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1987

Prey fish dynamics and salmonine predator growth in Lake Ontario, 1978-84

The size of hatchery-reared brown trout ( Salmo trutta ) and coho salmon ( Oncorhynchus kisutch ), 1&ensp;yr after release in Lake Ontario, declined when the stocking of salmonines was increased between 1978 and 1984. The principal prey species, alewife ( Alosa pseudoharengus ) and rainbow smelt ( Osmerus mordax ), failed to show the expected, predator-induced downturn in abundance. Instead, rainbow smelt remained moderately abundant and alewives very abundant. During this period, alewife year-classes were small, survival of yearling alewives was poor, growth of young-of-the-year of both alewives and rainbow smelt was slow (growth of most older alewives ceased), and rainbow smelt numbers gradually increased (the much larger alewife population presumably buffered older rainbow smelt from predation by large piscivores). When adult alewife numbers were halved by a winter die-off, the subsequent year-class of alewives was large and growth of brown trout during their first year in the lake increased. This suggested a causal relation between abundance of young alewives and brown trout growth. In the first year coho salmon were at liberty, their growth was related to abundance of young-of-the-year alewives; in their second year it was related to the abundance of yearling alewives and the condition of adult alewives. We hypothesize that abundant adult alewives suppressed production of young-of-the-year fish (necessary prey for salmonines during their first year in the lake) through competition for limited zooplankton production, and thus impeded the transfer of energy from the lowest trophic level to young salmonine predators.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1995

Seasonal growth and duration of the parasitic life stage of the landlocked sea lamprey ( Petromyzon marinus )

We used lengths and weights of 2367 live parasitic-phase sea lampreys ( Petromyzon marinus ) collected from Lake Huron, 1984–1990, to calculate their mean size at half-month intervals. Growth in weight was linear during June through September; increments averaged 11.1&ensp;g per half month. Growth increased sharply in October to several times the summer rate. We speculate that the increase in growth in October is explained partly by water temperature and partly by an increase in appetite related to the onset of gonadal development. The greater compression of biomass accumulation in autumn than has been previously demonstrated better explains the autumn pulse of sea lamprey induced host mortality. Based on the seasonal pattern of growth and on recaptures of marked sea lampreys, we conclude that landlocked individuals grow to adult size and mature in one parasitic growth year. Regressions of weight (grams) on total length (millimetres) differed significantly among months, and the season of collection must be considered in predicting weight from length.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2005

Occurrence and growth characteristics of Escherichia coli and enterococci within the accumulated fluid of the northern pitcher plant (Sarracenia purpurea L.)

Sarracenia purpurea L., a carnivorous bog plant (also known as the pitcher plant), represents an excellent model of a well-defined, self-contained ecosystem; the individual pitchers of the plant serve as a microhabitat for a variety of micro- and macro-organisms. Previously, fecal indicator bacteria ( Escherichia coli and enterococci) were shown as incidental contaminants in pitcher fluid; however, whether their occurrence in pitcher fluid is incidental or common has not been established. The purpose of this study was to investigate the occurrence, distribution, and growth potential of E. coli and enterococci in pitcher plant fluid from a protected bog in northwest Indiana. Escherichia coli and enterococci were recovered in pitcher fluids (n = 43 plants), with mean densities (log CFU mL -1 ) of 1.28 ± 0.23 and 1.97 ± 0.27, respectively. In vitro experiments showed that E. coli growth in fluid not containing insects or indigenous organisms was directly proportional to the fluid concentration (growth was 10-fold in 24 h in 100% fluid); however, in the presence of other indigenous organisms, E. col i and enterococci were only sustained for 5 days at 26 Â°C. Pulsed-field gel electrophoresis (PFGE) analysis showed that the plant Enterococcus faecalis isolates were genetically distinct from the human isolates; identical PFGE patterns were observed among plant isolates that fell into one of six clonal groups. These findings suggest that ( i ) E. coli and enterococci occurrence in pitcher plants is rather common in the bog studied, although their originating source is unclear, and ( ii ) the pitcher fluid contains adequate nutrients, especially carbon and energy sources, to promote the growth of indicator bacteria; however, under natural conditions, the biotic factors (e.g., competition for nutrients) may restrict their growth.

Canadian Journal of Microbiology↗

USGS2024

Thickness distributions and evolution of growth mechanisms of NH4-illite from the fossil hydrothermal system of Harghita Bai, Eastern Carpathians, Romania

The crystal growth of NH 4 -illite (NH 4 -I) from the hydrothermal system of Harghita Bãi (Eastern Carpathians) was deduced from the shapes of crystal thickness distributions (CTDs). The 4-illite-smectite (I-S) interstratified structures (R1, R2, and R3-type ordering) with a variable smectite-layer content. The NH 4 -I-S (40–5% S) structures were identified underground in a hydrothermal breccia structure, whereas the K-I/NH 4 -I mixtures were found at the deepest level sampled (−110 m). The percentage of smectite interlayers generally decreases with increasing depth in the deposit. This decrease in smectite content is related to the increase in degree of fracturing in the breccia structure and corresponds to a general increase in mean illite crystal thickness. In order to determine the thickness distributions of NH 4 -I crystals (fundamental illite particles) which make up the NH 4 -I-S interstratified structures and the NH 4, -I/K-I mixtures, 27 samples were saturated with Li + and aqueous solutions of PVP-10 to remove swelling and then were analyzed by X-ray diffraction. The profiles for the mean crystallite thickness (T mean ) and crystallite thickness distribution (CTD) of NH 4 -I crystallites were determined by the Bertaut-Warren-Averbach method using the MudMaster computer code. The T mean of NH 4 -I from NH 4 -I-S samples ranges from 3.4 to 7.8 nm. The T mean measured for the NH 4 -I/K-I mixture phase ranges from 7.8 nm to 11.7 nm (NH 4 -I) and from 12.1 to 24.7 nm (K-I). The CTD shapes of NH 4 -I fundamental particles are asymptotic and lognormal, whereas illites from NH 4 -I/K-I mixtures have bimodal shapes related to the presence of two lognormal-like CTDs corresponding to NH 4 -I and K-I. The crystal-growth mechanism for NH 4 -I samples was simulated using the Galoper code. Reaction pathways for NH 4 -I crystal nucleation and growth could be determined for each sample by plotting their CTD parameters on an α–β 2 diagram constructed using Galoper . This analysis shows that NH 4 -I crystals underwent simultaneous nucleation and growth, followed by surface-controlled growth without simultaneous nucleation.

Harghita Bai↗