Hydrologic changes of in-situ gravimetry

Inter-seasonal and geodynamics-related gravity changes are important geoscientific signals that are extractable from gravimeter observations after deducing background information as local hydrology gravity effect. With two superconducting gravimeters (SGs, OSG-053 and iGrav-007) located in different tectonic units, continuous Global Navigation Satellite System data, and AG observations, Wuhan (China) is an ideal location for investigating the effects of gravity resulting from significant local hydrology mass variations. We processed ∼26 months of gravity data collected from the SGs in Wuhan and obtain residuals of -40 nm.s2 for OSG-053 and 100 for iGrav-007. The hydrological observations show an estimated gravity increase of 42 nm.s2 near iGrav-007, which mainly resulted from the increased unconfined water level with an aquifer-specific yield of approximately 0.1. However, the gravity changes around OSG-053 are mainly from soil moisture and reach -90 nm.s2. The soil type, thickness and water content parameters were obtained from hydrogeological survey and drilling data. The deep confined water level rose by 2.5 m, which introduced a 1 nm.s2 gravity variation with a specific storage about 0.00001 from field unsteady flow pumping test. The modeled gravity is approximately -40 nm.s2 around OSG-053 and 90 around iGrav-007, in accordance with the observed gravity variations. The difference in gravity changes between the two SG observations can be explained by different local water storage environments. Our results suggest that unconfined and soil water significantly impact the in-situ gravimetry, which indicates that further detailed hydrogeological surveys are required. A combined investigation of gravity and water levels can be a useful approach to monitor aquifer storage conditions and groundwater management.

Beaver-Driven Peatland Ecotone Dynamics: Impoundment Detection Using Lidar and Geomorphon Analysis

This investigation focused on remotely detecting beaver impoundments and dams along the boreal-like peatland ecotones enmeshing Cranberry Glades Botanical Area, a National Natural Landmark in mountainous West Virginia, USA. Beaver (Castor spp.) are renowned for their role as ecosystem engineers. They can alter local hydrology, change the ratios of meadow to woodland, act as buffers against drought and wildfire, and influence important climate parameters such as carbon retention and methanogenesis. The Cranberry Glades (~1000 m a.s.l.) occupy ~300 ha, including ~40 ha of regionally rare, open peatlands. Given the likely historical role of beaver activity in the formation and maintenance of peatland conditions at Cranberry Glades, monitoring of recent activity may be useful in predicting future changes. We analyzed remotely sensed data to identify and reconstruct shifting patterns of surface hydrology associated with beaver ponds and dams and developed a novel application of geomorphons to detect them, aided by exploitation of absences and errors in Lidar data. We also quantified decadal-timescale dynamics of beaver activity by tallying detectable active impoundments between 1990–2020, revealing active/fallow cycles and changing numbers of impoundments per unit area of suitable riparian habitat. This research presents both a practical approach to monitoring beaver activity through analysis of publicly available data and a spatiotemporal reconstruction of three decades of beaver activity at this rare and imperiled “Arctic Island” of the southern High Alleghenies.

Paleo-environmental reconstruction of a Late Quaternary organic-rich section preserved near Ohakune, central North Island, New Zealand

<p>A 6m thick section of organic-rich sediment, exposed at Karioi, near Ohakune, central North Island (672m above sea level), presents an opportunity to form a detailed palynological record of Late Quaternary vegetation and climate change. The organic-rich sequence at Karioi lies beneath a 3.29m thick cover-bed sequence that contains towards its base the c. 25.4 ka cal BP Kawakawa/Oruanui Tephra, a key chronostratigraphic marker for the Last Glacial Maximum (LGM) throughout New Zealand. A previous palynological investigation of the underlying organic sediments suggested they extended back from the LGM (Marine isotope stage 2) to the previous interglacial (MIS 5). Such apparently continuous terrestrial records spanning this age range and located at this altitude are rare. A key feature of the Karioi organic sequence is the occurrence of numerous millimetre- to decimetre- thick tephra, derived from a variety of North Island eruptive sources. The possibility that volcanic processes have influenced vegetation change makes climate inferences at this important site potentially problematic. In this new study of the Karioi section, centimetre-scale palynological and diatom sampling conducted above and below three selected tephra (here named ‘Big Lower Lapilli’, ’Unknown’ tephra, and ‘Little’ tephra) at Karioi, were used to assess the influence of these volcanic events on the vegetation and local hydrology. Loss-on-ignition and magnetic susceptibility were used, alongside pollen and diatom analysis, to infer changes in local hydrology and depositional processes in relation to environmental stability. Together, these analyses helped determine the volcanic impacts on vegetation assemblages gained from the pollen record at the site and allowed these to be disassociated from larger scale climate influences of interest. The results of this study indicate a discernible volcanic impact on vegetation and hydrology following just one of the three volcanic events targeted in the record. High-resolution (0.5cm) pollen analysis above and below the largest of the three tephra layers, the 22cm thick ‘Big Lower Lapilli’ showed a notable change in vegetation assemblage immediately following tephra deposition. The most significant of these changes was the marked increase in herbs. This was an unexpected result thought to be due to the proximity of the site to sub-alpine and alpine herbaceous communities, which in turn were closer to the source of volcanism than other vegetation communities depicted in the pollen record. The changes to the pollen spectra are estimated to have taken 300 years to return to pre-eruption assemblages. Magnetic susceptibility and loss-on-ignition results further add to this research by indicating the comparative stability of the depositional environment around the time of deposition of the ‘Big Lower Lapilli’. Statistical analysis further identified a change in vegetation communities associated with tephra deposition, coinciding with an increase in diatom species abundance, which signified an increase in water volume and depth at the site. This was most clearly seen by the marked increase in Aulacoseira ambigua, which is almost exclusively found in water bodies of at least 2 metres depth. These results have major implications for pollen-based climate reconstructions from sequences with interbedded tephra layers. First, such investigations should include fine resolution analyses around prominent tephra layers to test for possible volcanic disturbance that may be a confounding factor in any paleoclimatic reconstructions applied. In this study, for example, vegetation assemblages may have taken up to 300 years to return to pre-eruption levels, but this recovery phase was well within the c. 1000 year inter-sample period of the original coarse (10cm) resolution record. Without the fine resolution study conducted here, the decline of shrubs and increase in grasses, with no obvious changes to trees following deposition of the ‘Big Lower Lapilli’ could have been inferred as a short-term cooling interval. Beyond this restricted zone of volcanic disturbance, greater confidence in the paleoclimatic interpretation of the Karioi pollen record has been achieved as a result of this finer resolution ‘test’ for volcanic disturbance. Second, the volcanic disturbance indicated following the ‘big lower lapilli’ has shed light on pollen taphonomic sources and pathways at this site and in turn, on spatial patterns of vegetation communities. In this case, the increase in tree pollen relative to non-arboreal pollen is interpreted as originating from more distant forest stands that have been comparatively less affected by the deposition of tephra than locally growing vegetation.</p>

Paleo-environmental reconstruction of a Late Quaternary organic-rich section preserved near Ohakune, central North Island, New Zealand

<p>A 6m thick section of organic-rich sediment, exposed at Karioi, near Ohakune, central North Island (672m above sea level), presents an opportunity to form a detailed palynological record of Late Quaternary vegetation and climate change. The organic-rich sequence at Karioi lies beneath a 3.29m thick cover-bed sequence that contains towards its base the c. 25.4 ka cal BP Kawakawa/Oruanui Tephra, a key chronostratigraphic marker for the Last Glacial Maximum (LGM) throughout New Zealand. A previous palynological investigation of the underlying organic sediments suggested they extended back from the LGM (Marine isotope stage 2) to the previous interglacial (MIS 5). Such apparently continuous terrestrial records spanning this age range and located at this altitude are rare. A key feature of the Karioi organic sequence is the occurrence of numerous millimetre- to decimetre- thick tephra, derived from a variety of North Island eruptive sources. The possibility that volcanic processes have influenced vegetation change makes climate inferences at this important site potentially problematic. In this new study of the Karioi section, centimetre-scale palynological and diatom sampling conducted above and below three selected tephra (here named ‘Big Lower Lapilli’, ’Unknown’ tephra, and ‘Little’ tephra) at Karioi, were used to assess the influence of these volcanic events on the vegetation and local hydrology. Loss-on-ignition and magnetic susceptibility were used, alongside pollen and diatom analysis, to infer changes in local hydrology and depositional processes in relation to environmental stability. Together, these analyses helped determine the volcanic impacts on vegetation assemblages gained from the pollen record at the site and allowed these to be disassociated from larger scale climate influences of interest. The results of this study indicate a discernible volcanic impact on vegetation and hydrology following just one of the three volcanic events targeted in the record. High-resolution (0.5cm) pollen analysis above and below the largest of the three tephra layers, the 22cm thick ‘Big Lower Lapilli’ showed a notable change in vegetation assemblage immediately following tephra deposition. The most significant of these changes was the marked increase in herbs. This was an unexpected result thought to be due to the proximity of the site to sub-alpine and alpine herbaceous communities, which in turn were closer to the source of volcanism than other vegetation communities depicted in the pollen record. The changes to the pollen spectra are estimated to have taken 300 years to return to pre-eruption assemblages. Magnetic susceptibility and loss-on-ignition results further add to this research by indicating the comparative stability of the depositional environment around the time of deposition of the ‘Big Lower Lapilli’. Statistical analysis further identified a change in vegetation communities associated with tephra deposition, coinciding with an increase in diatom species abundance, which signified an increase in water volume and depth at the site. This was most clearly seen by the marked increase in Aulacoseira ambigua, which is almost exclusively found in water bodies of at least 2 metres depth. These results have major implications for pollen-based climate reconstructions from sequences with interbedded tephra layers. First, such investigations should include fine resolution analyses around prominent tephra layers to test for possible volcanic disturbance that may be a confounding factor in any paleoclimatic reconstructions applied. In this study, for example, vegetation assemblages may have taken up to 300 years to return to pre-eruption levels, but this recovery phase was well within the c. 1000 year inter-sample period of the original coarse (10cm) resolution record. Without the fine resolution study conducted here, the decline of shrubs and increase in grasses, with no obvious changes to trees following deposition of the ‘Big Lower Lapilli’ could have been inferred as a short-term cooling interval. Beyond this restricted zone of volcanic disturbance, greater confidence in the paleoclimatic interpretation of the Karioi pollen record has been achieved as a result of this finer resolution ‘test’ for volcanic disturbance. Second, the volcanic disturbance indicated following the ‘big lower lapilli’ has shed light on pollen taphonomic sources and pathways at this site and in turn, on spatial patterns of vegetation communities. In this case, the increase in tree pollen relative to non-arboreal pollen is interpreted as originating from more distant forest stands that have been comparatively less affected by the deposition of tephra than locally growing vegetation.</p>

Microplastics and anthropogenic fibre concentrations in lakes reflect surrounding land use

Pollution from microplastics and anthropogenic fibres threatens lakes, but we know little about what factors predict its accumulation. Lakes may be especially contaminated because of long water retention times and proximity to pollution sources. Here, we surveyed anthropogenic microparticles, i.e., microplastics and anthropogenic fibres, in surface waters of 67 European lakes spanning 30° of latitude and large environmental gradients. By collating data from >2,100 published net tows, we found that microparticle concentrations in our field survey were higher than previously reported in lakes and comparable to rivers and oceans. We then related microparticle concentrations in our field survey to surrounding land use, water chemistry, and plastic emissions to sites estimated from local hydrology, population density, and waste production. Microparticle concentrations in European lakes quadrupled as both estimated mismanaged waste inputs and wastewater treatment loads increased in catchments. Concentrations decreased by 2 and 5 times over the range of surrounding forest cover and potential in-lake biodegradation, respectively. As anthropogenic debris continues to pollute the environment, our data will help contextualise future work, and our models can inform control and remediation efforts.

Intraspecific Variation on Palm Leaf Traits of Co-occurring Species—Does Local Hydrology Play a Role?

The study of plant species and trait distributions can provide answers to many of the ecological challenges of our times, from climate change to the biodiversity crisis. Although traits are classically measured at the species level, understanding intraspecific variation is necessary to determine the type of response species will have to climate change. Here we measured and analyzed seven leaf traits (leaf area—LA, specific leaf area—SLA, leaf thickness—LT, leaf dry mass content—LDMC, venation density—VD, stomata length—SL, and stomata density—SD) across 14 locally dominant palm species (10 individuals/species) distributed along hydro-topographic gradients (1.4–37 m of terrain height above nearest drainage) of a central Amazonian forest to disentangle the role of species identity, relatedness, and local hydrology on trait variation and covariation. Our results show that trait variation is not always larger between species than within species as expected. Intraspecific variation accounted for 23–74% of trait variation depending on the trait. Most of the variation happened at species level for SL, LA, LT, and SD but not for SLA, VD, and LDMC. For a third of the traits (LDMC, SLA, and SD), we found some evidence of phylogenetic inertia. This lack of independency among traits is confirmed by the maintenance of strong correlation among some of those traits after controlling for local environmental conditions. Intraspecific variation, however, was not related to height above nearest drainage for any of the traits. Most of the trait–environment relationships were species-specific. Therefore, the change in palm trait composition detected along topography, from higher community means of SLA and LA, lower LT, LDMC, SL, and SD in the wet valleys to opposite traits in drier plateaus, is mostly due to the turnover in species composition and relative abundance variation. We conclude these palm species have well-defined hydrological niches, but their large intraspecific variation in leaf traits does not contribute to the adjustment of individuals to the local hydrological conditions in this Amazonian forest.

Correlation of Tritium Concentration in Rainwater with Cosmic Rays: Preliminary Results

The Radiochronology Center has been established in 1999 as a member of the Horizontal Laboratories network of the University of Ioannina. Recently it has added to its activities the development of a tritium measurements laboratory as part of the Radiochronology Center. The laboratory is equipped with a super low level background liquid scintillation counter, which is capable to measure very low concentrations of tritium for applications in radioprotection, dating and hydrology.For the aims of the present continuing study rainwater samples are collected monthly. Each sample is distilled and then it is passed through an electrolysis process to increase the tritium concentration. Five mL of the enriched sample are mixed with 15 mL of a scintillation cocktail, specially designed for tritium measurements and its beta activity is measured for 200 min. The LLD of tritium in the samples is estimated 3 Bq/L or 27 TU.Our preliminary results show that, during the measuring period tritium concentration increased with time. The tritium values are correlated with the cosmic ray neutron flux data at ground level, available for Greece in the same period. The measured tritium concentrations in rainwater, which range from 36 ± 8 to 64 ± 8 TU, may be used for local hydrology studies.

Transgenerational plasticity and the capacity to adapt to low salinity in the eastern oyster, Crassostrea virginica

Salinity conditions in oyster breeding grounds in the Gulf of Mexico are expected to drastically change due to increased precipitation from climate change and anthropogenic changes to local hydrology. We determined the capacity of the eastern oyster, Crassostrea virginica , to adapt via standing genetic variation or acclimate through transgenerational plasticity (TGP). We outplanted oysters to either a low- or medium-salinity site in Louisiana for 2 years. We then crossed adult parents using a North Carolina II breeding design, and measured body size and survival of larvae 5 dpf raised under low or ambient salinity. We found that TGP is unlikely to significantly contribute to low-salinity tolerance since we did not observe increased growth or survival in offspring reared in low salinity when their parents were also acclimated at a low-salinity site. However, we detected genetic variation for body size, with an estimated heritability of 0.68 ± 0.25 (95% CI). This suggests there is ample genetic variation for this trait to evolve, and that evolutionary adaptation is a possible mechanism through which oysters will persist with future declines in salinity. The results of this experiment provide valuable insights into successfully breeding low-salinity tolerance in this commercially important species.

Finding “Glocal” Solutions to Flooding Problems

Scientists call for joint efforts to combine real-time global rainfall data with high-resolution local hydrology to better forecast floods.

Multiproxy approaches to investigating paleoecology and paleohydrology in the Upper Cretaceous Kaiparowits Formation USA

The Late Campanian-aged Kaiparowits Formation (72.5-76.6 Ma) is a thick, fossiliferous fluvio-overbank-lacustrine complex deposited in south-central Utah. Host to one of the richest, most diverse Campanian terrestrial fossil records in North America, the physical environment of the Kaiparowits ecosystem, particularly the dynamics of the hydrologic system, remains obscure. In 2014, an extensive bonebed was found in a conglomeratic sandstone unit of fluvial origin, known as the Rainbows and Unicorns quarry. Isotopic compositions of serially sampled tooth enamel phosphate (δ18Op) from tyrannosaur teeth were analyzed to see if they held data that could clarify the paleohydrology of the Kaiparowits Formation. To assess a greater paleoecological context for the tyrannosaurs, the isotopic composition of their teeth was compared to other faunal elements, including the giant alligatoroid Deinosuchus, and turtles (Baenid, Gilmoremys, Neurankylus and Trionychid) from the same quarry. The δ18Ow calculated from tyrannosaur was low, suggesting isotopically-light high-altitude runoff strongly influenced local hydrology of the Kaiparowtis Formation. The seasonal change in δ18O of tyrannosaur drinking water ranged from -21.0 to -14.4 ‰ V-SMOW while δ18Ow calculated from turtles and crocodiles ranged between an average of -9.3 and -10.9‰ respectively. The seasonal precipitation pattern and temperature of the Kaiparowits Formation was then compared to analogue settings such as the monsoonal climate of Hanoi, Vietnam and Cuiaba, Brazil. While similarities exist between these sites, the unique configuration of the Sevier Mountains adjacent to the nearby Western Interior Seaway provide the unique setting for a complex paleohydrologic system that results in a wide range of δ18Ow as a result of cold seasonal precipitation at high elevation that runs off and mixes with local precipitation (-4.68 to -6.0‰) sourced from the WIS. This study demonstrates the importance of serial- and micro-sampling of multi-taxa comparisons for isotopic investigations of palaeohydrologic systems.