Question

急求，专业英语翻译 不要软件翻译的！

Materials and methods
The study was carried out in Las Flores - a third-order plain stream of the LujAn River watershed, located in the NE of Buenos Aires Province. The main limnological features of 20 streams belonging to this watershed, including the one studied, are summarized in Table 1. All are characterized by high nutrient concentrations. Las Flores Stream has no point source inputs, but its watershed is located in an intensive livestock and agricultural area. Samples were taken monthly, from August 1993 to April 1995, in a macrophyte stand which was at least 8 years old. E. densa is a 'characteristic species' of the stand sensu Braun-Blanquet (Matteucci & Colma, 1982). Lemna gibba L., Ceratophyllum demersum L., Hydrocotyle ranunculoides L., and Rorippa nasturtium-aquaticum L. were also present. The number of macrophyte samples was five (Student's t-test, on normalized data of E. densa biomass in Las Flores Stream, using the TRANSNOR program). Samples were taken with a 400 cm2 square frame. All macrophyte species within a quadrat were harvested completely. Quadrats were distributed randomly within the E. densa stand. Herbivores (snails of the genus Ampullaria), were also sampled and their presence recorded. Plant material was examined to evaluate any damage produced by herbivory. At each sampling site we measured: depth, current velocity (with a propeller flowmeter), conductivity, pH, and temperature (with Luftman instruments). At three sample sites, a 5 cm diameter sediment core was taken with a PVC cylinder to determine nutrient content. The coring tube was pushed down to the tuff layer that forms the substratum of the stream. Triplicate water samples were taken above the macrophyte stand to determine dissolved oxygen and nutrient concentrations. Oxygen samples were fixed immediately. Nutrient samples were filtered through Whatman GF/C membranes (0.6-0.7 m pore size). Samples were transported to the laboratory within an hour. The macrophytic material was washed, sorted to species, and dried at 105 C to constant weight to determine biomass (Wetzel & Likens, 1991). Total phosphorus (TP) (AOAC, 1984), and total nitrogen (TN) (semi-micro-Kjeldahl method; AOAC, 1984; FAO, 1986) in E. densa were determined in triplicate. Apical shoots of E. densa were brushed and rinsed with filtered stream water to remove periphyton. Apical shoots were dried at 105 C until constant weight, and weighed. Periphyton samples were vacuum-filtered through Whatman GF/C membranes. Chlorophyll-a was estimated according to Lorenzen (see Wetzel & Likens, 1991). Sediment cores were frozen at -20 °C, the upper 3 cm cut, and TP (Andersen, 1976) and TN (AOAC, 1984; FAO, 1986) determined for each core in triplicate. Water was analyzed within 24 hours of sampling. Dissolved oxygen concentration was estimated by the Winkler method (APHA, 1992). Soluble reactive phosphorus (SRP), nitrate and nitrite were determined according to APHA (1992).
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Answer 1

材料与方法
这项研究进行了拉斯弗洛雷斯-三阶平原河流的卢汉流域，位于东北的布宜诺斯艾利斯省。湖沼的主要特点， 20条河流属于这一流域，其中包括研究，总结在表1 。所有的特点是高营养物质的浓度。拉斯弗洛雷斯流没有点源的投入，但其流域位于集约化畜牧和农业领域。样本，每月从1993年8月至1995年4月，在一个大型的立场是至少8岁。东密是一个'特征种'的立场意义布劳恩-布兰奎特（ Matteucci ＆ Colma ， 1982年） 。浮萍gibba属，金鱼藻，荽ranunculoides研究，并风水田，水生植物研究也出席了会议。植物的数量为5个样品（学生t -检验，对数据的归体育密生物质在拉斯弗洛雷斯流，利用TRANSNOR计划） 。样本与四〇 〇平方厘米平方米范围内。所有植物物种在样方收获完全。样方被随机分布在东密的立场。草食动物（蜗牛属瓶） ，也和他们的存在采样记录。植物材料进行了审查，以评估所产生的任何损害虫食。在每个取样点测定：深入，目前的速度（以螺旋桨流量计） ，电导率， pH值，温度（与迈克鲁夫曼文书） 。在三个样本的网站，一个直径5厘米的核心是泥沙与聚氯乙烯缸，以确定养分含量。在取芯管被推到凝灰岩层，形成了底层流。三份水样的采取了上述植物的立场，以确定溶解氧和营养物质的浓度。氧样本固定立即。营养样本过滤瓦特曼石墨/碳薄膜（ 0.6-0.7米孔径） 。样品被送到实验室在一个小时内。 macrophytic材料的清洗，整理的物种和干果105 C至恒重，以确定生物量（ Wetzel ＆比喻， 1991年） 。总磷（普瑞尔） （ AOAC ， 1984年） ，和总氮（田纳西州） （半微量凯氏法; AOAC ， 1984年;粮农组织， 1986年）在大肠杆菌中密决心，一式三份。心尖芽大肠杆菌密被刷和冲洗过滤溪水与删除periphyton 。心尖芽干105 ç直至恒重，并权衡。 Periphyton样品进行了真空过滤瓦特曼石墨/碳薄膜。叶绿素估计根据洛伦岑（见Wetzel ＆比喻， 1991年） 。沉积物被冻结在-20 ° C时，将上3厘米，和TP （安达信， 1976年）和TN （ AOAC ， 1984年;粮农组织， 1986年）确定的每个核心，一式三份。分析了水在24小时内的采样。溶解氧浓度估计，温克勒法（ APHA ， 1992年） 。可溶性活性磷（的SRP ） ，硝酸盐和亚硝酸盐含量据APHA （ 1992年） 。