Scaling of Soil Carbon,Nitrogen,Phosphorus and C:N:P Ratio Patterns in Peatlands of China

Inspired by the importance of Redfield-type C:N:P ratios in global soils,we looked for analogous patterns in peatlands and aimed at deciphering the potential affecting factors.By analyzing a suite of peatlands soil data(n = 1031),mean soil organic carbon(SOC),total nitrogen(TN) and total phosphorous(TP) contents were 50.51%,1.45% and 0.13%,respectively,while average C:N,C:P and N:P ratios were 26.72,1186.00 and 46.58,respectively.C:N ratios showed smaller variations across different vegetation coverage and had less spatial heterogeneity than C:P and N:P ratios.No consistent C:N:P ratio,though with a general value of 1245:47:1,was found for entire peatland soils in China.The Northeast China,Tibet,Zoigê Plateau and parts of Xinjiang had high soil SOC,TN,TP,and C:P ratio.Qinghai,parts of the lower reaches of the Yangtze River,and the coast zones have low TP and N:P ratio.Significant differences for SOC,TN,TP,C:N,C:P and N:P ratios were observed across groups categorized by predominant vegetation.Moisture,temperature and precipitation all closely related to SOC,TN,TP and their pairwise ratios.The hydrothermal coefficient(RH),defined as annual average precipitation divided by temperature,positively and significantly related to C:N,C:P and N:P ratios,implying that ongoing climate change may prejudice peatlands as carbon sinks during the past 50 years in China.

Impacts of Soil Fauna on Litter Decomposition at Different Succession Stages of Wetland in Sanjiang Plain,China

Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in the Sanjiang Plain, China using different mesh litterbags. The results show that in each succession stage of wetland, soil fauna can obviously increase litter decomposition rates. The average contribution of whole soil fauna to litter mass loss was 35.35%. The more complex the soil fauna group, the more significant the role of soil fauna. The average loss of three types of litter in the 4mm mesh litterbags was 0.3-4.1 times that in 0.058mm ones. The decomposition function of soil fauna to litter mass changed with the wetland succession. The average contribution of soil fauna to litter loss firstly decreased from 34.96% (Carex lasiocapa) to 32.94% (Carex meyeriana), then increased to 38.16% (Calamagrostics an- gustifolia). The contributions of soil fauna to litter decomposition rates vary according to the litter substrata, soil fauna communities and seasons. Significant effects were respectively found in August and July on C. angustifolia and C. lasiocapa, while in June and August on C. meyeriana. Total carbon (TC), total nitrogen (TN) and total phosphorus (TP) contents and the C/N and C/P ratios of decaying litter can be influenced by soil fauna. At different wetland succession stages, the effects of soil fauna on nutrient elements also differ greatly, which shows the significant difference of influencing element types and degrees. Soil fauna communities strongly influenced the TC and TP concentrations of C. meyeriana litter, and TP content of C. lasiocapa. Our results indicate that soil fauna have important effects on litter decomposition and this influence will vary with the wetland succession and seasonal variation.

Relationship between catchment characteristics and nitrogen forms in Cao-E River Basin, Eastern China

The distribution of different nitrogen forms and their spatial and temporal variations in different pollution types of tributaries or reaches were investigated. Based on the catchments characteristics the tributaries or reaches can be classified into 4 types, including headwater in mountainous areas （type Ⅰ）, agricultural non-point source （NPS） pollution in rural areas （type Ⅱ）, municipal and industrial pollution in urban areas （type Ⅲ）, and combined pollution in main stream （type IV）. Water samples were collected monthly from July 2003 to June 2006 in the Cao-E River Basin in Zhejiang, eastern China. The concentrations of NO3^--N, NH4^＋ -N, and total nitrogen （TN） were measured. The mean concentrations of NO3^- -N were decreased in the sequence type IV 〉 type Ⅱ〉 type Ⅲ 〉 type Ⅰ, whereas, NH4^＋-N, total organic nitrogen （TON）, and TN were in the sequence： type Ⅲ〉 type Ⅳ 〉 type Ⅱ〉 type Ⅰ. In headwater and rural reaches, CNO^-2-N was much higher than Crea^＋ 4-N. In urban reaches, TON and NH4^＋ -N were the main forms, accounting for 54.7% and 32.1% of TN, respectively. In the whole river system, Crea^＋ 4--N decreased with increasing distance from cities, and CNo^-3 -N increased with the increasing area of farmland in the catchments. With increased river flow, CNO^-3 N increased and Crea4^＋-N decreased in all types of reaches, while the variations of CTON and CTN were different. For TN, the concentration may be decreased with the increase of river flow, but the export load always increased.

Reconciliation of research on forest carbon sequestration and water conservation

Carbon sequestration and water conservation are two of the key ecosystem services that forests provide for societal need to address environmental issues.Optimization of the dual services is the ultimate goal in forest management for mitigating global climate change and safeguarding terrestrial water balance.However,there are some tradeoff s between gain in forest productivity and ecosystem water balance.We conducted literature review based on published articles for learned knowledge on forest carbon fi xation and hydrological regulations.Some knowledge gaps and research needs are identifi ed by examining the inter-connections between forest carbon sequestration and water conservation.Past researches have helped gain basic understanding of the mechanisms and controls of forest carbon fi xation and hydrological regulations as two separate issues.Tools and approaches are well established for quantifying and monitoring forest carbon and hydrological issues,operating at diff erent spatial and temporal scales.There are knowledge gaps on how to design aff orestation schemes facilitating enhanced ecosystem services in forest carbon sequestration and water conservation.For the top-down planning of aff orestation in regions where water availability is anticipated to be problematic,the questions of how much and where to plant for given land availability,known environmental implications,and sustained regional development and livelihood need to be addressed.For local management considerations,the questions of what and how to plant prevail.Eff orts are needed in joint studies of forest carbon sequestration and water conservation functionalities,specifi cally in relation to establishment and management of planted forests aiming for delivering regulatory ecosystem services in carbon sequestration,water conservation and other social values.We propose an integrated framework with dual consideration of carbon sequestration and water conservation in forest management for future research pursue.

Bacterial diversity, composition and temporal-spatial variation in the sediment of Jiaozhou Bay, China

Studies on the diversity and distribution of bacterial populations will improve the overall understanding of the global patterns of marine bacteria and help to comprehend local biochemical processes and environments. We evaluated the composition and the dynamics of bacterial communities in the sediment of Jiaozhou Bay (China) using PCR-denaturing gradient gel electrophoresis (DGGE). Sediment samples were collected from 10 different sites in May, August, and November 2008 and in February 2009. There was significant temporal variation in bacterial community composition at all sites. However, the spatial variation was very small. The DGGE analyses of bacterial communities were used to divide the 10 stations into three types. Canonical correspondence analysis (CCA) revealed that the changes in bacterial communities were driven by sediment properties. Sequence analysis of DGGE band-derived 16S rRNA gene fragments revealed that the dominant bacterial groups in the sediment were of the classes γ-proteobacteria and δ-proteobacteria and phyla Bacteroidetes and Nitrospirae. Our results provide considerable insight into the bacterial community structure in Jiaozhou Bay, China.

Distribution and Accumulation of Soil Carbon in Temperate Wetland, Northeast China

Estimating carbon sequestration and nutrient accumulation rates in Northeast China are important to assess wetlands function as carbon sink buffering greenhouse gas increasing in North Asia. The objectives of this study were to estimate accreting rates of carbon and nutrients in typical temperate wetlands. Results indicated that average soil organic carbon(SOC), total nitrogen(TN) and total phosphorus(TP) contents were 37.81%, 1.59% and 0.08% in peatlands, 5.33%, 0.25% and 0.05% in marshes, 2.92%, 0.27% and 0.10% in marshy meadows, respectively. Chronologies reconstructed by 210 Pb in the present work were acceptable and reliable, and the average time to yield 0–40 cm depth sediment cores was 150 years. Average carbon sequestration rate(Carbonsq), nitrogen and phosphorus accumulation rates were 219.4 g C/(m^2·yr), 9.16 g N/(m^2·yr) and 0.46 g P/(m^2·yr) for peatland; 57.13 g C/(m^2·yr), 5.42 g N/(m^2·yr) and 2.16 g P/(m^2·yr) for marshy meadow; 78.35 g C/(m^2·yr), 8.70 g N/(m^2·yr) and 0.71 g P/(m2·yr) for marshy; respectively. Positive relations existed between Carbonsq with nitrogen and precipitations, indicating that Carbonsq might be strengthened in future climate scenarios.

High Conductivity Water Treatment Using Water Surface Discharge with Nonmetallic Electrodes

Although electrohydraulic discharge is effective for wastewater treatment,its application is restricted by water conductivity and limited to the treatment of low conductivity water. For high conductivity water treatment,water-surface discharge is the preferred choice.However. the metallic electrodes are easily corroded because of the high temperature and strong oxidative environment caused by gas phase discharge and the electrochemical reaction in water.As a result. the efficiency of the water treatment might be affected and the service life of the reactor might be shortened.In order to avoid the corrosion problem,nonmetallic electrode water-surface discharge is introduced into high conductivity water treatment in the present study.Carbon-felt and water were used as the high voltage electrode and ground electrode,respectively.A comparison of the electrical and chemical characteristics showed that nonmetallic electrode discharge maintained the discharge characteristics and enhanced the energy efficiency,and furthermore,the corrosion of metal electrodes was avoided.

Mercury distribution and bioaccumulation up the soil-plant-grasshopper-spider food chain in Huludao City, China

The purpose of this study is to investigate total mercury （THg） distribution and its bioaccumulation up the soil-plant-grasshopperspider in the Huludao City, which is polluted seriously by chlor-alkali and zinc smelting industry in Northeast of China. Results indicated that average THg concentrations in soil, plant leaves, grasshopper Locusta migratoria manilensis and Acrida chinensis, and spider were 0.151, 0.119, 0.167 and 0.134 mg/kg, respectively. THg spatial distribution suggested that most of mercury came from the chlor-alkali plant and the two zinc smelteries. The highest mercury concentration was found in the wings among different grasshoppers’ organs. Although spiders are the predatory, THg concentrations in their bodies were not high, and only on the same level as in grasshoppers, which might be due to spiders’ special living habits. In the light of the mercury transportation at every stage of the soil-plant-grasshopper-spider food chain, the bioaccumulation factors were 0.03, 0.79–1.11 and 0.80–1.13 respectively. It suggested that mercury biomagnification up terrestrial food chains was not so large and obvious as it was in the aquatic food chain.

Polycyclic aromatic hydrocarbons in the centralized wastewater treatment plant of a chemical industry zone:Removal,mass balance and source analysis

Increased attention has been given to the fate of pollutants such as polycyclic aromatic hydrocarbons (PAHs) introduced to the wastewater treatment plants.Dissolved and adsorbed PAHs were detected in the centralized wastewater treatment plant of a chemical industry zone in Zhejiang Province,China.The most abundant PAHs were the low molecular weight PAHs (e.g.,Acy,Ace,Flu and Phe),accounting for more than 80% of the total 16 PAHs in each treatment stage.Phase partitioning suggested that the removal of PAHs in every treatment stage was influenced greater by the sorption of particles or microorganisms.The removal efficiencies of individual PAHs ranged between 4% and 87% in the primary sedimentation stage,between 1% and 42% in anaerobic hydrolysis stage,between <1% and 70% in aerobic bio-process stage,between 1.5% and 80% in high-density clarifier stage,and between 44% and 97% in the whole treatment process.Mass balance calculations in primary stage showed significant losses for low molecular weight PAHs and relatively good agreements for high molecular weight PAHs as well as in anaerobic hydrolysis,high-density clarifier stage and sludge stream for most PAHs.Great gains of 60%-150% were obtained for high molecular weight PAHs in aerobic bio-process stage due to biosorption and bioaccumulation.Our investigations found that PAHs entering the wastewater treatment plant (WWTP) could be derived from the dyeing chemical processes as the byproducts,and the contribution supported by the largest dyeing chemical group was up to 48%.

Variations in leaf litter decomposition across contrasting forest stands and controlling factors at local scale

Aims litter decomposition is a critical pathway linking the above-and belowground processes.However,factors underlying the local spatial variations in forest litter decomposition are still not fully addressed.We investigated leaf litter decomposition across con-trasting forest stands in central China,with objective to determine the spatial variations and controlling factors in forest floor leaf lit-ter decomposition in relation to changes in forest stands in a tem-perate forest ecosystem.Methods leaf litter decomposition was studied by using litterbag method across several typical forest stand types in baotianman Nature reserve,central China,including pure stands of Quercus aliena var.acuteserrata,Q.glandulifera var.brevipetiolata and Q.vari-abilis,respectively,and mixed pine/oak stands dominated by Pinus armandii and Q.aliena var.acuteserrata,as well as stands of pure Q.aliena var.acuteserrata trees ranging in stand age from~40 to>160 years.measurements were made on litter mass remaining and changes in litter chemistry during decomposition over a 2-year period,along with data collections on selective biotic and environmental factors.a reciprocal transplant experiment involv-ing Q.aliena var.acuteserrata and Q.variabilis was concurrently carried out to test the occurrence of‘home-field advantage(HFa)’in local forests when only considering contrasting oak tree spe-cies.Correlation analyses and path analyses were performed to identify the dominant drivers and their relative contributions to variations in leaf litter decomposition.Important findingssignificant variations were found in the rate of leaf litter decomposi-tion among stands of different tree species but not among stand age classes.The values of decay constant,k,varied from 0.62 in Q.aliena var.acuteserrata stands to 0.56 in Q.variabilis stands.The reciprocal litter transplant experiment showed that the rate of leaf litter decom-position was on average 5%slower in home-fields than on recipro-cal sites.Path analysis identified litter acid-unhydrolyzable residue(AUR)to N ratio,soil microbial biomass carbon(MBC),soil pH and soil organic carbon(SOC)as most prominent factors controlling the rate of leaf litter decomposition,collectively accounting for 57.8%of the variations;AUR/N had the greatest negative effect on k value,followed by weaker positive effects of SOC and MBC.our findings suggest that tree species plays a primary role in affecting forest floor leaf litter decomposition by determining the litter quality,with site environment being a secondary factor contributing to the local vari-ations in leaf litter decomposition in this temperate forest ecosystem.

A Deep Learning Application for Building Damage Assessment Using Ultra-High-Resolution Remote Sensing Imagery in Turkey Earthquake

Rapid building damage assessment following an earthquake is important for humanitarian relief and disaster emergency responses.In February 2023,two magnitude-7.8 earthquakes struck Turkey in quick succession,impacting over 30 major cities across nearly 300 km.A quick and comprehensive understanding of the distribution of building damage is essential for e fficiently deploying rescue forces during critical rescue periods.This article presents the training of a two-stage convolutional neural network called BDANet that integrated image features captured before and after the disaster to evaluate the extent of building damage in Islahiye.Based on high-resolution remote sensing data from WorldView2,BDANet used predisaster imagery to extract building outlines;the image features before and after the disaster were then combined to conduct building damage assessment.We optimized these results to improve the accuracy of building edges and analyzed the damage to each building,and used population distribution information to estimate the population count and urgency of rescue at different disaster levels.The results indicate that the building area in the Islahiye region was 156.92 ha,with an affected area of 26.60 ha.Severely damaged buildings accounted for 15.67%of the total building area in the affected areas.WorldPop population distribution data indicated approximately 253,297,and 1,246 people in the collapsed,severely damaged,and lightly damaged areas,respectively.Accuracy verification showed that the BDANet model exhibited good performance in handling high-resolution images and can be used to directly assess building damage and provide rapid information for rescue operations in future disasters using model weights.