Study on the Characteristics of Soil Moisture of Artificial Robinia pseudoacacia Forest Land in Different Latitudinal Zones of Northern Shaanxi

This article studies the soil moisture conditions of 30 years artificial Robinia pseudoacacia in the north of Shaanxi under different climate conditions in order to explore the relationship between soil moisture and impact factor of Robinia pseudoacacia in this area,and variation characteristics of soil moisture in the Loess Plateau region. The results show that soil moisture content decreases with increase of soil depth, and in 40- 50 cm depth the jump point of moisture reduction appears significantly. Soil moisture was lower than the growth critical moisture in 5 samples to the north of Chunhua,and has different degrees of deficit. Soil moisture deficit degree was more than 50% in sandy loam and light loam soils such as Yulin,Shenmu and Suide. With the increasing of latitude,both of soil accumulative storage and net rainfall tends to decrease,but the relationship between them is significant correlation,indicating that that climate conditions are the major factors causing significant difference of soil moisture.

Spatial and diel variations of the prokaryotic community in the Phaeocystis globosa blooms area of Beibu Gulf,China

While prokaryotes play key roles in nutrient cycling and energy flow during Phaeocystis globosa blooms,the information on the spatial and diel temporal distribution of the prokaryotic community during Phaeocystis blooms remains scarce.In January 2019,we used high-throughput sequencing of the 16S rRNA gene to explore the spatial and diel variations of particle-attached(PA)and free-living(FL)prokaryotic communities during the blooming phase of P.globosa in Beibu Gulf,Guangxi,China.The results suggested a significant spatial variation pattern in the horizontal distribution of prokaryotic communities,while there was no significant difference in the vertical direction.Both spatial distance and environmental variables shaped the horizontal distribution of the prokaryotic community structure,while environmental variables,particularly the abundance of P.globosa colony and Chl a,showed more significant influence and were closely related to the structure and variation of the prokaryotic community.Strong vertical mixing of the water column disrupted the vertical structure heterogeneity of the prokaryotic community in winter.There were significant differences in the diel samples of PA prokaryotic communities,but not in the FL prokaryotic communities.Nitrate,ammonium and the abundance of P.globosa colony were the key environmental variables impacting the diel variations of prokaryotic communities over the sampling period.The present study provided valuable information to depict the spatial-temporal variations of the microbial community and its association with environmental parameters during P.globosa bloom in the tropical gulf.

Selective Adsorption of Ag(I) from Electronic Waste Leachate Using Modified Silk Sericin

A novel biosorbent was synthesized by grafting bisthiourea(BTU)on a silk sericin(SS)matrix.This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy(FTIR),zeta potential measurements,elemental analysis,and X-ray photoelectron spectroscopy(XPS).As revealed by the adsorption experiments,both BTU-SS and SS showed low affinity towards coexisting base metallic ions in Ag(I)-Cu(II)-Zn(II)-Ni(II)-Pb(II)electronic waste leachate mixtures,while their adsorption capacities towards Ag(I)reached 30.5 and 10.4 mg∙g-1 at a pH of 5.0,respectively.BTU-SS showed higher selectivity towards Ag(I)than SS,as revealed by the Ag(I)partition coefficients between the biosorbents and the leachate(16634.6 and 403.3,respectively).As further demonstrated by column experiments,BTU-SS allowed the separation of Ag(I)from an electronic waste leachate.Thermodynamic studies showed that the adsorption of Ag(I)was exothermic and spontaneous,while adsorption kinetic experiments revealed that chemisorption dominated the adsorption process with activation energies of 47.67 and 53.27 kJ∙mol-1 for BTU-SS and SS,respectively.FTIR and XPS analyses of fresh and Ag(I)-loaded BTU-SS further revealed an adsorption mechanism mainly involving electrostatic and coordination interactions.

Heavy Metals Contamination in Greenhouse Soils and Vegetables in Guanzhong, China

This study used a flame atomic absorption spectrometer (FAAS) and atomic fluorescence spec-trophotometer (AFS) to detect the concentrations of chromium (Cr), cadmium (Cd), lead (Pb), hy-drargyrum (Hg) and arsenic (As) in soils and three genotypes of vegetables in greenhouse, as well as analyzed the physical and chemical properties of soils, including soil pH, soil organic matter (OM), basic nutrients, electrical conductivity (EC) and cation exchange capacity (CEC) in Guan- zhong areas, Shaanxi province, China. The results showed that comparing to subsoil, the sampled topsoil is enriched in Cr, Cd, Pb, As and Hg. Cd (0.83 - 3.17 mg·kg-1) and Hg (0.40 - 1.44 mg·kg-1) are exceeding the limited value stated in “the 2006 Greenhouse Vegetable Producing Environmental Quality Evaluation Standards” of 0.40 mg·kg-1 and 0.35 mg·kg-1 respectively. However, Nanzhuang greenhouse soil is within the limits. The heavy metal pollution index (HPI) of soil in Sanyuan (8.10) is the highest and in Dongzhang (4.23) is the lowest. The contents of Pb (0.201 - 0.376 mg·kg-1) were exceeding the limited value (0.20 mg·kg-1) in vegetables species, and Cd (0.0363 - 0.0572 mg·kg-1) in some place were also exceeding the limited value (0.05 mg·kg-1). Greenhouse soils were becoming acidified year after year;the ratios of N, P and K in soil were seriously imbalanced. According to the impacting factors, OM, pH, available P, EC and CEC have obviously effected the accumulation of Cr and Hg. However, there was not enough evidence for the effects of available nitrogen and available potassium.

Biodiversity in Qinling Area and Its Protection Strategy

[ Objective] The aim was to study the biodiversity and its protection measures in Qinling. [Method] The current situation and protection measures of the biodiversity in Qinling area were reviewed by the perspective of eco-safety and the eco-value. [Result] Qinling is the natural gene bank for the study of the origin and development of living beings. Forest ecological system is the main body, with many ecological systems and com- plete vertical spectrometer. The plants have various varieties, complicated components, rare species, rich special plant and old heritance. There were 722 species of vertebrates, including 162 species in 16 families of 7 orders of fish, 26 species in 8 families of 2 orders of amphibian, 44 species in 8 families of 2 orders of reptiles, 373 species in 53 families of 17 orders of birds, and 117 species in 27 families of 7 orders of animals. The num- ber of order, family and species of vertebrates was 70%, 53.04% and 22.06%. It was suggested to formulate policy promoting biodiversity protec- tion and sustainable development, building natural protection net system to protect biodiversity in Qinling. [ Coecluslon] The study provided theoreti- cal basis for the protection of biodiversity in Qinling area.