Acid rain in China-Input-output budgets of major ions in four forested catchments     

Thorjorn Larssen 《中国地球化学学报》2006,25(B08):49-49

Acid rain is one of China＇s major environmental problems and emissions of sulphur and nitrogen are still increasing. The acid rain situation in China is somewhat different from what is seen in Europe and North America. Sulfur deposition is very high, but there is also very high deposition of calcium and other base cations. The sources of atmospheric Ca are not well understood, although it is important for understanding long term impacts of acid deposition. The fate of S, N and Ca^2＋ in the catchment is crucial for the future development of the acidification situation of soils and waters in China. Very few studies presenting catchment input-output ion budgets in Chinese natural environments exist and there are several unknown factors regarding processes. Here, we present annual input-output budgets for three years （2001-2003） for major ions for four forested catchments in China receiving different loads of acid deposition. For the two sites receiving the highest SO4^2- inputs, the input-output budget for the upper 50 cm of soil is approximately balanced. For the most remote site the soil is a net sink for SO4^2-, suggesting that the pool of adsorbed SO4^2- in the soil is building up. This is in agreement with the fact that the site so far has received only moderate SO4^2- inputs. For the southemmost, the subtropical site there is a loss of SO4^2- in the soil, which at least partly may be related to high uptake from the dense and highly productive forest at the site. The Ca^2＋ budgets for the upper 50 cm of soil show large variations both within and between sites. For most locations there is production of Ca^2＋ in the soil that can be explained by weathering, and variation between years related to hydrology that can be explained by ion exchange. However, at some plots at the site receiving very high inputs of both SO4^2- and Ca^2＋, there is an unknown sink of Ca^2＋ in the soil at some plots.  相似文献   

Studying of quality parameters and organic contaminants in honey samples     

《中国地球化学学报》2006,25(B08):68-68

Honey is valuable food for mankind since the ancient times. It was the only sweetener till the start of the industrial sugar mass production. As honey plays an important role in our nutrition and its positive effects on health is well known, it is very important to study the nutritional properties and the origin of different honey samples. The usually determined quality parameters of honey： pH values, water content, sugar content, acidity, HMF content, enzyme activity, pollen content, amino acid content, ash content, etc. It is also important to know the content of the organic contaminants in honey. A short time ago there were some quality problems with Hungarian and Greek honey in the European Union. A toxic material （para-dichlorobensene） was found in honey originated from Greece. The amount was higher than the allowable limit in the EU. Therefore, it is necessary to build up a good and applicable traceability system for honey. During the past few years the traceability concept has become increasingly familiar in many sectors of the food industry. Traceability is an essential tool for ensuring both production and product quality. The opportunity to connect traceability with the whole documentation and control system represents an effective means for boosting the consumer＇s perception of a food＇s safety and quality. In our work we have done, which quality parameters can be used for a good identification system.  相似文献   

Determination and vertical distribution of nitrogen species in sediments of Funan Rivers, Chengdu City, China     

Yi WU Tingting WANG Qing XU Mengxia LIAO Tianong DENG 《中国地球化学学报》2006,25(B08):143-144

Although numerous papers have been published on nutrients in Great Lakes, estuaries, continental shelf areas and marines in the aspects of determination, sediment-water-interface exchange, fluxes and budget estimation, eutrophication and microbial processes as well as modeling study, the knowledge of river condition （especially urban river） is uncertain and simply considered as a contributor to eutrophication of estuary. After a series of determinations of nitrogen species corresponding to ammonia-N （AN）, Kjeldahl-N （K-N）, and total nitrogen （TN） by means of National Standards for China, the nitrate ＆ nitrite （Nitr-N） and org-N were obtained by the difference of TN with K-N, and K-N with AN, respectively. Therefore, the behaviors of vertical distributions in overlying waters and porewaters in the Fu and Nan Rivers located in Chengdu City were achieved.  相似文献   

Cascadia边缘与天然气水合物共生沉积物中有机质碳、氮同位素组成及意义   总被引：1，自引：1，他引：1  

于晓果  李家彪  龚建明  陈建芳  金肖兵  Young-Joo Lee  李宏亮  徐杰 《中国科学D辑》2006,36(5):421-429

Hydrate Ridge南高点ODP204航次5个站位54个沉积物样品中有机碳C, N同位素组成及C/N比值表明沉积物中的有机质主要来自海洋. 对1245B孔的系统分析表明天然气水合物的发育改变了沉积物中有机碳和氮同位素的成岩演化轨迹, 水合物发育处δ¹⁵N值和C/N比值同时变低, 且δ¹³C值相对较重; 在水合物稳定带内δ¹⁵N值的亏损将近2‰. 水合物发育处沉积物中氮含量的增加和δ¹⁵N值的亏损, 推断可能与天然气水合物发育处沉积物中细菌(包括古细菌)的固氮作用有关. 沉积物中有机质中碳、氮同位素的分布与沉积环境的变化同步响应, 同时亦反映流体活动的变化.  相似文献   

海相优质烃源岩发育的主要影响因素及沉积环境   总被引：6，自引：1，他引：6  

陈践发  张水昌  鲍志东  孙省利  吴庆余 《海相油气地质》2006,11(3):49-54

对海洋生物、现代海洋沉积和古代海相地层中有机质含量分布特征和实验室模拟实验的结果表明,水体中高生物生产率是海相环境形成富有机质沉积的关键因素;沉积和早期成岩作用期间水体的相对还原环境是有机质富集保存的有利条件;海底深部流体的活动是造成富有机质沉积的不可忽视的因素;沉积速率是影响海相沉积有机质富集的主要因素。现有研究表明,在海相盆地中最有利形成优质烃源岩的沉积环境主要有欠补偿浅水—深水盆地、台缘斜坡、半闭塞—闭塞欠补偿海湾和蒸发潟湖。  相似文献   

Sedimentary environments of organic matter from Middle Permian source rocks in northern Xinjiang, China   总被引：3，自引：0，他引：3  

苗建宇寇韩生  周立发韩宗元 《中国地球化学学报》2006,25(3):258-265

1IntroductionThe formation of the Junggar,Turpan and Ili ba-sins is ascribed to Hercynian orogeny between theJunggar and Tianshan Mountains during the MiddlePermian.The rock assemblage of thick and stable sedi-mentary dark muddy shales interbedded with th…  相似文献   

耕作土壤中砷的物质平衡模拟     

B.  Bar-Yosef  葛秀珍 《水文地质工程地质技术方法动态》2006,(3):18-25

本文描述了砷在耕作土壤中的作用过程中，有关砷的物质平衡的数学表述形式。需要用许多模型参数定义所涉及砷的物质平衡的数学表述形式，即使是简化的数学形式。根据参数值的范围和源于出版的文献的初始条件进行实例模拟。研究结果表明，由于对耕作土壤施肥和灌溉水，植被对砷的摄入量引起根部区总砷含量逐渐增加。搞清楚植物对砷的吸收和析出与弄清楚对增加砷的去除途径同等重要。反过来，矿物相的溶解动力学和吸附相的分布系数影响植物吸收和浸出的可用性。根据实验室砷矿相的分解、As（III）的矿化和氧化推导出参数，而砷植物的吸收似乎对砷在土壤中的传输估计过高。数学模型的研究是一个简明的过程，而用自信度定义的模型参数值的不同阻碍了它在实际情况中的应用。目前对土壤一一植被系统中砷的传输过程和作用的了解是不充分的，所以要校准或者验证模型。研究必须了解土壤中砷矿物分解和沉淀的动力学原理和土壤中根部生长以及植被砷吸收的动力学原理。  相似文献   

加氢和TSR反应对天然气同位素组成的影响   总被引：2，自引：1，他引：2  

刘文汇  张殿伟王晓锋 《岩石学报》2006,22(8):2237-2242

天然气形成过程中的加氢作用和 TSR 反应是有机-无机相互作用的重要方式。相邻水体和深部来源的氢,是天然气形成的重要氢源,塔里木盆地天然气的甲烷氢同位素组成明显表现出不同沉积水体对甲烷氢同位素的控制作用,大宛105～25井和阿克1井具有深部流体加氢的特征;TSR 反应中硫同位素在不同反应阶段和反应过程具有不同的分馏特征,这种特征在四川盆地高舍硫天然气中具有很好的表现,TSR 反应硫同位素分馏一般小于20‰,而单体硫、黄铁矿和硫酸盐矿物等其它反应过程的产物硫同位素分馏不明显。  相似文献   

新疆14C年代测定及数据集（I＊）     

阮成雯  高峰林 《内陆地震》1998,12(1):83-91

主要介绍新疆维吾尔自治区地震局放射性同位素碳测年实验室的１４Ｃ测年原理,样品的前处理、样品的化学制备,低水平放射性测量方法及测定年代。首次公布一批１４Ｃ年代测定数据。  相似文献   

陆相低成熟烃源岩有机硫与热解成烃动力学关系初探   总被引：5，自引：0，他引：5  

沈忠民  周光甲 《沉积学报》1998,16(4):133-139

对陆相低成熟烃源岩（R_o≤ 0.5 %）有机硫与成烃动力学关系进行了研究。结果表明:①有机硫含量与镜质体反射率（R_o）之间呈负相关关系,即有机硫含量随成熟度提高而减少;②源岩的平均活化能（E）有随有机硫含量增大而减小的趋势;③有机硫含量与源岩活化能分布最小值（E_min）和经可溶有机质抽提后的活化能分布最小值（E_min）之间存在正相关关系;④活化能分布范围E_min～ESE_min（ESE_min＞E_min）内的可溶有机质生烃能力与有机硫含量具有一定的相关性;⑤综上结果推断东营凹陷南斜坡东段沙四段（Es₄）源岩中的有机硫在成烃过程中可能起到了一定的作用。  相似文献