Benthic nitrate biogeochemistry affected by tidal modulation of Submarine Groundwater Discharge (SGD) through a sandy beach face, Ria Formosa, Southwestern Iberia

To investigate both the role of tides on the timing and magnitude of Submarine Groundwater Discharge (SGD), and the effect on benthic nitrogen biogeochemistry of nitrate-enriched brackish water percolating upwards at the seepage face, we conducted a study of SGD rates measured simultaneously with seepage meters and mini-piezometers, combined with sets (n = 39) of high resolution in-situ porewater profiles describing NH₄⁺, NO₃⁻, Si(OH)₄ and salinity distribution with depth (0–20 cm). Sampling took place during two consecutive spring tidal cycles in four different months (November 2005, March, April and August 2006) at a backbarrier beach face in the Ria Formosa lagoon, southern Portugal. Our results show that the tide is one of the major agents controlling the timing and magnitude of SGD into the Ria Formosa. Intermittent pumping of brackish, nitrate-bearing water at the beach face through surface sediments changed both the magnitudes and depth distributions of porewater NH₄⁺ and NO₃⁻ concentrations. The most significant changes in nitrate and ammonium concentrations were observed in near-surface sediment horizons coinciding with increased fraction of N in benthic organic matter, as shown by the organic C:N ratio. On the basis of mass balance calculations executed on available benthic profiles, providing ratios of net Ammonium Production Rate (APR) to Nitrate Reduction Rate (NRR), coupled to stoichiometric calculations based on the composition of organic matter, potential pathways of nitrogen transformation were speculated upon. Although the seepage face occasionally contributes to reduce the groundwater-borne DIN loading of the lagoon, mass balance analysis suggests that a relatively high proportion of the SGD-borne nitrogen flowing into the lagoon may be enhanced by nitrification at the shallow (1–3 cm) subsurface and modulated by dissimilatory nitrate reduction to ammonium (DNRA).     

闽江口入海悬沙输运的数值模拟

闽江河口位于福建省东部,本文利用欧拉-拉格朗日差分方法模拟闽江口及附近海域在不同径流下的潮流场,并建立拉格朗日水质点跟踪方法近似模拟了悬沙在海域中的迁移过程．水质点运动轨迹计算结果表明,闽江口悬沙在外海主要向南方或东南方输运,其轨迹呈现螺旋线．在洪峰流量下,悬沙运移距离较远．     

涠洲岛潮滩表层沉积物中重金属的空间分布及其环境质量评价

根据2006年4月对涠洲岛潮滩表层沉积物的调查资料,分析了表层沉积物中重金属元素Hg、Cu、Pb、Zn、Cd、Cr、As的含量水平及空间分布特征,运用单因子评价法对其环境质量进行了评估,并通过相关性分析、因子分析探讨了几种重金属元素的物源.结果表明:涠洲岛潮滩环境质量状况良好,各元素均未达到污染水平,多数地区存在Cu的玷污,个别地区存在As的玷污;各分析元素较多的累积在人为活动相对频繁的XKZ、W05断面附近区域;Hg、Cu、Zn、Cr显著正相关,以环境背景来源为主,Pb、As较多的受到人为因素的影响.     

地层测试评价仪在渤海油田的应用

电缆地层测试是求取储层流体性质、进行储层评价最为直接的方法之一。地层测试评价仪（FET）是国产新一代地层测试评价仪器,不仅可以精确测量地层压力并根据压力剖面确定地层流体类型和油气水界面,而且在目的层取样时可以抽排污染流体、实时检测地层流体特性,对确定地层流体性质和分析流体成分起到了重要作用,同时它也可以计算地层渗透率,进行储层产能预测。通过在渤海油田的成功应用,简单介绍FET的基本工作原理和主要用途,重点论述其优越性和局限性,以及在渤海油田成功应用的典型实例,这对FET在其它油田的推广应用具有参考意义。     

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发射光谱法测定化探样品中的Cu、Pb、Zn、Co、Ag、Sn、Mo和B

以Al2O3、K2S2O7、NaF、C作为缓冲剂与样品混匀,装入石墨电极中,以平头石墨电极为上电极,样品电极为下电极进行摄谱,由光电译谱仪测定谱线的黑度值,以锗为内标用内标法测定样品中Cu、Pb、Zn、Co、Ag、Sn、Mo和B的质量分数。     

回归直线的拟合度

采用模糊数学的方法研究回归直线与实测点的拟合度,提出回归直线的似合度,给出计算回归直线拟合度的方法。     

基于栅格叠合的沉积物底质图生成方法

文章提出了一种基于GIS空间插值和栅格图叠合技术,分析生成沉积物底质图的方法,并以曹妃甸海区为例,以170个海底表层沉积物样的粒度分析结果为依据,应用本文设计的方法生成这一海区的底质分布图,并用预留的20个采样点进行了精度分析和检验,在此基础上比较了不同的空间插值方法对生成的底质图结果的影响.结果显示出这一方法成图速度快、自动化程度高,但也存在对原始数据精度要求高、插值方法带来误差等问题.在借鉴传统底质图生成方法的基础上,运用三维TIN模型对成图结果进行改进,最终形成一种结合地貌要素的栅格叠合的沉积物底质图生成方法.     

不同类型沉积物磁化率的比较研究和初步解释

沉积物的磁化率分析以被广泛应用在第四纪古气候研究中,不同类型沉积物磁化率的解释可能存在明显的差异.本文选择了黄土、冲积物、湖积物、风沙堆积和南方红土等五种不同类型的沉积物,进行了磁化率的测试,粒度和孢粉分析,试图通过对沉积物磁化率和相关古环境指标的研究,对不同类型沉积物的磁化率予以对比并进行初步解释.研究结果表明,黄土和湖泊沉积中磁化率的变化主要受气候变化的影响,是指示古气候的重要指标;河流沉积物和风沙沉积物的磁化率主要受粒度的影响;影响南方红土磁化率的因素十分复杂,其磁化率的解释比较困难有待进一步的研究.这一研究表明,鉴于不同沉积物磁化率的影响因素存在明显的不同,因此在运用磁化率进行古环境解释时须持慎重态度.     

Distribution and possible sources of organochlorine residues in sediments of a large urban estuary,Port Jackson,Sydney

Sydney Harbour is surrounded by a large capital city of about four million people and its highly urbanised (86%) catchment supports a substantial industrial base and an extensive transport infrastructure. Large commercial and naval ports occupy the waterway and the harbour is an important recreational area. Surficial sediment in Sydney Harbour contains high concentrations of PCBs, HCB, total chlordane, total DDT, aldrin, dieldrin, heptachlor and heptachlor‐epoxide, but low concentrations of lindane. PCBs, total chlordane, and to a lesser extent dieldrin, are most elevated in sediment in creeks on the southern shores of the harbour suggesting sources within older, highly urbanised/industrialised catchments of western‐central Sydney. There are high concentrations of total DDT and HCB in sediments of the upper harbour and Homebush Bay suggesting that chemical industries on the shores of the estuary in this area are sources of these contaminants. Although no sediment quality guidelines apply in Australia, empirically derived biological effects criteria suggest that sediment over extensive areas of Sydney Harbour may have an adverse impact on biota. Especially of concern are sediments containing high concentrations of chlordane and DDT.