矿床形成条件与分布规律     

希洛.  HA 《国土资源信息化》1989,(11):12-21

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Bacterial community and some physico-chemical characteristics in a subtropical mangrove environment in Bahrain   总被引：5，自引：0，他引：5  

Al-Sayed HA  Ghanem EH  Saleh KM 《Marine pollution bulletin》2005,50(2):147-155

A study of bacterial communities and some physico-chemical parameters of a subtropical mangrove habitat in the Arabian Gulf (Bahrain) was carried out in 1993-1994. Six stations at different parts of the tidal channel were selected for sampling. The mangrove habitat was found to harbor diverse bacterial communities, included among them anoxygenic phototrophs (AP), oxygenic phototrophs (OP), organotrophs (OT), total coliforms (TC), faecal coliforms (FC) and haloalkaliphiles (HA). Spatial and temporal variations in bacterial communities and environmental parameters were found. Each of the OT, AP, TC, and FC were dominant in the innermost stations (S1&S2) and gradually decreased seaward. The HA community on the other hand, was dominant at the seaward stations (S5&S6) and was most likely to have originated from the sea through the tidal flows. Both AP and OT were considered as part of the mangrove native flora, whereas TC and FC were alien and believed to have been introduced through partially treated sewage released at the upstream of the tidal channel. Closely monitoring of the mangrove water revealed succession pattern in bacterial communities. The AP community was predominant from November 1993 to March 1994, succeeded by dominance of OP from June 1994 to October 1994. Both bacterial blooms gave water a pinkish, purple, or green color, respectively. Although OT prevailed during Transitional period between AP and OP eutrophication, it remained comparatively constant (not less than 2 x 10(5)cfu/ml) through other periods. Frequent eutrophication phenomena of OP, which took place in summer and autumn, coincided with increases in water temperature, chlorophyll a, and nutrients (NO(3)(-) and PO(4)(-)). On the other hand, OT and AP were negatively correlated with temperature, salinity and chlorophyll a, but no specific pattern was observed in relation to NO(3)(-) and PO(4)(-). In comparison with seawater, nutrients such as NO(3)(-) and PO(4)(-) were consistently higher in the mangrove habitat. Partially treated sewage and farm drainage canals are proposed to form additional sources of nutrients. Although, the mangrove habitat has been demonstrated to possess self-cleaning properties, data obtained suggest that anthropogenic pollution has a deleterious effect.  相似文献   

Byssal detachment underestimates tolerance of mussels to toxic compounds     

Rajagopal S  van der Velde G  van der Gaag M  Jenner HA 《Marine pollution bulletin》2005,50(1):20-29

Mussels are sedentary organisms attached to solid substrata by means of byssus threads. Mussels detached from their substratum tend to reattach by producing new byssus threads. Therefore, in bioassays using mussels, if the test animals are in an unattached status, increased byssogenic activity would expose their soft body parts to the toxic compound used. We test the tolerance of two mussel species (Mytilopsis leucophaeata and Mytilus edulis) to an oxidizing biocide (chlorine) and show that detached mussels are 24-28% less tolerant than byssally attached ones. Detached mussels also showed higher oxygen consumption, filtration rate, foot activity, byssus thread production and byssogenesis index, parameters which are associated with valve opening. A review of literature showed that most of the published data on toxicity against heavy metals and biocides are generated using unattached mussels. The data, therefore, represent an underestimation of the toxicity of the tested compound. Correction data are presented for chlorine tolerance of Dreissena polymorpha, Mytilopsis leucophaeata and Mytilus edulis. The present study suggests the importance of maintaining mussels in their attached status, while undertaking toxicity bioassays.  相似文献   

Large Proper-Motion Infrared     

Raines SN  Watson DM  Pipher JL  Forrest WJ  Greenhouse MA  Satyapal S  Woodward CE  Smith HA  Fischer J  Goetz JA  Frank A 《The Astrophysical journal》2000,533(2):L115-L118

When some magnetic field lines connect a Kerr black hole with a disk rotating around it, energy and angular momentum are transferred between them. If the black hole rotates faster than the disk, ca&solm0;GMH>0.36 for a thin Keplerian disk, then energy and angular momentum are extracted from the black hole and transferred to the disk (MH is the mass and aMH is the angular momentum of the black hole). This way, the energy originating in the black hole may be radiated away by the disk. The total amount of energy that can be extracted from the black hole spun down from ca&solm0;GMH=0.998 to ca&solm0;GMH=0.36 by a thin Keplerian disk is approximately 0.15MHc2. This is larger than approximately 0.09MHc2, which can be extracted by the Blandford-Znajek mechanism.  相似文献   

埃及年轻花岗岩的铀矿远景     

Huss.  HA 陆薇 《国外铀金地质》1992,(1):25-29

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近地表金矿床地质地球化学特征及其找矿准则     

K.  HA 董智慧 《黄金地质科技》1994,(4):29-37,41

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Preface to the Special Issue: Climate Change and Variability of Tropical Cyclone Activity     

Liguang WU  Bin WANG  Johnny CLCHAN  Kyung-Ja HA  Il-Ju MOON  Jun MATSUMOTO  Zhemin TAN  Ke FAN 《大气科学进展》2022,39(2):203-204

Tropical cyclones(TCs) are one of the most destructive natural phenomena on Earth in terms of human-life and economic losses. It is currently a matter of prodigious public and scientific interest how TC activity has changed and will change in a warming climate. This special issue focuses on a challenging subject raised in the Intergovernmental Panel on Climate Change(IPCC) report and numerous research papers.  相似文献   

Two Types of Diurnal Variations in Heavy Rainfall during July over Korea※     

Chang-Kyun PARK  Minhee CHANG  Chang-Hoi HO  Kyung-Ja HA  Jinwon KIM  Byung-Ju SOHN 《大气科学进展》2021,38(12):2201-2211

This study examined the characteristics of the diurnal variations of heavy rainfall (≥110 mm in 12 hours) in Korea and the related atmospheric circulation for July from 1980?2020. During the analysis period, two dominant pattens of diurnal variation of the heavy rainfall emerged: all-day heavy rainfall (AD) and morning only heavy rainfall (MO) types. For the AD-type, the heavy rainfall is caused by abundant moisture content in conjunction with active convection in the morning (0000?1200, LST; LST = UTC + 9) and the afternoon hours (1200?2400 LST). These systems are related to the enhanced moisture inflow and upward motion induced by the strengthening of the western North Pacific subtropical high and upper-tropospheric jet. For the MO-type, heavy rainfall occurs mostly in the morning hours; the associated atmospheric patterns are similar to the climatology. We find that the atmospheric pattern related to severe heavy rainfalls in 2020 corresponds to a typical AD-type and resembles the 1991 heavy-rainfall system in its overall synoptic/mesoscale circulations. The present results imply that extremely heavy rainfall episodes in Korea during the 2020 summer may occur again in the future associated with the recurring atmospheric phenomenon related to the heavy rainfall.  相似文献   

Contrast of tropical cyclone frequency in the western North Pacific between two types of La Nia events     

HA Yao  ZHONG Zhong 《中国科学:地球科学(英文版)》2013,(3):397-407

According to the different pattern of sea surface temperature anomaly(SSTA) in the previous year of La Nia events,we categorized La Nia events into two types to investigate the different characteristics of tropical cyclone(TC) activity over the western North Pacific(WNP) in TC peak season of two types La Nia events.One type is following the previous El Nio event(La Nia I);the other is following the previous neutral phase or developing La Nia event(La Nia II).Results show that TC genesis frequency in the WNP during TC peak season of La Nia I is less than normal year,whereas it has no differences from normal year during La Nia II.The main reason is attributed to the different amplitude SSTA in the East Indian Ocean(EIO) and the western Pacific Ocean(WPO).Similar to the capacitor effect,strongly positive SSTA in the EIO-WPO during La Nia I triggers an equatorial baroclinic Kelvin wave,which intensifies the easterly in the lower troposphere and weakens the East Asian summer monsoon,and thus the TC frequency decreased during La Nia I.However,the easterly anomaly shows a weak response to the SSTA in the EIO-WPO during La Nia II,and there is no significant change in the environmental pattern over the WNP;so is TC frequency.The modulation of strong EIO-WPO SSTA on large-scale circulation over the WNP reduces the environmental barotropic energy conversion into synoptic-scale disturbances during La Nia I,and also suppresses TC disturbances.The understanding of two different types of La Nia events could help improve the seasonal prediction of TC activity in the WNP during La Nia.  相似文献   

Sea water intrusion by sea-level rise: scenarios for the 21st century   总被引：4，自引：0，他引：4  

Loáiciga HA  Pingel TJ  Garcia ES 《Ground water》2012,50(1):37-47

This study presents a method to assess the contributions of 21st-century sea-level rise and groundwater extraction to sea water intrusion in coastal aquifers. Sea water intrusion is represented by the landward advance of the 10,000 mg/L iso-salinity line, a concentration of dissolved salts that renders groundwater unsuitable for human use. A mathematical formulation of the resolution of sea water intrusion among its causes was quantified via numerical simulation under scenarios of change in groundwater extraction and sea-level rise in the 21st century. The developed method is illustrated with simulations of sea water intrusion in the Seaside Area sub-basin near the City of Monterey, California (USA), where predictions of mean sea-level rise through the early 21st century range from 0.10 to 0.90 m due to increasing global mean surface temperature. The modeling simulation was carried out with a state-of-the-art numerical model that accounts for the effects of salinity on groundwater density and can approximate hydrostratigraphic geometry closely. Simulations of sea water intrusion corresponding to various combinations of groundwater extraction and sea-level rise established that groundwater extraction is the predominant driver of sea water intrusion in the study aquifer. The method presented in this work is applicable to coastal aquifers under a variety of other scenarios of change not considered in this work. For example, one could resolve what changes in groundwater extraction and/or sea level would cause specified levels of groundwater salinization at strategic locations and times.  相似文献