宝石和半宝石

绪言宝石分为两大类:即(ⅰ)透明宝石一有色的、着色的、无色的和(ⅱ)半透明或不透明宝石。大多数宝石和半宝石广泛用于珠宝饰物方面,因此,其应当能抗日常生活中的机械和化学作用。半宝石除了作珠宝饰物外,还可以用于建筑物墙壁、地板的装饰石,等等。有些,既不作为宝石,也不用于装饰目的,而是作为研磨材料,这要考虑硬度质量。     

前寒武系金矿床

以前我在《经过六千年的开采,世界金矿资源已经采完了吗?》(1967)和《世界金矿资源》(1976)这两篇文章中都强调了前寒武系金矿床的产量在世界黄金产量中占有很大比例。现在我要强调“非元古界砾岩型”的前寒武系金矿。 历史 据C.H.V.苏泽兰德所著《金》中记载,在哥伦布发现新大陆(1492年)以前的5500年人类历史中,采出的金不到10亿盎斯。可是,在那以后的487年中却开采了将近30亿盎斯。在这30多亿盎斯黄金产量中,前寒武系金矿床所产的金占一半以上。其中12.7     

大陆内部的古缝合带

大陆内部的古缝合带是包括残余古海盆的变形地区.它们是在两个早先被海盆分开的大陆块或岛弧,在板块活动时期发生会聚碰撞时形成的。今天我们所得到的唯一记录,是这些地带的深海壳和古海底。它们代表了地球形成历史的94%。为了认识和解释这些古老地带,本文讨论了十条标准。为研究这些地带而制定的这个规划对美国具有很大的科学意义和较高的经济价值。比起其它大型国家科研项目来讲亦较为经济.     

Composition and distribution of beach debris in Orange County, California

Many studies have quantified debris collected on beaches around the world. Only a few of those studies have been conducted in the United States, and they are largely limited to semi-quantitative efforts performed as part of volunteer clean-up activities. This study quantifies the distribution and composition of beach debris by sampling 43 stratified random sites on the Orange County, California coast, from August to September 1998. We estimated that approximately 106 million items, weighing 12 metric tons, occur on Orange County beaches. The most abundant items were pre-production plastic pellets, foamed plastics, and hard plastics. Debris density on the remote rocky shoreline was greater than that on high-use sandy beaches for most debris items. This finding partially reflects the periodic clean-up of high-use beaches by local municipalities, and also indicates that a high percentage of the observed debris was transported to the site from waterborne sources.     

A new approach for detecting and mapping sewage impacts

Increased nitrogen loading has been implicated in eutrophication occurrences worldwide. Much of this loading is attributable to the growing human population along the world's coastlines. A significant component of this nitrogen input is from sewage effluent, and delineation of the distribution and biological impact of sewage-derived nitrogen is becoming increasingly important. Here, we show a technique that identifies the source, extent and fate of biologically available sewage nitrogen in coastal marine ecosystems. This method is based on the uptake of sewage nitrogen by marine plants and subsequent analysis of the sewage signature (elevated delta 15N) in plant tissues. Spatial analysis is used to create maps of delta 15N and establish coefficient of variation estimates of the mapped values. We show elevated delta 15N levels in marine plants near sewage outfalls in Moreton Bay, Australia, a semi-enclosed bay receiving multiple sewage inputs. These maps of sewage nitrogen distribution are being used to direct nutrient reduction strategies in the region and will assist in monitoring the effectiveness of environmental protection measures.     

ENCORE: the effect of nutrient enrichment on coral reefs. Synthesis of results and conclusions

Coral reef degradation resulting from nutrient enrichment of coastal waters is of increasing global concern. Although effects of nutrients on coral reef organisms have been demonstrated in the laboratory, there is little direct evidence of nutrient effects on coral reef biota in situ. The ENCORE experiment investigated responses of coral reef organisms and processes to controlled additions of dissolved inorganic nitrogen (N) and/or phosphorus (P) on an offshore reef (One Tree Island) at the southern end of the Great Barrier Reef, Australia. A multi-disciplinary team assessed a variety of factors focusing on nutrient dynamics and biotic responses. A controlled and replicated experiment was conducted over two years using twelve small patch reefs ponded at low tide by a coral rim. Treatments included three control reefs (no nutrient addition) and three + N reefs (NH4Cl added), three + P reefs (KH2PO4 added), and three + N + P reefs. Nutrients were added as pulses at each low tide (ca twice per day) by remotely operated units. There were two phases of nutrient additions. During the initial, low-loading phase of the experiment nutrient pulses (mean dose = 11.5 microM NH4+; 2.3 microM PO4(-3)) rapidly declined, reaching near-background levels (mean = 0.9 microM NH4+; 0.5 microM PO4(-3)) within 2-3 h. A variety of biotic processes, assessed over a year during this initial nutrient loading phase, were not significantly affected, with the exception of coral reproduction, which was affected in all nutrient treatments. In Acropora longicyathus and A. aspera, fewer successfully developed embryos were formed, and in A. longicyathus fertilization rates and lipid levels decreased. In the second, high-loading, phase of ENCORE an increased nutrient dosage (mean dose = 36.2 microM NH4+; 5.1 microM PO4(-3)) declining to means of 11.3 microM NH4+ and 2.4 microM PO4(-3) at the end of low tide) was used for a further year, and a variety of significant biotic responses occurred. Encrusting algae incorporated virtually none of the added nutrients. Organisms containing endosymbiotic zooxanthellae (corals and giant clams) assimilated dissolved nutrients rapidly and were responsive to added nutrients. Coral mortality, not detected during the initial low-loading phase, became evident with increased nutrient dosage, particularly in Pocillopora damicornis. Nitrogen additions stunted coral growth, and phosphorus additions had a variable effect. Coral calcification rate and linear extension increased in the presence of added phosphorus but skeletal density was reduced, making corals more susceptible to breakage. Settlement of all coral larvae was reduced in nitrogen treatments, yet settlement of larvae from brooded species was enhanced in phosphorus treatments. Recruitment of stomatopods, benthic crustaceans living in coral rubble, was reduced in nitrogen and nitrogen plus phosphorus treatments. Grazing rates and reproductive effort of various fish species were not affected by the nutrient treatments. Microbial nitrogen transformations in sediments were responsive to nutrient loading with nitrogen fixation significantly increased in phosphorus treatments and denitrification increased in all treatments to which nitrogen had been added. Rates of bioerosion and grazing showed no significant effects of added nutrients. ENCORE has shown that reef organisms and processes investigated in situ were impacted by elevated nutrients. Impacts were dependent on dose level, whether nitrogen and/or phosphorus were elevated and were often species-specific. The impacts were generally sub-lethal and subtle and the treated reefs at the end of the experiment were visually similar to control reefs. Rapid nutrient uptake indicates that nutrient concentrations alone are not adequate to assess nutrient condition of reefs. Sensitive and quantifiable biological indicators need to be developed for coral reef ecosystems. The potential bioindicators identified in ENCORE should be tested in future research on coral reef/nutrient interactions. Synergistic and cumulative effects of elevated nutrients and other environmental parameters, comparative studies of intact vs. disturbed reefs, offshore vs. inshore reefs, or the ability of a nutrient-stressed reef to respond to natural disturbances require elucidation. An expanded understanding of coral reef responses to anthropogenic impacts is necessary, particularly regarding the subtle, sub-lethal effects detected in the ENCORE studies.     

Sorption of radioactive contaminants by sediment from the Kara Sea

The purpose of this study is to quantify some of the parameters needed to perform near-field modelling of sites in the Kara Sea that were impacted by the disposal of radioactive waste. The parameters of interest are: the distribution coefficients (Kd) for several important radionuclides, the mineralogy of the sediment, and the relationship of Kd to liquid-to-solid ratio. Sediment from the Kara Sea (location: 73 degrees 00'N, 58 degrees 00'E) was sampled from a depth of 287 m on August 23/24, 1992. Analysis of the material included mineralogy, grain size and total organic carbon (TOC). Uptake kinetics were determined for 85Sr, 137Cs, 241Am, 99Tc, 1251, 232U and 210Pb and distribution coefficients (Kd) were determined for these radionuclides using batch type experiments. Sorption isotherms, developed for 137Cs, 85Sr and 99Tc, were linear in each case. Increasing the liquid-to-solid ratio strongly increased uptake of 137Cs and moderately increased uptake of 99Tc. Analysis for anthropogenic radionuclides indicated the presence only of 239/240Pu in the sediment with the highest activity (at the top section of the core) being 0.420 Bq kg(-1). Other anthropogenic radionuclides were below detection limits.     

Spatial differences in persistent organochlorine pollutant concentrations between the Bering and Chukchi Seas (1993)

During August-September 1993, a joint Russian-United States expedition to the Bering and Chukchi Seas took place. Surface water samples were collected from 21 sites and separated into dissolved (duplicates) and suspended solids; 19 sediment and 6 air samples were also collected. These samples were analysed for 19 organochlorine pesticides, 11 chlorobenzenes and 113 PCB congeners. The report provides data on selected compounds which occured in > or = 75% of the water samples. Highest water concentrations were observed for HCH in open waters north and south of the Bering Strait, both regions being similar (alpha-HCH; 2.2 ng/L and lindane: 0.35 ng/L). Air levels observed were also constant (alpha-HCH; 0.041 ng/m3, lindane: 0.0093 ng/m3). Suspended solids and air particulares contributed little to the concentrations in their respective media, an observation common to all analytes except for the PCBs and the DDT residues. The sum of PCB concentrations in water were higher in the Bering Sea area compared to the Chukchi Sea (1.0 vrs 0.67 ng/L) and lower for air (0.46 vrs 0.23 ng/m3). Sum of DDT in water was higher in the Bering Sea than in the Chukchi Sea (0.23 vrs 0.15 ng/L) while in sediments and air, the Bering Sea concentrations were lower (0.95 vrs 1.6 ng/g and 36 vrs 56 pg/m3, respectively). Other organochlorine compounds for which data are presented include: pp'-DDE, pp'-DDT, dieldrin, HCB, 3 chlorobenzenes and 3 PCB congeners. Fluxes of all these chemicals through the Berin Strait are estimated; they ranged from 57 t/a (alpha-HCH) through 26 t/a (for sum of PCBs) to 0.2 t/a (pp'-DDE, dieldrin and 1,2,3-trichlorobenzene). Fugacity ratios for the HCHs and PCBs indicate the alpha-HCH is degassing in both the Bering and Chukchi Seas and that the gamma-isomer is degassing in the Bering Sea and is close to equilibrium (weakly absorbing) in the Chuchi Sea; the sum of PCBs are strongly absorbing in both areas.     

Can a pollution event be detected using a single biological effects monitoring method?

The trends of malformation prevalence in embryos of dab, Limanda limanda, in the southern North Sea after the year 1990 mirrored the drop in major pollutants in the rivers draining into the German Bight. Despite this general decline, we detected a pollution event in the southern North Sea in winter 1995/1996 employing the prevalence of malformations in pelagic dab embryos as an indicator. An abrupt rise in malformation prevalence in the embryos of dab, corresponded to a dramatic increase in DDT levels in parent fish from the same area, indicating a hitherto unnoticed introduction of considerable quantities of DDT into the system.     

Lysosomal membrane stability and metallothioneins in digestive gland of Mussels (Mytilus galloprovincialis Lam.) as biomarkers in a field study

The lysosomal membrane destabilization and the metallothionein content in the digestive gland cells of mussels (Mytilus galloprovincialis Lam.), collected along the east coast of the North Adriatic (Istrian and Kvarnerine coast, Croatia), were examined over a period of four years (1996–1999). The lysosomal membrane stability, as a biomarker of general stress, showed that the membrane labilization period in mussels from polluted, urban- and industrial-related areas was significantly decreased (p<0.05) when compared to mussels from control, clean sea water sites. In the harbour of Rijeka, the most contaminated site, the lysosomal membrane stability was reduced by more than 70% compared to the control. This method also proved to be a useful biomarker for detection of additional stress caused by short-term hypoxia that occurred once during this study inside the polluted and periodically quite eutrophic Pula Harbour. The concentration of metallothioneins in the mussel digestive gland, as a specific biomarker of exposure to heavy metals, did not reveal significant differences (p<0.05) between sites covered by this study.