Soil sealing causes substantial losses in C and N storage in urban soils under cool climate

Urban soil can store large amounts of carbon (C) and nitrogen (N). To accurately estimate C and N storage in urban soils, C and N contents underneath impervious surfaces - the most prevalent land cover type in cities - should be taken into account. To date, however, only few studies have reported urban soil C and N content underneath impervious surfaces, and no data exist for cities under cold/cool climates, such as the Boreal zone. Here, we studied, for the first time, the effects of sealing on soil C and N storage in a Boreal city. Sealed soils were sampled for physico-chemical and biological parameters from 13 sites in the city of Lahti, Finland, at three depths (0–10 and 45–55 cm, representing the construction layer composed of gravel, other moraine material and crushed rock, and the native soil layer beneath the ca. 1 m thick construction layer). Our results show that urban soils underneath impervious surfaces in Finland contain 11 and 31 times less C and N content, respectively, compared with warmer regions. This is due to a deep C and N deficient construction layer below sealed surfaces. Even though impervious surfaces cover ca. twice the area of pervious surfaces in the centre of Lahti, we estimate that only 6% and 4% of urban soil C and N, respectively, are stored underneath them. Furthermore, we found very little C and N accumulation underneath the sealed surfaces via root growth and/or leakage through ageing asphalt. Our results show that soil sealing, in concert with a massive top soil removal typical to cold climates, induces a considerable loss of C and N in Boreal urban areas.Peer reviewe

Plant functional type affects nitrogen dynamics in urban park soils similarly to boreal forest soils

Purpose Although plant functional type can modulate soils and their processes in natural, nitrogen (N)-limited ecosystems, little is known about their ability to influence soil N dynamics in urban ecosystems that have high excess N input. We investigated whether i) plant functional type effects on soil N dynamics in urban parks follow the same pattern as those in undisturbed natural/semi-natural forests, and ii) park age influences plant functional type effects on soil N dynamics under boreal climate. Methods We selected 13 urban parks of varying ages (young: 10 to 15, old: > 70 years), and 5 undisturbed natural/semi-natural forests (> 80 years) in southern Finland. In these parks and forests, we measured soil total N concentration, availability of inorganic N, nitrous oxide (N2O) flux and earthworm biomass under three plant functional types (evergreen tree, deciduous tree, lawn). Results Our results showed that plant functional type influenced N dynamics also in urban greenspace soils, which may relate to the clear effect of plant functional type on earthworm biomass. Evergreen trees tended to have the highest ability to foster N accumulation and reduce N2O emissions in urban parks. Moreover, with increasing park age, N accumulation increased under trees but decreased under lawns, further emphasising the role of vegetation in affecting soil N dynamics in urban greenspaces. Conclusions Our results show that, similar to natural/semi-natural forests, plant functional type, irrespective of park age, can influence soil N dynamics in urban parks.Peer reviewe

Loss of soil carbon and nitrogen indicates climate change-induced alterations in a temperate forest ecosystem

Climate warming is expected to influence terrestrial biogeochemical cycles by modifying the quality and quantity of plant litter input to soils. Although a growing number of studies recognize the importance of plant litter input in influencing the loss of soil organic matter (SOM) through a phenomenon called the priming effect (PE), the exact mechanisms behind PE are not well known. Importantly, most PE research is based on short term pot experiments in which fresh organic matter (FOM) input is represented by a single addition of compounds of unnaturally simple chemical composition. Furthermore, only a few studies exist in which the PE was explored in terms of organic C (SOC) and total N content in the soil. Here, we report results of a 3-year long litter manip-ulation study conducted under natural conditions in a broadleaved Korean pine forest in N-E China. We show that the extra supply (twice the normal input) of aboveground tree litter composing of conifer needles, leaves and small twigs was associated not only with slightly decreased SOC (by 5%) but especially that of soil total N (STN) (by 15%) content in the top soil (0-5 cm depth). In contrast, removal of litter resulted in an increased (ca. 15%) amount of both SOC and STN during the study when compared to control soils receiving natural litter input. Despite the enhanced leaf litter decomposition rate in the treatment receiving extra litter, the changes in SOC and STN were related neither to soil microbial biomass nor to community composition. The amount of N lost (40.0 g m- 2) in the soil due to litter addition was ca. three times the amount of N added (12.3 g m- 2) via the litter, while the amount of C lost (238 g m- 2) was about one third of that added (940 g m- 2), suggesting that soil N in our research site is more prone to the PE than soil C. As we did not manipulate belowground FOM input, our results suggest that input of aboveground litter rather than that by roots explained the PE in our study. Results of our long-term study conducted under natural conditions in undisturbed forest soils highlight the large potential of recalcitrant, aboveground litter to affect the PE, which should not go unnoticed when predicting the role of forest soils under conditions (such as climate warming) when these soils act as C sinks.Peer reviewe

Comparisons of serum miRNA expression profiles in patients with diabetic retinopathy and type 2 diabetes mellitus

OBJECTIVES: The aim of this study was to compare the expression levels of serum miRNAs in diabetic retinopathy and type 2 diabetes mellitus. METHODS: Serum miRNA expression profiles from diabetic retinopathy cases (type 2 diabetes mellitus patients with diabetic retinopathy) and type 2 diabetes mellitus controls (type 2 diabetes mellitus patients without diabetic retinopathy) were examined by miRNA-specific microarray analysis. Quantitative real-time polymerase chain reaction was used to validate the significantly differentially expressed serum miRNAs from the microarray analysis of 45 diabetic retinopathy cases and 45 age-, sex-, body mass index- and duration-of-diabetes-matched type 2 diabetes mellitus controls. The relative changes in serum miRNA expression levels were analyzed using the 2-ΔΔCt method. RESULTS: A total of 5 diabetic retinopathy cases and 5 type 2 diabetes mellitus controls were included in the miRNA-specific microarray analysis. The serum levels of miR-3939 and miR-1910-3p differed significantly between the two groups in the screening stage; however, quantitative real-time polymerase chain reaction did not reveal significant differences in miRNA expression for 45 diabetic retinopathy cases and their matched type 2 diabetes mellitus controls. CONCLUSION: Our findings indicate that miR-3939 and miR-1910-3p may not play important roles in the development of diabetic retinopathy; however, studies with a larger sample size are needed to confirm our findings

Pyrethroids as Promising Marine Antifoulants: Laboratory and Field Studies

【英文摘要】Due to the regulations and bans regarding the use of traditional toxic chemicals against marine fouling organisms and the practical impediments to the commercialization of natural product antifoulants, there is an urgent need for compounds that are antifouling-active, environmentally friendly, and have a potential for commercial application. In this study, a series of common, commercially available pyrethroid products, which are generally used as environmentally safe insecticides, was evaluated for antifouling activity in the laboratory using an anti-settlement test with cyprids of the barnacle Balanus albicostatus and also in a field experiment. Laboratory assay showed that all eleven pyrethroids (namely, rich d-trans-allethrin, Es-biothrin, rich d-prallethrin, S-prallethrin, tetramethrin, rich d-tetramethrin, phenothrin, cyphenothrin, permethrin, cypermethrin, and high active cypermethrin) were able to inhibit barnacle settlement (EC50 range of 0.0316 to 87.00 μg/ml) without significant toxicity. Analysis of structure–activity relationships suggested that the cyano group at the α-carbon position had a significant influence on the expression of antifouling activity in pyrethroids. In the field, the antifouling activity of pyrethroids was further confirmed, with the most potent pyrethroids being cypermethrin and high active cypermethrin, which displayed efficiency comparable with that of tributyltin. In summary, our investigation indicated that these pyrethroids have a great and practical commercial potential as antifouling agents

Plant-soil feedbacks as affecting ecosystem services in urban greenspaces

Soils play a fundamental role in many ecological processes and in the provision of a multitude of vital ecosystem services not only in natural/semi-natural ecosystems but also in disturbed urban milieus. As many soil-derived ecosystem services are closely linked to human health and climate change, it is important to acknowledge the ability of urban soils to provide ecosystem services in the context of rapid urbanisation. Growing evidence shows that, despite various disturbances in urban landscapes, sparse vegetation can still control the provision of soil-derived ecosystem services in urban greenspaces due to the close linkages between aboveground and belowground milieus. Therefore, knowledge on the role of urban greenspace soils, in connection with plants, in providing ecosystem services likely leads to better urban planning and management practices. The main objective of this thesis was to explore the mechanisms by which plants – plant functional types (evergreen trees, deciduous trees, lawns) in particular – affect soil carbon (C) and nitrogen (N) dynamics in urban parks of varying ages and in natural/semi-natural forests acting as a reference. Field experiments, including litter decomposition, root production, soil greenhouse gas emission, and soil inorganic N leaching, were conducted in boreal cities. Additionally, soils underneath impervious surfaces were investigated for the effects of soil sealing on soil C and N storage to better understand the role of urban soils (greenspace soils vs. sealed soils) in C and N accumulation under boreal climate. I showed that evergreen trees (spruce, mostly Picea sp.) accumulate C and retain N in soils more than deciduous trees (linden, mostly Tilia x vulgaris) and lawn (grass/herb, mostly Poa and Festuca species). This was likely due to slow rates of litter decomposition and high root production of evergreen trees. Moreover, evergreen trees modified soil properties by lowering soil pH and soil moisture content efficiently, both of which can retard litter decomposition and N denitrification. Evergreen trees reduced soil greenhouse gas emissions and thus have a higher potential to mitigate the negative effects of anthropogenic N pollution and climate change in urban environments. Importantly, despite the various disturbances and management practices in urban parks, the mechanisms through which plant type controls soil C and N dynamics are independent of both habitat (urban parks vs. natural/semi-natural forests) and park age (young vs. old parks). Additionally, soil sealing has substantial, negative impacts on soil C and N storage, which critically hampers their ability to provide ecosystems services in cities under boreal climate. I am the first to study the mechanisms behind plant-soil interactions as affecting ecosystem services in urban greenspaces in boreal cities. This thesis clearly highlights the importance of urban greenspace soils in providing ecosystem services under boreal climate and suggests that selecting the right plant type, here evergreen trees, in urban greenspaces boosts the ability of urban soils in ecosystem services provision. As the build-up of organo-mineral associations strongly affects soil organic matter stabilisation, further research is needed to explore the potential effects of plant type on soil organo-mineral associations in urban greenspaces. Further research is also required to study how far away from trees plant-soil interaction extends in urban parks, which is important for determining optimal tree density in urban parks, and in accurately calculating C and N budgets at the park level.Ekosysteemipalveluiksi kutsutaan luonnon ihmiselle tuottamia aineellisia ja aineettomia hyödykkeitä. Näiden palvelujen tarjoajana maaperällä on tärkeä rooli, olipa kyseessä sitten luonnon ekosysteemit tai ihmisen häiriöittämät systeemit, kuten kaupungit. Koska useat maaperän tarjoamat ekosysteemipalvelut liittyvät joko suoraan tai epäsuoraan esimerkiksi ilmaston muutokseen ja sitä kautta ihmisen terveyteen, maaperän hyvinvoinnista huolehtiminen on ensiarvoisen tärkeää alati kaupungistuvassa maailmassa. On tunnettua, että kasveilla on merkittävä vaikutus maaperään ja sen elintärkeisiin prosesseihin, mutta näiden vaikutusten syvällinen ymmärtäminen kaupunkimiljöössä on puutteellista. Väitöskirjatyössäni selvitänkin sitä, miten kaupunkien viheralueilla tutut kasvityypit – havupuut, lehtipuut ja nurmi – muokkaavat kaupunkimaaperää ja siten vaikuttavat kaupunkimiljöössä runsaina esiintyvien hiilen ja typen varastoitumiseen maaperään. Tutkittua tietoa näiden ekosysteemipalveluiden roolista kaupunkien viheralueilla on niukasti ja tietämyksemme siitä, mitä tapahtuu pinnoitetuilla alueilla, on erityisen puutteellista. Väitöstutkimukseni keskittyy näiden tietoaukkojen paikkaamiseen. Tutkimuksissani selvisi, että havupuut, kuten kuusi (Picea abies), varastoitoivat hiiltä ja pidättävät typpeä maaperässä enemmän kuin lehtipuut (esimerkiksi puistolehmus, Tilia x vulgaris) ja nurmi. Havupuiden ekosysteemipalveluvaikutus selittyi pääosin niiden runsaalla juurituotolla sekä hitaasti hajoavalla neulaskarikkeella. Havupuiden positiivinen vaikutus ilmeni myös maaperän vähentyneenä kasvihuonekaasutuotantona, mikä vähentää ilmastonmuutoksen ja typpisaasteen kielteisiä vaikutuksia kaupunkiympäristössä. Havaitsin myös, että maaperän pinnoittaminen asfaltilla ja betonilla vaikuttaa voimakkaan kielteisesti maan hiili- ja typpivarantoihin. ”Äiti maan” tukahduttaminen estää kasvien ja maaperän välisen mutualistisen vuorovaikutussuhteen, mikä heikentää oleellisesti maaperälähtöisiä ekosysteemipalveluita pohjoisen ilmastovyöhykkeen kaupungeissa. Tutkimukseni kaupunkimaaperän roolista ”ekosysteemipalvelukeitaana” on ensimmäinen laatuaan boreaalisessa ilmastovyöhykkeessä. Väitöstutkimukseni osoittavat selkeästi sen, että kaupunkien viheralueiden maaperä toimii suurelta osin samoin kuin luonnon ekosysteemien maaperä. Tutkimusteni perusteella väitän, että niukemmalla pinnoittamisella ja oikealla kasvi-/puulajivalinnalla voidaan vahvistaa maaperän tuottamia, elintärkeitä ekosysteemipalveluita

Evergreen trees stimulate carbon accumulation in urban soils via high root production and slow litter decomposition

Peer reviewe

Study on environmental impact of artificial horizontal freezing method in subway connecting passage

When the subway is built in complex urban strata, especially when excavating near buildings, it is necessary to strictly control the freezing amount by adopting artificial freezing method. At present, the theoretical calculation is aimed at the frozen rise under ideal conditions, but for complex geological conditions, the simplified model results are difficult to meet the actual requirements. However, numerical calculation can adapt to complex strata and complex boundary conditions. Therefore, in this paper, the environmental impact of artificial horizontal freezing method in subway connecting passage is studied by numerical simulation, and the change of thermophysical parameters with the change of temperature field is considered in the simulation. The simulation method in this paper provides guidance for actual construction

Polypyrrole Nanomaterials: Structure, Preparation and Application

In the past decade, nanostructured polypyrrole (PPy) has been widely studied because of its many specific properties, which have obvious advantages over bulk-structured PPy. This review outlines the main structures, preparation methods, physicochemical properties, potential applications, and future prospects of PPy nanomaterials. The preparation approaches include the soft micellar template method, hard physical template method and templateless method. Due to their excellent electrical conductivity, biocompatibility, environmental stability and reversible redox properties, PPy nanomaterials have potential applications in the fields of energy storage, biomedicine, sensors, adsorption and impurity removal, electromagnetic shielding, and corrosion resistant. Finally, the current difficulties and future opportunities in this research area are discussed

The Role of Arbuscular Mycorrhiza Fungi in the Decomposition of Fresh Residue and Soil Organic Carbon : A Mini-Review

Arbuscular mycorrhizal fungi (AMF) are widespread in terrestrial ecosystems. In addition to their contributions to plant nutrient uptake, AMF also provide many ecological functions including regulation of soil C dynamics. However, both stimulating and retarding soil organic decomposition by AMF have been observed. Here we discuss the possible reasons for such a contradiction. Arbuscular mycorrhizal fungi contribute to soil aggregation mainly through hyphal enmeshment, saprotrophic suppression, and production of glomalin-related soil proteins, while AMF can also stimulate organic decomposition through promoting degradative enzymes, modifying root production and activity, and/or through regulating the microbial community in the mycorrhizosphere and hyphosphere. The role of AMF in C decomposition is strongly dependent on the quality and quantity of different soil C pools. Arbuscular mycorrhizal fungi can stimulate fresh residue decomposition initially through stimulating the decomposition of fresh residues (particularly those having high C/N ratio), whereas for older or decomposed soil organic C, AMF tend to suppress decomposition by promoting soil aggregation. Under elevated CO2 (eCO(2)), AMF show additive effects on residue decomposition, priming effects, and changes in soil a regation. Despite organic decomposition rates differing in the short term and long term following litter experiments, our discussion highlights the role of AMF in organic C dynamics. We hypothesize that AMF would benefit soil C gain in the long term and thereby predict that disturbances that impacts negatively on AMF, such as tillage, residue burning, fertilization, and fungicide application, would lead to soil C decline particularly under eCO(2).Peer reviewe