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排序方式: 共有118条查询结果,搜索用时 19 毫秒
1.
1997-1999年夏天,对位于黄河下游的氯化物型盐碱地池塘底泥中的水溶性盐进行了分析。结果表明:底泥中的含盐量,SO^2-4,Ca^2 ,Mg^2 含量是随着塘龄的增加而升高,而其余离子基本不随塘龄的增加而变化。各离子的垂直分布为“泥-土”混合层的含量较低,“水-泥”交界层含量较高。  相似文献   
2.
滤食性贝类在对虾综合养殖生态系统中的作用   总被引:6,自引:0,他引:6  
就混养虾池中滤食性贝类如何影响虾池整个生态系统这个问题,综合了国内外这方面的文献,从滤食性贝类对混养虾池的水质、底质和其中的浮游植物、浮游动物的影响,以及混养对养殖效益的影响这几个方面作了探讨。  相似文献   
3.
于1992年4-10月在山东省青岛市黄岛前湾育苗场和胶南市红石崖镇邵家村养殖场,采用载玻片挂片和对中国对虾现场取样的方法,研究中国对虾育苗池和养成池载玻片挂 表面和对体表微型污着生物群落的组成和发展。  相似文献   
4.
Submarine groundwater discharge (SGD) to coastal southern Rhode Island was estimated from measurements of the naturally-occurring radioisotopes 226Ra (t1/2 = 1600 y) and 228Ra (t1/2 = 5.75 y). Surface water and porewater samples were collected quarterly in Winnapaug, Quonochontaug, Ninigret, Green Hill, and Pt. Judith–Potter Ponds, as well as nearly monthly in the surface water of Rhode Island Sound, from January 2002 to August 2003; additional porewater samples were collected in August 2005. Surface water activities ranged from 12–83 dpm 100 L− 1 (60 dpm = 1 Bq) and 21–256 dpm 100 L− 1 for 226Ra and 228Ra, respectively. Porewater 226Ra activities ranged from 16–736 dpm 100 L− 1 (2002–2003) and 95–815 dpm 100 L− 1 (2005), while porewater 228Ra activities ranged from 23–1265 dpm 100 L− 1. Combining these data with a simple box model provided average 226Ra-based submarine groundwater fluxes ranging from 11–159 L m− 2 d− 1 and average 228Ra-derived fluxes of 15–259 L m− 2 d− 1. Seasonal changes in Ra-derived SGD were apparent in all ponds as well as between ponds, with SGD values of 30–472 L m− 2 d− 1 (Winnapaug Pond), 6–20 L m− 2 d− 1 (Quonochontaug Pond), 36–273 L m− 2 d− 1 (Ninigret Pond), 29–76 L m− 2 d− 1 (Green Hill Pond), and 19–83 L m− 2 d− 1 (Pt. Judith–Potter Pond). These Ra-derived fluxes are up to two orders of magnitude higher than results predicted by a numerical model of groundwater flow, estimates of aquifer recharge for the study period, and values published in previous Ra-based SGD studies in Rhode Island. This disparity may result from differences in the type of flow (recirculated seawater versus fresh groundwater) determined using each technique, as well as variability in porewater Ra activity.  相似文献   
5.
重盐碱地养殖池塘水化学特性的研究   总被引:2,自引:0,他引:2  
2007年6月~10月对位于黄河下游重盐碱地凡纳滨对虾养殖池塘的水化学特性进行了研究.结果表明:(1)该地区水体的水型主要表现为ClNaⅢ,总含盐量较高,平均(2143.77±859.18)mg/L,在阴离子中,氯离子含量最高,平均(944.07±477.57)mg/L.(2)pH值较高,各池塘平均值为8.79~9.15,在整个养殖周期中水体pH>8.5的比例占87.9%,pH>9的比例占47.0%.(3)总硬度较高,平均为(11.96±3.69)mmol/L,极值范围为7.05~22.4mmol/L,主要表现为镁硬度.(4)水体中营养元素氮的含量较高,活性磷的含量相对较低,而总磷含量较丰富,能够满足浮游植物生长的需求.  相似文献   
6.
Little information is available on denitrification potential of marsh soils in natural saline-alkaline wetlands. The denitrification potentials of an open wetland in the floodplain(Erbaifangzi wetland) and a closed wetland(Fulaowenpao wetland) in backwater areas in Jilin Province of Northeast China were monitored by an anaerobic incubation at 30℃ for 25 days. Our results showed that the relative denitrification index(RDI) increased gradually with incubation time, and showed a rapid increase in the first 5 days of incubation. The RDI values declined quickly from surface soils to subsurface soils and then kept a small change in deeper soils along soil profiles over the incubation time. Denitrification proceeded much faster in the top 20 cm soils of open wetland than in the closed wetland, whereas no significant differences in RDI values were observed in deeper soils between both wetlands. The RDIs were significantly negatively correlated with bulk density and sand content, while a significantly positive correlation with clay content, soil organic matter, total nitrogen and phosphorous. The maximum net NO–3-N loss through denitrification in 1 m depth were higher in the open wetland than the closed wetland with higher soil pH values. Future research should be focused on understanding the influencing mechanisms of soil alkalinity.  相似文献   
7.
正Salt desert,saline-alkaline dust storm and saline-alkaline mixed dust storm are significant but ignored problems for a long time.After many years of observations and researches,the author believes that salt desert,saline-alkaline dust  相似文献   
8.
海水养殖池海洋原甲藻水华前后水化条件的变化   总被引:2,自引:0,他引:2  
本文研究了海水养殖池塘实验围隔中海洋原甲藻水华暴发前、后水化条件的变化,得出了如下结果:海洋原甲藻水华一般多发生在连续晴朗的天气,而常在阴雨天气崩溃;从水化条件方面来说,该藻水华也常发生于NO3-N浓度以及N/P比较大时。在扁灌等绿藻类与海洋原甲藻交替成为优势种时,可以利用水体中Ch1。总量及Ch1.b、Ch1.c之间 的波动情况来反映该水华的发生与崩溃。  相似文献   
9.
对凡纳滨对虾高位养殖池水质环境状况进行了研究。结果表明,养殖期间虾池水体透明度前期较高,中后期较低;虾池pH变化在7.89~9.02之间,变化幅度较小。虾池水体悬浮物数量和CODMn随养殖时间延长而持续升高,变化范围分别为18.5~162.3 mg/L和3.52~14.58 mg/L。虾池水体中营养盐各月份波动较大,无机氮的数量变化在0.206~1.621 mg/L之间,含量逐渐升高,磷酸盐数量变化在0.009~0.067 mg/L之间,含量逐渐下降。水环境中N、P比较高,平均为62.7。养殖水体中后期处于严重富营养化状态。  相似文献   
10.
Abstracts Species abundance and seasonal succession of copepods in saline-alkaline ponds were studied in Zhaodian Fish Farm, Gaoqing County, Shandong Province, from 5 April 1997 to 1 September 1998. The results indicated that in the conditions of salinity ranging from 1.36 to 20 g/L, total alkalinity changing from 2.4 to 7.2 mmol/L and pH 8-9, zooplankton in saline-alkaline ponds was composed of freshwater salt-tolerated species or halophile species, some of which are halobiont species and usually occurs in freshwater. In our study, copepods were predominant in many fish-culture ponds and all control ponds without fishes in spring, late autumn and early winter. Dominant species of copepods were Sinocalanus tenellus, Cyclops vicinus, Thermocyclops taihokuensis. The biomass of copepods in the control ponds without fishes was higher than that of the fish-culture ponds.  相似文献   
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