文登市建立耕地保护和利用长效机制的思考

土地是民生之本、发展之基。在发展阶段的人口大国,土地问题始终是现代化进程中一个带有全局性、战略性的重大问题。严格土地管理,既是贯彻科学发展观,确保经济社会可持续发展的长远大计,也是维护当前改革发展稳定良好局面的当务之急。该文重点围绕文登市开展耕地保护工作基本做法、存在的主要问题以及如何完善耕地保护长效机制对策进行了探讨。     

Preparation and in vitro Release Performance of Sustained-release Captopril/Chitosan-gelatin Net-polymer Microspheres

The captopril/Chitosan-gelatin net-polymer microspheres(CTP/CGNPMs) were prepared using Chitosan(CTS) and gelatin(GT) by the methods of emulsification,cross-linked reagent alone or in combination and microcrystalline cellulose(MCC) added in the process of preparation of microspheres,which aimed to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril(CTP). The results indicated that CTP/CGNPMs had a spherical shape,smooth surface and integral structure inside but no adhesive phenomena in the preparation. The size distribution ranged from 220 μm to 280 μm. The CTP release test in vitro demonstrated that CTP/CGNPMs played the role of retarding the release of CTP compared with ordinary CTP tablets. The release behaviors of CGNPMS were influenced by preparation conditions such as experimental material ratio(EMR) and composition of cross linking reagents. Among these factors,the EMR(1/4),CLR(FA SPP) and 0.75% microcrystalline cellulose(MCC) added to the microspheres constituted the optimal scheme for the preparation of CTP/CGNPMs. The ER,DL and SR of CTP/CGNPMs prepared according to the optimal scheme were 46.23±4.51%,9.95±0.77% and 261±42%,respectively. The CTP/CGNPMs had the good characteristics of sustained release of drug and the process of emulsification and cross-linking were simple and stable. The CGNPMs are likely to be an ideal sustained release formulation for water-soluble drugs.     

Quantification of permafrost creep provides kinematic evidence for classifying a puzzling periglacial landform

Mechanical processes operating on the slope surface or at depth control the dynamics of alpine landforms and hold critical information of their geomorphological characteristics, yet they often lack systematic quantification and in-depth interpretation. This study aims to address a long-standing issue concerning geomorphological classification from a kinematic perspective. A group of periglacial landforms consisting of several lobes were discovered in the East Kunlun Mountains of China 30 years ago but were ambiguously classified as rock glaciers and later as gelifluction deposits. Here, we use satellite Interferometric Synthetic Aperture Radar to quantitatively characterize the spatial and temporal changes of the surface movement of these landforms. We observe that: (1) its 17 lobes show a pattern of landform-scale and uniform surface movement, especially during May to October; (2) the lobes move at a spatial mean downslope velocity of 10 to 60 cm/yr and a maximum velocity as high as 100 cm/yr in summer; (3) the landforms are nearly inactive from winter to late spring. Based on these observations, we postulate that the movement of the lobes are driven by deep-seated permafrost creep which typically occurs in rock glaciers. The debris of Lobe No.4 is composed of both boulders and pebbles supported by fine-grained matrix generated from the in situ weathering process. It develops a talus-like oversteepened front around 40° and a convex transverse profile perpendicular to the creep direction, which are also characteristic features of a rock glacier. Piecing these observations together, we identify Lobe No.4 as a debris-mantled-slope-connected rock glacier, with the gelifluction process occurring on the surface as small-scale and discrete events. © 2020 John Wiley & Sons, Ltd.     

Atmospheric particle-bound mercury in the northern Indo-Gangetic Plain region:Insights into sources from mercury isotope analysis and influencing factors

Lumbini is a world heritage site located in the southern plains region of Nepal, and is regarded as a potential site for evaluating transboundary air pollution due to its proximity to the border with India. In this study, 82 aerosol samples were collected between April 2013 and July 2014 to investigate the levels of particulate-bound mercury(PBM) and the corresponding seasonality, sources, and influencing factors.The PBM concentration in total suspended particulate(TSP) matter ranged from 6.8 pg m^-3 to351.7 pg m^-3(mean of 99.7 ± 92.6 pg m^-3), which exceeded the ranges reported for remote and rural sites worldwide. The Hg content(PBM/TSP) ranged from 68.2 ng g^-1 to 1744.8 ng g^-1(mean of 446.9 ±312.7 ng g^-1), indicating anthropogenic enrichment. The PBM levels were higher in the dry season(i.e.,winter and the pre-monsoon period) than in the wet season(i.e., the monsoon period). In addition, the δ²⁰² Hg signature indicated that waste/coal burning and traffic were the major sources of Hg in Lumbini during the pre-monsoon period. Meanwhile, precipitation occurring during photochemical processes in the atmosphere may have been responsible for the observed Δ¹⁹⁹ Hg values in the aerosol samples obtained during the monsoon period. The PBM concentration was influenced mostly by the resuspension of polluted dust during dry periods and crop residue burning during the post-monsoon period. The estimated PBM deposition flux at Lumbini was 15.7 lg m^-2 yr^-1. This study provides a reference dataset of atmospheric PBM over a year, which can be useful for understanding the geochemical cycling of Hg in this region of limited data.     

晚白垩世(80Ma)东亚气候的数值模拟

利用美国国家大气研究中心(NCAR)的CCSM2全球气候系统模式以及重建的古地理资料研究了晚白垩世(80Ma)东亚的古气候特征。模拟结果表明:80Ma时期东亚地区大范围盛行的风向和气压系统随季节有显著变化,由此可以推断东亚地区当时是存在季风环流的。与现代气候比较,白垩纪时期大陆上空的大气环流系统经向特征更明显,这种特征可能与当时欧亚大陆东西向跨度较小有关。此外,在当时偏暖的背景下,东亚冬季风和夏季风呈现出一致的变化特征,即冬季风和夏季风都比现代强。年平均降水的分布型和现代的情况比较相似,降水最大值出现在10°S～10°N的赤道辐合带中,与西太平洋相邻的大陆东岸降水也较多,其中心超过1200mm,而在中纬度的内陆地区降水则稀少。虽然与现代情况相似,80Ma在30°N附近的西太平洋上也为多雨带,然而在东亚陆地上没有多雨带,这说明了青藏高原隆升在现代东亚夏季梅雨形成中的重要性。此外,模拟的80Ma时期东亚地区气候要比现代温暖,相同纬度的表面气温要高2℃以上,模拟的温度与地质证据估计的温度比较接近。     

文登市基本农田示范区建设的探索

基本农田保护是耕地保护工作的重中之重,事关粮食安全、经济发展和社会稳定。文登市坚持以科学发展观为指导,以保护基本农田为中心,以提高粮食综合生产能力为目标,以改善农业生产条件和区域生态环境为前提,按照“点面兼顾、合理布局、整体推进、全面提高”的建设原则,切实做好基本农田保护示范区的建设工作。     

扬子地台早寒武世古盘虫类的地层分布及其古地理控制?

早寒武世早期的黑色页岩系在扬子地台非常发育，但由于具有时代标志的化石稀少，这套黑色页岩系的层序问题一直未能很好解决。古盘虫类化石是早寒武世黑色页岩系中仅有的具有地层意义的化石类别,然而它们的分类混乱、层位不清，限制了其在地层对比中的应用。在古盘虫类分类重新厘定的基础上，通过对Tsunyidiscus 的4个种和Hupeidiscus orientalis地层分布的系统总结，认为T.aclis和T. armatus的层位限于筇竹寺早期，T. niutitangensis和T. tingi的层位主要是筇竹寺晚期，只有T. tingi延伸至沧浪铺早期。而H. orientalis在筇竹寺晚期开始出现，到沧浪铺早期繁盛。因此它们的层位分布特征可以用于地层学对比。通过对华南地区古盘虫类古地理分布和沉积相与环境分析，我们认为古盘虫类的分布受海平面升降、海水浑浊度、水深、含氧性等古海洋环境因素的控制： T. armats和T. aclis分布于近滨-远滨及外陆架上，适应水体平静，水动力能量较低，低沉积速率的相对较深的海域; T. tingi和T. niutitangensis在开阔的外陆架区域大量繁盛，T. niutitangensis生存在具有分层结构海洋的贫氧带和富氧带，海水较深，水体平静； 而H. orientalis在陆架边缘灰岩相中大量出现，适应于海水较深，水动力能量较低，浮游微生物丰富的洁净海水; 此外在粗碎屑岩、高碳质页岩、石煤发育的地层中无古盘虫类分布, 表明古盘虫类不适合海水动荡而混浊，沉积速率高的浅水高能环境和深水滞流缺氧的环境。     

岩石地球化学测量在北山找金中的应用效果

实践证明,不仅大比例尺岩石地球化学测量可以为圈定矿体、揭露工程的设计提供依据,在区调普查中,中、小比例尺的岩石地球化学测量同样可以提供足够的找矿信息。在干旱荒漠区岩石地球化学测量是一种比较理想的找矿方法。     

湖北宜昌王家坪下寒武统天河板组古杯礁丘及其成岩作用

王家坪古杯礁丘是由不规则古杯和蓝绿藻Renalcis、Epiphyton、Cirvanella等组成的障积礁丘。可分为:孤立小型古杯泥丘和由丘状藻-古杯粘结岩叠置而成的点礁。以Renalcis为主的藻-古杯粘结岩与孤立小型古杯泥丘一样形成于风暴浪基面之下的低能陆架。以Epiphyton为主的藻-古杯粘结岩形成于较动荡的中-高能陆架浅滩。除造礁生物的沉积作用外,早期海底胶结作用和充填固化作用对古杯礁丘的形成亦起了十分重要的作用。