Monitoring and modelling total phosphorus contributions to a freshwater lake with cage‐aquaculture

A mass‐balance modelling approach combined with a sensitivity analysis was utilized to gain an improved understanding of the relative contributions of phosphorus (P) loading from various anthropogenic and non‐anthropogenic sources into Lake Wolsey (Manitoulin Island, Ontario, Canada), a Type 2 freshwater lake with a cage‐aquaculture facility. Total P loadings were estimated from eight sources (inlet exchange, non‐point sources, cage‐aquaculture facility, internal loading, groundwater seepage, atmospheric deposition, leaf litter and dwellings) and three sinks (outlet exchange, sedimentation and sportfishing). Results indicated that over the study period (May–November 2007) the non‐point sources were the leading contributor of total P to Lake Wolsey (1120 kg P) followed by the cage‐aquaculture facility loading (915 kg P), inlet exchange (539 kg P), groundwater inputs (305 kg P), dwellings (219 kg P), internal P recycling loads from the hypoxic hypolimnion (186 kg P), atmospheric deposition (79 kg P) and decomposing leaf litter (8.1 kg P). When comparing the loadings in this study, the sensitivity analysis showed that non‐point sources were the only significant input parameter of total P loading to the in‐lake concentrations of P in Lake Wolsey(P = 0.05). Information from this project will provide water quality managers with sound scientific information to make defencible decisions pertaining to policy and regulatory approaches for water quality risk assessment and management of cage‐aquaculture in Type 2 sites.     

绍兴市凡纳滨对虾围垦滩涂养殖池塘的理化环境和浮游植物

2016年和2017年分别调查了位于浙江省绍兴市滨海新区的12口凡纳滨对虾围垦滩涂养殖池塘内的理化环境和浮游植物。结果显示:池塘内盐度变化范围为0~2,溶氧为6.2~13.9 mg/L,pH为7.5~9.8,总氨氮(TAN)为0.00~0.72 mg/L,亚硝酸盐氮(NO_2~--N)为0.00~1.70 mg/L,硝酸盐氮(NO_3~--N)为0.18~4.77 mg/L,总氮为1.74~6.08 mg/L,总磷为0.20~2.72 mg/L,总有机碳为1.88~42.57 mg/L,C/N为10~39。池塘内浮游植物种类隶属6门、24科、42属,其中蓝藻和绿藻为优势种。浮游植物生物量为(0.15~2.30)×107cell/L,叶绿素a(Chl.a)为2.62~37.24μg/L。Chl.a与蓝藻生物量显著正相关。NO_2~--N和NO3--N均与pH显著负相关。初步分析认为高pH可能是导致2016年池塘养殖凡纳滨对虾死亡率较高的重要原因,因此采取措施控制蓝藻生物量和水体的p H应有助于提高对虾养殖的存活率。     

Effects of dietary phosphorus level on non-faecal phosphorus excretion from yellowtail (Seriola quinqueradiata Temminck & Schlegel) fed purified and practical diets

Non-faecal phosphorus (P) was determined for large yellowtail to estimate a minimum available P requirement (Experiment  1) and to justify inorganic P supplementation in a fish meal-based diet (Experiment 2). In Experiment 1, purified diets with incremental P concentrations were fed to yellowtail (mean weight 917 g) at a feeding rate of 1.5% of body weight. The peaks of non-faecal P excretion appeared 5–6 h after feeding in fish fed more than 4.5 g available P kg⁻¹ dry diet. Broken-line analysis indicated that the minimum available P requirement was 4.4 g kg⁻¹ dry diet. In Experiment 2, a purified diet (PR) containing 6.5 g available P kg⁻¹ and a fish meal-based diet with (F1) and without (F0) additional phosphorus were fed to yellowtail (mean weight 1.1 kg) at 1.5% (PR) and 2% (F0 and F1) feeding rates respectively. There was no significant difference in P excretion between fish fed the F0 (5.5 g soluble P kg⁻¹ dry diet) and the PR diet. However, significantly higher (34.5%) amounts of non-faecal P excretions (7.4 g soluble P kg⁻¹ dry diet) were found in fish fed F1 compared with the F0 diet. This suggested that there was an excess of dietary P in the F1 diet and that supplementation is not needed in fish meal-based diets for large yellowtail.     

翅碱蓬生态化学计量内稳性对模拟氮磷沉降的响应

生物有机体元素组成内稳性是生态化学计量学核心概念之一,研究植物N、P生态化学计量内稳性及N、P分配可以明确其生态策略和适应性、竞争性。采用室内盆栽方法,研究了翅碱蓬(Suaeda heteroptera)N、P内稳性与生长对模拟N、P沉降增加的响应。结果表明,N沉降增加情况下,翅碱蓬吸收积累N表现为"绝对"的生态化学计量内稳性;P沉降增加情况下,翅碱蓬吸收积累P呈现一定的生态化学内稳性,调节系数HP为0.754,HN∶P为0.792。N沉降增加促进了翅碱蓬积累P,翅碱蓬生长可能受N限制。N、P沉降增加情况下,翅碱蓬株重、P吸收积累量与株高间均表现为异速生长。N沉降增加,翅碱蓬株重生长比株高快,P积累相对减慢。P沉降增加,翅碱蓬株高生长比株重快,P积累也相对更快。     

全站仪中间法高程测量及其精度探讨

通过对全站仪中间法高程测量方法的研究,推导了全站仪中间法高程测量的公式,并运用误差传播定律得出高程测量精度公式,分析并计算了各因素对高程测量精度的影响．通过实验验证,认为在一定范围内全站仪代替水准仪进行高程测量可达到三、四等水准测量的要求,并提出提高高程测量精度的几点建议．     

Biochar reduces uptake and accumulation of polycyclic aromatic hydrocarbons (PAHs) in winter wheat on a PAH-contaminated soil

For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar,and maize straw biochar(MSB) for an entire gro...     

Phosphorus‐enriched soils of urban and suburban Nanjing and their effect on groundwater phosphorus

Neither the phosphorus (P)‐rich soils in urban areas nor their environmental implications have been adequately studied. This study investigated soils of typical urban function zones in Nanjing/China, like park, residential areas, school yards, campus as well as suburb vegetable land and garbage filling sites, and meantime ground water in situ. Typical soils were also experimentally leached for P leaching evaluation. All studied soils were enriched with P with enrichment ratios varying from 2 to 10 for total P and 5 to 22 for NaHCO₃‐extractable P, as compared with the original parent soils. The C : P ratios also indicated strong enrichment of P in urban soils. In urban areas the maximum P layer appeared as buried under different depth while in suburban soils as epipedon. The various morphology of P distribution suggested different soil formation patterns, which were related to the land use history. Groundwater P was significantly correlated with the maximum extractable P content of P in soil profiles and even better with the weighted average P content of the whole profile or P content of the soil layer at or close to groundwater table. Dissolved P in experimental leachate was comparable with that of groundwater but higher than environmentally acceptable level. Furthermore, there was a significant correlation between solution P and different extractable P forms of the studied soils. Simple P tests can provide an evaluation of the potential risk of urban soils in discharging P to water system.     

Interactions between phosphorus availability and microbes in a wheat–maize double cropping system: A reduced fertilization scheme

Mechanisms controlling phosphorus (P) availability and the roles of microorganisms in the efficient utilization of soil P in the wheat–maize double cropping system are poorly understood.  In the present study, we conducted a pot experiment for four consecutive wheat–maize seasons (2016–2018) using calcareous soils with high (30.36 mg kg^–1) and low (9.78 mg kg^–1) initial Olsen-P content to evaluate the effects of conventional P fertilizer application to both wheat and maize (Pwm) along with a reduced P fertilizer application only to wheat (Pw).  The microbial community structure along with soil P availability parameters and crop yield were determined.  The results showed that the Pw treatment reduces the annual P input by 33.3% without affecting the total yield for at least two consecutive years as compared with the Pwm treatment in the high Olsen-P soil.  Soil water-soluble P concentrations in the Pw treatment were similar to those in the Pwm treatment at the 12-leaf collar stage when maize requires the most P.  Furthermore, the soil P content significantly affected soil microbial communities, especially fungal communities.  Meanwhile, the relative abundances of Proteobacteria and alkaline phosphatase (ALP) activity of Pw were significantly higher (by 11.4 and 13.3%) than those of Pwm in soil with high Olsen-P.  The microfloral contribution to yield was greater than that of soil P content in soil with high Olsen-P.  Relative abundances of Bacillus and Rhizobium were enriched in the Pw treatment compared with the Pwm treatment.  Bacillus showed a significant positive correlation with acid phosphatase (ACP) activity, and Rhizobium displayed significant positive correlations with ACP and ALP in soil with high Olsen-P, which may enhance P availability.  Our findings suggested that the application of P fertilization only to wheat is practical in high P soils to ensure optimal production in the wheat and maize double cropping system and that the soil P availability and microbial community may collaborate to maintain optimal yield in a wheat–maize double cropping system.     

不同施硼量对油菜叶片中不同形态硼含量的影响

采用盆栽试验研究了不同施硼量对不同生育期不同部位叶片中水溶性硼和全硼含量的影响,并对以水溶性硼代替全硼作为植株营养诊断的方法进行了初步探讨。当施硼量达到5 1kg/hm2,油菜苗期、抽薹期的生物产量以及子粒产量均下降,但叶片中的全硼和水溶性硼含量仍随施硼量的增加而增加。不同生育期和不同部位叶片的全硼含量虽然与施硼量有较好的相关性,但是不同处理之间的差异,特别是过量差异过小,很难用于营养诊断。水溶性硼含量与施硼量也有较好的相关性,而且苗期未完全展开叶片和完全展开叶片的水溶性硼含量可以较敏感地反应油菜的硼营养差异,因此,可以用作硼的营养诊断方法,但是水溶性硼的诊断临界指标需要进一步的研究。     

朱砂七总蒽醌研究概况

朱砂七是蓼科蓼属植物毛脉蓼的干燥块根,为"太白七药"之一.朱砂七所含化学成分主要包括蒽醌类、二苯乙烯类、鞣质、多糖等,蒽醌类为其主要成分之一.近年来,国内外许多研究已经证实朱砂七总蒽醌在抗肿瘤、抗菌、抗病毒、抗炎等方面作用显著,因其副作用低,而具有很好的开发及应用前景.论文简要概述朱砂七总蒽醌的化学组成、提取方法及相关...