Seasonal Variability of Phytoplankton Community Structure in Relation to Different Nitrogen-Phosphorus Ratios in the Southern Coastal Waters of Zhejiang, China

With the rapid development of economy and increase of population in the drainage areas, the nutrient loading has increased dramatically in the Changjiang estuary and adjacent coastal waters. To properly assess the impact of nutrient enrichment on phytoplankton community, seasonal microcosm experiments were conducted during August 2010-July 2011 in the coastal waters of Zhejiang Province. The results of the present study indicated that the chl a concentration, cell abundance, diversity indices, species composition and community succession of the phytoplankton varied significantly with different N/P ratios and seasons. Higher growth was observed in the 64：1 （spring）, 32：1 （summer）, 16：1 （autumn） and 128：1,256：1 （winter） treatments, respectively. The values of Shannon-Wiener index （H） and Pielou evenness index （J） were lower in the 8：1 and 16：1 treatments in autumn test, while H value was higher in the 128：1 and 8：1 treatments in winter test. A definite community succession order from diatoms to dinoflagel lares was observed in the autumn and winter tests, while the diatoms dominated the community throughout the culture in the spring and summer tests.

Response of Soybean and Lentil to a Seed-Row Placed Starter Nitrogen-Phosphorus Fertilizer Blend in a Brown Chernozem in South-Central Saskatchewan

Soybean and lentil are important legume crops in southern Saskatchewan (SK) that can supply the majority of their nitrogen (N) requirement through biological N fixation (BNF). However, the onset of BNF can be slow in cold;dry prairie soils and a small amount of seed-row placed fertilizer containing both N and phosphorus (P) may benefit the crop. Nevertheless, high rates of fertilizer in close proximity to the seed can also cause injury. This study was conducted to determine the response of lentil and soybean to a starter N-P fertilizer blend applied in the seed-row. A farm field located at the boundary of the Brown and Dark Brown soil zones in south-central Saskatchewan was selected to evaluate the effect of seed-row placed N-P fertilizer blend: 50% Urea + 50% mono-ammonium phosphate (MAP) applied at 0, 10, 20 and 30 kg N and P2O5 ha-1 on emergence, yield, and nutrient uptake. The proportion of nitrogen derived from fixation (ndff) was determined in the soybean using N-15 dilution technique. The rate of 10 kg N and P2O5 ha-1 was found to be the rate that did not significantly reduce emergence, stand count or proportion of N derived from fixation, and was sufficient to maximize yield, N and P uptake for both soybean and lentil under field conditions. Rates higher than 10 kg N ha-1 in the seed row as starter 28-26-0 blend reduced emergence and decreased the proportion of ndff.

Responses of Dodonaea viscosa growth and soil biological properties to nitrogen and phosphorus additions in Yuanmou dry-hot valley

Nitrogen(N) and phosphorus(P) are limited nutrients in terrestrial ecosystems, and their limitation patterns are being changed by the increase in N deposition. However, little information concerns the plant growth and the soil biological responses to N and P additions among different soils simultaneously, and these responses may contribute to understand plant-soil interaction and predict plant performance under global change. Thus, this study aimed to explore how N and P limitation changes in different soil types, and reveal the relationship between plant and soil biological responses to nutrient additions. We planted Dodonaea viscosa, a globally distributed species in three soil types(Lixisols, Regosols and Luvisols) in Yuanmou dry-hot valley in Southwest China and fertilized them factorially with N and P. The growth and biomass characters of D. viscosa, soil organic matter, available N, P contents and soil carbon(C), N, P-related enzyme activities were quantified. N addition promoted the growth and leaf N concentration of D. viscosa in Lixisols; N limitation in Lixisols was demonstrated by lower soil available N with higher urease activity. P addition promoted the growth and leaf P concentration of D. viscosa in Luvisols; severe P limitation in Luvisols was demonstrated by a higher soil available N: P ratio with higher phosphatase activity. Urease activity was negatively correlated with soil available N in Nlimited Lixisols, and phosphatase activity was negatively correlated with soil available P in P-limited Luvisols. Besides, the aboveground biomass and leaf N concentration of D. viscosa were positively correlated with soil available N in Lixisols, but the aboveground biomass was negatively correlated with soil available P. Our results show similar nutrient limitation patterns between plant and soil microorganism in the condition of enough C, and the nutrient limitations differ across soil types. With the continued N deposition, N limitation of the Lixisols in dry hot valleys is expected to be alleviated, while P limitation of the Luvisols in the mountaintop may be worse in the future, which should be considered when restoring vegetation.

A Novel Analytical Method of 1‑(3‑Trifluoromethylphenyl)piperazine and 1‑(3‑Chlorophenyl)piperazine in Fluids of Drug Addicts Using Liquid‑liquid Extraction–gas Chromatographic/Nitrogen–phosphorous Detection

In accordance with the research specifications and guidelines in China,we developed a novel experimental method to detect new piperazine‑type drugs,such as 1‑(3‑trifluoromethylphenyl)piperazine and 1‑(3‑chlorophenyl)piperazine.In this study,a new pretreatment method and gas chromatography(GC)/nitrogen–phosphorus detector detection technique were used to characterize these two kinds of drugs in urine and blood samples.For the purpose of isolation of these trace drugs from the samples,liquid‑liquid extraction/solid‑phase extraction was modified and validated for this specific study.The pretreatment method presented in this paper has many advantages,such as high recovery rate,high extraction efficiency,high detection sensitivity,low limit of detection,and simple operation.The GC/NPD instrument is popular in most laboratories because it can meet the routine requirements of forensic science.All these aspects make this combination of sample pretreatment and GC/NPD technique the most suitable choice for drug detection in biological samples.