Spatial and temporal variation of H and O isotopic compositions of the Xijiang River system, Southwest China

<p>Ratios of stable isotopes of hydrogen and oxygen (²H/¹H and ¹⁸O/¹⁶O) in river waters were measured to investigate the hydrological pathway of the Xijiang River, Southwest China. The <i>δ</i>²H and <i>δ</i>¹⁸O values of river waters exhibit significant spatial and temporal variations and the isotopic compositions vary with elevation, temperature and precipitation of the recharge area. Spatially, <i>δ</i>¹⁸O values of river waters from high mountain areas are lower than those from the lower reaches of the Xijiang River due to lower temperature and higher elevation for the recharge area. However, both ²H and ¹⁸O are enriched differently in river waters from the middle reaches during the high flow season, depending on the season and degree of anthropogenic disturbances (e.g. water impoundments). In contrast, deuterium excess (<i>d</i>-excess) values of waters from the middle reaches are substantially lower than those from the upper and lower reaches, suggesting that river waters may be resided in the reservoir and evaporation increases in the middle reaches of the Xijiang River.</p

(a) Branching length distribution and (b) the corresponding weighted cumulative distribution <i>F</i>(<i>l</i>).

<p>The different graphs depict (i) the same region on different observation days, (ii) the different regions on the same observation day, (iii) the distributions of different regions on observation days selected to have the same hyphal age.</p

Branching length distributions at different hyphal ages and their fitted curves.

<p>(a) 8-day-old (experimental data from R2 on the 10th day and R3 on the 12th day); (b) 10-day-old (experimental data from R1 on the 10th day, R2 on the 12th day and R3 on the 14th day); (c) 12-day-old (experimental data from R1 on the 12th day and R2 on the 14th day).</p

Average tip extension rate obtained using Eq (2) and relative increase of branch number per hypha during two consecutive observations.

<p>Average tip extension rate obtained using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0162469#pone.0162469.e002" target="_blank">Eq (2)</a> and relative increase of branch number per hypha during two consecutive observations.</p

Description and values of the identified parameters to be applied in the simulation of the mycelial growth.

<p>Description and values of the identified parameters to be applied in the simulation of the mycelial growth.</p

Distribution of branch angle measured in the observation on the 12th day.

<p>(a) AB angles and LB angles in three regions; (b) two types of branch angles respectively in R1, R2 and R3; (c) two types of branch angles in three regions and fitted curve. The similar branch angle distributions were observed in each of the different regions and they follow a Gaussian distribution.</p

Spatial distribution of tip extension rate (<i>R</i>_<i>tip</i>(<i>i</i>; <i>x</i>, <i>y</i>)) during 17 days of observations.

<p>(<i>x</i>, <i>y</i>) are the coordinates of the position of tip <i>i</i>. The colors display the different ranges of rate: from green, less than 25 <i>μm</i>/<i>h</i>, to orange for the > 25 <i>μm</i>/<i>h</i>. Grey points represent dormant tips.</p

Method of the measurement of branching characteristics.

<p>(a) Three regions with equal gap to partition the young and old hyphae: (i) R1, (ii) R2 and (iii) R3, covering almost the entire colony on the 5th, 7th and 10th day following inoculation. (b) (i) Four portions selected for the measurement in each of the three regions (e.g., P1.1, P1.2, P1.3 and P1.4 in R1). (ii) Zoom of a color projection for measurement to show a cross of two hyphae with two types of branch sites and branch angles (AB angle (<i>θ</i>_<i>bra</i>) and LB angle (<i>θ</i>_<i>brl</i>)). The color bar shows the depth of the mycelium along the z-axis. (iii) Errors between real values and projective ones caused by z-direction growth of hyphae: (left) real branch angle (<i>θ</i>_<i>r</i>), projective branch angle (<i>θ</i>_<i>p</i>), and angle of the real hypha to the xy plan (<i>θ</i>_<i>z</i>); (right) real branch length (<i>l</i>_<i>r</i>) and projective branch length (<i>l</i>_<i>p</i>).</p

Age of region for R1, R2 and R3.

<p>(a) Biomass growth measured throughout the 4 portions of R1, R2 and R3 as a function of days after inoculation (the inset graph shows the three curves translated by Δ<i>x</i>). (b) The starting time of growth for R1, R2 and R3 is the inoculation day, the second day and the fourth day. The age axis is related with time axis to determine the age of each region on different observation days (E.g. the age of R1 on the 12th day is 12 days old but 10 and 8 days old for R2 and R3; the R1, R2 and R3 are 10 days old respectively after 10 days, 12 days and 14 days.) The age of region represented approximately the age of the oldest hyphae in that region.</p

Distribution of the extension rate (<i>R</i>_<i>tip</i>(<i>i</i>; <i>x</i>, <i>y</i>)) of active tips calculated during two consecutive observations.

<p>Different observations are displayed from the 4th to 17th day post inoculation.</p