Increasing Transport Distance Research Articles

Sourcing and long-range transport of particulate organic matter in river bedload: Río Bermejo, Argentina

Abstract. Fluvial transport of organic carbon from the terrestrial biosphere to the oceans is an important term in the global carbon cycle. Traditionally, the long-term burial flux of fluvial particulate organic carbon (POC) is estimated using river suspended sediment flux; however, organic carbon can also travel in river bedload as coarse particulate organic matter (POMBed). Estimates of fluvial POC export to the ocean are highly uncertain because few studies document POMbed sources, flux, and evolution during long-range fluvial transport from uplands to ocean basins. This knowledge gap limits our ability to determine the global terrestrial organic carbon burial flux. In this study we investigate the flux, sources, and transformations of POMBed during fluvial transport over a ∼1300 km long reach of the Río Bermejo, Argentina, which has no tributary inputs. To constrain sourcing of POMBed, we analyzed the composition and stable hydrogen and carbon isotope ratios (δ2H, δ13C) of plant wax biomarkers from POMBed at six locations along the Río Bermejo and compared this to samples of suspended sediment, soil, leaf litter, and floating organic debris (POMfloat) from both the lowland and headwater river system. Across all samples, we found no discernible differences in n-alkane average chain length or nC29 δ13C, indicting a common origin for all sampled POMBed. Leaf litter and POMfloat nC29 δ2H values decrease with elevation, making it a useful proxy for POMBed source elevation. Biomarker δ2H values suggest that POMBed is a mix of distally derived headwater and locally recruited floodplain sources at all sampling locations. These results indicate that POMBed can be preserved during transport through lowland rivers for hundreds of kilometers. However, the POMBed flux decreases with increasing transport distance, suggesting mechanical comminution of these coarse organic particles and progressive transfer into the suspended load. Our provisional estimates suggest that the carbon flux from POMBed comprises less than 1 % of the suspended load POC flux in the Río Bermejo. While this represents a small portion of the river POC flux, this coarse, high-density material likely has a higher probability of deposition and burial in sedimentary basins, potentially allowing it to be more effective in long-term CO2 drawdown relative to fine suspended particles. Because the rate and ratio of POMBed transport versus comminution likely vary across tectonic and climatic settings, additional research is needed to determine the importance of POMBed in the global carbon cycle.

Mapping the Sustainability of Waste-to-Energy Processes for Food Loss and Waste in Mexico—Part 1: Energy Feasibility Study

Mexico generated 8.9 Mt of food loss and waste (FLW) at food distribution and retail centers in the year 2022. Traditional management methods in Latin America primarily involve final disposal sites, contributing to national greenhouse gas emissions of 0.22 Mt CO2 eq y−1. This creates an urgent need for sustainable valorization strategies for FLW to mitigate environmental impacts. This comprehensive study analyzes the geographical distribution of FLW generation and proposes a valorization approach using WtE-AD plants. Geographic information systems were employed for geographical analysis, life cycle assessment was used for environmental evaluation, and circular economy business models were applied for sustainability assessment. The primary objective of this first part of the contribution is to evaluate the technical feasibility of implementing waste-to-energy anaerobic digestion (WtE-AD) plants for FLW management in Mexico considering their geographical locations. The results demonstrate that WtE-AD plants with treatment capacities exceeding 8 t d−1 can achieve positive energy balances and significantly reduce greenhouse gas emissions. Specific findings indicate that these plants are viable for large-scale implementation, with larger plants showing resilience to increased transport distances while maintaining energy efficiency. The results highlight the critical influence of methane yields and transport distances on plant energy performance. This study underscores the importance of strategically placing and scaling WtE-AD plants to optimize resource efficiency and environmental sustainability. These findings provide essential insights for policymakers and stakeholders advocating for the transition of Mexico’s food supply chain toward a circular economy. Future parts of this study will explore detailed economic analyses and the policy frameworks necessary for the large-scale implementation of WtE-AD plants in Mexico. Further research should continue to develop innovative strategies to enhance the techno-economic and environmental performance of WtE-AD processes, ensuring sustainable FLW management and energy recovery.

Characteristics and long-runout mechanisms of the coarse-grained debris avalanche deposit in the ancient continental rift basin

Debris avalanche deposits are developed on slopes in various environments, including submarine volcanoes, continental volcanoes, continental slopes, and mountain ranges. In contrast, research is relatively scarce on the coarse-grained subaqueous debris avalanche deposits formed by the collapse of steep basin margins in continental small rift basins, which are controlled by tectonics. Through the interpretation of satellite imagery, field investigations, and the study of the morphological characteristics and internal structures of sediments, a massive debris avalanche event during the Early Cretaceous, Xiguayuan Formation of the Luanping Basin at the northern edge of the Yanshan tectonic belt on the North China Block, named the Wangying Debris Avalanche Deposit (WYDAD), has been identified and analyzed for its kinematics, dynamics, and long-runout mechanisms. The study reveals that based on sedimentology, internal structures, and basal characteristics, five different types of sedimentary morphologies can be identified from the source zone to the distal zone: convergent ridges and grooves (longitudinal expansion and lateral compression), transverse ridges and grooves (compression), longitudinal ridges and grooves (shearing and stretching), arcuate ridges and grooves (compression), and mixed sediments (radial extension). The grain size of coarse-grained debris avalanche deposits decreases with increasing transport distance and fragmentation due to jigsaw cracking, while matrix content increases. Additionally, the entrainment of fine-grained substrate and the mixing of lake waters during the transport of debris avalanches often evolve into secondary debris flows or high-density turbidity currents. Debris avalanches are likely primarily controlled by regional tectonic activity and volcanic action. Compared to subaerial debris avalanche deposits, the subaqueous WYDAD exhibits characteristics such as low fragmentation, smooth underwater terrain due to water resistance and buoyancy, and higher fluidity. The mechanism for the long-distance, high-speed transport of the WYDAD is explained by “hydroplaning” and high pore pressure generated by non-draining shear. This study provides insights into the transport processes of coarse-grained subaqueous debris avalanche deposits in continental rift basins. It verifies whether such sediments can serve as a primary sedimentary system for CCUS or potential resource storage.

Revised Heart Allocation Policy Improved Waitlist Mortality and Waiting Time With Maintained Outcomes in En-Bloc Heart-Lung Transplant Candidates and Recipients.

The revised United Network for Organ Sharing heart allocation policy was implemented in October 2018. Using a national transplant database, this study evaluated the transplant rate, waitlist mortality, waiting time, and other outcomes of en-bloc heart-lung transplantation recipients. Adult patients registered on the national database for heart-lung transplants before and after the policy update were selected as cohorts. Baseline characteristics, transplant rates, waitlist mortality, waiting times, and other outcomes were compared between the two periods. In total, 370 patients were registered for heart-lung transplants during the pre- and post-periods. There were significantly higher transplant rates, shorter waitlist times, and substantially reduced waitlist mortality in the post-period. Registered patients waitlisted in the post-period had significantly higher utilization of intra-aortic balloon pumps, extracorporeal membrane oxygenation, and overall life support, including ventricular assist devices. Transplant recipients had significantly longer ischemic times, increased transport distances, and shorter waiting times before transplantation in the post-policy period. Transplant recipients held similar short-term survival before and after the policy change (log-rank test, p = 0.4357). Therefore, the revised policy significantly improved access to en-bloc heart-lung allografts compared with the prior policy, with better waitlist outcomes and similar post-transplant outcomes.

Abundance, distribution and deposition of PM2.5-bound iron in northern China during 2021 dust and dust storm periods

Dust storms have the ability to transport and deposit contaminants and nutrients, such as iron (Fe), to downwind regions through atmospheric processes. However, there is a lack of reported data on the high-resolution variations and deposition of particulate iron in multiple locations during dust storms. This study aimed to address this gap by employing standardized analytical methods to measure the concentrations of PM10, PM2.5, and PM2.5-associated Fe in Taiyuan, Beijing, Tianjin, Ji'nan, and the Bohai Bay of China during the dusty events of 2021. A total of 13 blowing sand or dust storms were recorded, with average PM10 and PM2.5 concentrations of 262 ± 322 and 85 ± 652, 171 ± 403 and 53 ± 448, 153 ± 211 and 57 ± 315, and 207 ± 249 and 63 ± 301 μg/m3 at the above-mentioned sites, respectively. These elevated concentrations were attributed to stronger winds in northern China and severe wind erosion in the sand source areas. During these events, the average concentrations of PM2.5-bound Fe reached 2730.2 ± 4587.9, 2030.2 ± 3877.9, 1342.1 ± 2251.4, and 1785.1 ± 2536.6 ng/m3 in Taiyuan, Beijing, Tianjin, and Ji'nan, respectively, with the highest concentrations recorded as 48.8, 48.0, 29.2, and 22.7 μg/m3. A significant positive correlation was observed between Fe and Si in PM2.5 in the four cities, with higher Fe/Si slopes recorded in or near the source regions, while the homogenized Fe/Si values were observed after long-distance transport. The mean dry deposition fluxes (FFe) of PM2.5-bound Fe were calculated as 0.34 ± 0.64, 0.31 ± 0.91, 0.21 ± 0.56, and 0.17 ± 0.28 mg/m2/d for Taiyuan, Beijing, Tianjin, and Ji'nan, respectively, based on both hourly observation data and model-based calculations of dry deposition velocities. It is worth noting that FFe decreased from west to east in China, consistent with a previous study that showed a decrease in dust deposition rates with increasing transport distances. Peaks in FFe corresponded to the highest concentrations of PM2.5-associated Fe, indicating that these concentrations played a significant role in Fe. Furthermore, the atmospheric deposition of dissolved Fe from blowing sand or dust storm events was found to contribute to carbon fixation in the Bohai region of China, providing a range of 7.8 × 104–3.9 × 106 mol. This research provides valuable insights into the quantitative relationship between atmospheric deposition and marine productivity during dust events.

Characteristics of loess wind sorting and its structural mechanical significance

As loose sediment transported and deposited by wind, changes in the grain size of loess is the main source of changes in its macromechanical properties, mesostructural characteristics and microparticle effects. However, at present, there is almost no relevant research on the relationship between grain size and structural mechanics of wind-sorted loess, which significantly restricts the in-depth understanding of the mechanism and evolution of geological disasters and resulting engineering damage. In this paper, grain size optimization is performed by a wind sorting device developed in this laboratory to reveal the intrinsic mechanism associated with sorting, structural mechanics and particle interactions. The results show that the average grain size is positively correlated with the wind speed and negatively correlated with the transport distance. Further study finds that the grain size of aeolian loess consists of superimposed medium and fine particle fractions with good distribution sorting and coarse particle fractions with poor distribution sorting. Under the same conditions of water content and dry density, cohesion increases with increasing transport distance and wind speed. However, the internal friction angle first decreases and then slowly increases during the whole wind transport process. Fine particle content is the decisive factor for the change in shear parameters. Microscopic analysis shows that the contact mode, pore characteristics, azimuth of particles and variations in coarse, medium and fine ternary particle accumulations are closely related to the grain size distribution caused by wind sorting. The negative (loosening, wall, wedge) and positive (filling, adsorption) effects in these microstructures correspond to the structural characteristics of soil at different transport distances, and different structural characteristics correspond to different mechanical properties. This correspondence fully reveals the close relationship between the grain size characteristics produced by wind sorting and structural mechanics. This study helps to elucidate the relationship between grain size variation and mechanical characteristics of aeolian loess and provides theoretical references for relevant applications in the fields of geological and geotechnical engineering.

Multiphase migration and transformation of BTEX on groundwater table fluctuation in riparian petrochemical sites

Light non-aqueous phase liquids (LNAPL) are considered to be a composition-based risk, containing multiple chemical ingredients that release dissolved- and vapor-phase plumes. In dissolved form, there is a saturation-based risk as the water source expands, affecting groundwater aquifers on a larger scale in the aquifer. As a typical pollutant found in petrochemical contaminated sites, the migration and transformation of benzene, toluene, ethylbenzene, and o-xylene (BTEX) between gas, aqueous, and NAPL phases are distinctly affected by groundwater table fluctuation (GTF). BTEX multiphase migration and transformation pattern in a petrochemical factory at the riverside was simulated based on the TMVOC model in differentiating pollution distribution and interphase transformation under stable or fluctuating groundwater tables conditions. TMVOC model performed an excellent simulation effect on the migration and transformation of BTEX in GTF circumstances. In comparison with the stable groundwater table condition, the BTEX pollution depth under GTF increased by 0.5m, the pollution area increased by 25%, and the total mass increased by 0.12 × 102kg. In both cases, the mass reduction of NAPL-phase pollutants was more significant than the total mass reduction of pollutants, and GTF further promoted the mass conversion of NAPL-phase pollutants to water pollutants. Prominently, as the groundwater table rises, the GTF can correct for evacuation, and the transport flux of gaseous pollutants at the atmospheric boundary decreases with increasing transport distance. Furthermore, descended groundwater table will intensify the transmission flux of gaseous pollutants at the atmospheric boundary with the transmission range expanding, which can be harmful to human health on the surface due to gaseous pollutants entering into the air.

A Comparative Life Cycle Assessment: Polystyrene or Polypropylene Packaging Crates to Reduce Citrus Loss and Waste in Transportation?

Packaging plays a key role in preserving food products during transportation. Therefore, selecting proper packaging crates to transport fruits from farms to the market can dramatically reduce loss and waste. This study aims to evaluate the environmental impact of two packaging alternatives when transporting citrus products in Jordan using the loss ratio, as an indicator to select the best packaging, based on the traveled distances. The research team tracked transportation trucks from several farms to the market. In addition, data were collected from the department of statistics in Jordan to build the model using OpenLCA Software with defined system boundaries. However, the results revealed that polypropylene crates performed better than polystyrene crates. Citrus loss during transportation was cut by at least 60% when using polypropylene crates. The use of polypropylene crates reduced product damages by handling better the vibration and load stress, especially with increased transport distances to the “Central Market of fruits and vegetables”. Different impact categories were evaluated. We selected 3 categories based on the hotspot analysis performed: climate change, resource depletion, and water resource depletion. Farm waste has the highest impact with ranges of 58–69%, 77–85%, and 77–81%, respectively. Other impactful waste is waste from packaging and inedible parts; they influence the impact categories up to 23%, 11%, and 17%, in the same order. In terms of environmental impact, the polypropylene crates have fewer impacts since they are reusable and recyclable at the end of the product life cycle. Therefore, we recommend adopting polypropylene crates when transporting citrus products to the market. As a future research direction, the study suggests performing a similar analysis to evaluate the effect of packaging crates on other agricultural products in Jordan.

What Does a Notion of Weight Mean to Chimpanzees?

How to best understand how animals think about the world? Considering that cognition develops in interactions with the outside world, we need to compare the cognitive performance of individuals of the same species living under different ecological conditions. I propose here to compare the notion of weight studied in captive chimpanzees to the ones observed in a wild chimpanzee population that is using hammers of different weights to crack nuts during many months of the year. Detailing different situations where the chimpanzees have to select a hammer for cracking two species of nuts of different hardness, my colleagues and I could illustrate the flexibility of the causal reasoning performed by the chimpanzees, including stable anticipation of weight, combining weight with density and transport distance, and the gradual shift of selection criteria with increasing transport distance. Combined with results from captive studies on the notion of weight in chimpanzees, this suggests that when individuals face specific ecological challenges, they may acquire sophisticated causal reasoning generalized over different contexts. The evolution of cognition in chimpanzees suggests a complex interplay with ecology, memory demands, individual differences, and technical challenges important to the population.

The Promotion/Inhibition of the Seepage Transport of Copper Ions by Suspension-Colloidal Particles with Wide Size Gradation

Sand column tests were conducted to investigate the seepage transport of silicon powders (SPs) with two wide particle size ranges (30-2000 nm and 2-70 μm), including the cotransport of SPs and copper ions. The results show that the graded large-scale SP has an obvious inhibiting influence on the transport of copper ions. In contrast, in the presence of the graded small-scale SP, the concentration of copper ions in the effluent tends to increase; i.e., there appears to be a promoting effect. However, after a long transport distance, the presence of SPs, regardless of particle size, has an overall retarding effect on heavy metal pollutants (e.g., copper ions). The promoting effect of the increase in seepage velocity on the concentration of copper ions in the effluent is greater with the graded large-scale SPs than with the graded small-scale SPs. In terms of the microstructural characteristics by metallographic microscopy, the average particle size of the deposited graded small-scale SPs is almost constant at different transport distances, while that of the deposited graded large-scale SPs tend to decrease significantly with increasing transport distance; i.e., notable bed filtration is exhibited in the latter case. This physical mechanism also determines the sequence and rate of the retarding effect of SPs on heavy metal ions under seepage flow.

The Life Cycle Energy Consumption and Emissions of Asphalt Pavement Incorporating Basic Oxygen Furnace Slag by Comparative Study

Basic Oxygen Furnace Slag (BOF), as alternatives for aggregate in asphalt pavement construction, is beneficial to the environment by reducing land occupation and resource consumption. However, the quantitative effects on energy consumption and emissions reduction remains poorly understood due to the unavailability of local life cycle inventory. Therefore, its LCI needs to be built by accounting for the properties of BOF aggregate in terms of high porosity and dust content in BOF, the rainy interference condition that reducing efficiency in production, and transportation distance. Here we investigated the life cycle energy consumption and global warming potential (CO2-eq emission) of asphalt pavement incorporating BOF aggregate by performing a case study with uncertainty analysis. Five scenarios were elaborated and performed in the case study. The results show that the energy required for BOF production is 0.024 MJ/kg, approximately half the energy required for crushed stone of 0.044 MJ/kg. The pavements with BOF can reduce up to 12% of emission compared to ordinary pavement. Considerably more negative impacts of rainy weather on energy consumption of BOF than natural crushed stone can be concluded. Monte Carlo simulation indicates that the order of magnitudes of the energy values were varied, from materials extraction as the maximum contributor to transportation. The benefits for BOF utilization are gradually offset by increased transport distances and the displacement ratios of fine crushed stones, due to the increase in fuel and resource consumption for mixing, construction, and transportation.

Experimental investigations on scale-dependent dispersivity in three-dimensional heterogeneous porous media.

The relationship between the scale-dependent dispersivity and heterogeneous sedimentary structures is investigated through conducting non-reactive tracer experiments in a three-dimensional heterogeneous sand tank. The heterogeneous porous media consists of three sedimentary facies of silty, fine, and medium sands collected from the west of the Songnen Plain, China. Moreover, several corresponding individual facies soil columns were constructed for comparison. A conservative tracer was continuously injected from an upstream source. The effective parameters were estimated by inverse modeling of a one-dimensional transport model. The results show that the scale dependence of the estimated dispersivities was discovered in the individual facies column (with relatively weaker effect) and the heterogeneous porous media (with more significant effect). With increasing transport distances, the dispersivities of the individual facies tend to reach an asymptotic value, while those of the heterogeneous media increase continuously. Furthermore, the results show that a power function can describe the relationship between effective dispersivities and transport distances. The exponent of the function is greater than one for the heterogeneous media, but less than one for the individual facies. The results also indicate that the dispersion plume is macroscopically dominated by the distribution of facies. The heterogeneity of hydraulic conductivity causes the variations of flow velocity, which further enhances the scale dependence of dispersivities. The tracer experiment in heterogeneous media provides the fundamental insight into the understanding of contaminant transport processes.

Simulating the forest fuel market as a socio‐ecological system with spatial agent‐based methods: A case study in Carinthia, Austria

AbstractThe paper presents an agent‐based modeling and simulation approach to model the forest fuel supply chain for heating purposes (i.e., heating plants). The paper focuses on the simulation of the processes of timber harvesting by forest enterprises and the competition of heating plants for the limited resource of wood chips. In particular, the work identifies different stakeholders having an adaptive behavior—with respect to the overall market conditions and timber prices. The agent‐based model developed here—called SimFoMa—uses three types of agents—forest enterprises, heating plants, and traders. The agents are interacting in an environment that has rich information on the forests and road network. The SimFoMa model is applied to a test area, the province of Carinthia, Austria. We defined six different simulation scenarios that cover different market situations—from increasing timber prices, volatile market conditions, or decreasing market conditions—and evaluated the harvest patterns, transport distances and the forest itself. The paper utilizes the agent‐based modeling methodology to model the agent's adaptive behavior of the forest fuel supply chain and to model the competition of heating plants for forest fuels. To evaluate this phenomena we mainly analyze transport distances of the simulation runs. For the test area of Carinthia, the experiments show that the behavior of small forest owners influences the supply of forest fuels. Timber prices not meeting the expectations of small forest owners might not motivate them to produce timber and forest fuels. On the long run the overall forest fuel supply does not meet the demand in the test area Carinthia—hence it relies on biomass imports. Furthermore, we witnessed increasing transport distances from harvest site to heating plant.Recommendations for Resource Managers The results of the spatial Agent‐based simulation of the forest fuel market with agents competing for the limited resource forest biomass show that transport distances for forest fuels can vary and may increase over time. Hence, the planning of the forest fuels supply and the respective transport distances is crucial to reduce the carbon footprint of the timber for heating purposes. As small forest owners produce timber on a more irregular basis (based on the price in the market), the motivation of small forest owners is crucial for the steady supply of biomass for heating purposes—for the case of Carinthia. In the long run it is not possible to fulfill the demand of biomass for heating purposes for Carinthia, without imports of timber. Again, crucial is the motivation of small forest owners to produce timber.

Supply of agricultural biomass residues for on-farm composting: a cross-analysis of relevant data sets for the most sustainable management combination

ABSTRACT Agricultural crop production can generate significant residues and their management is generally a disposal problem. Composting can be a solution. It is essentially an efficient bioconversion technique to process organic wastes (manure, food, crop and forestry residues, solid digestate) into humus-like substances destined to different uses (soil amendment, organic fertilization, plant nursery substrates). Life Cycle Assessment, Energy Analysis, and Life Cost Costing were used to perform a cross-analysis aimed to assess the environmental, economic, and energy sustainability of some procurement systems of compostable materials (bulking agents and agricultural crop residues) to be allocated to composting on the farm. The procurement systems were characterized by different mechanization levels in order to explore the possible scenarios related to the availability of vehicles within the farm and increasing transport distances. Our findings underline that the most sustainable option for the environment it was not often the most cost-effective choice. Therefore, the cross-analysis of these relevant data sets allowed us to detail the different operative steps and guide the procurement system choice toward those showing the best compromise for both the environment and farmers (cheaper, with no or low impactful).

Counterintuitive role of geometry in transport by quantum walks

Quantum walks are accepted as a generic model for quantum transport. The character of the transport crucially depends on the properties of the walk like its geometry and the driving coin. We demonstrate that increasing transport distance between source and target or adding redundant branches to the actual graph may surprisingly result in a significant enhancement of transport efficiency. We explain analytically the observed nonclassical effects using the concept of trapped states for several intriguing geometries, including the ladder graph, the Cayley tree, and its modifications.

Controls of stable isotopes in precipitation on the central Tibetan Plateau: A seasonal perspective

Determining the temporal controls on stable isotopes in precipitation is essential for the paleoclimate reconstruction and hydrological regimes in the Tibetan Plateau (TP). Although related studies have been conducted throughout most of the TP, conclusions for the central TP remain unclear. Therefore, in this study, we evaluated the climatic controls on precipitation isotopes on a seasonal basis using a 3-year (January 2014 to December 2016) dataset of daily precipitation isotopes from Xainza station in the Siling Co Basin of the central TP. Results showed that the precipitation δ18O displayed a distinct seasonal variation, with enriched values occurring in the pre-monsoon season and relatively depleted values in the monsoon season. Significant positive correlations between precipitation δ18O and temperature have been observed during the pre-monsoon and westerly seasons with short-distance moisture trajectories with a large percentage. In comparison, during the monsoon season, the strongest control was provided by integrated regional convections that occurred over several previous days (0–20 days). The increased transport distances extending to the humid ocean with enhanced upstream convections along the trajectory lead to more depleted isotopic values and thus the weakening of convections may be responsible for the increase of δ18O values during the post-monsoon season. Additionally, the comparison of d-excess values with other stations in the TP demonstrated the ever-present significant influence of continental moisture throughout the year. A slighter decrease in d-excess values during the monsoon season retained more signals of moisture evaporated from the continent and thus may lead us into more consideration of local recycles. These results indicated that the effects of different moisture sources, including the Indian monsoon and convections, should be considered when interpreting δ18O from the climate proxies and tracing the water cycles on the central TP.

Platinum-Group Minerals of Pt-Placer Deposits Associated with the Svetloborsky Ural-Alaskan Type Massif, Middle Urals, Russia

The alteration of platinum group minerals (PGM) of eluval, proximal, and distal placers associated with the Ural-Alaskan type clinopyroxenite-dunite massifs were studied. The Isovsko-Turinskaya placer system is unique regarding its size, and was chosen as research object as it is PGM-bearing for more than 70 km from its lode source, the Ural-Alaskan type Svetloborsky massif, Middle Urals. Lode chromite-platinum ore zones located in the Southern part of the dunite “core” of the Svetloborsky massif are considered as the PGM lode source. For the studies, PGM concentrates were prepared from the heavy concentrates which were sampled at different distances from the lode source. Eluvial placers are situated directly above the ore zones, and the PGM transport distance does not exceed 10 m. Travyanistyi proximal placer is considered as an example of alluvial ravine placer with the PGM transport distance from 0.5 to 2.5 km. The Glubokinskoe distal placer located in the vicinity of the Is settlement are chosen as the object with the longest PGM transport distance (30–35 km from the lode source). Pt-Fe alloys, and in particular, isoferroplatinum prevail in the lode ores and placers with different PGM transport distance. In some cases, isoferroplatinum is substituted by tetraferroplatinum and tulameenite in the grain marginal parts. Os-Ir-(Ru) alloys, erlichmanite, laurite, kashinite, bowieite, and Ir-Rh thiospinels are found as inclusions in Pt-Fe minerals. As a result of the study, it was found that the greatest contribution to the formation of the placer objects is made by the erosion of chromite-platinum mineralized zones in dunites. At a distance of more than 10 km, the degree of PGM mechanical attrition becomes significant, and the morphological features, characteristic of lode platinum, are practically not preserved. One of the signs of the significant PGM transport distance in the placers is the absence of rims composed of the tetraferroplatinum group minerals around primary Pt-Fez alloys. The sie of the nuggets decreases with the increasing transport distance. The composition of isoferroplatinum from the placers and lode chromite-platinum ore zones are geochemically similar.

Petrography and geochemistry of Oligocene to Lower Miocene sandstones in the Baiyun Sag, Pearl River Mouth Basin, South China Sea: Provenance, source area weathering, and tectonic setting

There is a controversy regarding the source area and weathering intensity of Oligocene to Lower Miocene sediments in the Baiyun Sag of the Pearl River Mouth Basin. Detrital modes, geochemistry, heavy mineral data, and detrital zircon U–Pb ages were analysed to understand the provenance, source area weathering, and tectonic setting of Oligocene to Lower Miocene sandstones in the Baiyun Sag. Petrographic data reveal that the sandstones were derived from a recycled orogen. With increasing transport distance, sediment maturity increased correspondingly. The Oligocene to Lower Miocene sandstones in the Baiyun Sag have low compositional maturity and have experienced low to moderate weathering. The sediments of the Zhuhai Formation have experienced relatively strong weathering intensity compared with those of the Enping and lower Zhujiang formations. Due to low degree of illitization and differences in the geochemical compositions of the sediments, the continental island arc data from different boreholes in the Baiyun Sag are more irregularly distributed in the A‐CN‐K plot. The modal composition (e.g., quartz, feldspar, and lithic fragments) and geochemical indices (Al2O3/TiO2 ratio; Al2O3‐TiO2 diagram; discriminant F1‐F2 diagram; Eu/Eu*, La/Sc, La/Co, Th/Sc, and Th/Co ratios; Hf‐La/Th and La/Sc‐Co/Th diagrams; and rare earth element patterns) indicate that the sediments in the Baiyun Sag are mainly derived from felsic source rocks. Although the uplift around the Baiyun Sag includes multistage magmatism and basic rocks, it has little influence on the sediment in the depression, and no sediments were transported by the Han River to the Baiyun Sag. Geochemical data and detrital zircon U–Pb ages suggest that the Pearl River was formed in the Early Oligocene and became the main source for the sediments in this area. The river carried felsic material from the South China Coast forming a large delta on the northern slope of the Baiyun Sag. The ratios of Eu/Eu*, La/Sc, La/Co, Th/Sc and Th/Co, and heavy mineral data indicate that the sediments transported by the Pearl River to the Baiyun Sag were changed from the arc‐dominated coastal zone to the interior of the South China Block during the Late Oligocene to Early Miocene and even reached the south‐eastern margin of the Tibetan Plateau (West Yunnan Plateau). The La‐Th‐Sc and Th‐Sc‐Zr/10 diagrams suggest that the provenance of these sandstones is evolved continental island arc or an active continental margin setting.

Environmental consequences of introducing genetically modified soy feed in Sweden

Most environmental assessments of soy production and trade do not distinguish between genetically modified (GM) and non-GM soy. In reality though, soybean imports to European Union maintain identity preservation through segregated supply lines. We, therefore, perform an attributional life cycle assessment (ALCA) of the global soy chain separately for the GM and non-GM imports. First a detailed mapping of the soy-feed supply chain is done, beginning from the farm in Latin America to the animal farmer in European Union. Subsequently, life cycle is assessed to calculate the environmental impacts of each supply line for 14 impact categories, including global warming potential. Since non-GM soy based compound feed is expensive, in countries such as Sweden where there is zero tolerance for genetically modified organisms, animal farmers face a higher cost of production. As a result, there exists the possibility for a policy shift towards use of only GM soy. Hence, a consequential life cycle assessment (CLCA) is performed that includes the market effects for a scenario of shifting from GM to non-GM soy. This also ensures robustness in our estimation of the differential environmental impacts. Results from ALCA reveal that there are no significant environmental gains from importing non-GM soy over GM soy. Global warming potential and freshwater ecotoxicity are very high from non-GM imports while GM soy imports have a larger effect on land uses and terrestrial eutrophication. Increased transport distances due to segregation for non-GM soy is a major contributor to the higher negative environmental effects. Results from the CLCA, however, show that GM soy has a higher negative impact in most of the impact categories including global warming potential and freshwater and terrestrial acidification. This is possible when high demand for low cost GM triggers greater production in Latin America and substitution of locally grown protein, such as rapeseed cake, in Sweden.

3‐D Characterization of Detrital Zircon Grains and its Implications for Fluvial Transport, Mixing, and Preservation Bias

AbstractDetrital zircon studies can suffer from selective loss of provenance information due to U‐Pb age discordance, metamictization, metamorphic overprinting and fluviatile transport processes. The relationship between isotopic composition and zircon grain shape, and how grain shape is modified during transport, is largely unknown. We combine X‐ray tomography with U‐Pb geochronology to quantify how fluvial transport affects 3‐D zircon shape, detrital age signature, and grain density along the Murchison River, whose catchment comprises Eoarchean to Early Paleozoic source rocks in Western Australia. We acquired tomographic volumes and isotopic data from 373 detrital zircons to document changes in size, shape and density in transport direction, and explore how grain shape, age spectra and the proportion of discordant material vary along the channel. Results show that shape characteristics are sensitive to transport distance, stream gradient, proximity to source material, and whether the source consists of primary or recycled zircons. With increasing transport distance, grain lengths decrease more than their widths. Furthermore, the loss of metamict grains occurs at a near constant rate, resulting in a linear increase of mean calculated zircon density by ca. 0.03 g/cm3 per 100 km transport distance. 3‐D grain shape is therefore strongly linked to detrital age signature, and mean grain density is a function of the absolute transport distance. 3‐D shape characteristics provide valuable information on detrital zircon populations, including the interaction between source materials with fluvial transport processes, which significantly affects preservation bias and, by inference, the representativeness of the sampled data.