Ecological environment changes in Daya Bay, China, from 1982 to 2004

Data collected from 12 marine monitoring stations in Daya Bay from 1982 to 2004 reveal a substantial change in the ecological environment of this region. The average N/P ratio increased from 1.377 in 1985 to 49.09 in 2004. Algal species changed from 159 species of 46 genera in 1982 to 126 species of 44 genera in 2004. Major zooplankton species went from 46 species in 1983 to 36 species in 2004. The annual mean biomass of benthic animals was recorded at 123.10 gm(2) in 1982 and 126.68 g m(2) in 2004. Mean biomass and species of benthic animals near nuclear power plants ranged froth 317.9 g m(2) in 1991 to 45.24 g m(2) in 2004 and from 250 species in 1991 to 177 species in 2004. A total of 12-19 species of hermatypic corals and 13 species of mangrove plants were observed in Daya Bay from 1984 to 2002. 2008 Elsevier Ltd. All rights reserved.

Main geochemical characteristics and key biogeochemical carbon processes in the East China Sea

Research related to carbon geochemistry and biogeochemistry in the East China Sea is reviewed in this paper. The East China Sea is an annual net sink for atmospheric CO, and a large net source of dissolved inorganic carbon to the ocean. The sea absorbs CO, from the atmosphere in spring and summer and releases it in autumn and winter. The East China Sea is a CO, sink in summer because Changjiang River freshwater flows into it. The net average sea-air interface carbon flux of the East China Sea is estimated to be about 4.3 X 10(6) t/y. Vertical carbon transport is mainly in the form of particulate organic carbon in spring; more than 98% of total carbon is transported in this form in surface water, and the number exceeds 68% in water near the bottom. In the southern East China Sea, the average particulate organic carbon inventory was about one-tenth that of the dissolved organic carbon. Research indicates that the southern Okinawa Trough is an important site for particulate organic carbon export from the shelf. The annual cross-shelf exports are estimated to be 414 and 106 Gmol/y for dissolved organic carbon and particulate organic carbon, respectively. Near-bottom transport could be the key process for shelf-to-deep sea export of biogenic and lithogenic particles.

Inorganic carbon of sediments in the Yangtze River Estuary and Jiaozhou Bay

JGOFS results showed that the ocean is a major sink for the increasing atmospheric carbon dioxide resulting from human activity. However, the role of the coastal seas in the global carbon cycling is poorly understood. In the present work, the inorganic carbon (IC) in the Yangtze River Estuary and Jiaozhou Bay are studied as examples of offshore sediments. Sequential extraction was used to divide inorganic carbon in the sediments into five forms, NaCl form, NH3 H2O form, NaOH form, NH2OH HCl form and HCl form. Studied of their content and influencing factors were also showed that NaCl form < NH3 H2O form < NaOH form < NH2OH HCl form < HCl form, and that their influencing factors of pH, Eh, Es, water content, organic carbon, organic nitrogen, inorganic nitrogen, organic phosphorus and inorganic phosphorus on inorganic carbon can be divided into two groups, and that every factor has different influence on different form or on the same form in different environment. Different IC form may transform into each other in the early diagenetic process of sediment, but NaCl form, NH3 H2O form, NaOH form and NH2OH HCl form may convert to HCl form ultimately. So every IC form has different contribution to carbon cycling. This study showed that the contribution of various form of IC to the carbon cycle is in the order of NaOH form > NH2OH HCl form > NH3 H2O form > NaCl form > HCl form, and that the contribution of HCl form contributes little to carbon cycling, HCl form may be one of end-result of atmospheric CO2. So Yangtze River estuary sediment may absorb at least about 40.96x10(11) g atmospheric CO2 every year, which indicated that offshore sediment play an important role in absorbing atmospheric CO2.

Nitrogen deposition and carbon sequestration in alpine meadows

Nitrogen deposition experiments were carried out in alpine meadow ecosystems in Qinghai-Xizang Plateau in China, in order to explore the contribution of nitrogen deposition to carbon sequestration in alpine meadows. Two methods were used in this respect. First, we used the allocation of N-15 tracer to soil and plant pools. Second, we used increased root biomass observed in the nitrogen-amended plots. Calculating enhanced carbon storage, we considered the net soil CO2 emissions exposed to nitrogen deposition in alpine meadows. Our results show that nitrogen deposition can enhance the net soil CO2 emissions, and thus offset part of carbon uptake by vegetation and soils. It means that we have to be cautious to draw a conclusion when we estimate the contribution of nitrogen deposition to carbon sequestration based on the partitioning of N-15 tracer in terrestrial ecosystems, in particular in N-limited ecosystems. Even if we assess the contribution of nitrogen deposition to carbon sequestration based on increased biomass exposed to nitrogen deposition in terrestrial ecosystems, likewise, we have to consider the effects of nitrogen deposition on the soil CO2 emissions.

Burrowing rodents as ecosystem engineers: the ecology and management of plateau zokors Myospalax fontanierii in alpine meadow ecosystems on the Tibetan Plateau

1. Plateau zokors, Myospalax fontanierii, are the only subterranean herbivores on the Tibetan plateau of China. Although the population biology of plateau zokors has been studied for many years, the interactions between zokors and plants, especially for the maintenance and structure of ecological communities, have been poorly recognized. In the past, plateau zokors have been traditionally viewed as pests, competitors with cattle, and agents of soil erosion, thus eradication programmes have been carried out by local governments and farmers. Zokors are also widely and heavily exploited for their use in traditional Chinese medicine.2. Like other fossorial animals, such as pocket gophers Geomys spp. and prairie dogs Cynomys spp. in similar ecosystems, zokors may act to increase local environmental heterogeneity at the landscape level, aid in the formation, aeration and mixing of soil, and enhance infiltration of water into the soil thus curtailing erosion. The changes that zokors cause in the physical environment, vegetation and soil clearly affect the herbivore food web. Equally, plateau zokors also provide a significant food source for many avian and mammalian predators on the plateau. Zokor control leading to depletion of prey and secondary poisoning may therefore present problems for populations of numerous other animals.3. We highlight the important role plateau zokors play in the Tibetan plateau ecosystem. Plateau zokors should be managed in concert with other comprehensive rangeland treatments to ensure the ecological equilibrium and preservation of native biodiversity, as well as the long-term sustainable use of pastureland by domestic livestock.

微生物——铊相互作用的生物地球化学研究——以真菌（Fungus）为例

铊是一种有毒有害的重金属元素，已经引起了广泛的关注。本论文通过对黔西南铊矿区土壤和沉积物样品的菌株分离、铊高耐受性菌株的筛选、胞外吸附、富集、亚细胞水平区系分布、絮凝实验及ITS序列等实验研究分析，并结合铊的地球化学相关研究，较系统地阐述了真菌--铊的生物地球化学过程机理，得出以下结论： 1、与环境背景区相比，黔西南滥木厂铊矿区内的河流、土壤中铊的已有不同程度的积累，直接导致了当地微生物生物量在很大程度上的降低，微生物生物量与铊含量间有显著的负相关关系。研究区内的沉积物、土壤中的微生物区系结构和数量发生了明显变化，细菌、真菌及放线菌数量均出现显著降低，而且三大微生物对重金属污染的敏感性大小也不一样，即放线菌>细菌>真菌。从土壤样品中分离到的主要菌群仍为常见种属，如青霉属（Penicillium）、木霉属（Trichoderma）、拟青霉（Paecilomyces）等。 2、经过初筛菌株的铊耐受性实验，在1000 mg/L水平筛选得到九株高耐受性菌株。吸附实验表明：微生物菌株对铊的吸附效率在4.63～16.89%，且随着环境中铊浓度的上升而降低，这可能是因为铊浓度的升高加大了对微生物生长的抑制作用，所形成的菌丝体（或菌丝球）减少，表面积也相应减少，从而导致了吸附效率的下降。各种常量元素和铊的关系呈显著相关性，钙、钾和钠等常量元素也是微生物赖以维持生存的因子，可能由于微生物细胞对钙、钾的吸附方式与对铊的吸附方式类似。因此，随着铊处理浓度的上升，钙和钾的吸附量也随之减少，而钠则呈现相反的趋势。 3、富集实验表明，九株菌株对铊的富集量随着铊处理浓度上升而降低，其影响趋势与对生物量的影响趋势基本一致，最高可达到7189 mg/kg，最大富集系数为7.2。九株菌株对常量元素的富集与对铊的富集并无明显的相关性，但在考察铊处理浓度对常量元素的富集影响时发现，铊处理浓度的上升与对钙的富集量表现出较强的正相关；而对钾、钠、镁的富集影响并不明显。 4、亚细胞水平上的铊分布研究表明，铊的富集优先顺序为：细胞质>细胞壁>细胞器。亚细胞水平的区隔化作用是微生物对铊的主要耐受机制，细胞质是赋存铊的主要场所（53.83～79.45 %）。结合各亚细胞组分中常量元素与铊之间的相关性，并联系前人的研究，Tl+主要是通过细胞壁的Na+ -K+ ATPase和K+ -电位门通道进入细胞内的从而影响细胞的正常代谢的，而Ca2+的活化更有助于这一过程。 5、絮凝实验表明，培养三天后的发酵液对矿区废水中铊的去除率最高可达到70.49 %，最佳影响因子组合为：pH=8，温度为16℃，搅拌时间为4分钟。菌株的絮凝活性最高可达到57.32%，最佳影响因子组合为：pH=8，温度为14℃，搅拌时间为4分钟。 6、通过对九株铊高耐受性菌株的ITS序列分析及其在Gene Bank中的BLAST比对结果表明，五株菌株同属于木霉属（Trichoderma），两株菌株同属于青霉属（Penicillium）。这表明这两类真菌对铊的适应性较强，为以后寻找铊高耐受性菌株及其资源化利用提供了理论基础。