Design of a Multi-Level Monitoring Well for Continuous Sample Collection     

Jerry F. Ayers  David C. Gosselin 《Ground Water Monitoring & Remediation》1995,15(4):119-124

As part of a study of the flow dynamics and sampling environment around a high-capacity irrigation well, it was necessary to design and install a multi-level monitoring well network close to the production well. A requirement of the monitoring well network was the capability of continuous pumping over periods typical of those used during water sample collection. This was accomplished through the use of a control valve and air manifold system connected 10 a common gasoline engine-operated air compressor. The system provided adequate air pressure to operate 24 half-size bladder pumps to depths between 21 feet (6.4 m) and 56 feet (17.1 m) below the surface. Preliminary data collected from the monitoring well network indicate that the system will meet the requirements of the high-capacity well study.  相似文献   

Hydrogeology of an Atoll Island: A Conceptual Model from Detailed Study of a Micronesian Example   总被引：1，自引：0，他引：1  

Jerry F. Ayers  H. L. Vacher 《Ground water》1986,24(2):185-198

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Some observations on the acidity and composition of rainwater in Sydney,Australia, during the summer of 1980–81     

G. P. Ayers  R. W. Gillett 《Journal of Atmospheric Chemistry》1984,2(1):25-46

During the summer of 1980–81, a rudimentary form of wet-only event sampling was employed to collect a total of 294 rainwater samples at 12 sites spread across the metropolitan region of Sydney, Australia's largest city. From the samples were determined conductivity, pH, ammonium, chloride and nitrate ion concentrations as well as deposited water volume. Supplementary data consisting of city-wide averaged SO₂, NO₂, NO, and O₃ concentrations and 950 mb wind speed and direction were obtained for times coinciding with the period during which each event occurred.The pH of rainwater upwind of the city and unaffected by urban/industrial emissions was found to be usually 5, whereas the volume-weighted mean pH of all the metropolitan samples was 4.4, indicating that local emissions significantly increased rainwater acidity in the near field. Time available for conversion of precursors to acids averaged 1–2 h only.Considerable day-to-day variability in rainwater composition was observed. Factors identified as contributing to this variability included precursor gas concentration, wind speed, wind direction, amount of water deposited per event and possibly time of day. These results show that physical/meteorological factors cannot be excluded from consideration if variance in rainwater composition data is to be explained.  相似文献   

Conjunctive Use of Geophysical and Geological Data in the Study of an Alluvial Aquifer   总被引：1，自引：0，他引：1  

Jerry F. Ayers 《Ground water》1989,27(5):625-632

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Regional estimation of total recharge to ground water in Nebraska   总被引：4，自引：0，他引：4  

Szilagyi J  Harvey FE  Ayers JF 《Ground water》2005,43(1):63-69

Naturally occurring long-term mean annual recharge to ground water in Nebraska was estimated by a novel water-balance approach. This approach uses geographic information systems (GIS) layers of land cover, elevation of land and ground water surfaces, base recharge, and the recharge potential in combination with monthly climatic data. Long-term mean recharge > 140 mm per year was estimated in eastern Nebraska, having the highest annual precipitation rates within the state, along the Elkhorn, Platte, Missouri, and Big Nemaha River valleys where ground water is very close to the surface. Similarly high recharge values were obtained for the Sand Hills sections of the North and Middle Loup, as well as Cedar River and Beaver Creek valleys due to high infiltration rates of the sandy soil in the area. The westernmost and southwesternmost parts of the state were estimated to typically receive < 30 mm of recharge a year.  相似文献   

An editorial synthesis of the ACEP project: Ecosystem Processes in the KwaZulu-Natal Bight     

ST Fennessy  MJ Roberts  RG Barlow 《African Journal of Marine Science》2016,38(1):S217-S223

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Circulation of shelf waters in the KwaZulu-Natal Bight,South Africa     

MJ Roberts  C Nieuwenhuys  LA Guastella 《African Journal of Marine Science》2016,38(1):S7-S21

Ship-based acoustic Doppler current profiler (S-ADCP) technology, used in survey mode, has enabled near- synoptic views of the in situ 3-D current field in the KwaZulu-Natal (KZN) Bight to be elucidated for the first time. Data acquired by the research vessels RS Africana and RS Algoa in June 2005, September 2007, March 2009 and July 2010 are presented. Each S-ADCP dataset showed similar circulation characteristics whereby the continental slope and outer shelf of the KZN Bight were strongly influenced by the south-westward flowing Agulhas Current. This was particularly evident in the extreme north between Cape St Lucia and Richards Bay where the shelf is narrowest and velocities exceeded 200 cm s?1. The widening of the bight to the south moves the Agulhas Current further from the coast, resulting in a diminishing velocity gradient on the outer shelf which terminates around the midshelf axis. The southern region of the bight was mostly influenced by the Durban cyclonic eddy (Durban Eddy), and in June 2005 and September 2007, by a cyclonic ‘swirl’ that occupied the entire southern half of the KZN Bight, the latter identified by a combination of S-ADCP-, satellite-derived SST- and ocean colour data. Satellite data showed low-chlorophyll offshore water to move into this swirl and northwards along the inner- and midshelf, reaching the Thukela River. Inner-shelf circulation north of the Thukela River was weak (<20 cm s?1) and highly variable. Satellite-tracked surface drogues deployed in the Durban Eddy found their way into the northward coastal current in the KZN Bight, with velocities exceeding 90 cm s?1 at times. The drogues also highlighted the strong influence of wind, especially in the northern bight between Durnford Point and Cape St Lucia, with residence times on the shelf exceeding 14 days, suggesting this region to be of biological importance particularly for recruitment.  相似文献   

Describing gonad development and gametogenesis in southern Africa’s endemic box jellyfish Carybdea branchi (Cubozoa,Carybdeidae)     

R Mohamed  H Skrypzeck  MJ Gibbons 《African Journal of Marine Science》2019,41(1):83-91

Information on the reproductive development of species of box jellyfish (class Cubozoa) is poor globally, despite their significance as potent stingers and worrying projections about range expansions. While most species are confined to tropical and subtropical waters, the South African box jellyfish Carybdea branchi is commonly found in the cold-water (especially southern) Benguela ecosystem. Its biology is unknown. Here, we examine reproductive development and describe gametogenesis in this dioecious species. Four and five maturity classes were determined for males and females, respectively, as well as five oocyte developmental stages. Oocyte sizes differed significantly between developmental stages. Mature and immature medusae differed significantly in size, but males and females did not. Individuals matured at approximately 30 mm average bell dimensions. Carybdea branchi displayed gonadal development characteristic of a semelparous organism.  相似文献   

新疆哈密香山西铜镍-钛铁矿床系同源岩浆分异演化产物——矿相学、锆石U-Pb年代学及岩石地球化学证据   总被引：19，自引：9，他引：10  

肖庆华  秦克章  唐冬梅  苏本勋  孙赫  三金柱  曹明坚  惠卫东 《岩石学报》2010,26(2):503-522

香山西岩体是东天山地区发现的唯一的一个铜镍-钛铁复合型含矿岩体,前人对香山西铜镍-钛铁矿床成因认识一直存在争议。本次通过矿相学研究结合电子探针分析,在香山西铜镍矿石中发现了铜镍硫化物与钛铁氧化物共生的现象,并首次测定了香山西钛铁辉长岩的SIMS锆石U-Pb年龄为278.6±1.8Ma(MSWD=1.2),与前人测得香山中岩体角闪辉长岩的锆石U-Pb年龄基本一致,证实了香山西铜镍矿与钛铁矿为共生关系,两者空间上渐变过渡。岩石地球化学研究表明,香山岩体(包括钛铁辉长岩)为同源岩浆经结晶分异作用形成的一套镁铁-超镁铁质岩体,具有拉斑玄武质岩浆分异演化趋势,并且经历了与地壳物质的混染。与中段和东段岩石相比,香山西辉长岩类具有相对高的REE、SiO₂(平均48.99%)、K₂O+Na₂O(平均3.43%)、TiO₂(平均1.26%)和明显低的Mg^#值(平均62.4),表现出分异演化程度高于中段和东段。经反演得出香山岩体原始岩浆含MgO约10%,FeO约9%,TiO₂约1.14%,与同一成矿带内其它含铜镍矿岩体原始岩浆成份相近,应为 普通的拉斑玄武质岩浆。因此,香山西钛铁矿床的形成机制可能是由普通的拉斑玄武质岩浆,经历了较高程度的分异演化导致钛铁氧化物在残余岩浆中逐步富集,岩浆在上升侵位过程中与地壳物质的混染,不仅促使了岩浆中硫化物的饱和,同时提高了岩浆体系的氧逸度,进而促使了钛铁氧化物结晶沉淀。对香山西钛铁矿床成因研究的启示意义在于,除我国攀西地区高钛的玄武质岩浆外,普通的拉斑玄武质岩浆,在有利的分异演化条件下(如初始低氧逸度、相对高度的分异演化、后期与地壳物质混染)也有可能形成大型钛铁矿床。  相似文献   

Characterising shelter preferences in captive juvenile Jasus edwardsii (Palinuridae)     

John D. Booth  Dieter Ayers 《新西兰海洋与淡水研究杂志》2013,47(2):373-382

Any attempt to enhance rock lobster production by increasing survival after settlement, or by ongrowing or outplanting young juveniles, requires knowledge of the shelter preferences of young juveniles. For juvenile Jasus edwardsii in the wild these are not well known. Information available suggests that juveniles up to c. 35 mm carapace length (CL) occupy shelters that generally conform closely to their body dimensions but that larger juveniles use shelters of more variable dimension, often much larger than their body size. We investigated mainly physical factors important in shelter choice by 15–59 mm CL (c. 2–24‐month‐old juveniles) in laboratory tank experiments. In overnight tests, all sizes of juvenile lobster chose to occupy holes (shelters with sides) over open horizontal gaps. Preference for open horizontal gaps versus horizontal crevices (where the height reduces from a maximum at the mouth to zero at the opposite end) was much less clear‐cut; choice varied according to lobster size. For the number of entrances into holes, there was evidence for an ontogenetic shift in preference, small lobsters preferring two openings over one, whereas those >30 mm CL (c. 9 months old) preferred one over two. For lobsters <40 mm CL, the hole size and gap size preferences revealed were generally consistent with the field evidence for J. edwardsii in that there was a close and proportional relationship between lobster size and shelter size; what differed was that the open gaps chosen in the tanks by the smallest lobsters (15–19 mm CL) were larger than the holes used in the tank experiments and 30–50% larger than those reportedly used in the field. For lobsters >40 mm CL, the holes and gaps chosen in the tanks were generally larger and more variable in size, as in the field.  相似文献