LEADAT: a MATLAB-based program for lead-210 data analysis of sediment cores

The program described herein （LEADAT） serves to calculate sediment date and sedimentation rate using the ^210pb method for the studies of environmental processes and pollution history on a time scale of 100 - 150 a. The program written in MATLAB （ Version7.0） permits the user to select the principal models of ^210pb method, i. e. , the constant fluxes of sediment and lead-210 （ CF- SL） model, the constant flux of lead-210 （CFL） model, the constant initial concentration of lead-210 （CICL） model and the twolayer mixing （TLM） model. Although appropriate model selection is essentially based on understanding of the sedimentary processes, the pattern of the excess ^210pb profile is also helpful for model selection. The excess ^210pb profiles for two sediment cores collected from a brackish lake and an embayment respectively are used to demonstrate the application of the program. With a graphical user interface, the program can be easily executed. Not only ASCII but also graphical output can be generated by means of the program. Meanwhile, the code can be modified easily for extension.

含小水电配电网的感性无功配置方法

详细分析了有小水电接入的配电网在丰水期小方式系统电压偏高问题,建立了小水电丰水季节小方式的配电线路仿真模型,提出了水轮发电机进相运行、加装并联电抗器等改善策略,着重对比了在小水电高低压侧进行无功补偿的效果。结果表明,在小水电升压变低压侧加装并联电抗器补偿时,电压控制能力显著增强,具有良好的实用价值和可操作性。

A 200-Year Record of Polycyclic Aromatic Hydrocarbons Contamination in an Ombrotrophic Peatland in Great Hinggan Mountain, Northeast China

Peat bogs are regarded as one of the faithful archives of atmospheric polycyclic aromatic hydrocarbons(PAHs) deposition, and a large number of studies on PAHs accumulation in peatlands have been reported in Europe and North America. Comparatively little information is available on peat chronological records of atmospheric PAHs flux in China. We investigated the concentrations and historical accumulation rates of PAHs(AR PAHs) through geochemical analysis of three 210Pb-dated ombrotrophic peat cores from Great Hinggan Mountain, northeast China. Eight USEPA priority PAHs were detected and they are naphthalene(Nap), acenaphthylene(Acl), acenaphthene(Ace), fluorence(Flu), phenanthrene(Phe), anthracene(Ant), fluoranthene(Fla) and pyrene(Pyr), respectively. The average total eight PAHs(tPAHs) concentrations are 135.98- 262.43 μg kg-1 and the average AR tPAHs over the last two centuries are 96.45- 135.98 μg m-2 yr-1. The Ace, Acl and Phe account for 30.93- 54.04%, 25.29- 35.81%, and 9.14- 19.84% of the tPAHs, respectively, and have significant positive correlations with the tPAH. As a result, they are regarded as the iconic compounds of PAHs pollution in this area. A ca.200-yr atmospheric PAHs contamination history was reconstructed from the temporal sequences of bothconcentration and AR tPAHs, suggesting the variation of local environmental pollution. The main sources of the PAHs are identified by two isomer ratios as petrogenic origin including oil extraction and refining process as well as their combustions for industrial development. In addition, the contribution of coal combustion for industrial activities and resident heating could not be ignored. But prior to 1860, the undeveloped industry and most of agricultural activities might mainly account for the low level of PAHs, although it could infer a long-range input of atmospheric PAHs from other industrial areas. Therefore, there is a global implication to study longterm PAHs pollution records and all the results will provide practical significance in formulating policies to achieve sustainable and healthy development.

Sinking of particulates ^(234)Th_(xs),~7Be and ^(210)Pb_(xs) in the Changjiang estuary,China

The time scale of transport and reaction processes in the ocean can be evaluated using natural radionuclides of different half-lives.In the present study,we evaluated the residence times of particulate reactive radionuclides 7 Be,210 Pb xs and 234 Th in the Changjiang (Yangtze River) estuary,which is a high turbidity estuary,in June,2006.The residence times of particulate 7 Be,234 Th xs and 210 Pb xs in the Changjiang estuary were calculated to be 0.7-20.4,0.18-4.1 and 0.6-89.8 d,respectively.The obtained residence times of those nuclides are comparable with those of other estuaries and bays.For 234 Th xs and 7 Be,the residence times decreased with increasing concentrations of suspended particulate matter (SPM);however,those of 210 Pb xs increased.Moreover,scavenging residence times of 234 Th and 7 Be increased from coast to offshore,while those of 210 Pb xs decreased.

A Record of Anthropogenic Effects on Sedimentation in the Manatee River, Florida

Increased sedimentation rates have been attributed to increased anthropogenic activity in watersheds throughout Florida and many parts of the world. The Manatee River, located on the west coast of Florida （USA）, like many other coastal watersheds, has experienced depletion in natural resources, increased nutrient loading, and increased pollution. LARs （linear accumulation rates） from watersheds throughout Florida suggest that anthropogenic activity increased bulk sedimentation by as much as 4-fold. The objective of this study was to construct a record of sedimentation and improve upon previous studies by determining individual sedimentary constituent MARs （mass accumulation rates） based on short lived radioisotopes （2~~pb and 234Th） to characterize changes in sedimentation attributed to increased anthropogenic development. This study constructed records of sedimentary accumulation rates to compare pre-development records to the past 100 years of anthropogenic development and identified specific changes in sedimentation attributed to anthropogenic activity. Anthropogenic development increased deposition of terrigenous material into the river from 2-fold to I 0-fold （0.3-2.0 g/cm2/yr） over three periods： （1） predevelopment period （1900-1941）; （2） agricultural development period （1941-1970）; （3） urban development period （1970-2010）. The mobilization of this amount of terrigenous material has implications for effects on water quality and biological communities within the river.

The Origin of Pb-Zn Deposits in the Northern Kuandian Area, Liaoning Province

Carbonates and clastic rocks are well developed in the second-order basins of an Paleoproterozoic aulacogen in the northern Kuandian area, Liaoning Province. The carbonates cousist of two parts, the upper and the lower carbonate forma- tions. The clastic rocks occured between the two formations. Two Pb-Zn ore belts exist in both of upper and lower carbo- nate formations and are called B and A-belt respectively. Several tens of Pb-Zn ore bodies are found in A-belt. Some Pb -Zn ore bodies are apparent in vertical zoning in a sequence of Fe-Zn-Pb-Ba from the lower to the upper. Geological and geochemical researches show that the ore components in the A-belt was exhalated from the liquid source bed deeply and was precipitated in a closed second-order basins. While those in the B-belt was derived from the upper crust and was de- opsited in a normal oceanic enviornment. The second-order basins in Liaodong-Ji’nan-North Korean Peninsular aulaco- gen at the margin of the Archean craton are promising sites for looking for the deposits formed by exhalation of the liquid source bed deeply under crust.