Aboveground Sources Research Articles

Dissemination of antibiotic resistance genes from aboveground sources to groundwater in livestock farms

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are prevalent in various environments on livestock farms, including livestock waste, soil, and groundwater. Contamination of groundwater by ARB and ARGs in livestock farms is a growing concern as it may have potentially huge risks to human health. However, the source of groundwater-borne ARB and ARGs in animal farms remains largely unknown. In this study, different types of samples including groundwater and its potential contamination sources from aboveground (pig feces, wastewater, and soil) from both working and abandoned swine feedlots in southern China were collected and subjected to metagenomic sequencing and ARB isolation. The source tracking based on metagenomic analysis revealed that 56–95 % of ARGs in groundwater was attributable to aboveground sources. Using metagenomic assembly, we found that 45 ARGs predominantly conferring resistance to aminoglycosides, sulfonamides, and tetracyclines could be transferred from the aboveground sources to groundwater, mostly through plasmid-mediated horizontal gene transfer. Furthermore, the full-length nucleotide sequences of sul1, tetA, and TEM-1 detected in ARB isolates exhibited the close evolutionary relationships between aboveground sources and groundwater. Some isolated strains of antibiotic-resistant Pseudomonas spp. from aboveground sources and groundwater had the high similarity (average nucleotide identity > 99 %). Notably, the groundwater-borne ARGs were identified as mainly carried by bacterial pathogens, potentially posing risks to human and animal health. Overall, this study underscores the dissemination of ARGs from aboveground sources to groundwater in animal farms and associated risks.

The Management of Drinking Water in Trondheim from 950 to 1777 as a Source of Changing Attitudes toward Health

Abstract This article aims to illuminate how the management of drinking water and public health in Trondheim, Norway changed from 950 to 1777, from a private to public responsibility. A systematic analysis of five excavations in Trondheim shows that during the Middle Ages, only a few citizens had a well or a cistern on their property. This suggests that fetching water from above-ground sources was a regular practice. In the post-medieval period, this changed as the number of wells increased. However, the well water got polluted, and alternative water sources were too far away for the rising population. 18th-century political ideas emphasised how the citizens were now the state’s greatest resource, which prompted new mentalities on how authorities had to take care of the people. In 1777, the public authorities of Trondheim finally established a public water pipe system, ensuring clean water to its citizens.

Responses of aboveground litterfall respiration to unexpected snowfall events in Ailao subtropical forests in Southwest China

Soil respiration, the second largest CO2 flux in terrestrial ecosystems, involves the microbial respiration of litter from aboveground sources, belowground litter and root respiration, from rhizodeposition. In the subtropical forests of the Ailao Mountain, a chamber with automated CO2 efflux was set up with two treatments: a control treatment with litterfall to measure the total soil respiration (RT) and a litter removal treatment to measure aboveground litterfall respiration (RL). This study aimed to examine the responses of RL to unexpected heavy snowfall events and soil temperature (ST), soil moisture (SM), rainfall (RF), total litterfall (TL), litter water content (LWC), nitrate nitrogen (NO3−-N), and ammonium nitrogen (NH4+-N). The period of the study was divided into two: before the heavy snowfall event (BS) and during and after the heavy snowfall event (AS). The rate of RL was slightly decreased in AS (1.18 ± 0.03 μmol CO2 m−2 s−1) compared with that in BS (1.19 ± 0.02 μmol CO2 m−2 s−1). The relationships between RL and ST, SM, RF, and LWC, respectively, were all statistically significant (p < 0.05) in both periods. However, the relationships between RL and TL and NH4+-N, respectively, were not statistically significant for either period. The relationship between RL and NO3−-N was statistically significant for AS but not for BS. The relationship between RL and RF was statistically significant from 2011 to 2018. The temperature dependence of soil respiration was higher in BS than in AS, and the effect of litter removal was 2.55 % and 2.32 % for AS and BS respectively. The results indicate that current global terrestrial models underestimate RL trends for the feedback of global climate change in subtropical forests.

Carbon emissions from a temperate coastal peatland wildfire: contributions from natural plant communities and organic soils

BackgroundOne of the scientific challenges of understanding climate change has been determining the important drivers and metrics of global carbon (C) emissions and C cycling in tropical, subtropical, boreal, subarctic, and temperate peatlands. Peatlands account for 3% of global land cover, yet contain a major reservoir of 550 gigatons (Gt) of soil C, and serve as C sinks for 0.37 Gt of carbon dioxide (CO2) a year. In the United States, temperate peatlands are estimated to store 455 petagrams of C (PgC). There has been increasing interest in the role of wildfires in C cycling and altering peatlands from C sinks to major C sources. We estimated above- and below-ground C emissions from the Pains Bay Fire, a long-duration wildfire (112 days; 18,329 ha) that burned a coastal peatland in eastern North Carolina, USA.ResultsSoil C emissions were estimated from pre- and post-burn Light Detection and Ranging (LIDAR) soil elevation data, soils series and C content mapping, remotely sensed soil burn severity, and post-burn field surveys of soil elevation. Total above-ground C emissions from the fire were 2,89,579 t C and 214 t C ha−1 for the 10 vegetation associations within the burn area perimeter. Above-ground sources of C emissions were comprised of litter (69,656 t C), shrub (1,68,983 t C), and foliage (50,940 t C). Total mean below-ground C emissions were 5,237,521 t C, and ranged from 2,630,529 to 8,287,900 t C, depending on organic matter content of different soil horizons within each of the 7 soil series. The mean below-ground C emissions within the burn area were 1,595.6 t C ha−1 and ranged from 629.3 to 2511.3 t C ha−1.ConclusionsIn contrast to undisturbed temperate peatlands, human induced disturbances of the natural elevation gradient of the peatland has resulted in increased heterogeneity of floristic variation and assemblages that are a product of the spatial and temporal patterns of the water table level and the surface wetness across peatlands. Human induced changes in surface hydrology and land use influenced the fuel characteristics of natural vegetation and associated soils, thus influencing wildfire risk, behavior, and the resulting C emissions.

Subsurface aeration of tidal wetland soils: Root-system structure and aerenchyma connectivity in Spartina (Poaceae)

Root-aerenchyma in wetland plants facilitate transport of oxygen from aboveground sources (atmosphere and photosynthesis) to belowground roots and rhizomes, where oxygen can leak out and oxygenate the otherwise anoxic soils. In salt marshes, the soil oxygenation capacity varies among different Spartina-taxa, but little is known about structural pattern and connectivity of root-aerenchyma that facilitates this gas transport. Both environmental conditions and ploidy level play a role for the root-system morphology. Root-system morphology of polyploid Spartina-taxa was studied, quantifying root-tissue volume and root-aerenchyma volume of hexaploid Spartina alterniflora, Spartina maritima, and Spartina × townsendii as well as dodecaploid Spartina anglica from different habitats. Computed tomography (CT)-scan image analysis was applied to quantify the volume of roots and aerenchyma, and to determine the root-system structure (ratio of aerenchyma to root-tissue volumes) and aerenchyma connectivity. On average, Spartina-roots accounted for 12% (v/v) and root-aerenchyma accounted for 1% (v/v) of the soil volume in the pioneer marsh. About 90% (v/v) of all roots were associated with aerenchyma. Root-system structures of S. × townsendii and S. anglica differed and showed clear responses to habitat conditions, such as flooding regime and redox potential. The development of large well-connected aerenchyma fragments were specifically shown in S. anglica and to a minor extend in S. maritima. Aerenchyma in S. alterniflora and S. × townsendii consisted only of smaller fragments. Spartina-dominated tidal marsh soils show high connectivity with the atmosphere via root-aerenchyma. The high ploidy level in S. anglica comes along with high connectivity in root-aerenchyma.

Plant-Mediated Rhizosphere Oxygenation in the Native Invasive Salt Marsh Grass Elymus athericus.

In the last decades, the spread of Elymus athericus has caused significant changes to the plant community composition and ecosystem services of European marshes. The distribution of E. athericus was typically limited by soil conditions characteristic for high marshes, such as low flooding frequency and high soil aeration. However, recently the spread of E. athericus has begun to also include low-marsh environments. A high-marsh ecotype and a low-marsh ecotype of E. athericus have been described, where the latter possess habitat-specific phenotypic traits facilitating a better adaption for inhabiting low-marsh areas. In this study, planar optodes were applied to investigate plant-mediated sediment oxygenation in E. athericus, which is a characteristic trait for marsh plants inhabiting frequently flooded environments. Under waterlogged conditions, oxygen (O2) was translocated from aboveground sources to the roots, where it leaked out into the surrounding sediment generating oxic root zones below the sediment surface. Oxic root zones were clearly visible in the optode images, and no differences were found in the O2-leaking capacity between ecotypes. Concentration profiles measured perpendicular to the roots revealed that the radius of the oxic root zones ranged from 0.5 to 2.6 mm measured from the root surface to the bulk anoxic sediment. The variation of oxic root zones was monitored over three consecutive light–dark cycles (12 h/12 h). The O2 concentration of the oxic root zones was markedly reduced in darkness, yet the sediment still remained oxic in the immediate vicinity of the roots. Increased stomatal conductance improving the access to atmospheric O2 as well as photosynthetic O2 production are likely factors facilitating the improved rhizosphere oxygenation during light exposure of the aboveground biomass. E. athericus’ capacity to oxygenate its rhizosphere is an inheritable trait that may facilitate its spread into low-marsh areas. Furthermore, this trait makes E. athericus a highly competitive species in marshes facing the effects of accelerated sea-level rise, where waterlogged sediment conditions could become increasingly pronounced.

Impact of selected sources of transport vibrations on the perception of vibrations by people in buildings

Vibrations propagating through the soil into the building can not only be harmful to the building structure or cause its accelerated wear, but can also effect on the vibrational comfort in the rooms. They can also be annoying for residents and building users, and in extreme cases can lead to sleep disorders, headaches and neurotic conditions. Especially vibrations from the low frequency range from 5 to 25 Hz are undesirable, because there are resonance frequencies of human internal organs in this frequency range. The human perception of vibrations in buildings, despite many researches made in the past, despite standards and requirements in this area, is still a topic not fully understood mainly due to the subjective nature of the perception of vibrations by various people. It is widely known that the type of transport vibration source has an impact on human perception. Vibrations generated by above-ground sources are more felt on the upper floors as opposed to vibrations generated from the underground. In this paper three types of transport vibrations are analyzed on one chosen building located in Warsaw. Human perception of vibration is evaluated according to two methods: root mean squared (RMS) and vibration dose value (VDV).

Pathways of mineral-associated soil organic matter formation: Integrating the role of plant carbon source, chemistry, and point of entry.

To predict the behavior of the terrestrial carbon cycle, it is critical to understand the source, formation pathway, and chemical composition of soil organic matter (SOM). There is emerging consensus that slow-cycling SOM generally consists of relatively low molecular weight organic carbon substrates that enter the mineral soil as dissolved organic matter and associate with mineral surfaces (referred to as "mineral-associated OM," or MAOM). However, much debate and contradictory evidence persist around: (a) whether the organic C substrates within the MAOM pool primarily originate from aboveground vs. belowground plant sources and (b) whether C substrates directly sorb to mineral surfaces or undergo microbial transformation prior to their incorporation into MAOM. Here, we attempt to reconcile disparate views on the formation of MAOM by proposing a spatially explicit set of processes that link plant C source with MAOM formation pathway. Specifically, because belowground vs. aboveground sources of plant C enter spatially distinct regions of the mineral soil, we propose that fine-scale differences in microbial abundance should determine the probability of substrate-microbe vs. substrate-mineral interaction. Thus, formation of MAOM in areas of high microbial density (e.g., the rhizosphere and other microbial hotspots) should primarily occur through an in vivo microbial turnover pathway and favor C substrates that are first biosynthesized with high microbial carbon-use efficiency prior to incorporation in the MAOM pool. In contrast, in areas of low microbial density (e.g., certain regions of the bulk soil), MAOM formation should primarily occur through the direct sorption of intact or partially oxidized plant compounds to uncolonized mineral surfaces, minimizing the importance of carbon-use efficiency, and favoring C substrates with strong "sorptive affinity." Through this framework, we thus describe how the primacy of biotic vs. abiotic controls on MAOM dynamics is not mutually exclusive, but rather spatially dictated. Such an understanding may be integral to more accurately modeling soil organic matter dynamics across different spatial scales.

The Importance, Content and Teaching of the Political Geography Course in Social Studies Undergraduate Programs

Today, big countries and other countries inside their axes have entered power wars in regions where underground and aboveground sources are important. One of the characteristics of countries where these power wars take place is them not being able to understand the current world politics and elements of political geography. These countries cannot develop modern strategies for current political needs. Like these countries, Turkey has not yet understood the importance of political geography and could not produce an effective work on today’s world politics. We cannot use our regional power in line with our interests due to policies without a specific objective and system and changeable with each government. To use and direct our regional power, tremendous responsibility falls on the shoulders of social studies teachers. Bequeathing the importance of our geopolitical location to young generations is one of the most important responsibilities of social studies teacher candidates. In addition to not being current, the content of political geography course taught in social Studies undergraduate programs are repetition of old information. Therefore, political geography subjects in these programs should be organized according to today’s word politics and more emphasis should be given to the importance of our current geopolitical location. Having an important geopolitical location and being a great power in the Middle East, in a country like Turkey, people should be more aware in this subject.

Heavy Rainfall Impacts on Trihalomethane Formation in Contrasting Northwestern European Potable Waters.

There is emerging concern over the impact of extreme events such as heavy rainfall on the quality of water entering the drinking water supply from aboveground sources, as such events are expected to increase in magnitude and frequency in response to climate change. We compared the impact of rainfall events on streamwater quality in four contrasting upland (peatland and mineral soil) and lowland agricultural catchments used to supply drinking water in France (Brittany) and the United Kingdom (North Wales) by analyzing water samples collected before, during, and after specific events. At all four streams, heavy rainfall led to a considerable rise in organic matter concentration ranging from 48 to 158%. Dissolved organic carbon (DOC) quality, as determined using specific ultraviolet absorbance, changed consistently at all sites during rainfall events, with a greater proportion of aromatic and higher molecular weight compounds following the onset of rainfall. However, the change in DOC quality and quantity did not significantly alter the trihalomethane formation potential. We observed small increases in trihalomethane (THM) generation only at the Welsh peatland and agricultural sites and a small decrease at the Brittany agricultural site. The proportion of brominated THMs in chlorinated waters was positively correlated with bromide/DOC ratio in raw waters for all sites and hydrological conditions. These results provide a first indication of the potential implications for surface-based drinking water resources resulting from expected future increases in rainfall event intensity and extension of dry periods with climate changes.

CURRENT ENVIRONMENT STATE OF COASTAL MARINE WATER OF DAGESTAN

Aim . We analysed current environmental state of the Dagestan coast of the Caspian Sea. Data on the spatial variability of contaminants in the coastal areas of the Dagestan segment of the Caspian Sea from the northern districts (Lopatin) to the central (Sulak coastal land) and, further, to the southern district (within Russian subsoil management) confirm that it is caused by irregular contamination of the sea by above-ground sources. Location . Dagestan coastal area of the Caspian Sea Methods . Concentration analysis of background contamination of chemical agents in the Dagestan coastal water from northern districts (Lopatin) to southern (Sulak coastal land) during the period between 2004 and 2007. Results . Data on the spatial variability of contaminants in the coastal areas of the Dagestan segment of the Caspian Sea from the northern districts (Lopatin) to the central (Sulak coastal land) and, further, to the southern district (within Russian subsoil management) confirm that it is caused by irregular contamination of the sea by above-ground sources. Main conclusions . The envisaged large-scale hydrocarbon resource development requires regular monitoring of sea currents on Makhachkala, Izberbash and Derbent roads.

Whole-tree dynamics of non-structural carbohydrate and nitrogen pools across different seasons and in response to girdling in two temperate trees.

Despite extensive research on the seasonal dynamics of non-structural carbohydrate (NSC) and nitrogen (N) concentrations, the size and relative contributions of NSC and N pools across different tree organs are not well understood. We have measured the changes in NSC and N concentrations in leaves, branches, stems and all root branch orders at monthly intervals in control and girdled trees of larch (Larix gmelinii) and ash (Fraxinus mandshurica). The biomass of each plant compartment was also determined to calculate the size of the NSC and N pools. In both species, 13-37% of the NSC and N pools were mobilized at the beginning of the growing season. Among the mobilized pools, stems and non-absorptive roots (branch orders 4-9) acted as the largest NSC sources in larch and ash, respectively, while branches served as the largest N source in both species. After stem girdling, 22 and 50% of the root NSC stores in larch and ash, respectively, were mobilized to maintain root activities during the growing season. Tree mortality was observed 1 year after girdling, at which time there was still an abundant NSC pool in the roots. We conclude that (1) different storage organs differ in their contribution to new tissue growth at the beginning of the growing season and that those storage organs holding higher fractions of the NSC or N pool are not necessarily those which mobilize more NSC or N; (2) tree growth may not be limited by carbon (C) availability; (3) C storage in non-absorptive roots plays an important role in maintaining tree survival after the termination of photosynthate flow from aboveground sources.

Polycyclic aromatic hydrocarbon storage in a typical Cerrado of the Brazilian savanna.

There may be important biological sources of polycyclic aromatic hydrocarbons (PAHs) to the global environment, particularly of naphthalene, phenanthrene, and perylene, that originate in the tropics. We (i) studied the distribution of PAHs among different compartments of a typical Cerrado to locate their sources and (ii) quantified the PAH storage of this ecosystem. The sum of 20 PAH (sigma20PAHs) concentrations ranged from 25 to 666 microg kg(-1) in plant tissue, 7.4 to 32 microg kg(-1) in litterfall, 206 to 287 microg kg(-1) in organic soil, and 10 to 79 microg kg(-1) in mineral soil. Among the living biomass compartments, the bark had the highest mean PAH concentrations and coarse roots the lowest, indicating that PAHs in the plants originated mainly from aboveground sources. Naphthalene and phenanthrene were the most abundant individual PAHs, together contributing 33 to 96% to the sigma20PAHs concentrations. The total storage of the X20PAHs in Cerrado was 7.5 mg m(-2) to a 0.15-m soil depth and 49 mg m(-2) to a 2-m soil depth. If extrapolated to the entire Brazilian Cerrado region, roughly estimated storages of naphthalene and phenanthrene correspond to 7300 and 400 yr of the published annual emissions in the United Kingdom, respectively. The storage of benzo[a]pyrene, a typical marker for fossil fuel combustion, in the Cerrado only corresponds to 0.19 yr of UK emissions. These results indicate that the Brazilian savanna comprises a huge reservoir of naphthalene and phenanthrene originating most likely from the aboveground parts of the vegetation or associated organisms. Thus, the Cerrado might be a globally important source of these PAHs.

Source-sink balance and carbon allocation below ground in plants exposed to ozone.

The role of tropospheric ozone in altering plant growth and development has been the subject of thousands of publications over the last several decades. Still, there is limited understanding regarding the possible effects of ozone on soil processes. In this review, the effects of ozone are discussed using the flow of carbon from the atmosphere, through the plant to soils, and back to the atmosphere as a framework. A conceptual model based on carbohydrate signaling is used to illustrate physiological changes in response to ozone, and to discuss possible feedbacks that may occur. Despite past emphasis on above-ground effects, ozone has the potential to alter below-ground processes and hence ecosystem characteristics in ways that are not currently being considered. Contents Summary 213 I. Introduction 213 II. Source-sink model: carbohydrate signaling 214 III. Effect of ozone on above-ground sources and sinks 216 IV. Decreased allocation below ground 218 V. Carbon flux to soils 220 VI. Soil food web 223 VII. Summary, conclusions and future research 223 Acknowledgements 223 References 223.

Oxygen loss from Spartina alterniflora and its relationship to salt marsh oxygen balance.

Spartina alterniflora has been reported to lose significant amounts of oxygen to its rhizosphere with potentially important effects on salt-marsh biogeochemical cycling and plant productivity. The potential significance of this oxidative pathway was evaluated using laboratory split-chamber experiments to quantify oxygen loss from intact root systems under a wide variety of pre-treatment and incubation conditions including antibiotics to inhibit microbial respiration. The aerenchyma system of S. alterniflora was found to transport O2, N2, Ar, and CH4 from above-ground sources to its below-ground roots and rhizomes. While non-respiratory gases were observed to move from the lacunae to water bathing the root systems, net O2 loss did not occur; instead oxygen present outside of the roots/rhizomes was consumed. Net oxygen loss was found when resistance to gas transport was reduced in the lacunae-rhizosphere pathway by placing the root systems in a gas phase and when plant respiration was significantly reduced. Root system respiration appeared to be the major variable in the plant oxygen balance. When root and rhizome respiration was inhibited using poisons or lowered by cooling, the oxygen deficit was greatly reduced and oxygen loss was indicated. The effect of seasonal temperature changes on root system "oxygen deficit" presents a possible explanation as to why Spartina produces root systems with respiration rates that cannot be supported by gas transport. Overall, while oxygen loss from individual plant roots is likely, integrating measured root system oxygen loss with geochemical data indicates that the mass amount of oxygen lost from S. alterniflora root systems is small compared to the total oxygen balance of vegetated salt marsh sediments.

A comparison of mineral uptake and translocation by above-ground and below-ground root systems ofSalix syringiana

Nutrient uptake and translocation by above-ground adventitious roots and below-ground roots of woodySalix syringiana saplings were studied with gamma spectrometry. Each of four radionuclides (75Se,138Cs,54Mn, and65Zn) administered to adventitious and belowground roots were detected in stems and leaves within one month. Nuclides tended to be immobilized in the leaves and branches closest to the adventitious roots that absorbed them, while nuclides absorbed from below-ground sources were distributed more evenly throughout the plant. The capacity of adventitious roots to acquire nutrients from above-ground sources suggests they function as a potential ‘auxiliary’ pathway of nutrient uptake and might enhance plant nutrient status where below-ground root uptake it hindered by adverse soil conditions.

Nutrient changes in surface soils after an intense fire in jarrah (Eucalyptus marginata Donn ex Sm.) forest

AbstractThe effects of an intense fire on the nutrient status of jarrah(Eucalyptus marginata Donn ex Sm.) forest soils were investigated. At seven experimental sites, representing a range of soil and vegetation types, surface soils were sampled to a maximum depth of 20 cm before, immediately after, and 1 year after the fire.Immediately after the fire, concentrations of total and extracted nutrients in surface (0–3 cm) soils increased markedly. One year later, concentrations of extracted nutrients in surface soils had returned to levels close to pre‐burn concentrations. During this period, some properties of sub‐surface (3–20 cm) soils also changed: Bray‐extractable phosphorus and electrolytic conductivity decreased, whereas ex‐tractable potassium and pH increased relative to pre‐burn concentrations. Initial increases in concentrations of extractable forms of nutrients were determined largely by the amounts of nutrients deposited in fine ash, whereas the changes after 1 year depended more on the leaching of ions and their reactions with the mineral soil.Increases in total amounts of major nutrients in surface soils arising from additions of fine ash were generally well correlated with amounts in pre‐burn litter and with amounts in the components of organic matter likely to be consumed in the fire. Significant quantities of all nutrients are redistributed from aboveground sources to the soil surface during intense fires, including nutrients which are most susceptible to losses through volatilization. This redistribution of nutrients is discussed in relation to short‐term and long‐term effects on plant growth and functioning of the jarrah ecosystem.