Beth Weinman

California State University, Fresno | Fresno State · Department of Earth and Environmental Sciences

Regional comprehensive universities with access-oriented missions provide critical pathways for increasing the number and diversity of STEM graduates. The BOND program at California State University, Fresno supports the transition to college for first-time, full-time freshmen in selected STEM majors. BOND incorporates a learning community, active l...

Steep soil-mantled hillslopes are thought to be important sources of sediments and organic carbon (OC) to rivers. Minerals in these sediments may protect OC from decomposition, yet the significance of such interactions in steep upland soils remains poorly constrained particularly in relation to erosion rates. We examined a tributary basin draining...

In this article we will describe the development of an interdisciplinary general education course focusing on water. As part of a faculty cohort charged with teaching and studying this topic, we considered a number of projects, including community outreach, teacher professional development, and collaborative research. We decided on an interdiscipli...

The spatial heterogeneity of dissolved arsenic (As) concentrations in shallow groundwater of the Bengal Basin has been attributed to transport of As (and reactive carbon) from external sources or to the release of As from within grey sand formations. We explore the latter scenario in this detailed hydrological and geochemical study along a 300 m tr...

Compared to the natural geologic time span, human activity over the past 100 years has released mercury at unprecedented rates within the New Idria mining region of San Benito County, California—a rate ~4 orders of magnitude faster than the natural background crustal processing (Hazen, 2012; Studemeister, 1984). Today, river sediments and soils sur...

A sedimentological and geochemical study was carried out to explore the origin of arsenic contamination in sediments in Nawalparasi district, in the western Terai of Nepal. The investigation tools include major, trace and rare earth element analyses of core sediments, as well as 14C datings, and O, C isotopic analyses on mollusk shells. The results...

The characteristics of the sediment transported by rivers (e.g. sediment flux, grain size distribution – GSD) dictate whether rivers aggrade or erode their substrate. They also condition the architecture and properties of sedimentary successions in basins. In this study, we investigate the relationship between landscape steepness and the grain size...

The time minerals spend in the weathering zone is crucial in determining soil biogeochemical cycles, solid state chemistry and soil texture. This length of time is closely related to erosion rates and can be modulated by sediment transport, mixing rates within the soil and the temporal evolution of erosion. Here we describe how time length can be a...

California’s Central Valley water quality and soils are essential to the survival of the valley’s communities and agriculture. Therefore, detection of possible contaminants within the valley streams and soils are paramount to the protection of this land and the people that depend upon it. Here we explore the impact of the contaminated stream beds n...

Soil, river bank, and sediment samples were collected from Panoache Creek's mine tailings and its drainages in the Mendota Pool area of California's Central Valley. The samples were collected in order to understand the transport mechanisms of mercury and other heavy metals from the abandoned New Idria Mercury Mine (NIMM) in San Banito County, CA. I...

Groundwater drawn daily from shallow alluvial sands by millions of wells over large areas of south and southeast Asia exposes an estimated population of over a hundred million people to toxic levels of arsenic. Holocene aquifers are the source of widespread arsenic poisoning across the region. In contrast, Pleistocene sands deposited in this region...

We are investigating the impact of exotic earthworms on the rate of nutrient and ion release from soil chemical weathering along an ~200 m invasion chronosequence in a northern Minnesota sugar maple forest. The earthworms belong to three ecological groups that represent different feeding and burrowing behaviors, all of which were introduced from Eu...

Landscapes evolve through time, both in terms of their geomorphology and their geochemistry. Past studies have highlighted that topography suffers from the problem of equifinality: the topographic configuration of landscapes can be the result of many different, yet equally plausible, erosion histories. In hillslope soils the properties and chemistr...

Generation and transport of sediment across hillslopes and rivers are closely tied to mechanisms that produce and remove weathered material; in uplands this production and transport controls the thicknesses of weathering profiles. These processes, by controlling the residence time of minerals in the weathering profiles, further regulate the interac...

The efficiency with which sediment is transported on soil-mantled hillslopes is controlled by climate and lithology. In this study we perform quantitative analysis of airborne Light Detection and Ranging (LiDAR) digital terrain models (DTMs) to investigate the topographic signature of two distinct lithologies in the Feather River catchment in north...

Over geologic timescales, the weathering of silicate rocks has helped to maintain a mostly habitable planet, and it is clear that understanding rates of chemical weathering is key to accurately interpreting past changes in climate and seawater chemistry. However, the mechanisms that drive changes in weathering rates through time are incompletely de...

In arsenic-prone regions, an important question is the provenance of arsenic in shallow groundwaters (< 30 m). Some studies suggest that arsenic is sourced from the overlying local soils of an aquifer, whereas others surmise it to be due to weathering of the underlying aquifer matrix. Most work on chemical weather-ing suggests that 'younger/fresher...

How and how fast do hillslope soils form as the landscape's morphology changes over time? Here results are shown from an ongoing study that simultaneously examines the morphologic and geochemical evo-lution of soil mantled hillslopes that have been exposed to distinctively different denudation history. In Northern Sierra Nevada, California, the aut...

When deciphering the history and future of landscape morphology, we focus on the evolution of ground surface elevation. A convenient unit to study this particular problem is the volume per area per time, which is often the unit that is used to present physical and total denudation rates. This unit, however, needs to be combined with the bulk densit...

When hillslopes respond to incision triggered by tectonic uplift, there is a competition between chemical and physical processes in shaping the landscape. We are studying a tributary basin of the Middle Folk Feather River (FR) in Sierra Nevada CA, where an incision signal is still propagating throughout the basin. Soils were sampled along 3 hillslo...

Tectonically driven changes in channel incision rates lead to changes in hillslope erosion rates that propagate upslope. In an effort to understand how these changes affect soil geochemistry, this study theoretically and empirically integrates sediment transport and chemical weathering. Here, we focus on a tributary basin of the Middle Folk Feather...

While processes in the critical zone are important in soil formation and ecosystem dynamics, they have been shown to influence chemical compositions of groundwater. In the case of areas with elevated groundwater arsenic of natural origin, mobilization of arsenic from the critical zone between soil and aquifer has been invoked to supply much of the...

The generation of sediment and its transport occurs within and at the boundaries of colluvial soils. Models that predict the evolution of soil mantled landscapes are most commonly based on statements of mass conservation that quantify mass fluxes (i.e., sediment transport) and mass sources (e.g., soil production) within colluvial soil. Traditionall...

After a decade of research, there is still no broad-scale understanding of why Asian aquifers support such heterogeneous distributions of groundwater arsenic. In countries like Bangladesh, Nepal, and Vietnam, it is often the case that wells spaced a few meters apart and drilled to the same depth have vastly different concentrations of dissolved ars...

Extreme spatial heterogeneity has emerged as a salient characteristic of groundwater arsenic in many complex fluviodeltaic environments. Here we examine patterns of arsenic heterogeneity in the shallow (<23 m) groundwaters of a well-studied floodplain setting in Araihazar, Bangladesh. Ninety-five augers and 200 shallow wells sampled at spacings of...

The spatial variability of As concentrations in aquifers of the Red River Delta, Vietnam, was studied in the vicinity of Hanoi. Two sites, only 700 m apart but with very different As concentrations in groundwater (site L: <10 μg/L vs. site H: 170–600 μg/L) in the 20–50 m depth range, were characterized with respect to sediment geochemistry and mine...

One of the reasons the processes resulting in As release to groundwater in southern Asia remain poorly understood is the high degree of spatial variability of physical and chemical properties in shallow aquifers. In an attempt to overcome this difficulty, a simple device that collects groundwater and sediment as a slurry from precisely the same int...

Whereas serious health consequences of widespread consumption of groundwater elevated in As have been documented in several South Asian countries, the mechanisms responsible for As mobilization in reducing aquifers remain poorly understood. We document here a previously unrecognized and consistent relationship between dissolved As concentrations in...

Elemental mercury (Hg(0)) is a metal with a number of atypical properties, which has resulted in its use in myriad anthropogenic processes. However, these same properties have also led to severe local subsurface contamination at many places where it has been used. As such, we studied the influence of various parameters on Hg(II) sorption onto pyrit...

The high-degree of spatial variability of dissolved As levels in shallow aquifers of the Bengal Basin has been well documented but the underlying mechanisms remain poorly understood. We compare here As concentrations measured in groundwater pumped from 4700 wells <22 m (75 ft) deep across a 25 km2 area of Bangladesh with variations in the nature of...

We investigated the mobility of freshly prepared and aged ferrihydrite colloids through sequentially encountered porous matrices with contrasting isoelectric points, quartz and calcite sands. Influent solutions varied in suspension density, arsenate concentration and pH. X-ray diffraction was performed on 1mm ID plasticrit columns mounted on an ele...

Shallow aquifer groundwater arsenic heterogeneity is well documented in many of the fluvial regions of Asia. To this day, the cause for the heterogeneity remains poorly understood in part because of the heterogeneity of sediment properties inherent to a young floodplain depositional environment. In April 2006, a needle-sampler device was used to ob...

A new sampling device was used to obtain 8 detailed profiles of groundwater and associated sediment properties to ∼30 m depth in a 4 km2 area of Bangladesh that is characterized by high spatial variability in groundwater As. Concentrations of dissolved As, Fe, and Mn ranged from < 0.1 to 600 μg/L, < 0.1 to 18 mg/L, and < 0.1 to 4 mg/L, respectively...

The extremely heterogeneous distribution of As in Bangladesh groundwater has hampered efforts to identify with certainty the mechanisms that lead to extensive mobilization of this metalloid in reducing aquifers. We show here on the basis of a high-resolution transect of soil and aquifer properties collected in Araihazar, Bangladesh, that revealing...

One of the bewildering aspects of the current arsenic crisis in Bangladesh and other South Asian countries is the extreme degree of spatial variability of groundwater As concentrations. This presentation focuses on the origin of this variability in the top 20 meters of shallow aquifers by combining surface geophysical measurements (EM31) with groun...

The proliferation of geogenic arsenic has been documented in several fluvial systems, including areas of Inner Mongolia and the deltas off the Amazon River and in the Bengal Basin. Currently, however, our understanding of the arsenic cycling within many of these systems has yet to be explained geologically. In this study, we focus on determining ho...

Shallow aquifer groundwater arsenic heterogeneity is well documented in the floodplain of Bangladesh. The cause for this heterogeneity is poorly understood in part because of the heterogeneity of sediment properties inherent to a young floodplain depositional environment. In January 2004, a Needle-sampler device was used to obtain depth transects o...

This paper describes a rapid procedure that allows precise analysis of Mo, Cd, U and Th in sediment samples as small as 10 mg by using a novel approach that utilizes a “pseudo” isotope dilution for Th and conventional isotope dilution for Mo, Cd and U by ICP-MS. Long-term reproducibility of the method is between 2.5 and 5% with an advantage of rapi...

Thesis (M.S.)--Stony Brook University, 2005. Includes bibliographical references (leaves 39-43).