铁质宇宙尘中的有机分子的发现

于1983年5－7月，利用向阳红16号考察船在太平洋7—11°N，167－178°W海域进行锰结核调查，从深海沉积物中分离出大量字苗尘（或称宇宙球粒）。此后对宇宙尘进行了全面研究，取得一定进展。最近，又利用激光拉曼分子探针测定了铁质宇宙尘中的分子组成。结果表明，铁质字宙尘中除了含有Fe－Fe，Fe3＋O，Fe－Ni，Al－O，Fe－Obr－Si和Si-Onb分子外，还含有较丰富的C－H－O和C－H－S－O有机分子，无定形碳C=C和C=C，CH2，CH3和挥发分子CO2，H2O，OH－，H2S，SO2等。这些成份与刍星尘埃的分子成分相一致。这一结果对于深入研究行星际尘埃微粒的起源以及探索生命物质的起源都具有重要意义。     

厦门西港表层沉积物的化学特征

本文根据1990年厦门西港重要站点的表层沉积物中的重金属(Fe、Mn、Cu、Pb、Zn、Cd、Hg)、有机污染物(总有机碳、石油、DDT、666)和磷(无机磷、有机磷和总磷)等测定资料,讨论了它们的地球化学性质及环境影响。结果表明,沉积物中Pb和Zn含量明显偏高,Pb、cu含量与1983年相比已有一定积累,也产生了有机污染现象。     

Biogeochemistry of surface sediments off Concepción (∼36°S), Chile: El Niño vs. non-El Niño conditions

We compared the signals of several water column properties (upwelling intensity, sea level anomaly, temperature, nutrients, dissolved oxygen, chlorophyll-a, and surface sediments) of the continental shelf off Concepción (36°S) during the 1997-1998 El Niño with those of a normal year (2002-2003). We found that the primary hydrographic effect of El Niño 1997-1998 was a reduction in the input of nutrient-rich, oxygen-poor Equatorial Subsurface Water over the shelf. This affected the biology of the water column, as evidenced by the reduced phytoplankton biomass. Surface sediment properties (biogenic opal, organic carbon, bulk δ¹⁵N) observed during El Niño 1997-1998 reflected a reduced export production and the sediments failed to show the water column seasonality that occurs under normal conditions. In addition, weakened denitrification and/or upper water column fertilization could be inferred from the sedimentary δ¹⁵N. Although diminished, export production was preserved in the surface sediments, revealing less degraded organic matter in the upwelling period of the El Niño year than in the normal year. We suggest that the fresher organic material on the seafloor was probably associated with a severe reduction in the polychaete Parapronospio pinnata, which is considered to be the most important metazoan remineralizer of organic carbon at the sediment-water interface in the study area.     

Estimating soil zinc concentrations using reflectance spectroscopy

Soil contamination by heavy metals has been an increasingly severe threat to nature environment and human health. Efficiently investigation of contamination status is essential to soil protection and remediation. Visible and near-infrared reflectance spectroscopy (VNIRS) has been regarded as an alternative for monitoring soil contamination by heavy metals. Generally, the entire VNIR spectral bands are employed to estimate heavy metal concentration, which lacks interpretability and requires much calculation. In this study, 74 soil samples were collected from Hunan Province, China and their reflectance spectra were used to estimate zinc (Zn) concentration in soil. Organic matter and clay minerals have strong adsorption for Zn in soil. Spectral bands associated with organic matter and clay minerals were used for estimation with genetic algorithm based partial least square regression (GA-PLSR). The entire VNIR spectral bands, the bands associated with organic matter and the bands associated with clay minerals were incorporated as comparisons. Root mean square error of prediction, residual prediction deviation, and coefficient of determination (R²) for the model developed using combined bands of organic matter and clay minerals were 329.65 mg kg⁻¹, 1.96 and 0.73, which is better than 341.88 mg kg⁻¹, 1.89 and 0.71 for the entire VNIR spectral bands, 492.65 mg kg⁻¹, 1.31 and 0.40 for the organic matter, and 430.26 mg kg⁻¹, 1.50 and 0.54 for the clay minerals. Additionally, in consideration of atmospheric water vapor absorption in field spectra measurement, combined bands of organic matter and absorption around 2200 nm were used for estimation and achieved high prediction accuracy with R² reached 0.640. The results indicate huge potential of soil reflectance spectroscopy in estimating Zn concentrations in soil.     

Developing a semi-analytical algorithm to estimate particulate organic carbon (POC) levels in inland eutrophic turbid water based on MERIS images: A case study of Lake Taihu

Particulate organic carbon (POC) plays an important role in the carbon cycle in water due to its biological pump process. In the open ocean, algorithms can accurately estimate the surface POC concentration. However, no suitable POC-estimation algorithm based on MERIS bands is available for inland turbid eutrophic water. A total of 228 field samples were collected from Lake Taihu in different seasons between 2013 and 2015. At each site, the optical parameters and water quality were analyzed. Using in situ data, it was found that POC-estimation algorithms developed for the open ocean and coastal waters using remote sensing reflectance were not suitable for inland turbid eutrophic water. The organic suspended matter (OSM) concentration was found to be the best indicator of the POC concentration, and POC has an exponential relationship with the OSM concentration. Through an analysis of the POC concentration and optical parameters, it was found that the absorption peak of total suspended matter (TSM) at 665 nm was the optimum parameter to estimate POC. As a result, MERIS band 7, MERIS band 10 and MERIS band 12 were used to derive the absorption coefficient of TSM at 665 nm, and then, a semi-analytical algorithm was used to estimate the POC concentration for inland turbid eutrophic water. An accuracy assessment showed that the developed semi-analytical algorithm could be successfully applied with a MAPE of 31.82% and RMSE of 2.68 mg/L. The developed algorithm was successfully applied to a MERIS image, and two full-resolution MERIS images, acquired on August 13, 2010, and December 7, 2010, were used to map the POC spatial distribution in Lake Taihu in summer and winter.     

环渤海地区水污染物排放的时空格局及其驱动因素

本文基于地级行政单元的水污染物排放和社会经济截面数据,分析环渤海地区水污染物排放的流域特征与时空分异,定量解析环渤海地区及高强度排放聚集区内水污染物排放的驱动因素。研究结果表明：①海河流域是环渤海地区纳污量最大、增量最突出的流域,其化学需氧量和氨氮排放分别占区域排放总量的38.94%、39.23%。②2005年以来,环渤海地区水污染物高排放区从零星分布向连片分布转变,京津冀、山东半岛、辽中南已成为水污染物高排放区的叠加区域。③环渤海地区水污染物排放具有显著空间溢出效应,且空间关联程度呈增大趋势,水污染排放热度呈沿海向内陆递减态势,海河流域热度显著高于其他流域,沿海合作区显著高于内陆协作区;京津冀长期处于热点区和次热区,热区覆盖范围由海河向淮河流域拓展。④不同水污染物排放的驱动因素差异显著,对化学需氧量排放而言,经济增长速度、固定资产投资因素呈较强的正向带动,而城镇化水平和工业化程度表现出显著负向影响;对氨氮排放来说,人口规模呈正向带动,固定资产投资和外商直接投资亦有一定正向影响,经济发展水平则呈现显著的抑制作用。     

Surface associations of enzymes and of organic matter: Consequences for hydrolytic activity and organic matter remineralization in marine systems

The extent to which marine organic matter is associated with surfaces and the consequences of such associations for organic matter remineralization are the focus of considerable attention. Since extracellular enzymes operating outside microbial cells are required to hydrolyze organic macromolecules to sizes sufficiently small for substrate uptake, the effects of surface interactions–on enzymes as well as on substrates–for hydrolytic activity also require investigation. We used a simplified laboratory system consisting of a free (dissolved) polysaccharide (pullulan) and the same polysaccharide tethered to agarose beads to restrict mobility, plus the corresponding free enzyme (pullulanase) and the same enzyme sorbed to montmorillonite (Mte), to investigate systematically the consequences of surface associations of enzymes and of substrates on hydrolytic activity. Changes in substrate molecular weight were monitored with time to measure the course of enzymatic hydrolysis. Although hydrolysis of free substrate was nearly complete after 2 min incubation with the free enzymes, the sorbed enzymes also effectively hydrolyzed free substrate, and the data suggest that they retained activity longer in solution compared to the free enzymes. Sorbed enzymes progressively hydrolyzed the free substrate from > 50 kD to lower molecular weights during a 24 h incubation, with a final product distribution on average showing only 1.4% and 10.3% of substrate still in the > 50 kD and 10 kD size classes, while 46.6%, 29.3%, and 12.5% of substrate was in the 4 kD, monomer, and free tag size classes, respectively. This product distribution was very similar to that of the free substrate/free enzyme experiment. Tethering the substrate to agarose beads led to lower substrate release (2–3% of total substrate after 98 h incubation) into solution compared to the free substrate case. For tethered substrates, the state of the enzyme (free or sorbed) measurably affected the molecular weight distribution of the hydrolysis products, with free enzymes producing a higher fraction of high molecular weight hydrolysis products (28.7 ± 5.4% of substrate > 50 kD at the end of the incubation) compared to sorbed enzymes (11.6 ± 2.8% of substrate > 50 kD at the end of the incubation.) Tethered substrates were also hydrolyzed in a sediment slurry from surface sediments from Cape Lookout Bight, North Carolina; 0.1% of total substrate was released by enzymes naturally present in 1 cm³ of sediment after 144 h incubation, demonstrating that the enzymes naturally present in marine sediments are also capable of accessing tethered substrates. These investigations suggest that surface associations of enzymes in marine systems may extend the active lifetime of such enzymes, providing an opportunity for hydrolysis over longer periods of time and producing a different size spectrum of hydrolysis products relative to free enzymes. Furthermore, in well-mixed systems, surface-associated enzymes can hydrolyze substrates whose mobility is restricted, highlighting the importance of processes such as resuspension and bioturbation on organic matter remineralization.     

Marine vs. terrigenous organic matter in Louisiana coastal sediments: The uses of bromine:organic carbon ratios

Recent data on the sources of organic carbon buried in the ocean have emphasized the probable importance of terrigenous organic matter in burial budgets of deltaic depocenters. The many markers used to assess relative importance of marine vs. terrestrial sources each have ambiguities. We use the ratio of bromine to organic carbon (Br:OC) as a source indicator for organic matter in the Mississippi delta. Progressive increases in bromine concentrations from the river to the slope indicate increasing content of marine-derived organic matter. Quantitative estimates of marine vs. terrigenous organic matter using Br:OC ratios in a two-endmember mixing model are consistent with recent estimates using a combination of three other source markers [Gordon, E.S., Goñi, M.A. 2003. Sources and distribution of terrigenous organic matter delivered by the Atchafalaya River to sediments in the northern Gulf of Mexico. Geochim. Cosmochim. Acta, 67:2359–2375]. The Br:OC vs. δ¹³C relationship indicates seaward increase in δ¹³C without proportionate incorporation of marine organic matter, consistent with recent arguments that isotopically depleted terrestrial detritus derived from C3 plants is separated from C4-derived terrigenous organic matter during transport. Decreasing Br:OC ratios downcore at many sites that have significant amounts of marine organic matter indicate that the marine organic matter is preferentially lost during burial diagenesis. This preferential loss constrains the contribution of organic matter burial in deltaic environments to global removal of Br.     

八所近岸海域排污口选址及水质预测

在所建潮流场的基础上,建立了八所近岸海域拉格朗日余流模型及乎流——扩散输运模型。预测八所污水集中排海对海域水质的影响,选COD为有机物污染的指标因子,经多方案比较,提出推荐位置及相应位置下的最大允许排放量。     

中国环境污染的时空差异与集聚特征

通过地市单元和主体功能区单元的定量分析,研究2005~2012年中国环境污染物排放的时空变化和空间集聚格局,提出降低污染物排放强度的对策建议。结果表明：① 环境污染物排放强度呈优化开发区域-重点开发区域-农产品主产区-重点生态功能区依次递减态势,各类主体功能区水环境面临的污染物胁迫程度持续加剧,且以农产品主产区和重点生态功能区最为突出,尽管优化开发区域和重点开发区域的大气污染物排放量呈现小幅下降,但仍然是大气污染物胁迫程度最高的地区。② 地市单元水环境受污染物胁迫态势“总体在加剧、局部有缓解”,东北、东部、中部板块的大部分区域以及西部板块的成渝、新疆中部、呼包鄂等地区呈高排放区连片分布格局;大气环境受污染物胁迫态势“总体较稳定、局部有缓解”,高排放区主要位于山西、内蒙古中西部、陕甘宁豫沿黄地带、环渤海、长三角等地区。③ 中国环境污染排放具有显著的空间集聚效应且呈现增强趋势,其中,华北地区已经成为高污染物排放的主要集聚区,并表现出较强的路径依赖与空间锁定。