Analysis of chlorophyll diagenesis—II. Solvent effects on metal incorporation into chlorophyll diagenetic products

We are attempting to quantify selected transitions in the diagenetic pathway of chlorophyll in deep ocean sediments. To analyze the aromatization from phorbides (less stable) to porphyrins (more stable), we used a model system which closely resembles the compounds identified in oceanic sediments. Kinetic parameters were determined for the incorporation of copper into deoxomesopyropheophorbide a methyl ester (DOMPP) and deoxophylloerythrin methyl ester (DPE) in a series of solvents ranging from highly polar and protic to non-polar and aprotic, representing varying sedimentary environments. In the reaction of copper with these two compounds, the activation parameters for the reaction with DOMPP indicate that DOMPP is more sensitive to the environment than DPE. Also, over the temperature range studied, DOMPP always reacted faster than DPE under similar conditions. These two observations lend support to our previous hypothesis that the phorbide to porphyrin transition includes the metallophorbide as a short-lived intermediate in the reaction sequence.     

A case study of the abuse of science in sewage planning

A regional sewage system is under construction bordering southern Monterey Bay, California. It is replacing small treatment plants at Monterey, Seaside, Ford Ord, Marina and Salinas. The existing plants are mostly secondary, discharge no industrial wastes, and except for Salinas all discharge into the open ocean. The regional-system is the result of a zone of prohibition of waste discharge that was established in 1971. Justification for the zone was created by the Regional and State Water Boards several years after the zone was established. Our investigation of the evidence used to support the zone indicated that the water boards were clearly in error. The zone has been appealed through the Regional and State Boards and the courts. Over $100 000 000 (US) has already been spent on construction.     

Accretion and canal impacts in a rapidly subsiding wetland II. Feldspar marker horizon technique

Recent (6–12 month) marsh sediment accretion and accumulation rates were measured with feldspar marker horizons in the vicinity of natural waterways and man-made canals with spoil banks in the rapidly subsiding environment of coastal Louisiana. Annual accretion rates in aSpartina alterniflora salt marsh in the Mississippi deltaic plain averaged 6 mm in marsh adjacent to canals compared to 10 mm in marsh adjacent to natural waterways. The rates, however, were not statistically significantly different. The average rate of sediment accretion in the same salt marsh region for a transect perpendicular to a canal (13 mm yr^?1) was significantly greater than the rate measured for a transect perpendicular to a natural waterway (7 mm yr^?1). Measurements of soil bulk density and organic matter content from the two transects were also different. This spatial variability in accretion rates is probably related to (1) spoil bank influences on local hydrology; and (2) a locally high rate of sediment input from lateral erosion associated with pond enlargement. In a brackishSpartina patens marsh on Louisiana’s Chenier plain, vertical accretion rates were the same along natural and canal waterways (3–4 mm yr^?1) in a hydrologically restricted marsh region. However, the accretion rates for both waterways were significantly lower than the rates along a nonhydrologically restricted natural waterway nearby (11 mm yr^?1). The vertical accretion of matter displayed semi-annual differences in the brackish marsh environment.     

Old cannery wastes,a potential source of trace metals in the marine environment

High levels of lead and zinc have been measured in the California Mussel Mytilus californianus taken from southern Monterey Bay as part of the California State Mussel Watch programme. The levels of lead and zinc increase steadily from Cypress Point towards Cannery Row. The California State Water Resources Control Board (which funded but did not conduct the State Mussel Watch) has attributed the high levels to heavy metals contributed by sewage. The state mussel watch data reports have not considered the historic canning wastes from more than 30 canneries along Cannery Row as a possible source of trace metals. Leachates from old cannery wastes may be a major source of lead and zinc in mussels in southern Monterey Bay and must be considered in assessing any data from the State Mussel Watch programme.     

Analysis of chlorophyll diagenesis—I. Kinetics of the phorbide to porphyrin transition

The objective of this project is to quantify selected transitions in the diagenetic pathways of chlorophyll in deep ocean sediments, initially the aromatization from phorbides (unstable) to porphyrins (stable), using a model system which closely resembles the compounds identified in oceanic sediments. We determined the kinetic parameters for the aromatization of deoxomesopyropheophorbide a methyl ester (DOMPP) to deoxophylloerythrin methyl ester (DPE) in the presence of Cu(II) in a series of solvents ranging from highly polar and protic to nonpolar and aprotic, representing varying sedimentary environments. With Cu(II) in ethanol, the aromatization occurs through a pathway which involves a relatively slow initial formation of CuDOMPP, rapid aromatization to CuDPE, and finally an equilibrium reaction in the presence of clay which induces demetalation to form the free base DPE. Based on our model studies, only DOMPP, CuDPE and some DPE would be detected in significant quantities in more polar, protic sedimentary environments on a geologic time scale, although the story might be different with changed environment polarity. Our model studies may ultimately reconcile laboratory observations with those based on DSDP cores which appear to indicate that the diagenetic sequence proceeds from phorbide to free base porphyrin, followed by metalation of the porphyrin.     

Hazard area and probability of volcanic disruption of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, USA

Models that calculate the probability that a new volcano or a dike from a nearby eruption will intersect the footprint of the proposed high-level nuclear waste repository are generalized based on a conceptual model developed for the space transportation industry. The proposed hazard area, defined such that every new eruption that occurs there will disrupt the repository, plays a fundamental role in developing probability models. This hazard area is used not only to hedge the uncertainties in predicting patterns of future volcanic activity, but also to account for the characteristics of a new eruption during the post-closure performance period of an underground geologic repository. The paper discusses the advantages of probability comparisons, capabilities of conservativeness measurements and expert-elicitation on model parameters, and the implications to the proposed repository.Paper funded by a contract from the Agency for Nuclear Projects, State of Nevada, USA.     

堪察加地区现今地壳运动与变形特征研究

利用俄罗斯堪察加地区1995～2005年的GPS观测数据,研究了该区现今地壳水平运动速度场特征.在球坐标系中解算了各应变率分量,分析了应变率场的空间分布特征,并与地震学和地质学研究结果进行了综合对比分析.结果表明,堪察加半岛北部的微板块边界并不明显,堪察加南部测站运动速度大于中部和北部地区,愈靠近东部板块汇聚区,测站速度越大.从东海岸到西海岸,测站水平速度存在明显的梯度衰减特征,水平运动方向与太平洋板块向西北的俯冲方向基本一致.各应变率分量具有东部海岸大于中部和西海岸、从东至西呈梯度衰减的特点.堪察加大部分地区处于EW和NS向压缩状态,局部存在拉张.面应变率结果显示绝大部分为压缩区;刚性转动结果表明大部分地区表现为顺时针转动,北部地区和南端顺时针旋转性明显.东部有效应变率明显大于西部地区,东西向梯度衰减关系明显.主压应变率明显大于主张应变率,特别是在东海岸地区.主压应变率方向与中等以上地震的主压应力轴在水平方向的投影方向基本一致.地壳变形场在空间分布上的不一致性主要与太平洋板块在堪察加半岛东南侧的俯冲深度、俯冲方位角、俯冲倾角和俯冲带的耦合强度有关.     

Sulfate Land Application Enhances Biodegradation in a Petroleum Hydrocarbon Smear Zone

Delivery of sulfate to petroleum hydrocarbons (PHCs) source zones and groundwater plumes is desirable to enhance biodegradation rates when treatment has become limited due to depletion of sulfate. Sulfate land application involves spreading sulfate salts on ground surface and allowing their dissolution and infiltration of sulfate into subsurface. The objectives of this pilot-scale investigation were to capture the vertical transport of sulfate beneath an application area, confirm that sulfate reduction was occurring, and explore how the added sulfate affected biodegradation of benzene and toluene. Approximately 4000 kg of gypsum was spread over a 30 m × 30 m study area above a smear zone located approximately 2 m below-ground surface. Precipitation was augmented by two irrigation events. Groundwater samples, collected over 1058 days from multilevel wells and a conventional long-screened monitoring well, were analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX), sulfate, bromide, dissolved inorganic carbon (DIC) and methane. Compound-specific isotope analyses (CSIA) for benzene and toluene, and isotope analyses of ¹³C-DIC and ³⁴S-SO₄²⁻ were performed. Following application, an increase in sulfate concentration was noted in the smear zone. ³⁴S-SO₄²⁻ enrichment and ¹³C-DIC depletion indicated that sulfate reduction and mineralization of PHCs were enhanced. CSIA results provided unequivocal evidence of anaerobic biodegradation of benzene and toluene. After 1058 days when sulfate was depleted, methane concentrations were about three times greater than baseline conditions suggesting syntrophic benefit of the delivered sulfate. Observations from this investigation support the viability of sulfate land application to enhance biodegradation rates in shallow PHC smear zones.     

受压水生物群落生态系统目标函数的变化

The changes of biomass, exergy and structural exergy under the action of various chemical pollution (addition of nutrient compounds, pesticides, chlorinated phenols, oil, heavy metal ions, acidification etc.) are analysed for 50 experimental works with model aquatic ecosystems -microcosms, mesocosms and experimental ponds.Structural exergy is shown to remain at constant level or to increase when the allochtonous compounds can be metabolised by ecosystem, or when the ecosystem can adapt itself to the input of toxicant by structural changes. When the substance is too conservative, too toxic or/and is coming in too high concentrations, structural exergy is decreasing, demonstrating the inability of ecosystem to adapt to this influence and irreversibility of changes in ecosystem.The possibility to use such parameter as structural exergy for estimation of ecosystem state and its changes under various external influences is demonstrated. It reflects the state of ecosystem and can indicate the degree of ecosystem adaptation, decreasing when important for ecosystem functioning components are eliminated.In experiments with mathematical model of lake Baikal ecosystem exergy content is shown to increase after addition of nutrients and to decrease after addition of phenolic compounds, reflecting the general shifts in ecosystem.