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151.
Dinh TD Moreau J Van MV Phuong NT Toan VT 《Pakistan journal of biological sciences: PJBS》2010,13(14):683-690
The population dynamics of eight commercial species of shrimp (Haliporoides sibogae, Harpiosquilla harpax, Metapenaeus affinis, Metapenaeus brevicornis, Metapenaeus tenuipes, Parapenaeopsis cultrirostris, Parapenaeopsis gracillima and Parapenaeus maxilipedo) distributed in littoral marine zone of the Mekong Delta were investigated. Length-based stock assessment using FiSAT II software package was used to assess the growth and mortality parameters: Asymptotic size (L8), growth coefficient (K), total (Z) and natural (M) mortality, exploitation rate (E), recruitment pattern, current probability of capture and selectivity of fishing gears. Yield-per-recruit analyses were carried out showing different levels of the exploitation. Results showed that the maximum sustainable yield would be reached for an exploitation rate higher than the current one for each population. However, the size of first capture should be increased for every population. The findings indicated that the current exploitations of shrimp populations distributed in littoral marine zone of the Mekong Delta are under exploitation level for maximum sustainable yield; however, all the shrimp populations are subject to growth over-exploitation. 相似文献
152.
153.
Edyta Łokas Przemyslaw Wachniew Dariusz Ciszewski Piotr Owczarek Nguyen Dinh Chau 《Water, air, and soil pollution》2010,207(1-4):57-71
This study focuses on the distribution of selected trace metals, 137Cs and 210Pb, in floodplain deposits of the lowland Warta River (southern Poland) downstream of Cz?stochowa, a large city with an iron smelter. The depth profiles of trace metal (Zn, Pb, Cu, Ni, Cd and Mn), 210Pb and 137Cs contents in floodplain sediments were used to derive deposition rates on the floodplain for the twentieth century. The applicability of particular chronometric tools is considered within the context of their mutual relationships and confirmed by the consistency of the results. Deposition rate estimates for the past 50 years based on the vertical patterns of trace metal concentrations, which were correlated with particular events in the development of the smelter, range from 0.4 cm·year?1 in profiles situated in backswamps far from the channel to over 1.1 cm·year?1 in profiles of the natural levee adjacent to the river. Deposition rates based on 210Pb inventories in the profiles range from 0.08 to 0.66 g·cm?2·year?1, which corresponds to linear sedimentation rates of 0.10 to 0.91 cm·year?1, respectively. Dating of characteristic levels associated with peak fallout of 137Cs gives sediment accretion rates resembling those obtained from trace metals and 210Pb. The period of the highest sediment accumulation rate could be related to the highest loads of effluent from the iron smelter and city of Cz?stochowa, which were substantially reduced after the construction of effluent treatment plant. 相似文献
154.
Kien Chu Ngoc Noi Van Nguyen Bang Nguyen Dinh Son Le Thanh Sota Tanaka Yumei Kang Katsutoshi Sakurai Kōzō Iwasaki 《Water, air, and soil pollution》2009,197(1-4):75-89
This study assessed the arsenic and heavy metal contaminations of agricultural soils around the tin and tungsten mining areas in Dai Tu district in northern Vietnam. Among the examined elements, high total contents of As and Cu were found in the agricultural fields at both tin and tungsten mining sites. Although the major part of the accumulated As and Cu were bound by various soil constituents such as Fe and Mn oxides, organic matter, and clay minerals, increases in water soluble As and Cu were observed, especially for the paddy fields. The results suggest that, in the studied area, As and Cu dispersion from their pollution sources into farmlands is mainly via fluvial transportation of mine waste through streams that cross the paddy fields around the tin mining area, and soil erosion at the tea fields located at lower positions of the slope in the tungsten mining area. 相似文献
155.
Mai-Van?Dinh Alexander?GuhrEmail authorView authors OrcID profile Alfons?R.?Weig Egbert?Matzner 《Biology and Fertility of Soils》2018,54(6):761-768
Drying and rewetting (D/W) of soils often leads to a pulse of total dissolved phosphorus (TDP) by lysis of sensitive microorganisms. The relevance of D/W on the P cycle in ecosystems depends on the duration of the TDP release. In forest soils, the forest floor represents a hotspot of microbial activity and is often prone to D/W. Here, we investigated the dynamics of TDP, the microbial P pool (Pmic), and the composition of microbial communities after D/W. Samples were taken from Oi and Oe layers of a European beech and a Norway spruce site and desiccated up to ??100 MPa (pF 6) at 20 °C, while controls were kept moist. TDP and Pmic were measured 0, 1, 3, 7, and 14 days after rewetting and the composition of microbial communities was analyzed by automated ribosomal intergenic spacer analysis after 14 days. After D/W, the largest TDP net release (D/W-control) was from Oe layers with 40–50 mg P kg?1 and inorganic P as the dominant fraction. The TDP concentrations decreased strongly in Oi layers within 1 (beech) to 4 (spruce) days, while remaining stable in Oe layers. The TDP dynamics were linked to the decrease and recovery of Pmic after D/W. Pmic dynamics differed between layers and stand types, suggesting the influence of microbial communities with different D/W sensitivities. The composition of microbial communities varied strongly among sites and layers, while D/W only affected the composition of bacterial and fungal communities in the spruce Oe layer. D/W of forest floors increases the plant available P and affects the P cycle in forest ecosystems. 相似文献
156.
Effects of VC application on tomato production and media properties can last for the third successive season, which was verified in this study to evaluate effects of VC application on growth, productivity and fruit quality of cherry tomato for the third season. Six treatments were designed similarly in the first and second seasons (unchanged design compared to the previous season), including: VC with rice husk ash (RHS) and coconut fiber (CF) 0% VC+ 50% RHS +50% CF (T1- control), respectively. 20%VC + 40% RHS + 40% CF(T2), 40% VC+ 30% RHS + 30% CF(T3), 60% VC + 20% RHS + 20% CF(T4), 80% VC + 10% RHS + 10% CF(T5), and 100% VC(T6). The results showed that the pH, EC, N, P, K, Ca, and Mg available in media were increased with the addition of VC. This finding revealed that the addition of VC significantly improved the physic-chemical media properties, increasing the EC and also increasing the macronutrients in the media resulting in substantial increased the yield and quality of tomato fruits. It is concluded that EC of VC was the key factor for the positive increase of the productivity and quality of tomato and the salinity (EC at 3.52 dS/m) causing restriction of water to fruits that resulted in the increase of the total soluble solids in tomato fruit and without affecting yield reduction. 相似文献