Determining the relative contributions of climate change and multiple human activities to variations of sediment regime in the Minjiang River,China   总被引：1，自引：0，他引：1  

Qiang Tang  Xiubin He  Yuhai Bao  Xinbao Zhang  Feng Guo  Hongwei Zhu 《水文研究》2013,27(25):3547-3559

In‐stream sediment transport plays an important role in delivery of sediment‐associated terrestrial elements. Investigating the history of fluvial sediment regime responding to changes in natural and anthropogenic driving forces provides a theoretical basis for establishment of optimal strategies on catchment management. The present study aims to systematically detect the patterns of change in sediment load at two key hydrological stations (Pengshan and Gaochang) in the Minjiang River and quantitatively evaluate the relative contributions of regional precipitation change and multiple local human activities to the observed sediment variations. Abrupt change in annual sediment load was detected in 1990 at Pengshan and in 1968, 1980 and 1992 at Gaochang. Compared with the baseline period of 1957–1990, precipitation decline and human activities had respectively contributed to 5 × 10⁶ t and 2 × 10⁶ t of reduction in mean annual sediment load at Pengshan during 1991–2007. For the entire Minjiang basin, taking 1956–1968 as the baseline period, precipitation decline and human activities had relatively contributed to 10 × 10⁶ t and 18 × 10⁶ t of reduction in mean annual sediment load at Gaochang during 1969–1980. During 1981–1992, precipitation decline had relatively contributed to 5 × 10⁶ t of reduction in mean annual sediment load, but human activities had led to 3 × 10⁶ t of increase in mean annual sediment load. During 1993–2009, 13 × 10⁶ t and 17 × 10⁶ t of reduction in mean annual sediment load may be attributed to precipitation decline and human activities, respectively. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The measurement of gamma-emitting radionuclides in beach sand cores of coastal regions of Ramsar,Iran using HPGe detectors     

Marziyeh Tari  Sayyed Ali Moussavi Zarandi  Kheirollah Mohammadi  Mohammad Reza Zare 《Marine pollution bulletin》2013

Radionuclides which present in different beach sands are sources of external exposure that contribute to the total radiation exposure of human. ²²⁶Ra, ²³⁵U, ²³²Th, ⁴⁰K and ¹³⁷Cs analysis has been carried out in sand samples collected at six depth levels, from eight locations of the northern coast of Iran, Ramsar, using high-resolution gamma-ray spectroscopy. The average Specific activities of natural radionuclides viz., ²²⁶Ra, ²³⁵U, ²³²Th, ⁴⁰K and ¹³⁷Cs, in the 0–36 cm depth sand were found as: 19.2 ± 0.04, 2.67 ± 0.17, 17.9 ± 0.06, 337.5 ± 0.61 and 3.35 ± 0.12 Bq kg⁻¹, respectively. The effects of organic matter content and pH value of sand samples on the natural radionuclide levels were also investigated. Finally, the measured radionuclide concentrations in the Ramsar beach were compared with the world average values, as reported by UNSCEAR (2000). None of the studied beaches were considered as a radiological risk.  相似文献   

Characteristics of metals in the aerosols of Zhongshan Station, Antarctica   总被引：1，自引：0，他引：1  

汪建君  陈立奇  杨绪林  张远辉 《极地研究(英文版)》2010,21(1):46-59

Instrumental neutron activation analysis (INAA) was applied to analyze the bulk, high-volume aerosol samples, collected at Zhongshan Station in the Eastern Antarctica, during 1998-2001, to study the chemical species. .A graphical technique was applied to the INAA data. Results showed that Na, Cl, Mg, Ca, Sr, Br, I, Sr and Rb were marine elements while Al, Sc, Fe and Mn were crustal elements. Compared to marine and crustal elements, five elements (Se、Co、Sb、Zn、Cr) were highly abundant in the aerosols collected at Zhongshan station, which indicated that they might come from the petroleum burning, heating and equipment operation. The presence of pollutant elements suggested that human activities have affected the local environments in Antarctica.  相似文献   

近60年黄河水沙变化及其对三角洲沉积的影响   总被引：1，自引：1，他引：0  

彭俊  陈沈良 《地理学报(英文版)》2010,20(4):613-627

In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×109 m3 and 3.41×108 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×1010 m3 and 2.42×108 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×108 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×108 t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea (SSCT) is 25.4–26.0 kg/m3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997.  相似文献   

人类产业活动对湿地环境的影响研究进展     

闫长平  马延吉 《湿地科学》2010,8(1):98-104

人类产业活动对湿地环境影响很大。产业的大规模、高强度活动对脆弱的湿地生态环境产生了诸多不利影响,导致湿地环境的水文条件发生改变、水质遭到污染、湿地面积萎缩、湿地景观破碎化、动植物减少,并最终导致湿地环境的退化。通过综述产业活动对湿地环境的影响路径,从产业规模、产业布局、产业结构等方面总结了产业活动对湿地环境的影响及其动力机制,总结分析了湿地环境和产业活动两者协调发展的途径,提出了未来产业活动与湿地环境保护研究的重点。  相似文献